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iii
Strategies for Arresting Land Degradation
in
South Asian Countries
Editors
Dr. Dipak Sarkar
Director, NBSS & LUP (ICAR)
Dr. Abul Kalam Azad
Director, SAC
Dr. S.K. Singh
Principal Scientist, NBSS & LUP (ICAR)
Nasrin Akter
Senior Program Officer (Crops), SAC
SAARC Agriculture Centre
iv
v
Content
Page
Preface
Part-I
vii
Keynote paper
1-31
Introduction, Extent and severity of degradation, Driving
energy for land degradation, Impact of inappropriate land
use and management, Techniques for restricting/preventing
land degradation, Estimating extent and severity of land
degradation, Diversification of agriculture, Conservation
agriculture, Gene mining for drought avoidance, Inclusion
of legumes in crop calendar, Legume based forage
production, Silvipasture and silviculture based agriculture,
Agro-forestry, Strategies for arresting land degradation
Part-II
Country paper from Bangladesh
33-56
1. Introduction 2. Land degradation: Situation in South Asia
3. Factors affecting Land Degradation 4. Impacts of Land
Degradation 5. Major types of land degradation in
Bangladesh 6. Levels of Land Degradation 7. Climate
Change induced Land Degradation 8. Minimizing Land
Degradation 9. Land Resources Conservation Strategy
10. Combating Land Degradation and Appropriate Cropping
11. Conclusion
Part-III
Country paper from Bhutan
57-73
1. Introduction 2. Land degradation - a global issue 3. Land
degradation in Bhutan - a natural and man-made process
4. Status of land degradation 5. Types of land degradation
6. Factors contributing to land degradation 7. Current
Strategies to address land degradation 8. Conclusion
Part-IV
Country paper from India
75-132
1. Introduction 2. Unculturable Wastelands 3. Causes
4. Impacts of Land Degradation 5. Soil Physical Constraints
6. Strategies for Arresting Land Degradation
Part-V
Country paper from Nepal
1. Introduction 2. Land Degradation 3. Causes of Land
Degradation in Nepal 4. Types of Land Degradation and Its
Extent 5. Status of Land Degradation in Nepal 6. Impact of
Land Degradation in Nepal 7. Government Policy,
Strategies
and
Programs
8.
Conclusion
and
Recommendations
vi
133-149
Part-VI
Country paper from Sri Lanka
151-170
1. Abstract 2. Introduction 3. Severity of Land Degradation
in Sri Lanka 4. The Policy Issues 5. Arresting Land
Degradation: Some Recommendations
Part-VII
Special papers from India
• Acid Soil Management
Opportunities
Part-VIII
171
and
172
• Issues and Strategies for Managing Degraded Lands in
Rainfed Ecosystem in India
191
• Land Degradation due to Selenium: Causes, Implications
and Management
208
Appendices
233
in
India-Challenges
Appendix-A
:
Concept note prepared by SAARC
Agriculture Centre
234
Appendix-B
:
Recommendations of the regional
consultation
243
Appendix-C
:
Programme
247
Appendix-D
:
List of participants of the regional
consultation
253
Appendix-E
:
Consultation Photo Album
257
vii
Preface
Land degradation is a concept in which the value of bio-physical environment is
adversely affected. Deforestation, nutrients depletion, overgrazing, irrigation and over
drafting, urban sprawl and commercial development, land pollution are the causes of
degradation. Land vulnerable to degradation was estimated to 81, 63, 53, 39.21 and
2.99% in India, Bangladesh, Sri Lanka, Pakistan, Nepal and Bhutan, respectively. About
eighty three million hectare is affected by water erosion in the South Asian region or 25%
of the total area under crops and pasture. The most affected areas are the populated
mountain regions of Himalaya, Deccan region of India (Western Ghats) and Sri Lanka. A
part from this a total of 59 million hectare is affected by wind erosion, lying entirely in
the arid zone. Wind erosion affects 42% area in Pakistan, whilst the dry region of India
has the same total area affected as Pakistan (11 million hectare).
Salinity/ sodicity and waterlogging are the other major concern of land degradation in the
irrigated command areas and in the coastal regions. In India, Bangladesh and Pakistan
together have 14.23 million hectare salt affected area. This also includes dry and subhumid coastal strip. The sizeable area affected with lower pH and aluminum toxicity
which is other form of degradation, are also reported from India, Bangladesh and Sri
Lanka.
Loss of nutrient and /or organic matter depletion is another form of degradation. It is
estimated that about 65% of agriculture land in Bangladesh and 61% in Sri Lanka
affected by this type of degradation. In Bangladesh, the average organic matter is said to
have declined in 50% area by 2 to 1% over the past twenty years. For the Indian State of
Haryana, soil test reports over 15 years show a decrease in soil carbon. Negative soil
nutrient balances have been reported for all three major nutrients in Bangladesh and
Nepal; for phosphorus and potassium in Sri Lanka and a large deficit for potassium in
Pakistan. Nutrient depletion has been reported for each of the 15 agro-climatic regions of
India.
Imbalance fertilization is one of the dominant causes of nutrient depletion in the region.
Fertilization use in the region is dominated by nitrogen; N: P and N: K ratios are higher
than the other parts of the world. For example, the N: P: K ratio for India is
1.00:0.33:0.17 compared with 1.00; 0.52:0.40 for the world. This trend obtained in early
years of green revolution. In such system nitrogen is simply used as shovel to mine the
soil for other nutrients. Long-term experiments in India show depletion of soil P and K
are higher for plots with N fertilizer, and depletion of K still higher with N+P fertilizers.
Increasing incidence of sulphur and zinc deficiency has been reported in the region. In
Bangladesh, 3.9 million hectare is reported deficient in sulphur and 1.75 million hectare
in zinc, including areas of continuous swamp rice cultivation. This happened because
increase in fertilizer nutrient has not been equaled by the rates of yield increase for wheat,
rice and sugarcane.
Considering the importance and urgency related to land degradation the present
publication on “Strategies for arresting land degradation in the South Asian Countries”
would help to (a) formulate policy issue (b) draw strategies (c) undertake joint project
viii
and also national programmes to address the issue of major concerns collectively (d) find
out the measures to minimize the impact of land degradation on the millions of affected
people in the SAARC regions. The publication helps in developing strategies for
arresting land degradation, reversing the adverse effects of land degradation on land
productivity without risk of further degradation. The beneficiaries will be policy makers
in the Governments of SAARC countries, agriculture and social scientists,
environmentalists, NGO, donor agencies and ultimately the farmers. I acknowledge the
sincere efforts of my colleagues and the distinguished contributing authors from different
member SAARC countries for completing this daunting task. My compliments to the
members of editorial committee for editing the book and bring it in the present status.
SAC always appreciates receiving feedback, comments and suggestions from the users of
our products and services to help us enable to do better.
Dr. Abul Kalam Azad
Director
SAARC Agriculture Centre (SAC)
ix
2
Strategies for Arresting Land Degradation in South Asian Countries
Strategies for Arresting Land Degradation
in South Asian Countries
Abstract
Land degradation, synonymous to desertification in arid, semi arid and sub-humid
region, covers the processes adversely affecting productive capacity of land under
different land use systems. Present paper reports the extent, type and severity of land
degradation in south Asian countries. Impact of land degradation contributing factors
including population and poverty, climate change and natural hazards, agriculture
globalization, overgrazing and livestock, summer fallowing and inappropriate land use
management are discussed. Emerging human induced degradation types such as
acidification, nutrient and organic carbon depletion, salinity and sodicity, surface
truncation and sub-soils densification are highlighted. Influence of technologies including
alternate land use, integrated nutrients and water managements for smothering/arresting
land degradation are discussed. Reasons for failure of various technologies in arresting
land degradation are elaborated. A conceptual model is suggested to develop strategies
for combating land degradation. Essence of the model is the selection of right cultivar
and appropriate technologies at the right place. Model is based on GIS database and three
expert systems. Database has four modules. First module is polygon based; second
module contains point information; third and fourth modules are designed for raster and
non-spatial database, respectively. Expert system I delineates management unit at an
appropriate scale based on soils, climate and irrigation potentials. The scale may be
watershed, district, state or regions. Expert system II identifies land uses and
management practices by utilizing the database on socio-economic conditions, land use
requirement, available technologies, market trends and demands. Expert system III
optimizes the different land use systems for each management unit by using scenario
analysis and projections. After validating and refining land use and management, same
may be up-scaled, using appropriate algorithms for the use at district, state or regional
level planning. The entire process is elaborated in the text by giving suitable examples.
Introduction
Land degradation is a concept and signifies the temporary or permanent decline in the
productive capacity of the land under rain-fed, arable, irrigated, rangeland and forest
system of land use or in farming systems (e.g. smallholder subsistence). It is synonymous
to desertification in arid, semi arid and humid regions and covers the processes which
affect the productivity capacity of cropland, rangeland and forests, such as lowering of
water table and deforestation. Four set of indicators viz. pressure (driving energy for
degradation such as climate, population, socioeconomic, water resources and long-term
management practices), state (characterize the state of land resources in terms of wind
and water erosion, vegetation degradation, salinization, sodification and water logging),
impact (measured by change in land use, land use pattern, socioeconomic, food security,
health, infrastructure, air and water quality and land pollution) and implementation (used
for studying the influence of management for combating desertification such as
Strategies for Arresting Land Degradation in South Asian Countries
3
socioeconomic standard of the people and improvement in the soil and environmental
quality) indicators explain the type and severity of degradation in totality (TPN 2001).
Soil is very important state indicator. It integrates a variety of important processes
involving vegetation growth, overland flow of water, infiltration, land use and
management. Therefore, soil erosion and soil fertility decline including reduction in soil
organic carbon, deterioration of physical properties, change in soil nutrient stock and
build up of toxic substances are considered as the state indicator. Water logging, salinity
and sodicity, acidity, soil pollution, loss of vegetation, sedimentation or burial of soils
and exposure of stoniness/rockiness are the other state indicators of degradation.
South Asian countries with 4.13 million km2 area, covering mountainous belt of
Himalaya, alluvial land of Indus and Ganges and uplands of Deccans in India suffer from
various kind of degradation. Recent estimates indicated that 42 % of its land is affected
with various kind of degradation. Fifty percent area of the dry lands faces the threat of
desertification. As many as 63 million hectares of rainfed cropland and 16 million
hectares of irrigated land have been lost due to desertification, especially in Pakistan and
India. Loss accrued on account of desertification is equivalent to seven percent of the
regions combined agricultural gross domestic product.
Agriculture scenario in south Asian countries is characterized by small holdings, too
many people on too little land, production largely for subsistence, high rate of tenancy
and pre-modern technologies. Rice is the staple food crops generally grown under wet
conditions. Forest cover ranges from 64 % in Bhutan to 3 % in Bangladesh and Pakistan.
Agriculture still contributes 20 % in GDP and supports 60 % of labour force.
Dependency of 90 % labour force on agriculture is reported in Nepal and Bhutan.
Productivity of most of the crops is either declined or stagnant in rice, rice-wheat,
highland mixed and rainfed mixed systems of farming prevailing in south Asian
countries. Further enhancement in productivity is very remote with the present set of
management inducing mass degradation of natural resources. Expected change in climate
is not encouraging for the agrarians. If the present situation continues, there may be the
shortage food for ever growing population in the region.
Therefore, managing degradation and increasing productivity per unit area are the
challenges for researchers, administrators, planners, extension workers and farmers. It
calls for very systematic studies involving causes of land degradation, its impact in terms
of extent and severity on natural resources, status of technologies for arresting/preventing
land degradation. Present paper highlights these issues in reference to south Asian
countries.
Extent and severity of degradation
It is estimated that nearly two billion (Table 1) hectare of soil resource in the world
have been degraded, approximately 22 % of the cropland, pasture, forest and woodlands.
Globally soil erosion, chemical deterioration and physical degradation are the important
parts amongst various land degradation types. Water erosion is the most important type of
soil degradation (55 %) followed by wind erosion (28 %), nutrient depletion (7%),
salinization (4%) and compaction (3%). In all countries water erosion is the most
4
Strategies for Arresting Land Degradation in South Asian Countries
dominant type of land degradation, except for West Asia and Africa, where water and
wind erosion have equal importance. In South America nutrient depletion was more
important than wind erosion. West Asian countries are severely affected with salinity and
compaction. In Europe about 19 million hectare land is affected by soil pollution
(Oldeman 1994).
Table 1: Global estimate of degradation
Type
Light
Moderate
Strong+ extreme
Total
Water erosion
3.43
5.27
2.24
10.94
Wind erosion
2.69
2.54
0.26
5.49
Chemical degradation
0.93
1.03
0.43
2.39
Physical degradation
0.44
0.27
0.12
0.83
Total
7.49
9.11
3.05
19.65
Source: Oldman (1994)
Land vulnerable to degradation was estimated to be 81, 63, 53, 39.21 and 2.99 % in
India, Bangladesh, Sri Lanka, Pakistan, Nepal and Bhutan, respectively (Table 2).
Table 2: Extent of land degradation vulnerability in SAARC Countries
Low
Moderate
High
Very high
Countries
(% of total geographical area)
Afghanistan
0.46
6.04
6.77
67.41
Bangladesh
63.30
0.0
0.0
0.0
Bhutan
2.99
0.0
0.0
0.0
India
42.96
25.03
6.94
5.58
Nepal
14.72
6.36
0.0
0.17
Pakistan
4.04
5.09
2.19
23.31
Sri Lanka
9.79
37.68
5.28
0.0
Source: UNEP (1994)
Accelerated water and wind erosion are the dominant manifestations of land
degradation. About eighty three million hectare is affected by water erosion in south
Asian region or 25 % of the total area under crops and pasture. This is made up of 33
million hectare with slight erosion, 36 million hectare moderate and 13 million hectare
strong erosion. The most affected areas are the populated mountain regions of Himalaya,
Deccan region of India (Western Ghats) and Sri Lanka. Hot spots vulnerable to
degradation screened from different sources are listed in table 3. Apart from this a total
of 59 million hectare is affected by wind erosion, lying entirely in the arid zone. Wind
Strategies for Arresting Land Degradation in South Asian Countries
5
erosion affects 42 % area in Pakistan, whilst the dry region of India has the same total
area affected as Pakistan (11 million hectare). The intensity of erosion is predominantly
moderate and about 48 % land in the arid region under crops and pasture is affected.
Table 3: Hotspots of land degradation in south Asian Countries
Degradation types
Hotspots
Nutrient depletion
Mid-altitude hills of Nepal, Northern India
Salinization
Indus river basin, Southern coast line of Sri Lanka
Water erosion
Foothills of the Himalayas; Riverbank erosion in the major
floodplains (Ganges, Brahmaputa, Jamuna , Tista and
Meghna rivers) of Bangladesh.
Wind erosion
Western Rajasthan, coastal regions of India and dry region of
Pakistan
Agro-chemical pollution
Pakistan (Heavy use of Agrochemicals)
Salinity/sodicity and water logging are the other major concern of land degradation in
the irrigated command areas and in the coastal regions. India, Bangladesh and Pakistan
together have 14.23 million hectare salt affected area. This also includes dry and sub
humid coastal strip. Lower pH and aluminum toxicity are also included under land
degradation. These are reported as sizeable in area from India, Bangladesh and Sri Lanka.
Loss of nutrient and /or organic matter depletion is another form of degradation. It is
estimated that about 65 % of agriculture land in Bangladesh and 61 % in Sri Lanka is
affected by this type of degradation. In Bangladesh, the average organic matter is said to
have declined in 50% area from 2 to 1% over the past twenty years. For the Indian State
of Haryana, soil test reports over 15 years show a decrease in soil organic carbon.
Negative soil nutrient balances have been reported for all three major nutrients in
Bangladesh and Nepal; for phosphorus and potassium in Sri Lanka and a large deficit for
potassium in Pakistan. Nutrient depletion has been reported for each of the 15 agroclimatic regions of India.
Desertification is the land degradation in the dry land of India and Pakistan. The
desert in the Western India is the biggest in the south Asian countries. The majority of the
area suffers from moisture stress, sand movement, high wind velocity and very limited
canopy cover. Since Thar Desert constitute the major part of the dry region of south
Asian countrie, therefore most of the examples in the present text are quoted from the
arid part of India.
Driving energy for land degradation
(A) Population and poverty
The region is home to 1.567 billion people (23.7 % of global population). Of the
world’s ten most populous countries, three are in south Asia; India, Pakistan, and
Bangladesh. South Asia has a population density of 15 people per hectare compared to
6
Strategies for Arresting Land Degradation in South Asian Countries
world average of 4 people per hectare. World population is expected to grow by some 3
billion people by 2050, and these three countries are expected to account for 30 % of this
growth (UNDP 2003).
The share of the region in global land and water resources is however much lower
than the population share e.g. regions geographic coverage is mere 3.95 % of global land
mass. Population pressure on land is very high because percentage of arable land to total
area is much higher than the global average. In a study on population supporting capacity
of soils in Central Arid Zone Research Institute (CAZRI), it was estimated that soils of
arid region can support 0.71, 1.15 and 1.5 person / hectare / year under low, medium and
high management, respectively. The region had supported 0.50 person /hectare /year in
the year 1971, which was escalated to 0.81 in 2001 under farmer’s management.
Presently in the year of estimation 2004, region supported 1.21 person / hectare / year,
and by the end of 2020 figure is expected to rise by 1.5 person /hectare / year. With
farmer’s management exploring beyond the capacity of resources triggers mass
degradation of natural resources (CAZRI 2004).
Low per capita Gross National Income (GNI) may also be related with the mass
degradation of natural resources. GNI in the eight member states ranged from £345 to
3,277; lowest per capita income is in Afghanistan while the highest is in Maldives. Per
capita income in India and Pakistan is around £1000. Low level of income is one of the
primary cause for non or partial adoption of green revolution technology as a package.
This together with increasing demography, climate change ultimately result into the
degradation of the natural resources. Poverty and dependency on agriculture for
livelihood in SAARC countries are given in table 4.
Table 4: Poverty and dependency on natural resources for livelihoods
Bangladesh Bhutan
HDI ranks (2001)
India
Maldives
Nepal Pakistan Sri Lanka
139
136
127
86
143
144
99
Human Poverty
index rank
72
-
53
20
70
65
34
Population below
poverty line (less
than $1 a day)
%
36
-
34.7
-
37.7
13.4
6.6
Traditional fuel
consumption (%)
46
-
20.7
-
89.6
29.5
46.5
Source: UNDP (2003)
(B) Climate change and Natural disasters
Climate change is now an accepted reality and in some cases is practiced to cause
heavy damage to the region. South Asia is among the most vulnerable regions in the
world to natural disasters related to climate change. Two main dimensions of climate
change, that would impact agriculture, are increased temperature and changes in
Strategies for Arresting Land Degradation in South Asian Countries
7
precipitation pattern. It is predicted that drought incidence, cloud burst and frequency of
high intensity of precipitation will increase in the changed scenario of climate. Risk of
run-off will increase in high latitudes and decreased in mid-latitudes (Arnell 2004 and
Nohara et al. 2006). Rise of sea level will be the most serious consequence of climate
change in the region. Over 80% of the land area in the Maldives is very vulnerable to
inundation and beach erosion. Presently 50% of inhibited islands and 45% of tourist
resorts face varying degrees of beach erosion. Climate change and projected sea level rise
will aggravate this problem. It can submerge 10-20% of the coastal land of Bangladesh,
including the Sundarbans.
According to the World Banks strategy for the region, south Asia stands out as a
region most vulnerable to natural disasters such as drought, flood, earthquake and
cyclones. From 1990 to 1998, the region accounted for over 60% of disaster related
deaths world-wide (Table 5). The geological faults are still active between the south
Asian plate and the main Asian plate. This results in earthquakes, which cause the
Himalayas to rise further. The earthquakes of September 1999 in Maharashta and 2000 in
Gujarat of India are two of the recent examples of the level of seismic action in this area.
Earthquakes in Nepal often results in landslides from unstable slopes, which have been
deforested and degraded by human activities.
The immediate effect of drought is the reduction of organic residues recycled in the
soils. Indirectly drought stimulates soil erosion and increase inorganic carbon
sequestration. These altogether activate/or enhance land degradation. An analysis of
recent climatic data in CAZRI indicated that frequency of drought years has increased in
the block year of five years from 1975 to 2004 (Fig.1). In the scenario of high torrential
rainfall, risk of water erosion and landslides will be magnified. It is evident from massive
cutting and transportation of sediments (Fig.2) during the flash flood of Barmer in
Rajasthan (Singh et al. 2007a).
Table 5: Natural disaster in India
Type
Location /area
Affected
Cyclones
Entire coast line of Southern India covering 9 states
Floods
08 major river valleys spreading over 40 million Ha of area of
entire India
260
Droughts
Around 68% of total sown area and 16% of total Area of the
country spread in 14 states
86
Earthquakes
56% of the total area of the country susceptible to seismic
disturbances
400
Landslides
Entire sub Himalayan region and Western Ghats
10
Avalanches
Many parts of the Himalayas
01
Fires
States of Bihar, West Bengal, Orissa and North eastern states
140
Source: CPCB/MATMP (2001): Environmental Atlas of India
10 million
8
Strategies for Arresting Land Degradation in South Asian Countries
Fig. 1: Increasing incidence of drought frequency in
Jodhpur, Rajasthan, India
Fig. 2: Devastation of torrential flood in
Barmer district, Rajasthan in 2006, India
(C) Globalization of agriculture
Subsistence farming is economically favorable on the marginal land and it
simultaneously produces curative action for preserving soil quality. Intensive agriculture
appears to be non-sustainable in the absence of holistic land management. In search of
high productivity intensive agriculture was pursued and holistic management was
ignored. Low water requiring crops is being replaced by high water demanding crops;
new areas are brought under irrigation; use of chemical fertilizers and agro-chemicals
have increased manifold. Area under irrigation is expanded from 19% in Pakistan to 39%
Strategies for Arresting Land Degradation in South Asian Countries
9
in India from 1993 to 2020. Excessive tractorization and massive infrastructure
development have taken place. These have disturbed the equilibrium among the different
facets of landscape and made them prone to severe erosion. Activation of sand dunes
increased overburden of sand and truncation of surface horizons at the benchmark sites
are the evidence of increased erosion (Singh et al. 2009a). Use of high RSC water for
irrigation increased pH and inorganic carbon concentration in soils (Singh et al., 2009a).
(D) Overgrazing and livestock
India’s livestock population, which is roughly about 13 % of the world total, depends
on pastures and rangelands accounting for 0.5% of the world total. This implies an
average of 42 animals grazing in one hectare of land against the threshold level of 5
animals per hectare. In the absence of adequate grazing lands, the fodder requirements
are met from forests, leading to increased deforestation. Annual rate of change of forest
cover is negative in most of the SAARC countries except India and Bangladesh (Table
6).
Table 6: Annual rate of change of forest cover in South Asian Countries
Countries
Forest cover (000 ha)
1999
2000 as % of land area
Annual rate of
change
2000
Bangladesh
1169
1334
10
1.3
Bhutan
1316
3016
64
-
63732
64113
22
0.1
1
1
03
-
Nepal
4683
3900
27
-1.8
Pakistan
2755
2361
03
-1.5
Srilanka
2288
1940
30
-1.6
709336
76665
19
-1.2
India
Maldives
South Asia
Source: FAO (2003)
(E) Summer fallowing
It is one of the principle causes of soil fertility decline in arid and semi arid part of
the region. Doran and Zeiss (2000) estimated soil organic carbon depletion to the tune of
320 to 350 kg/year in semi arid tropics on account of summer fallowing. About seven to
eight months after the harvest of summer crop, fallowing is the most common practice in
arid India because of limited water availability for raising second crop in a year. As a
result canopy cover, which protects the soil organic carbon from sun beating and intense
temperature, is available only for the brief period. The practice together with tillage for
summer crop exposes the arid soils for longer duration to the intense sunshine, high
temperature and microbial decomposition.
10
Strategies for Arresting Land Degradation in South Asian Countries
(F) Inappropriate land use and management
In the ideal situation of farming, there should be delicate balance between agriculture
and none agriculture uses. The area under crops should not exceed to 70% even on land
quality class (LQC) I (Eswaran 2001). However, on the advent of green revolution
marginal land not suitable for agriculture was brought under the plough. Study on the
marginal lands of arid part of Rajasthan in India indicated that about 16.5 to 149% excess
land was put up for arable cropping in 1975 than the recommended area to be utilized for
this purpose. The situation worsens on land quality class VI and VII where in 30 to 35 %
excess land was being utilized for cropping (Narain and Singh 2006). In 2004 repeated
study of the same area indicated that areas under the crops have further increased
manifolds (Fig. 3).
An analysis of land use data on the marginal lands of arid India from 1958 to 2002
indicated that about 37% area was utilized for cropping in 1958-59, which has gone to
52.45% in 2001-02 with a simultaneous decline of fallow lands, generally used for
community-grazing for sustaining livestock. Similarly area under double cropping has
shifted from 0.87% in 1958-59 to 8.58% in 2001-02 (Narain and Singh 2006). Excessive
tillage on marginal land break up soil structure, enhances soil erosion that causes mass
degradation of soil quality. Inadequate land use management such as imbalanced
fertilization and poor quality of water for irrigation further compounded the degradation.
Fig. 3: From left land use of Jhunjhunu district Rajasthan in 1968 and 2004, India
Impact of inappropriate land use and management
Acidification
Increased acidity is one of the offshoots of partial or non adoption of complete
package of green revolution technology. This form of degradation is dominantly reported
in India, Bangladesh and Sri Lanka. The root cause is erosion and movement of acidic
Strategies for Arresting Land Degradation in South Asian Countries
11
sediments down the slope in high rainfall areas due to the cultivation of high management
requiring crops on the marginal land. Such sediment covers good cultivable plain land
and acidifies surface layer over neutral non acidic sub-soils. Such process of acidification
has been reported dominantly on the fringes of Chhotanagpur plateau in West Bengal
(Fig.4) and Bihar, India (NBSS & LUP 2010).
Fig. 4: Induced acidity in the fringes of Chhotanagpur plateau, West Bengal, India
Apart from this, practicing intensive agriculture on marine affected lower part of
Indo-Gangetic plains exposes relict organic carbon and sulphur rich sediments. These are
expected to induce acidity and/or environmental degradation on the replacement of
prevailing rice based cropping sequence with other low water requiring crops. Such
problems are very extensive in Haora (Fig.5) and 24-Parganas of West Bengal India.
Selection of acid producing crops and cropping sequences are the other factor, which
reduces soil pH. Study at Central Rice Research Institute Hazaribagh, India indicated that
black gram and rice based cropping sequence enhanced the acidity, while pigeon pea
based cropping sequence maintained soil pH to its initial level (Singh et al. 2009b).
However, black gram-rice-finger millet is the preferred cropping sequence in Jharkhand,
India and that may be one of the reasons for increasing acidity.
12
Strategies for Arresting Land Degradation in South Asian Countries
Fig. 5: Outcropping of sulphidic material in Haora district, West Bengal, India
Nutrient stock depletion
Inappropriate land use and management induces deficiency of single or multiple
nutrients in Bangladesh, SriLanka, Pakistan and all fifteen agro-climatic zones of India.
Cultivating hybrids with inadequate and imbalanced fertilizers is the main cause of
nutrient depletion. Recent studies in Birbhum district of West Bengal, India indicated that
about 97.4% area is affected either with the deficiency of single or multiple nutrients
(NBSS&LUP 2010), of which multiple nutrient deficiency of phosphorus, potassium and
zinc together was mapped on 47% area of the district. Interpretation of data on smaller
scale revealed that potassium mining was extensive in prevailing rice-rice or ricevegetable or rice-potato cropping sequence (NBSS&LUP 2010).
The influence of imbalanced fertilization on the depletion of phosphorus and
potassium was also reported to the tune of 17.2 and 9.2% in a span of twenty seven years
under millet production system of arid India (CAZRI 2004). A depletion of potassium
was also noticed even at the research farm of Central Arid Zone Research Institute of
India at Jodhpur maintained from last thirty years under pearl millet-legume cropping
sequence (Singh et al., 2007b).
Soil organic carbon depletion
Soil organic carbon oscillates between a threshold limit of maxima and minima,
which is governed by geographic settings and land use (Buyanovsky et al., 1998). In
general cultivation depletes soil organic carbon if its value is at maxima (Buyanovsky et
al. 1998) by opening them to erosion and microbial decomposition. Otherwise growing
of crops enhances soil organic carbon. Therefore, selection of right land use and
management at right place is imperative to maintaining/sequestration of soil organic
carbon on its upper limit. The hypothesis was evaluated in light of present land use and
Strategies for Arresting Land Degradation in South Asian Countries
13
management on temporal scale from 1975 to 2002 in arid region of India. During the
period a loss of soil organic carbon by 17.2% was reported and fine loamy organic carbon
rich soils suffered heavily in the process (Singh et al. 2007c). Another study in 2002 for
0-100 cm soil depth indicated that soil organic carbon was depleted by 9.7% in a span of
27 years. Depletion was the highest (19.7 and 17.7%) in sandy and gravelly soils
respectively, while coarse loamy deep soils suffered from soil organic carbon loss of only
0.9% (Singh et al. 2007b). A comparison was also made between the soils organic carbon
status in the farmers field and in the field maintained on the research farm under millet
production system. Former experienced higher soil organic carbon loss than latter (Singh
et al. 2007b). In the end it was concluded that soil organic carbon tended to move from
maxima to minima with the present land use and management.
Salinity and sodicity
The problem of salinity and sodicity is associated with many ways in cultivating the
marginal land with inadequate management. For example an increase of soil pH was
reported by 0.2 units in a span of twenty seven years in arid region of India without
appreciable increase in salt content (Singh et al. 2009a). Probably in the situation of low
soil buffering capacity, clay micelle have high tendency to adsorb sodium (Poonia et al.
1998). That means adequate measures have not been taken up for increasing buffering
capacity of marginal soils for sustaining the productivity.
Another problem is associated with irrigation management. The soils which are not
suitable for irrigation were brought under the command area. For example excess
irrigation in black soils and gypsiferrous soils is the cause of ground water table rise, high
salinity and water logging (Fig. 6).
Fig. 6: Rise salinity in Tungbhadra command area, Karnatka, India
One or other kind of drought further deteriorates the situation. As a result many water
logged area is completely dried out and become one of the factors for spreading air borne
salinity in the adjoining area (Fig. 7). Cultivation of natural saline depressions, which are
14
Strategies for Arresting Land Degradation in South Asian Countries
the remnants of Tythis and Arbian sea in Indo-Gangetic plain and in arid part of
Rajasthan, India respectively, is also one of the reasons of salt movement in the adjoining
area.
Fig. 7: Dried waterlogged area in Western Rajasthan, India
Brackish water irrigation is another way of inducing degradation. This is usually
observed at the tail end of the command area where water is available for irrigation in the
beginning of growing season. However at the fag end of the cropping season, water
scarcity is very common and farmers are forced to irrigate their crop with brackish
ground water. Such case was noted in Sri Ganganagar, Abohar & Fazilka district in arid
part of India and the entire episodes ends with an increased salinity after few years of
such practice. The impact is perceptible in terms of surface sealing and deformation of
physical properties (Fig. 8). At the extreme end a good cultivable land was converted to a
wasteland (Fig. 9).
Fig. 8: Surface sealing
Fig. 9: Deformation of morphological properties
on brackish water irrigation
Strategies for Arresting Land Degradation in South Asian Countries
15
Irrigating soils with brackish water also enhances inorganic carbon sequestration. In a
study in western Rajasthan, an increase of inorganic carbon was observed by 64, 44, 14
and 3.1 to 5.5 and 3.2 g/m2 in Malkosani, Pipar, Bhagasani, Chirai and Bap variant soil
series of Jodhpur, respectively (CAZRI 2004) in a span of 27 years from 1975 to 2002.
The increased inorganic carbon in the soil system may be one of the causes for
degradation appearing as secondary salinization and sodification (Singh et al. 1999).
Irrigating crops with sodic water in upper part of Indo-Gangetic plain could also be
correlated with the re-emergence of sodicity in reclaimed soils.
Truncation of surface horizon
It is one of the very important processes of land degradation in the cropland.
Ignorance of soil and water conservation practices on the flat or stable landscape for
fairly long time is the main cause of this type of degradation. In the known history of
twenty five years of cultivation a soils loss of 15 cm from their place in parts of red and
lateritic regions of southern peninsular region of India was reported (Fig.10).
Fig. 10: Surface truncation due to sheet erosion in Karnataka, India
Sand dune reactivation
Cultivating dunes and inter dunes; overgrazing and deforestation on marginal lands in
arid region results in sand movement, which affects good cultivable land (Fig.11). Sand
movement is also related with the deformation of land. During summer sand moves and
trapped on the shoulder slope of hills. Cutting of such loose sand during rains forms
ravines and Bad lands (Fig.11). Movement of such sand also affects adversely to
adjoining good cultivable land on deposition.
16
Strategies for Arresting Land Degradation in South Asian Countries
Fig. 11: Reactivation of sand dunes Rajasthan, India
Densification of sub-soils
Use of high Residual Sodium Carbonate (RSC) and sodic water for irrigation,
excessive ploughing and silt movement down to the depth together or alone densifies
subsoil’s (Fig. 12). This results temporary perch water table and restrict solute and root
movement. Such problem is very severe and acute in upper part of Indo-Gangetic plain. It
is also likely that densification affects grain filling and solute transport adversely in rice.
Fig. 12: Densification of soils and its adverse impact on grain filling rice
in upper and middle part of Indo-Gangetic plain.
Techniques for restricting/preventing land degradation
Agro-techniques those are sustainable under the aberrant situation of farming or
improve the farming situation are helpful in restricting/preventing land degradation.
Adding new organic matter every year is perhaps the most important way to protect the
soils from the onslaught of degradation. Regular additions of organic matter improve soil
structure, enhance water and nutrient holding capacity, protect soils from erosion and
compaction, and support a healthy community of soil organisms. The other practices that
increase organic matter in the soils are also helpful in preventing land degradation. We
have screened some of the techniques that include: adequate soil erosion preventive
measures, moisture conservation, correcting water quality, integrated nutrient
Strategies for Arresting Land Degradation in South Asian Countries
17
management, diversification of agriculture, conservation tillage and gene mining for
drought avoidance and ameliorating acid soils. Alternate land use planning covering
inclusion of legumes in crop calendar, legume based forage production, silvipasture and
silviculture based agriculture; agro-forestry may be the other focal point for improving
present farming situation and restricting deterioration of land in future. Prior to the
execution of agro-technique for restricting soil degradation, its extent and severity is to be
mapped on an appropriate scale. The importance of these practices is briefly discussed in
light of some of the most relevant available data.
Estimating extent and severity of land degradation
Desertification/degradation maps generally fails to delineate the line between ‘state’
and ‘process’, i.e. the area already degraded, versus the area thought to be at the risk of
degradation (Oldeman and Van Lynden 2001). In such a complex situation, a
conventional method of mapping is far from standardization (Hill 2004). Satellite remote
sensing technology combined with geographical information systems (GIS) have
emerged as a powerful tools for assessment, monitoring and mapping of desertification/
degradation trends (Hussein 2003). More specifically, GIS and/or remote sensing has
been or could be used to identify physiographic units, which may be used as common
base for assessments of different kinds of soils, degradation and conservation. Overlay
data layers for different map units, making area calculations, linking spatial data with
non-spatial, making geo-referenced information easily accessible to non-GIS users,
bridging the scale gap are added advantage of GIS (Van Lynden and Mantel 2002).
Integration of satellite imagery, GPS, GIS, and advanced computer modeling techniques
into natural resource management provide managers with the tools to better adapt
themselves with the dynamics of multi-use management. GIS and remote sensing
technology provides the power to model quantitatively, describe the resource, and
objectively analyze the multiple demands of the resource in almost real time (Landsberge
and Grower 1997). During desertification/degradation studies, GIS is used to combine
vegetation, rain use efficiency, surface runoff and erosion maps for highlighting the areas
of greatest degradation susceptibility in sub-Saharan Africa (Simeonakis and Drake
2004).
Generally high resolution remotely sensed data are recommended for accurate, viable
and specific applications (Jianjun et al. 2004). NOAA AVHRR data of 1.1x 1.1 km2
resolutions with frequent repetitive coverage, twice daily to the earth, widely used to
detect change in biomass production at global and regional scale particularly in cloud free
days (Tucker 1980 & 1987). NOAA AVHRR data was also utilized for desertification
mapping in China (Long Zing 2002), and for vegetation degradation mapping on 66
million hectare area of South East Asia (Harahsheh and Tateshi 2001). Vegetation
degradation dynamics through 1982 to 1994 was studied in Sudan (Ali and Bayoumi
2004), using NOAA AVHRR data.
Landsat images have been successfully utilized to map the change of sand denudation
in west Asia (Dwivedi et al. 1993; Mering et al. 1987; Robinov et al. 1981). These on
merging with radar data show its ability to detect desertification process more closely
(Rebillard et al. 1984). Landsat images of 1982 and 1992 were effectively utilized for
18
Strategies for Arresting Land Degradation in South Asian Countries
monitoring desertification processes on crop-rangeland boundary of Argentina (Alfredo
2002). Multi-temporal analysis of Landsat TM images highlighted the negative impact of
irrigation on vegetation cover during the period of 1983-1997 (Hussein, 2003). Thematic
mapper (TM image data) has also been utilized for mapping desertification rate in Egypt
(Abid-El Hamid 1994) and in Gazera Sudan (Fadul and Mohmmed 1999). Thus
depending upon the complexity and job requirement remote sensing data are to be
procured and used.
Adequate soil erosion preventive measures
Protecting soils at the place through conservative measures reduces the risk of soil
erosion and runoff. Erosion erodes 5334 and 6 million tones of soils and nutrients yearly.
Stubble mulching with the residue of pearl millet (Mishra 1971), alternate strip of erosion
susceptible and erosion resisting crops (Gupta and Aggrawal 1980), stabilization of sand
dune with vegetative cover consisting of trees, grasses and shrubs in checker board
pattern (Kaul 1985), shelterbelts plantation (Gupta et al. 1983) are the effective measures
for controlling erosion and runoff. In an experiment of wind erosion during 1994 to
1999, an increase of soil organic carbon, nitrogen, phosphorus and potassium is reported
beneath the shelterbelts (Solanki et al. 1999). The practice may indirectly helps in
maintaining soil aggregates and good physical condition of soils that may reduce/prevent
runoff and erosion vis-à-vis land degradation.
Integrated water management
Increased availability of good water quality for irrigation enhances soil organic
carbon by increasing period of vegetative cover, vegetative input to the soils and
microbial population. These altogether lead to increase water stable aggregates that offer
protection mechanism for preventing land degradation. Ex-situ moisture conservation
including storage of rainwater in tanks, revival of farm village ponds, developing small
farm reservoir, creation of subsurface barrier for ground water recharge and khadin
management are some of the techniques that can be helpful for increasing the availability
of fresh water for irrigation. In situ moisture conservation including inter row water
harvesting, field bunding, mulching, deep ploughing and other agronomic practices such
as drought tolerant cultivars, optimum plant density and proper sowing time, balance
fertilization are the other useful techniques. Pressurized irrigation system such as use of
sprinklers and drips for irrigation on the undulated topography may have beneficial effect
and can increase water use efficiency by 30 to 70 %, reduce runoff and may be helpful in
avoiding the drought influence and erosion inducing land degradation. Farm water
management including land leveling, methods of irrigation, check basin and border strip
irrigation, furrow/surge flow irrigation may be further helpful in enhancing water use
efficiency vis-a-vis land degradation.
Correcting ground water quality
The present trends of irrigation in India leads to over-exploitation water, which is
manifested in terms of declining water level, saline water intrusion in coastal area, salty
and high water upcoming in inland aquifers, arsenic and fluoride contamination.The
irrigation of land with such water deteriorates the soil quality and magnifying the menace
Strategies for Arresting Land Degradation in South Asian Countries
19
of land degradation.
Gypsum application reduces the adverse impact of saline and high RSC water used
for irrigation. Joshi and Dhir (1990; 1991) observed that gypsum application @ 50 and
100% of the total requirement effectively reduces the carbonate and bicarbonate salinity
of ground water and enhanced soil quality as witnessed in terms of reduced soil pH by
0.3 to 0.4 units and depressed SAR by 6.4 to 10.7. Availability of nutrients also increased
during the course of investigation (Joshi and Dhir 1994). Thus decreasing pH and SAR
together with increasing available nutrients are favorable for enhancing stable soil
aggregates and improving good soil physical conditions. The practice ultimately helps in
covering the ill effects of land degradation.
Integrated nutrient management
Integrated nutrient management including chemical fertilizers, manures and
biofertilizers such as Azospirillum, Rhizobium, blue green algae, phosphate solubilizing
micro organisms, and VAM fungi (Rao and Venkateswarlu 1987) enhanced vegetative
cover and over all biomass production. The ultimate effect of which is the greater
vegetative input to the soils and higher soil organic carbon. What is equally important is
that such increase in soil organic carbon acts as cementing agent for the stability of soil
aggregates (Masri et al. 1996), improves total nitrogen content (Harris 1995),
mineralization potentials (Ryan 1997) and vis-à-vis stability of soils. These altogether
reduce the impact of torrential rainfall or continuous drought possibly expediting land
degradation. This could be verified from a long term experiment conducted in drought
affected area of Ranchi India on Typic Rhodustalfs where recommended dose of
fertilizers and FYM application @ 2.5 t/ha together significantly enhanced the available
nitrogen, phosphorus, and potassium over control and also raised soil organic carbon by
27.6 to 43.2% over its initial level in legume and rice based cropping sequence (Singh et
al. 2009b). Applying fertilizers through irrigation water, particularly through the drip
system, termed as fertigation, provides the most effective way of supplying nutrients to
the plant roots and enhancing nutrient use efficiency. It can be used to apply any water
soluble fertilizer or chemical in precise amounts, as and when required to match the plant
needs. It provides an option of improving nutrient use efficiency as the fertilizer applied
remains confined to the root zone of the crop and may helpful in raising the level of soil
organic carbon and reducing green house gas emission (Table 7).
Table 7: Integrated Nutrient Management to reduce emissions in paddy
Rice
yield
t/ha
Denitrification Losses
kg/ha
N2O
Emissions
kg/ha
Nitrate
Leaching
kg/ha
Soil
Organic-C
g/kg
Control
3.4
18
6.9
59
3.7
120 kg N/ha
5.6
58
12.4
94
3.7
GM20+ 32 kg N/ha
5.9
50
11.8
78
4.1
CR6+GM20 + 32 kg N/ha
5.9
52
11.8
-
4.9
LSD (0.05)
0.2
6
3.4
12
0.4
Treatment
CR: Crop residue, GM: Green manure;
20
Strategies for Arresting Land Degradation in South Asian Countries
Source : CRRI, Cuttak, India
Precision agriculture
For avoiding the wasteful use of irrigation water and nutrient, precision agriculture is
one of the options to negate land degradation. Currently, in India precision farming
implies site specific nutrient management. In reality, it signifies delivery of all inputs
including herbicides, pesticides, as per the actual site requirement. It would require a
seamless merging of multi-source data through remote sensing, GIS, GPS and sensors of
various kinds and appropriate machinery and use of linear and non-linear programming
(optimization techniques), response surface methodology and probit analyses for
optimizing the land use and management.
Diversification of agriculture
Diversified farm means growing of variety of crops in a rotation together with
animals. These are economically sustainable and resilient. Poor soil physical condition
that make them prone to soil erosion and runoff, not only occurs because of growing of
annual crops, requiring specific and high management but also keeping land out of
agriculture. Diversification of agriculture integrating both crops and livestock in the
farming system may be beneficial to each other because latter may supplement manure to
the soils for increasing/ maintaining soil health. Pasture and forage crops included in
rotation may also contribute significantly in raising soil organic carbon and reducing the
risk of soil erosion and land degradation.
Conservation agriculture
Tillage operations disturb soil structure and redistribute energy rich organic
substances in the soils. Researchers have shown that the use of mould board plough
reduced organic matter by an average of 256 lb/acre/year (Reicosky et al. 1995).
Conservation agriculture is an umbrella, covering a wide range of diverse tillage practices
that have the potential to reduce soil and water loss relative to conventional tillage
(Mannering and Fenster 1983). An well accepted operational definition of conservation
agriculture is planting and tillage combination that retain a 30 % or higher cover of crop
residue on the soil surface. Conservation agriculture also increases soil organic matter,
improves nutrients, water use efficiency and physical properties besides restricting soil
erosion.
Management tools commonly used to achieve the above operational definition for
conservation tillage are; (i) non inversion tillage (usually implies replacement of a mould
board plough with a chisel plough or cultivator) (ii) tillage depth confined to <15 cm
(Deeper tillage may be retained in the row for row crops and (iii) number of tillage
passed minimized. The major outcome of these management option (relative to some
conventional system that implies full soil profile tillage) is to provide some degree of
permanent soil cover (i.e. 30% or more residue in the non crop period) to increase the
organic matter content and structural stability of the soils over the time and to improve
soil structure below the plough layer. Soil stratification, which mainly involves
enrichment of the soil surface with organic matter, is the dominant management outcome
Strategies for Arresting Land Degradation in South Asian Countries
21
of the conservation tillage (Franzluebbers 2002). Stratification can also have impact on
nutrient storage and soil aggregation, improved water regulation at the surface and
throughout the soil profile (Carter 1994).These altogether helps significantly to improve
agriculture for avoiding land degradation.
Gene mining for drought avoidance
It is the other important practice to develop drought hardy plants. There are several
species in sub-Saharan Africa and other desert, which have very extensive root system for
water mining from large volume of soils, such as Prosopis Juliflora serving in the rainfall
zone ranging from 200 mm in Bhuj to 1000 mm around Ramnathpuram of east coast.
Short duration crop of moth bean is another classical example of deep root system.
Genetic and molecular characterization of such plants can help to introduce new genotype
in the plants through genetic engineering. Thus genetically modified plants can manage a
biotic stress of droughts, salinity, heat and cold waves and such attempts may be
beneficial for averting land degradation.
Inclusion of legumes in crop calendar
The ability of legume to fix atmospheric nitrogen is perhaps the most notable aspect
that set them apart from another plant. In addition legume has benefit to improve soil
structure, reduce soil pH and increases the availability of native phosphorus. This could
be seen from a long-term trial conducted at CAZRI Jodhpur; with Pearl millet- moth bean
based cropping sequence in a rotation of four years. The sequence maintains initial soil
organic carbon of 0.22 and 0.14% in surface and subsurface horizons. Another sequence
with legume-legume-legume-pearl millet increased soil organic carbon. Other rotation
consisting of fallow-legume-legume-pearl millet also gave the similar results (Kumar et
al. 1997). The result from drought prone area of Ranchi with legume based cropping
sequence and recommended dose of fertilizers was in agreement with the earlier findings
(Singh et al. 2009b). In contrast, rice based cropping sequence with recommended dose
of fertilizers produced higher yield on the cost of declining soil quality. Thus legumes are
the potential land use that may be frequently utilized for restricting land degradation at
the place.
Legume based forage production
Growing of grasses is well known for improving soil organic carbon; binding soil
particles and considered as another potential land utilization types in the changed
scenario of land degradation. Inclusion of leguminous grasses with traditional forage in
arid region is found more beneficial. This type of rotation is known for addition of high
residue in the soils, which increases the organic matter, aggregate stability, biological
diversity (Magdoff 1992), water movement, aeration, porosity and reduces bulk density
(Schnitzer 1991). A study conducted in the arid region indicated that intercropping of
Cenchrus cilliaris and Clitoria ternatia and Cenchrus cilliaris and Lablab purpures
added higher soil organic matter both at the surface and in the subsurface during three
years of experimentation as compared to the pasture with Cenchrus cilliaris alone
22
Strategies for Arresting Land Degradation in South Asian Countries
(Tripathi et al., 2002) in sandy soils.
Silvipasture and silviculture based agriculture
Plantations (silviculture) alone or in combination with grasses (silvipasture) are
another very important practice for improving soil organic carbon and maintaining good
soil physical conditions for countering the influence of land degradation. Plantations with
Acacia tortolis, Colophospermum mopane, Hardwickia binata and Cenchrus ciliaris are
noted for increased organic matter, available nitrogen, phosphorus and micronutrients in
degradation hit arid region of India (Aggrawal et al. 1978). Silvipasture and plantations
have 185 and 141% respectively higher potentiality of soil organic carbon sequestration
than traditional pearl millet-fallow system of arid region. These could sequester 9.6 and
7.4 kg/m2 higher CO2 than pearl millet-fallow system, approximately in the same period
(Singh et al. 2007b). Therefore, silvipasture and plantations should be integral part of
agriculture particularly for improving the severely eroded areas, community land and
wasteland for reducing/mitigating the influence of degradation.
Agro-forestry
Growing of crops with shrubs, herbs and grasses are the old age practice for
providing fodder to the animals, timber to the farmers and shades to the soils. The
practice simultaneously could enrich the soils by sequestering 121% higher organic
carbon than the pearl millet-fallow system. Growing of trees with crops could sequester
6.29 kg/m2 higher atmospheric CO2 than the cultivation of crops alone (Singh et al.
2007c). This could be possible because of higher biomass production (Aggrawal et al.
1978) and higher soil moisture profile (Gupta and Saxena 1978) beneath the agro forestry
system. Extensive research revealed that agro forestry including moth, cluster bean and
local variety of pearl millet as a crop component with Calligonum polygonoides and
Lasiurus sindicus as perennial trees and grass, respectively are more successful in 100 to
250 mm rainfall region of arid areas, while plantation of Prosopis and Ziziphus species in
the field and Capparis decidua on the boundary with pearl millet, moth bean, sesame and
cluster bean is beneficial in 250 to 350 mm rainfall areas. However, growing of Prosopis
cineraria and Tecomella undulata with pearl millet, green gram, moth bean and cluster
bean is advantageous in the area of 250 to 450 mm rainfall adjoining to the semi arid
region. In the irrigated area of arid region plantation of Prosopis cineraria and Acacia
nilotica with wheat, barley, mustard and gram in winter cotton, sorghum, pearl millet and
sesame in summers are expected to improve soil organic carbon and physical conditions
of soils. These altogether may help to sustain agriculture and prevent land degradation.
Strategies for arresting land degradation
The following discussion reveals a wide variability in type and severity of land
degradation within and between the set of conditions. A piece of land may be affected
with one or combination of land degradation processes. For example erosion, salinity and
nutrient depletion may occur independently or these may act together on a piece of land.
It may arise either by inappropriate land use and management or by severity of natural
hazards or calamities. Number of technologies has evolved and executed targeting to
address one or other kind of degradation. Execution of such technology could not bring
Strategies for Arresting Land Degradation in South Asian Countries
23
desired results on the farmers field.
Therefore for solving very complex problem like degradation, which has cascading
effect on natural resources and man kind, a holistic approach is needed. The essence of
holistic approach is the selection right type of cultivars and appropriate technologies at
right place depending on the specificity of problem. Execution of the programme should
be done at right scale. It may be at watershed, district or region depending on problem
and client requirement. Use of GIS, GPS, remote sensing data and decision support
system may be very handy for the execution and monitoring of preventing/ correcting
land degradation programme. A conceptual model for such activity is given in fig 13.
Fig. 13: Conceptual model for integrating land use,
technology and planning environment
Database in GIS is very important component of the model. It consists four model.
Module one is polygon based, module two consists of points, whereas module three and
four framed for raster and non spatial data, respectively. Component of each module is
given in fig. 14.
24
Strategies for Arresting Land Degradation in South Asian Countries
Module 1
Polygon based module
9 Administration
9 Soil resource map on 1:250, 000
scale
9 Soil resource map on 1:50,000
scale
9 Soil resource map on 1:4 to
10,000 scale
9 Geology of the state/region
9 Physiography
Module 2
Point data based module
9 Grid points collected during
SRM
9 Typifying pedons
9 Grids and typifying pedons of
subsequent surveys
9 Climatic variant
9 Ground water status and quality
from prominent locations
9 Land use and yield data
9 Agro-technology - management
and yield of demonstration plots
and research farms
9 Physiography
Module 3
Raster based module
9 Ground and surface water
prospects and irrigation
potentials
9 Climatic history punctuated
with rainfall pattern and
drought frequency
9 Land use dynamics
9 Periodic RS data
9 Physiography
Module 4
Non-spatial data based module
9 Human and livestock profile
9 Land use requirement
9 Market demand and trends Nonspatial data based module
9 Human and livestock profile
9 Land use requirement
9 Market demand and trends
Fig.14: Database framework in GIS
Expert system is another novel aspect of the model. Three is a provision of three
expert system in the model. Expert system I is designed for delineating the homogeneous
area with respect to soil, climate and irrigation potentials at various scale. Preferably in
the initial stage the exercise is to be performed on larger scale. Expert system II identifies
the land use options and management by utilizing the database on socio-economic
conditions, land use requirement, available technologies, market trends and demands.
Expert system III is designed for scenario analysis and projections. After validating and
refining land use and management, same may be up-scaled, using appropriate algorithms
for the use at district or regional level planning.
By utilizing expert system I the potential area for agriculture and alternate land use
was delineated for watershed planning in Silai basin of West Bengal depending upon soil
Strategies for Arresting Land Degradation in South Asian Countries
25
depth, texture and available water capacity (Fig.15).
Fig.15: Potential area for agriculture and alternate
land use in Silai basin of West Bengal, India
Land quality class (Narain and Singh, 2006) has been delineated depending upon
various kinds of stresses for district planning (Jodhpur district Rajasthan) by applying
expert system I. Similarly other bases for district level planning such as agro-ecounit and
land management unit could be delineated by applying expert system I. In the present
endeavor agro-ecounit map of Jodhpur district (Fig. 16) and land management unit in
Nadia district (Fig. 17) are given an examples (Singh and Tarafdar 2009; NBSS&LUP
2010). For the regional level planning agro-ecological zone map (Singh and Tarafdar
2009) has been developed for arid region of India (Fig. 18).
Fig. 16: Land quality class and agro-ecounit map Jodhpur district, Rajasthan, India
26
Strategies for Arresting Land Degradation in South Asian Countries
Fig. 17: Soil management units of Nadia district,
West Bengal, India
Fig. 18: Agro-ecological sub-zone map for arid regions
of India
By applying expert system II intercropping system and alternate land uses (Narain
and Singh 2006) and for different land quality classes of arid region has been identified
(Table 8).
Table 8: Optimum Land Use Plan for Arid Region by using expert system II
Quality Classes
Intercropping
Alternate land uses
III (50:45)*
Pearl millet+ green gram/ cow pea
(3:1)
Cenchrus cilliaris, Prosopis cineraria, Acacia albida, C.
mopane,
IV (45:50)
Pearl millet+ cluster bean/ moth bean Cenchrus cilliaris, Acacia tortolis, Acacia senegal,
(3:1)
Tecomella undulata
Va (40:55)
Pearl millet+ green gram/ cow pea/
moth bean (2:1)
Vb(40:55)
Pearl millet+ cluster bean/ moth bean Lasiurus sindicus, Acacia tortolis, Acacia senegal
(1:2)
VI (30:65)
Pearl millet+ cluster bean/ moth bean Lasiurus sindicus, Acacia senegal, Acacia tortolis
(1:2)
VII (20:75)
Pearl millet+ cluster bean/ moth bean Lasiurus sindicus, Acacia senegal, Acacia tortolis
(1:2)
VIII (5:95)
Cluster bean + green gram (2:1)
Cenchrus cilliaris, Acacia senegal, Acacia tortolis
IX (5:95)
Pearl millet+ cluster bean/ moth
bean (1:3)
Lasiurus sindicus, Acacia tortolis, Zizyphus nummularia,
Calligonum polygnoides
Cenchrus cilliaris, Prosopis cineraria, Acacia albida
Strategies for Arresting Land Degradation in South Asian Countries
27
A regression model for ascertaining the impact of intercrops and alternate land uses
on soil organic matter in arid region (SOC density kg/m2 for 0-100 cm soil profile) =
4.4+0.0001052 (Rainfall, mm) +0.43914 (period of canopy cover)-0.00505 (Clay %)
+0.008722 (Silt %) +0.955712 (AWC)-4.53 (tillage) -----R2=0.98 was utilized as expert
system III for scenario analysis (Singh et al. 2007c). By utilizing above model potential
organic carbon, SOC attached with finer (inert soil organic carbon) and coarser soil
particle (Floatable soil organic carbon) were predicted (Table 9).
Table 9: Model potential organic carbon, SOC attached with finer
Particle size class
Max. potential
Inert SOC
Added SOC
CL deep
4.3-4.5
2.4-3.0
1.3-1.8
CL mod. deep
4.3-4.5
1.7-3.0
1.4-2.6
Fine loamy
4.2-4.6
2.1-4.1
0.5-1.6
Loamy-skeletal
4.0-4.1
0.4-0.8
3.4-3.7
Sandy
4.2-4.3
0.9-1.5
2.7-3.2
These calculations were valid if canopy cover is maintained round the year under
prevailing normal situation of rainfall and temperature (Singh et al. 2007). Based on the
model untapped organic carbon (Fig. 19) potential for the soils of Jodhpur district
Rajasthan India was calculated (Singh and Tarafdar 2009). Modeled values of soil
organic carbon potential was tested under different land use systems (Fig.20). Soil
organic carbon was much closer to the predicted potential soil organic carbon under
silvipasture system and was far from prediction under pearl millet system of land use.
Fig.19: Untapped soil organic carbon in g/m2 in Arid India
28
Strategies for Arresting Land Degradation in South Asian Countries
Fig.20: Validation of module value in different land use system
Conclusions
With the advent of green revolution, no doubt food productivity has increased many
times. However, non/partial adoption of package of practices, high population pressure,
erratic behavior of monsoon and miseries imposed by nature induced various kind of
degradation. Menace of degradation is more serious in south Asian countries because of
high population pressure. Majority of the farmers belonged to low income group and their
capacity to adopt green revolution technology in totality is questioned. As a result full
package of technology was not adopted and desired impact of technologies could not be
perceived. Therefore strategies of holistic approach consisting of right cultivars,
appropriate technologies at the right place may be the options for sustainability and for
enhancing growth in agriculture
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34
Strategies for Arresting Land Degradation in Bangladesh
Content
1. Introduction
2. Land degradation: Situation in South Asia
3. Factors affecting Land Degradation
4. Impacts of Land Degradation
5. Major types of land degradation in Bangladesh:
5.1. Soil erosion
5.2. Water erosion
5.3. River Bank Erosion
5.4. Wind erosion
5.5. Salinization
5.6. Acidification
5.7. Water logging
5.8. Decline in Soil Fertility
6. Levels of Land Degradation
7. Climate Change induced Land Degradation
7.1. Rainfall
7.2. Temperature
7.3. Flood
7.4. Carbon Sequestration and Land Degradation
7.5. Drought management
8. Minimizing Land Degradation
8.1. Plantation
8.2. Organic agriculture
8.3. Shifting cultivation
8.4. Preserving soil fertility/Fertilizer management
8.5. Carbon Management Approaches
9. Land Resources Conservation Strategy
10. Combating Land Degradation and Appropriate Cropping
10.1. Research
10.2. Extension
10.3. Policy Options
11. Conclusion
12. References
Page
35
35
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54
55
Strategies for Arresting Land Degradation in Bangladesh
35
1. Introduction
Land is the nature’s most precious gift to mankind. Land with all its attributes as a
versatile resource base played the key role here. It is the most fundamental of natural
resources which provided all of food, feed, fiber and shelter, for the human race and its
civilization to thrive on this planet. About one-fifth of humanity lives in South Asia.
Despite rapid urbanization in recent years and a fall in the share of agriculture in GDP,
the overwhelming majority of South Asians are still villagers, dependent on land for their
livelihood. Bangladesh lies in the north-eastern part of South Asia. The rate of
urbanization is for 31.5%, 25.7% and 20% for Pakistan, India and Bangladesh
respectively. The pressure in agricultural land is high in all the three countries. However,
it is highest in Bangladesh, with 73.8%, while India has 64.9% and Pakistan has 51.2% of
the working force dependent on agriculture (Siddique, 1997).
Land degradation is one of the greatest challenges for mankind. Although the problem is
old as the settled agriculture, its extent and impact on human welfare and global
environment are now more alarming than ever before. Large scale degradation of soil
resources has been reported from many parts of the world (Hillel, 1991). Land degradation
leading to change in cropping and agricultural productivity and vice versa is threatening the
agricultural sustainability of many countries, especially the developing and least developed
countries with scare land resources. Soil degradation is "the decline in soil's productivity
through adverse changes in nutrient status and soil organic matter, structural attributes and
concentrations of electrolytes and toxic chemical (Blaikie and Brookfield, 1987).
In Bangladesh, land and soils are the most valuable natural resources. Unfortunately,
these important natural resources are being used non-judiciously without proper
replenishment. Boosting crop production has been confronted by many soil related problems
like depletion of organic matter, nutrient deficiency/imbalance, soil salinity, soil acidity,
topsoil erosion, degradation of physical properties, low water holding capacity and
draughtiness, drainage impedance and water-logging prevailing in many parts of the country
which hamper crop production. These problems are partly due to natural cycle of events and
mostly because of irrational human interventions. In this paper, an attempt has been made to
review the nature and kind of soil degradation in South Asian Countries and its possible
remedies to improve the situations.
Under the above circumstances, the issue of land degradation has to be addressed.
Land degradation, as an issue, is not something new, but recent developments in the food
sector do not bode well for the South Asian countries striving to provide food security
and improve the quality of life for their teeming millions. Assessment of the land
resources and evaluation of the land degradation knowledge is to be developed by
creating awareness and develop ways, means and policy level interventions to halt land
degradation for the countries are necessary. The vulnerability of agricultural land to
degradation and the capacity of the farmers to respond to the threat of degradation thus need
social, economic and policy consideration.
2. Land degradation: Situation in South Asia
Asia, the most thickly populated area in the world has been influenced by
desertification. With the rapid economic development in Asian countries, the rapidly
36
Strategies for Arresting Land Degradation in Bangladesh
growing population is placing ever-increasing demands on the land, clearing natural
vegetation and tilling soil without fallow or inadequate nutrient replenishment. With
increasing use of unsustainable resources, land degradation further degraded, which leads
to increased poverty and many people have to face deteriorating living conditions. About
35% of the arable land in Asia has been influenced by desertification. Nearly 1.3 billion
people or 39% of the total population in Asian region are exposed to desertification and
arid conditions. Hence the area under land degradation is increasing. World soil
degradation situation (FAO, 2000) is presented in Table 1.
The food demand and internal supply situations in most SAARC countries have not
been satisfactory as the scope of horizontal expansion of agriculture has almost exhausted
and crop yields began to stagnate or even decline in many cases. The recent food price
hikes and limited availability of food in the international market have further complicated
the issues related to achieving food security in the SAARC countries and at the same time
maintaining the pace of their socio-economic development. The implication is that,
countries must produce enough food for their present populations and check population
growth rates to ensure that food shortage do not occur in the future, virtually all of the
food increase will have to come from land. The population growth rate was high,
around 2% per annum in the impoverished, developing nations of Asia. For example in
the SARC countries, the total population was 1418.5 million in 2004 which is estimated
to be about 1800 million by the year 2020 (SAARC Statistical Data Book, 2006-2007),
about 22 percent of the world’s population live in the eight SAARC countries.
Table 1: Soil degradation in the world (Land in "00000' hectare, FAO, 2000)
Type of Degradation
Plant
nutrient
depletion
Asia
Salinization
Chemical
pollution
Acidification
Organic
matter
depletion
150
530
30
50
20
South East Asia
130
200
15
50
20
West Asia
45
360
15
-
-
Africa
500
150
-
25
-
South America
700
20
-
-
-
Central America
45
20
-
-
-
North America
22
-
-
-
-
Europe
35
40
2
-
20
Oceania
10
10
-
-
-
1637
1330
62
125
75
Region
World (Total)
There are limited data on the latest information and statistics about the nature and
extent of the different land degradation components in the SAARC countries varying in
content and precision from country to country. However, what is known to date may be
Strategies for Arresting Land Degradation in Bangladesh
37
largely qualitative and not always precise but these do provide food for thought for policy
makers and agricultural scientists of the region for future action plans to protect the
region from the bad effect of land degradation. For the practical purpose of assessment of
land degradation in SAARC countries and determination of the needs for technological
and policy interventions, the following list showing the causes of land degradation,
natural or human induced, should suffice:
•
•
•
•
•
•
•
•
•
•
•
•
Natural hazards e.g., flood, drought, tidal surge, snow melt, etc. (some or the other in
all SAARC countries - e.g., floods and tidal surges in Bangladesh, drought in
Pakistan and India, snow melt and landslides in Nepal and Bhutan)
Erosion by water and wind (e.g., serious land erosion from river water currents in
Bangladesh during recurrent floods, wind erosion in the semi-arid regions of India
and Pakistan)
Salinization and acidification (natural and anthropogenic e.g., tidal flooding, shrimp
culture in crop land in Bangladesh, faulty irrigation and drainage in India and
Pakistan, arid and semi-arid conditions in India and Pakistan, draining and drying of
potentially acid sulphate soils, etc.)
Formation of hardpan, compaction and water logging (mostly human induced in all
SAARC countries)
Deforestation, shrinkage of vegetation cover on land, overgrazing (natural and / or
human induced in India and Pakistan, for example)
Inappropriate management in cultivation of land on steep slopes (human induced e.g., in Nepal)
Nutrient mining and inadequate nutrient replenishment (human induced - all SAARC
countries)
Soil organic matter depletion (mostly human induced - e.g., serious problem in
Bangladesh)
Over-exploitation of ground water in excess of natural recharge capacity (faulty
irrigation practice, human induced)
Use of poor quality irrigation water (e.g. use of groundwater containing high arsenic
concentrations for irrigation in Bangladesh and West Bengal of India, risk of toxic
levels arsenic accumulation in soils and foodstuff)
Pollution of soil and surface water bodies (rivers, ponds) by urban industrial waste,
excessive use of agrochemicals, oil spills etc. (human induced - e.g., in India, the
most industrialized SAARC country)
Global warming and consequent sea level rise, an impending calamity (mostly human
induced, mainly responsible are the industrialized countries of North America and
Europe, but the SAARC countries are under the influence of severe consequences).
3. Factors affecting Land Degradation
A big difficulty in studying these components of land degradation and their impacts
on agricultural production separately is that, these are caused by both natural factors and
38
Strategies for Arresting Land Degradation in Bangladesh
human interventions mostly in overlapping ways. For example, soil degradation may
occur due to fertility decline caused by loss of nutrients through erosion (natural cause)
and simultaneously, intensive cropping without appropriate fertilization (human factor)
and it has some adverse affect which result a huge crop loss. The crop loss could be
measured, it would be almost impossible to determine exactly which factor contributed
how much in causing yield loss. Some statistics gleaned from various countries (SAARC
Statistical Data Book, 2006-2007) are given below as references:
• Water erosion and chemical degradation are the most devastating land degradation
pathways in the SAARC region. Erosion risk is the highest (53% of the total area) in
Bhutan, followed by 42% in Sri Lanka, 31% in Nepal, 29% in India, 15% in
Bangladesh and 13% in Pakistan
• Soil salinity/sodicity is a problem in Pakistan (20% of the total area), India (8%) and
Bangladesh (6%).
• Land with shallow soils (poor fertility and physical properties): 24% in Pakistan,
21% in Nepal, 13% in Bhutan, 10% in Sri Lanka, 9% in India and 1% in Bangladesh.
• Soil fertility decline due to organic matter depletion is a growing problem in all
countries. In Bangladesh about 60% of the soils have low organic matter content,
often less than 1%.
• In India 41% of the land area is under major soil constraints, the figures for Sri
Lanka, Bangladesh, Nepal, Bhutan and Pakistan are 37%, 29%, 26%, 22% and 9%,
respectively.
• On a SAARC regional basis, only 24% of the total land area in without major soil
constraints.
Land degradation through human activities is progressing at a fast pace in all South
Asian countries. Human induced land degradation in India is the highest (58% of the total
degraded area) followed by Sri Lanka 54%, Bangladesh 27%, Nepal 27% and Pakistan
24%. It is in this aspect of land degradation, i.e., human induced land degradation, where
there is the greatest scope and necessity to intervene with national and regional policy
measures and technological innovations. This is the time to give emphasis to initiate
research work extensively to solve the problems of soils of Bangladesh that occupies
60% area of which 0.88 m ha in salinity, 35 m ha in drought, 26 m ha in water-logging,
0.83 m ha in char land and 1.2 m ha in high temperature zone.
A more recent estimate-projection on the impact of land degradation in Bangladesh is
quite frightening (Kholiquzzaman, 2007):
•
Loss of 180 ha arable land/day, 7.5 ha hr-1 due to building of homes, industries, roads
and other structures.
•
Loss in food production estimated at 5000 t day-1 or 1.6 million t yr-1.
•
At this rate of loss of arable land, not even a sq inch would be available for
agriculture after fifty years onward.
•
In 1974 59% of the net land area of the country was under agriculture; decreased to
53% in 1996. During the period 1983-1996, the rate of decrease in arable land area
was 87,000 ha yr-1.
Strategies for Arresting Land Degradation in Bangladesh
39
•
During 1983-1996, food production suffered a loss of about 2.1 million ton due to
continuously decreasing arable land area
•
In total since 1996, the loss of arable land over 10 years was 0.65 million ha yr-1.
There are some examples of the present and potential impacts from one SAARC
country only (Bangladesh). Land degradation in almost all its known forms is going on in
all other SAARC countries. The extent and intensity of the various land degradation
processes would differ, however, from country to country. For example, arsenic
contamination of the irrigation water-soil-crop systems is known to be quite a serious
water quality/soil degradation problem in Bangladesh and West Bengal of India, but this
is not much of a problem in Pakistan, other parts of India and other SAARC countries.
Again, sea level rise due to global warming could be a very serious threat to Bangladesh
and Maldives, but Nepal and Bhutan are not supposed to be directly affected. Since no
generalization can be made regarding the causes and effects of land degradation, it is
imperative that dependable data for each country be available so that scientist, policy
makers and farmers can take appropriate measures to face the problem nationally and
regionally.
4. Impacts of Land Degradation
Estimating the impact of land degradation is a very difficult task as this would
involve not only the biophysical and agro-ecological issues but also socio-economic and
development issues. However, this is very important since policy makers, donor agencies
and international development partners would be more interested in quantitative estimates
of the impacts of land degradation than just qualitative statements about what could
happen. A concerted effort by agricultural and social scientists is very much needed. A
study of the effect of land degradation in south Asia concluded that land
degradation was costing countries in the region and economic loss of the order no
less than US$ 10 billion, equivalent to 7% of their combined agricultural GDP (FAO,
1994). The current figures could be much higher.
Over the last 2-3 decades, enormous pressure has been exerted on the land resources
of the country. The rapid population growth and the concurrent increase in demand for
agricultural land, food, water and shelter has put pressure on the land and water
resources. This is resulting in environmental degradation in the region and the trend is
intensifying unceasingly. In Bangladesh, roughly 220 hectares of land goes out of
cultivation per day which means, nearly 1 percent of the cultivable land is being lost
every year (BBS, 1997). This has serious implication on the sustainability of agricultural
development potential, food supply and food security of the country.
Due to decline in natural vegetation and unsustainable agriculture, the capacity of soil
and water resources to support life has been steadily reduced. According to the data from
UNEP in 1997, of the 1.96 billion ha of soil resources in the world, that have been
degraded, Asia ranked the highest rate with approximately 38% percent of total
declination. Due to overgrazing and deforestation, natural vegetative cover continues to
decline, which created negative impact on the biodiversity. There are a number of
40
Strategies for Arresting Land Degradation in Bangladesh
interrelated land degradation components, as follows, all of which may contribute to a
decline in agricultural production (FAO, 2000):
•
Soil degradation : Decline in the productive capacity of the soil
•
Vegetation degradation: Decline in the quantity and quality of the natural biomass
and loss of vegetative cover (For example, the supper cyclone “Sidr” in Bangladesh
caused at least 5% loss of the Sundarbans, the largest mangrove forest of the world,
As a result the “green wall” against cyclone has been seriously lost in Bangladesh)
•
Water degradation : Serious increase of pollution of ground water due to arsenic,
industrial effluents. Decline in the quantity and /or quality of the surface and
groundwater resources
•
Climate deterioration : Changes in climatic conditions that increase the risk of crop
failure. This components caused yield reduction in wheat and mustard
5. Major types of land degradation in Bangladesh:
Major types of land degradation that occur in Bangladesh constitute:
i) soil erosion, ii) water erosion, iii) river bank erosion, iv) salinization, iv)
sedimentation, v) acid sulphate soil, vi) Acidification, vii) water logging and viii) soil
fertility depletion. The types of land degradation and extent are provided in Table 2.
Table 2: Different types/areas of land degradation and their extent in Bangladesh
Types of land degradation
Areas (in m ha) affected by different
degrees of degradation
Total area
(m ha)
Light
Moderate
Strong
Extreme
0.1
0.3
1.3
-
1.7
-Bank erosion
-
1.7
-
-
1.7
2. Wind Erosion
-
-
-
3.8
4.2
-
-
8.0
- P deficient (for HYV rice)
5.3
3.2
-
-
8.5
- P deficient (for Upland crops)
3.1
2.5
-
-
5.6
- K deficient (for HYV rice)
4.0
3.4
-
-
7.4
- K deficient (for Upland crops)
2.1
5.4
-
-
7.5
- S deficient (for HYV rice)
4.4
3.3
-
-
7.7
- S deficient (for Upland crops)
4.1
4.6
-
-
8.7
Soil Organic Matter depletion
1.94
1.56
4.05
-
7.55
4. Water logging
0.69
0.008
-
-
0.7
5. Salinization
0.29
0.43
0.12
-
0.84
1. Water Erosion
3. Soil Fertility Decline
-
Strategies for Arresting Land Degradation in Bangladesh
Types of land degradation
41
Areas (in m ha) affected by different
degrees of degradation
Total area
(m ha)
Light
Moderate
Strong
Extreme
6. Pan formation
-
2.82
-
-
2.82
7. Acidification
-
0.06
-
-
0.06
8. Lowering of water table*
-
-
-
-
-
9. Active floodplain
-
-
-
-
1.53
10. Deforestation
-
0.3
-
-
0.3
11. Barind
-
-
-
-
0.773
Source: BARC, 1999.
* No quantitative estimate available
5.1. Soil erosion
Soil erosion has been remarkably encountered in the hilly regions of the country
which occupy about 1.7 million hectares and the areas which are susceptible to different
degrees of erosion in the hilly areas of Bangladesh is shown in Table 3 (SRDI, 2005).
Sheet erosion is a general phenomenon occurring throughout the country. It poses a
serious problem locally in parts of level to gently undulating high terraces of the
Madhupur, Barind and Akhaura tracts in terms of considerable amount of topsoil and
nutrient loss. There is also visible evidence of fertile topsoil loss in the flood plain, but a
quantitative estimate of soil loss has not yet been scientifically made.
5.2. Water erosion
Water erosion is a serious problem in Bangladesh. Because of high seasonal rainfall,
low organic matter content, poor soil structure, poor soil management and rapid
destruction of vegetative covers in different slopes of the hills, the surface soils are being
continuously washed away. Water erosion covers all forms of soil erosion by water
including sheet and rill erosion and gullying. Human induced enhancement of landslides,
caused by clearing of vegetation, earth removal, road construction, etc., are also included.
Water erosion is the most widespread form of degradation affecting 25% of agricultural
land. Accelerated soil erosion has been remarkably encountered in the hilly regions of the
country which occupy about 1.7 million hectares and the areas which are susceptible to
different degrees of erosion in the hilly areas of Bangladesh is shown in Table 3 (SRDI,
2005). The data reflects that about 75% of the hilly areas have very susceptibility to
erosion while about 20% have high susceptibility and 5% have moderate susceptibility to
erosion.
42
Strategies for Arresting Land Degradation in Bangladesh
Table 3: Land susceptible to different degree of soil erosion in the hill areas of
Bangladesh (in km2)
Moderately
susceptibility
to erosion
High
susceptibility
to erosion
Very high
susceptibility
to erosion
Total
Chittagong Hill tracts
350
1,814
10,765
12,929
Chittagong & Cox’s Bazar
414
949
954
2,317
Greater Sylhet district
161
462
964
1,587
-
35
102
137
925 (5%)
3,260 (20%)
12,785 (75%)
16,970
Areas
Others (Comilla, Brahmanbaria,
Netrokona, Jamalpur etc)
Total
Rill and gully erosions in severe forms occur in the hill areas due to rapid removal of
the vegetable cover. Over 17% of the growing stock was depleted between 1964 and
1985 in the inaccessible state forest of the Chittagong Hill Tracts (SRDI, 2005), while
there is no data available for the unclassed state forests occupying 10,085 km2. They are
open to shifting cultivation, pineapple plantation and many other forms of disturbances.
A study shows that sediment loss from well stocked slopes ranged from 2.7 to 7.2 t-1ha1
year-1, while that from the clean field slope was 102 t-1ha-1year-1 (SRDI, 2005). More
severe forms of soil erosion are occurring in different parts of the hills due to nontraditional practices of the pineapple and rubber plantations (Layzell, 1982). It was
estimated that the annual soil loss under pineapple was in excess of 200 t-1ha-1year-1.
Landslide occurs in Bangladesh in the hills with 70% slope or steeper during heavy
depressional rainfalls. These are observed in the forms of landslip, mud flow, flow side,
slump and occasional rock fall. The area and extent increase with the increase of rapid
destruction of vegetable covers in the hills.
About 10,000 hectares of forest land, including reserve forest, have been brought
under jhum cultivation in the current season at eight upazilas in Khagrachari. Jhum is a
traditional method of cultivation of indigenous people in the Chittagong Hill Tracts.
Continuous tilling of hill slopes is also appears as a major concern of massive soil erosion
as forests and shrubs are cleared off
damaging biodiversity that may cause
environmental disaster. It was observed that soil loss from Jhum on steep slope, moderate
slope and gentle slope were 40.0, 35.0 and 32.0 t-1ha-1year-1, respectively (Khan et al.,
2008). On the other hand Jhum with vegetative barrier resulted soil loss of 9.0, 10.0 and
17.0 t-1ha-1year-1 in gentle slope, moderate slope and steep slope, respectively (Table 4).
Strategies for Arresting Land Degradation in Bangladesh
43
Table 4: Soil loss from Agricultural land use at different slopes due to Jhum
cultivation
Slope
Steep slope
Moderate slope
Gentle slope
Land use
Soil loss (t-1ha-1year-1)
Jhum
39.70
Jhum hedgerow
8.85
Local Jhum paddy
13.54
BRRIdhan 26
12.50
BRRIdhan 27
11.60
Jhum
35.05
Jhum hedgerow
9.85
Local Jhum paddy
13.72
BRRIdhan 26
11.63
BRRIdhan 27
11.95
Jhum
32.48
Jhum hedgerow
16.90
Local Jhum paddy
11.52
BRRIdhan 26
8.35
BRRIdhan 27
4.70
Source: (SRDI, 2005)
5.3. River Bank Erosion
River bank erosion is rampant in areas along the active river channels of the Ganges,
the Jamuna, the Meghna and the Tista and in the coastal and off-shore areas of
Bangladesh. In Bangladesh, bank erosion is caused mainly due to strong river current
enhanced by mechanized river traffic and/or channel diversion during the rainy season.
Bank erosion causes extensive loss of land, crops and hose holds and urban migration of
the landless and uprooted rural populace. This has created an unchangeable chronic
socio-economic problem in Bangladesh. About 1.7 million hectares of floodplain areas
are prone to river bank erosion.
Table 5: Rate of silt deposition in different types in Sylhet district of Bangladesh
Land Types
Silt deposition (kg/ha/year)
High land
2256
Medium highland
4120
Lowland
6696
Very lowland
10417
Source: Chowdhury (SRDI, unpublished)
44
Strategies for Arresting Land Degradation in Bangladesh
5. 4. Wind erosion
In Bangladesh, some areas are affected by wind erosion mainly in the districts of
Rajshahi and Dinajpur during the drier months of the year. Sand dunes in the young
alluvial lands (charlands) of Kustia and sandy beaches along the seashore are some of the
visual evidence of wind erosion in Bangladesh. Droughty situation leading to wind
erosion and its impact on agricultural production has been documented by Karim et al.
(1990), but quantitative data has not yet been estimated.
5.5. Salinization
In Bangladesh, salinization is one of the major natural hazards contributing towards
land degradation. Soil salinity is a seasonal problem that goes, among the three seasons,
in rabi season salinity affects crop production severely in the saline belt whereas in
kharif-1 salinity reaches about to neutral and does not affect crop production which is
unusual to rabi season. Maximum salinity occurs in the month of March and April, the
peak dry season and minimum salinity occurs in the month of July and August after the
onset of monsoon rains (Mondol, 1997). The coastal area of Bangladesh is about 710 km
long. Out of 2.85 million hectares of coastal and off-shore area (30 % of net cultivable
area) about 0.85 hectare of arable land were affected by varying degrees of soil salinity.
Recently, salinity both in terms of severity and extent has increased much due to the
intrusion of saline sea water because of the diversion of the Ganges water in the dry
season.
Impact of salinization is more apparent than other forms of land degradation. This is
partly because, its effects are substantial and visibly apparent, partly because the
degradation can be readily quantified. In Bangladesh, mainly rabi season crops (wheat,
barley, maize, boro, mustard and vegetables) are affected due to different degrees of
salinity. Production loss is estimated here for wheat considering an average yield of 2.0 t
ha-1 (Table 6).
Table 6 : Loss of production due to Salinization at different degrees of land
degradation (Karim and Iqbal, 2001)
Degree of degradation
Area (mha)
Relative
production loss
Total production loss
(million ton) of wheat
Light
0.40
15%
0.12
Moderate
1.60
65%
2.1
Strong
1.10
100%
2.2
Total
4.42
For management of saline soil in different areas of Bangladesh, Bangladesh
Agricultural Research Institute (BARI) conducted some experiments on mungbean,
tomato, watermelon and chilli to find out the effective measures as well as to have better
yield and their findings showed that drip irrigation in raised bed with mulch for tomato
Strategies for Arresting Land Degradation in Bangladesh
45
and watermelon and manual pump irrigation at an interval of seven days in raised beds
with mulch for chilli was found more effective for the production of the crops (BARI
Annual Report, 2007). Introducing high yielding salt tolerant variety (BRRI dhan 47) for
boro and BR 23, BRRI dhan 40 and BRRI dhan 41 could be able to produce sustainable
grain yield in the coastal regions (BRRI Annual Report, 2007). Special crop and soil
management practice should be developed for saline water irrigated agriculture.
Introduction of salt tolerant varieties and technologies of different crops like mungbean,
barley, soybean, mustard and adaptation to coastal crops agriculture to combat salinity
under wet-bed-tillage method and tidally flooded agro-ecosystem through conventional
relay cropping systems would be better possible option.
Table 7: Comparative study of the salt affected area between 1973 to 2009 in
Coastal areas
Year
1973
2000
2009
833.45
1020.75
1056.19
Salt affected area
increased during last
9 years (000’ha,
2000-09)
Salt affected area
increased during last
36 years (000’ha, 197309)
35.44 (3.5%)
222.74 (26.7%)
5. 6. Acidification
Loss due to acidification has been estimated in terms of relative loss in rice
production assuming an average yield of 3.0 t ha for high yielding varieties of rice. The
relative production (rice) loss due to acidification is 15, 50 and 100 percent due to light,
moderate and strong acidity, respectively (Table 8).
Table 8: Land degradation due to Acidification at different degrees (Karim and
Iqbal, 2001)
Degree of degradation
Light
Moderate
Strong
Area (mha)
Relative
production loss
Total production loss
(million ton)
-
15%
-
0.06
50%
0.09
-
100%
-
Total
0.09
5.7. Water logging
In Bangladesh 2.6 m ha land is affected by water logging. Sometimes heavy monsoon
rain may cause water logged soil condition which is one of the serious environmental
constraints for crop production. Screening and development of waterlogged tolerant
varieties, switching to alternative cropping patterns with respect to altered agroecological zones etc. could help to mitigate the problem.
46
Strategies for Arresting Land Degradation in Bangladesh
The low-lying area surrounded by higher ground and having no natural outlet for
surface drainage; usually flooded deeply during wet season is common in Bangladesh and
covers the Beel, Jheel, Haor , Baor that accumulates surface runoff water through internal
drainage channels. Many of the beels dry up in the winter but during the rains expand
into broad and shallow sheets of water. In Bangladesh, there are thousands of beels of
different sizes. Some of the most common beels are Chalan beel, Hakaluki haor,
Gopalganj-Khulna beel and Arial beel. About 8000 hectares of water logged land in
Khulna-Jessore areas (popularly known as Bil Dakatia) is the result of human induced
degradation due to faulty construction of embankment. More than 276 numbers of smallbig sizes having moderately shallow and deeper depth types comprises in Hakaluki haor
from where rice is harvested each year.
The Jheels are commonly seen in the southwestern Ganges deltaic parts of the
country. They remain deeply flooded in the wet season. In dry season, jheel lands are
used for agriculture and as pasture for cattle. Total gross area of Bhabadah (Avaynagar,
Monirampur and Keshabpur upazillas of Jesore district) and its adjacent area is about
94,900 ha. Out of which 61, 280 ha has been promoted to cultivable area though this area
is being inundated for a long time and it is curse for the farmers. In the reclaimed area,
Aus (3610 ha), Aman (6815 ha) and Boro (10,160 ha) are now cultivated after
improvement by the co-operation of Bangladesh Army during 2007-2008 (The Daily
Prothom Alo, 25th April, 2008).
Haors are located in the north eastern part of greater Sylhet and greater Mymensingh
regions. During monsoon a haor is a vast stretch of turbulent water. The basin includes
about 47 major haors (some important haors are; Hail, Hakaluki, Tangua, Kawadighi,
Balai, Gurmar) and some 6,300 beels of varying sizes, out of which about 3,500 are
permanent and 2,800 are seasonal water bodies. During the dry season, most of the water
drains out and these lands are extensively used for Aman rice cultivation. No cropping
pattern is developed centering the areas. Boro rice crop is practiced in the haor areas only
in dry season of the year.
All wetlands are subject to sedimentation composed of clay soils rich in organic
matter, and crops, which can tolerate water logging and inundation are grown. Before the
introduction of mechanized dry-season irrigation, deep water rice or broadcast aman rice
(floating rice) were is the major crops in the wetlands during the rainy season. The
immediate lands adjacent to the highlands are shallowly flooded and should be used for
agriculture. BR-22, BR-23, BR-47, BINA shail, Nijershail and local aman rice are
recommended to broadcast in the seedbed in early August (AIS, 2007). BARI has
developed some water logged varieties on Sesame (BARI Til 3; BARI Annual Report,
2007).
5. 8. Decline in Soil Fertility
A good soil should have an organic matter content of more than 3.5 percent. But in
Bangladesh, most soils have less than 1.7 percent, and some soils have even less than 1
percent organic matter. Considering the NARS data base, organic matter content of
Bangladesh soils has been summarized (Karim and Iqbal, 2001). In Bangladesh,
depletion of soil fertility is mainly due to exploitation of land without proper
Strategies for Arresting Land Degradation in Bangladesh
47
replenishment of plant nutrients in soils in addition to decline the organic matter content.
The problem is enhanced by intensive land use without appropriate soil management. The
situation is graver in areas where HYVs are being cultivated using low and unbalanced
doses of mineral fertilizers with little or no organic recycling. Research results have
shown that quite high rates of fertilizer (about 200 kg NPKS nutrients/ha) are necessary
for HYV rice cultivation where the soil has been degraded (low fertility level) due to
prolonged cropping. For light type of degradation, an average input of 100 kg nutrients
(NPKS) ha-1 will be required to obtain moderate yield of cereals (Karim and Iqbal, 2001).
1969-70
2.5
1989-90
1999-2000
2004-2005
OM %
2.0
1.5
1.0
0.5
0.0
Z
AE
28
Z
AE
25
Z
AE
1
Z3
E
A
Z
AE
29
Z
AE
19
Z
AE
11
Z
AE
9
Changes in SOM in different AEZ
6. Levels of Land Degradation
The degree to which the land is presently degraded is estimated in relation to changes
in agricultural suitability, in relation to declined productivity and in some cases in
relation to its biotic functions. Three levels of degradation namely; light, moderate and
strong are recognized. In terms of the effects, the farmer is still using land with moderate
degrees of degradation, but the boundary with strong degradation is the point at which
land use has to be abandoned. It is uncommon for the farmers that they are not aware of
the land degradation situation. According to Karim and Iqbal (2001), total cereal
production loss was 1.06 and 4.27 t yr-1 due to water erosion and fertility declination,
respectively. The estimated cost was 140.72 and 544.18 million U.S. dollar in case of
water erosion for cereal and nutrient loss, respectively (Table 9). Similar estimated cost
was 566.84 and 461.04 million U.S. dollar in case of fertility for cereal and nutrient loss,
respectively. However, in case of salinization, estimated cost was 586.75 U.S. Dollar. In
case of severe forms of degradation, like salinization and water logging, land productivity
can be restored by reclamation. In case of soil erosion, some of the effects may appear to
be reversible. Arresting further erosion by soil conservation measures and restoring lost
nutrients and organic matter are some of the measures.
48
Strategies for Arresting Land Degradation in Bangladesh
Table 9: Estimates of economic losses from different types of land degradation in
Bangladesh
Types of land
degradation
Degraded area
(million ha)
Water erosion
(mostly floods
and riverbank
erosion)
1.70
Fertility
decline
3.20
Degree of
degradation
Light to
strong
Light to
moderate
Loss estimate
(million ton year-1)
Financial loss
(million $ year-1)
Cereal production loss:
1.06
Nutrient loss: 1.44
140.72
Cereal production loss:
4.27
additional input loss:
1.22
566.84
544.18
461.04
Salinization
3.10
Light to
strong
Total production loss:
4.42
586.75
Acidification
-
Light to
moderate
Total production loss:
0.09
11.95
Source: Land degradation situation in Bangladesh, BARC, 1999
7. Climate Change induced Land Degradation
Bangladesh will face another hazard, the sea level rise due to global warming. The
losses could be really colossal; i) inundation of the whole coastal belt, ii) displacement of
some 30 million people who will become refugees in their own country, iii) huge loss of
agricultural production will result in widespread hunger and poverty and iv) more than
10% of the GDP could be lost. The above are some examples of the present and potential
impacts in Bangladesh. The extent and intensity of the various land degradation processes
would differ, however, from country to country. The sea level rise due to global warming
could be a very serious threat to Bangladesh in future. It is the time that the scientists,
policy makers and farmers can take appropriate measures to face the problem nationally
and regionally. Therefore, climate parameters should be considered seriously to minimize
land degradation.
7.1. Rainfall
Rainfall is the most important climatic factors in determining land degradation and
potential desertification. Rainfall plays a vital role in the development and distribution of
plant life, but the variability and extremes of rainfall can lead to soil erosion and land
degradation. Rainfall intensity is the most important factor governing soil erosion caused by
rain (Zachar, 1982). Dry land precipitation is inherently variable in amounts and intensities
and so is the subsequent runoff.
7.2. Temperature
Seasonal and daily changes in temperature can affect the soil moisture, biological
activity, rates of chemical reactions, and the types of vegetation. High temperatures will
Strategies for Arresting Land Degradation in Bangladesh
49
also increase evaporation and further reduce available soil moisture for plant growth. The
minimum sea level rise of 5.18 millimeter occurred in the Khulna region, south-western
part of the country. Although the rate of sea levee rise is very slow, if continues at this
rate the sea level may rise 85 centimeter by year 2050. Water stagnation and salinity will
increase in many areas.
7.3. Flood
Flood is a natural phenomenon that has occurred for millions of years and
continuously shapes the earth. Bangladesh was affected with floods more than 23 times
during 1971-2000 at different intensities (FAO, 2000). More than 1.32 m ha of net
cultivated area (NCA) was severely affected and 5.05 m ha of NCA was moderately
affected due to floods (flash, rain water, river water and tidal floods) which directly and
indirectly affect land degradation. The cyclones and wind affect 2.80 m ha of coastal area
and are subjected to damaging effect.
Flood water usually causes damage to current crop as well as future crops. Besides, it
also hampers seed-bed, orchards and agro-forestry. Moreover, Agro-based material and
other properties are affected by flood especially, standing food crops, fisheries, livestock,
and house hold and other community structures and roads, trees etc. A havoc cyclone
“SIDR” (November 15 2007) affected the southern parts of Bangladesh which causes
inflicted losses. These are given below according to “The Daily Ittefaq” (18 December,
2007)
ƒ Loss of lives
ƒ Monetary losses
ƒ Affected people
ƒ Damages of crops
ƒ Household’s affected
ƒ Affected roads & highways
ƒ Untraced people
ƒ Injured
ƒ Affected educational institute
ƒ Affected sanitary systems
3363
6100 crores (Tk.)
1 crore
13 lacs m tons
15 lacs (fully damaged 5.64 lacs)
8000 km
871
55 thousands
8000 (4489 Pri sch, 3750 H. sch & coll)
70%
7.4. Carbon Sequestration and Land Degradation
Scientists agree that global climate change such as global warming is attributable to
elevated levels of atmospheric carbon dioxide which created an impact on the increasing
droughts and desertification in the Asian region. Land degradation is an insidious process
that threatens the sustainability of agriculture, not only in the arid and semi-arid regions,
but also in the sub-humid and humid regions, as a result of the loss of agro-ecosystem
capacity to meet its full potential (Lal, 2004). Resulting from complex, and little
understood, interactions among periodic weather stresses, extreme climatic events, and
management decisions, land degradation is a serious global concern in a world searching
50
Strategies for Arresting Land Degradation in Bangladesh
for sustainable development to meet the needs of a rapidly increasing human population,
to reverse the negative impacts of our choices on the environment in which we live, and to
fairly distribute the world's resources in a socially justifiable manner. Three of the most
important green house gases (GHGs) related to agricultural activities is carbon dioxide
(CO2), methane (CH4), and nitrous oxide (N2O) which are responsible for global
warming (Schlesinger, 2000).
7.5. Drought management
Drought is a major disaster affecting the people, especially in the rural areas, who
maintained their livelihood from farms and natural resources. Since the people of the rural
areas are quite dependent on the sources available to them which are prone to drought
leading to low products and eventually lower income so they are extremely vulnerable to
drought. Poverty is both a cause and consequences of drought.
Drought is a multi-faceted phenomenon which is an inevitable part of normal climate
fluctuation and should be considered as a recurring environmental feature. The droughts
are of: meteorological, hydrological, agricultural and socio-economic (Wilhite and
Glantz, 1985). Drought of different intensities occur in Bangladesh, which severely
affects annually about 2.3 million ha in the Kharif season and 1.2 million ha in the dry
(Rabi and pre Kharif) seasons (Khan et al., 2008). Drought is a very common natural
phenomenon in Bangladesh. It can cause from 30 to 70% crop loss in a year. Drought
occurs due to; i) lack of rainfall, ii) lack of irrigation water, iii) excessive heat wave and
iv) no organism coverage on sandy and sloppy soils etc.
The inter action between these types of drought is illustrated meteorological,
hydrological, agricultural and socio-economic drought occurs less frequently than
meteorological drought alone because impacts in these sectors are related to the
availability of surface and subsurface water supplies. It usually takes several weeks before
precipitation deficiencies begin to produce soil moisture deficiencies leading to
stress on crops, pastures and rangeland. Continued dry conditions for several months at a
time bring about a decline in stream flow and reduced reservoir and lake levels and
potentially, a lowering of the groundwater table. When drought conditions persist for a
period of time, agricultural, hydrological and socio-economic drought occurs, producing
associated impacts. The droughts are of four types in context of agriculture. These can be
classed as; extreme, moderate and regular drought is treated if there is one crop loss is of
70-90, 40-70 and 15-40 percent, respectively.
8. Minimizing Land Degradation
In agriculture, there are many management practices that can be employed to counter
land degradation. These are:
8.1. Plantation
Trees can accumulate C in perennial biomass of above-ground and below-ground
growth, as well as in the deposition of soil organic matter (Baral and Guha, 2004).
Carbon accumulation in the soil is the major sink for hedgerow inter-cropping systems
used to produce biomass for improving soil fertility. Since animal manure contains 4060% C, its application to land should promote soil organic carbon sequestration
(Makumba, 2007).
Strategies for Arresting Land Degradation in Bangladesh
51
8.2. Organic agriculture
Organic agriculture uses a whole system approach based upon a set of processes
resulting in sustainable ecosystems, safe food, good nutrition, animal welfare and social
justice. Organic agriculture minimizes carbon dioxide emissions from agricultural ecosystems (Layzell, 1982).
8.3. Shifting cultivation
It avoids the need for farmers to use to restore soil fertility since it increases yield
per unit area through organic intensification integrated with animal production.
8.4. Preserving soil fertility/Fertilizer management
Maintanance of soil fertility through enhancing the natural nutrient cycles can combat
pests and weeds through ecological techniques and thus reduces fossil fuel consumption.
The emphasis on strengthening the internal nutrient and energy cycles inherent in organic
agriculture offers a means to sequester carbon dioxide in the soil and in the vegetation.
The study looks at how organic agriculture could contribute to reducing green house
gas (GHG) emissions and mitigate the impacts of climate change. Specifically, organic
agriculture encourages and enhances biological cycles within the farming system;
maintains and increases long-term fertility in soils and minimizes all forms of pollution
(IFOAM 1998). It is generally recognized that the most important environmental factor
that is causing climate change is the production of green house gases (GHG), particularly
carbon dioxide, methane and nitrous oxide. Agriculture is the main contributor of
methane and nitrous oxide, and to a lesser extent of carbon dioxide (IGBP, 1998).
Organic agriculture is often equated with the use of organic fertilization techniques systematic application of manure and compost from animal and crop residues, croplegume rotations, green manuring with legumes, and agro-forestry with multipurpose
leguminous trees (Franzlubbers, 2004). Much expertise has been developed in these
techniques and the use of these practices has produced outstanding improvements to
productivity and environmental health.
8.5. Carbon Management Approaches
Maximizing C input to the terrestrial biosphere from the atmosphere is possible in
agricultural systems (Lal et al., 1998) through a variety of management options,
including: i) plantation, ii) tillage management, iii) fertilizer management, iv) integrated
management, v) minimizing C loss on C sequestration, vi) reducing soil disturbance by
less intensive tillage and erosion control, vii) maintaining surface residue cover to
increase plant water use and production and viii) surface residue cover promotes greater
stabilization of soil aggregates and resistance of soil organic C to decomposition.
If the current momentum for expansion of the organic sector in agricultural
production can be maintained, it will also bring environmental benefits and significantly
contribute to reducing emissions of green house gases and to preventing further land
degradation in the region. The availability of huge amount of biomass may be the only
problem in expansion of organic farming.
52
Strategies for Arresting Land Degradation in Bangladesh
Management Approaches
It is the technique for efficient utilization of the soil through an agricultural system
that protects soil against physical and chemical degradation. This protection is a function
of all the factors such as slope, initial acidity, morphological and chemical properties of
the soil, and ragouts of the climates.
Principles of Soil Conservation from Water Erosion
Many practices have been developed to reduce soil erosion by water erosion. Not all
practices are applicable in all regions. However, the principles are same everywhere.
These principles are: i) reduce raindrop impact on the soil, ii) reduce runoff volume and
velocity of water and iii) increase the soil’s resistance to erosion.
Principles of Soil Conservation from Wind Erosion
Many practices have been developed to reduce soil erosion by wind erosion. These
principles are ; i) reduce wind velocity near the ground level below the threshold velocity
that will initiate soil movement, ii) remove the abrasive material from the wind stream
and iii) reduce the erodibility of the soil.
The purpose and use of various conservation techniques can be described under the
widely accepted headings of agronomic or biological measures, soil management, and
mechanical methods. Agronomic/biological measures utilize role of vegetation to
minimize erosion. Soil management concerned with preparation of soil to improve
structure and promote vegetation which will ultimately reduce erosion. Mechanical or
physical methods manipulate topography, reduce slope length by structure and thus
reduce erosion.
Conservation versus Reclamation
Conservation implies continued good management of preferred land uses.
Reclamation of severely degraded land implies drastic costly action. Usually, including
remedial changes in land use, soil amelioration and construction of specialized works
need to be done. Soil conservation techniques that ensure prevention of damage to the
land should be applied in every situation, but reclamation of seriously degraded land
should only be attempted when there are compelling reasons to do so.
Planning a Soil Conservation Strategy
The success of conservation schemes depends on:
i)
how well the nature of the erosion problem has been identified;
ii)
the suitability of the conservation measures selected to deal with the problem; and
iii)
the willingness of the farmers to implement the proposed agricultural or land use
system.
9. Land Resources Conservation Strategy
The major reasons of land degradation in Bangladesh are human interference and
water-related activities on the land especially in intensive agricultural areas. Considering
Strategies for Arresting Land Degradation in Bangladesh
53
the major reasons of land degradation, the following conservation strategies are outlined
below:
i.
In Bangladesh there are many uses of land and there are many misuses and abuses of
land also. That is why there should be a land use policy which comprise of land
zoning as per land suitability, proportionate and equitable distribution and protection
of land from misuse and abuse.
ii. An effective policy should be framed for the disposition and utilization of fragile
newly accreted land in the estuary.
iii. People’s participation needs to be ensured in land resources conservation creating
awareness through mass media and other means.
iv. Prioritization in land management research through NARS institute of Bangladesh
for sustainable land resources conservation.
v. Institutional facilities need to be developed for effective land resources, land
utilization and soil conservation programmes.
10. Combating Land Degradation and Appropriate Cropping
•
Adjustments in cropping patterns either through rice or jute based cropping patterns
incorporating legume/green-manuring crops and grain-legume crops to improve soil
health and status of soil-organic matter and promoting crop diversification.
•
Inclusions of Modern Crop Varieties are to be adopted to promote biodiversity as
well as for conservation of local germ plasm.
•
Land degradation is to be managed for safe environment and sustainable crop
production. More attention is needed for the following aspects:
10.1. Research
‰ Survey of the present state of degradation, cropping and land capability and
‰
‰
‰
‰
‰
‰
‰
assessment of the severity and extent of the problem.
Monitoring of change (both physical and chemical) in soil characteristics.
Conduct long term soil fertility researches.
Develop practical methods of improving and maintaining soil organic matter status.
Research on the underlying causes of degradation, and the integration of land
resource management with wider aspects of population policy.
Restoration of degraded land and appropriate crop planning.
Reclamation of saline soils and introduction of salt tolerant crop varieties.
Soil conservation and watershed management
10.2. Extension
‰
Balanced use of chemical fertilizers and adoption of IPNS (Integrated Plant
Nutrition System)
‰ Encouragement of organic recycling to maintain soil organic matter and soil health.
54
Strategies for Arresting Land Degradation in Bangladesh
‰ Introduction of GM/Grain legumes in the pattern and use of bio-fertilizers in legumes
‰ Creation of mass awareness about soil degradation and appropriate cropping
‰ Planted withdrawal of ground water to avoid over exploitation
‰ Afforestation
and development of agro-forestry including applications for
conservation.
‰ Mangrove plantation in the coastal and offshore islands in order to create wind-break
against ravaging cyclones and tidal surges
10.3. Policy Options
‰ Comprehensive land use policy and its strict adherence
‰ Policy framework in line of international/regional agreements on deforestation and
water sharing
‰ Development of sustainable long-term and environmentally sound site-specific
production plan for optimum utilization of land, soil and water resources
‰ Ensure effective participation of the people
11. Conclusion
Land degradation is a threat to natural resources with consequences on food security,
poverty and environment stability. The increase in temperature will create an impact on
land degradation processes, including floods, mass movements, soil erosion, salinization,
water logging and carbon sequestration in all parts of the globe. It is essential to improve
the monitoring of land degradation as well as climate change. Innovative and adaptive
land management responses to inherent climatic variability and natural hazards must be
identified for sustainable land management. Land degradation typically occurs because of
land management practices or intervention that is not sustainable over a period of time. An
increase of CO2 will cause an increase in temperature and increased land degradation due to
increase in frequency and intensity of severe weather and extreme climatic events (floods &
droughts). Global warming and climate change have detrimental impact on soil fertility
and crop productivity. Soil organic matter is decreasing due to rise of soil temperature.
Extent and severity of natural disaster like flood, drought, cyclone and tidal surges
will be more in the coming years. Increased drought and salinity, prolonged inundation
and excessive soil erosion will reduce the crop area and yield. Appropriate crop
management practices should be followed in the affected areas. Selection of appropriate
crop species/variety should be chosen for specific area. Increased land degradation will
lead to reduced retention of soil moisture and increased soil erosion, and hence desert
encroachment. The information on land degradation must be applied in developing
sustainable practices to land degradation. Many things are common in South Asian
countries. There should be some joint program to combat land degradation. All the countries
will be mutually benefited if sharing of knowledge, joint pilot program, information and
exchange visit of scientist of South Asian countries are made possible. It is the high time to
exchange views and share ideas with the SAARC countries and work together to save the
man kind from the devastating effect of land degradation and its consequences.
Strategies for Arresting Land Degradation in Bangladesh
55
12. References
Acock, B. and Acock, C. 1993. Modeling approaches for predicting crop ecosystem
response
to climate change. In: International Crop Science, Vol..I., Madison, Wisconsin, USA. Crop
Science Society of America.pp.299-306.
AIS. 2007. Agricultural Information System. Agricultural Extension Office, Khamarbari, Dhaka.
BARI Annual Report. 2007. Bangladesh Agricultural Research Institute, Annual Report 20062007, Joydebpur, Gazipur.
BARC (Bangladesh Agricultural Research Council). 1999. BARC Publications. No. 34, Farmgate,
Dhaka.
BBS. 1997. Bangladesh Bureau of Statistics, Dhaka.
BRRI Annual Report. 2007. Bangladesh Rice Research Institute, Annual Report 2006-2007,
Joydebpur, Gazipur.
Baral, A., and Guha, G. S. 2004. Trees and carbon sequestration or fossil fuel substitution: The
issue of cost vs. carbon benefit . Biomass Bioenerg 27:41-55.
Blaikie, P. and Brookfield, H. 1987. Land Degradation and Society. Methuen London and New
York.
FAO. 1994. Drought Planning: A process for state government, Water Resources Bulletin,
Volume 27, No 1, pp 29-38.
FAO. 2000. The Role or organic Agriculture in Mitigating Climate change-a scoping study,
IFOAM, Bonn.
Franzluebbers A. J. 2004. Tillage and residue management effects on soil organic matter. In:
Magdoff F, Weil RR (eds). Soil organic matter in sustainable agriculture. CRC Press, Boca
Raton FL, pp 227-268.
Hillel, D. 1991. Identification of Strategies and basics of drought management in raugeland. 225
pp. Farsi language.
IFOAM (International Federation Organic Agriculture Movements). 1998. Basic Standards for
Organic Production and Processing-version 2005.IFOAM, Bonn.
Karim, Z. and Anwar Iqbal. 2001. Impact of Land Degradation, BARC Soils Pub. No. 42, Dhaka,
Bangladesh.
Karim, Z., Hussain, S.G. and Ahmed, M. 1990. Salinity problems and crop intensification in the
coastal region of Bangladesh. BARC Pub. No. 33, Dhaka, Bangladesh.
Khan, M. S., Rahman, M. M., Begum, R. A., Mondal, Alam, K., A. I., Islam, M. S. and Salahin,
N. 2008. Experiences with Problems Soils of Bangladesh. Soil Science Division,
Bangladesh Agrilcultural Research Institute, Joydebpur, Gazipur.
Kholiquzzaman, K. 2007. Report in the daily Bengali newspaper “Janakantha”, July 08, 2007,
Bangladesh.
Lal, R. 2004. Soil carbon sequestration to mitigate climate change. Geoderma 123:1-22.
Lal, R., Kimble J. M, Follett R. F. and Cole C. V. 1998. The potential of U.S. cropland to
sequester carbon and mitigate the green house effect. Ann arbor Press, Chelsea MI.
Layzell, D. 1982. Soil Consernation needs in Bangladesh. FAO/UNDP, Dhaka.
Makumba, W., Akinnifesi, F. K., Janssen, B. and Onema, O. 2007. Long term impact of a
gliricidia-maize intercropping system on carbon sequestration in southern Malawi. Agric
Ecosyst Environ 118:237-243.
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Mondal, M. K.1997. Management of soil and water resources for higher productivity of Coastal
saline rice land of Bangladesh. Ph.D. Thesis, UPLB, Philippines.
Siddique, K. 1997. Land Management in South Asia: A comprehensive study. The University
Press, Dhaka, Bangladesh.
Sivakumar, M. V. K. and Stefanskii, R. 2007. Climate and land degradation-an overview.
Environmental Science and Engineering. Subseries: Environmental Science. Series Editors
R. Allan, U. Forstner and W. Salomons. Springer-Verlag, Berlin, Heidelberg 2007.
Schlesinger, W. H. 2000. Carbon sequestration in soils: Some cautions amidst optimism. Agric
Ecosystem ENVIRON 82:121-127.
SAARC Statistical Data Book, 2006-2007, Volume 5, 2006/2007. SAARC Agriculture Centre,
Dhaka, Bangladesh.
SRDI (Soil Resources Development Institute). 2005. Reconnaissance Soil Survey Technical
Report, Khamarbari, Farmgate, Bangladesh.
UNEP. 1997. World Atlas of Desertification. Editorial Commentary by N. Middletown & D.S.G
Thomas. Edward Arnold, London
Wilhite, D. A. and Glantz, M. H. 1985. Understanding the drought phenomenon, The role of
definitions. Water Int 10:11-20.
Zachar, D. 1982. Soil Erosion. Chapter IV. Erosion factors and conditions governing soil erosion
and erosion processes. Elsevier Scientific Publishing Company. Amsterdam, Netherlands.
58
Strategies for Arresting Land Degradation in Bhutan
Content
1. Introduction
2. Land degradation - a global issue
3. Land degradation in Bhutan - a natural and man-made process
4. Status of land degradation
5. Types of land degradation
6. Factors contributing to land degradation
6.1. Unsustainable Agriculture
6.2. Forest degradation
6.3. Forest harvesting
6.4. Forest Fires
6.5. Livestock Rearing and Grazing
6.6. Land use intensification and competition
6.7. Mining and quarrying
6.8. Infrastructure development
6.9. Policy gaps
7. Current Strategies to address land degradation
7.1. Overall policy support
7.2 Institutional setting for land and environmental management
7.3 Bhutan – party to the United Nations Convention to
Combat Desertification (UNCCD)
7.4 Sustainable Land Management (SLM) Projects
7.5 National Action Program (NAP)
7.6 Land Management Campaign (LMC)
7.7 National Land Management Coordination Committee (NLMCC)
7.8 Other programs to strengthen SLM to combat land degradation
8. Conclusion
9. References
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Strategies for Arresting Land Degradation in Bhutan
59
1. Introduction
The Kingdom of Bhutan lies on the steep, long and complex southern slopes of the
eastern Himalayas (latitudes 26o47’N to 28o26’N and longitudes 88o52’E to 92o03’E,
landlocked between China to the north and India to the south. It has a geographical area
of 38,394 km2 and stretches roughly 300 km east to west and 170 km north to south. The
country is mostly mountainous and the elevation ranges from about 150 m asl in the
south to over 7,550 m asl in the north, resulting in extreme variation in climate,
vegetation, landscape and soils.
The country can be divided into three distinct climatic zones corresponding to three
main geographical regions, namely, the southern foothills, inner Himalayas, and higher
Himalayas. The southern belt has a hot humid climate with temperatures remaining fairly
constant throughout the year, between 150C and 300C and rainfall ranging between 2,500
and 5,500 mm. The central inner Himalayas have a cool, temperate climate with average
rainfall of about 1,000 mm and a mean annual temperature of about 15oC. The higher
northern region has an alpine climate with annual rainfall around 400 mm and 2 to 6
months of frost per year. Much of the rainfall is concentrated in the summer with the
southwest monsoon accounting for 60 percent of the total rainfall.
About 72.5 percent of the land is under forest cover, 7.8 percent is arable land, 3.9
percent of pasture or meadows, 0.1 percent each under horticulture and settlement and the
remaining areas are permanent snow, barren rocks and scrubland. Out of the total
cultivable land, 17.7 percent is wetland, 76.4 percent is dryland, 5.8 percent is orchard
and the rest constitutes pangshin and kitchen garden (Table 1 & 2). The total population
of the country in 2005 was 634,982. The urban population consisted of 31 percent while
69 percent were in the rural areas. The population for 2008 was projected at 683,407
(Statistical Yearbook of Bhutan 2008). The population density of 16 persons/km2 is one
of the lowest in the world. The annual rate of population growth is estimated at 2.5
percent.
Agriculture is the mainstay of the Bhutanese economy contributing 22 percent to the
GDP (Poverty Analysis Report 2007). While about 69 percent of the Bhutanese are still
dependent on land-based income or on complete subsistence farming, Bhutan has limited
resources of productive land because of its rugged terrain and steep slopes. On an
average, each household has about 3.5 acres of arable land but more than 60 percent of
the total households have less than 3 acres.
Table 1: Land use of Bhutan
Land use
Forest Cover
1. Parks and wildlife sanctuary
2. Biological corridors
Pasture
Horticulture
Agricultural land
Settlement
Others
Percentage of area (%)
72.5
40.2
9.5
3.9
0.1
7.7
0.1
15.7
Source: Facts and figures of RNR Sector 2003 & RNR Compendium 2008
60
Strategies for Arresting Land Degradation in Bhutan
Table 2: Distribution of land under Arable Agriculture
Classification
Percent
Area (acre)
Wetland (irrigated)
17.7
68,382
Dryland (rainfed)
76.5
2,95,252
5.8
22,570
Orchard
Total
100
3,86,204
Source: Statistical Yearbook of Bhutan, 2008
2. Land degradation - a global issue
Land degradation is defined as “the aggregate diminution of the productive potential
of the land, including its major uses (rain-fed, arable, irrigated, rangeland, forest), its
farming systems (e.g. smallholder subsistence) and its value as an economic resource”. It
is seen as a major environment and sustainable development issue across many countries
around the world. Its connection to rural poverty, livelihood and climate change are well
observed phenomena. The global recognition of this important issue has led to signing of
important protocols and conventions. The United Nation Convention to Combat
Desertification (UNCCD) was adopted in June 1994 and as of July 2008, 193 countries
had become party to this international treaty. Realizing the benefit and the need to join
UNCCD, the 81st National Assembly session in August 2003 ratified Bhutan’s
membership to the Convention with the aim to combat land degradation.
3. Land degradation in Bhutan - a natural and man-made process
Land degradation in Bhutan is a natural phenomenon as well as man-made. In the
dynamic mountain setting of Bhutan, land degradation is a natural and inevitable process.
Mass movements, floods and soil erosion occur & driving for gravity are water on steep
mountain slopes with complex geology and geomorphology. As in most parts of the
relatively young Himalayan mountains, much of the landscape of Bhutan is only quasi
stable, and needs only a small trigger to destabilize it from its equilibrium state and for its
surface materials to slip down slope and eventually be washed downstream. Therefore,
the natural events, waiting to happen, can easily be triggered off by human activities
(Chenccho et al., 2003).
The natural process of land degradation is further compounded and accelerated by
anthropogenic factors such as unsustainable agriculture practices, deforestation, forest
fires, overgrazing, infrastructure development, urbanization and mining. These practices
have resulted in the loss of soil and land productivity through erosion and for some
households, the land holding sizes have reduced due to mass movements and severe
erosion. Further, the limited land resource is constantly competing for, especially
between agriculture and fast growing urban areas. The rural-urban migration resulting in
increasing fallow land is also reducing the total area of arable land under production. In
the absence of regular management and maintenance, land left fallow is susceptible to
Strategies for Arresting Land Degradation in Bhutan
61
degradation through exposure to various forms of erosion. The land fragmentation mainly
due to split inheritance among families result in unsustainable intensification of both land
and land based resources.
In Bhutan, land degradation occurs mostly in eastern and southern regions. These
areas constitute over 70 percent of the country’s arable land with more dryland
cultivation on steep slopes in the east and high monsoon rainfall intensity in the south,
combined with relatively higher population density. Across the country, the arable land
mostly located on steep slopes is often cultivated without any soil conservation measures
and hence surface runoff carrying fertile topsoil is a common farming problem
throughout the country. Landslides along roads, gullies along water courses, increased
stoniness and shallow soil depths, decline in soil fertility in the farmers’ fields and
hydropower plant siltation are some visible signs of land degradation.
4. Status of land degradation
Land degradation in Bhutan is not well documented. Information on land degradation
aspects such as the cause, extent, trends, and other related issues such as the economic
and social implications of land degradation is scarce and sketchy. However, while no
definitive figures are available, there are sufficient physical evidences of various forms of
land degradation taking place. FAO/AGL, 2005 provides some rough estimates on the
extent and severity of land degradation in Bhutan. It is estimated that about 8.39 percent
or 3,365 km2 of the country’s land is degraded with varying degrees of intensities. While
1.69 percent and 4.15 percent are degraded lightly and moderately, respectively, about
2.54 percent is degraded very severely (Table 3). The extent of degraded land compared
to other countries in the region might be relatively small but in the Bhutanese context this
is significant as it has limited area of arable land. Some of the important and common
impacts of the current land use pattern and practices in Bhutan could be summarised as:
• Farming on steep slopes resulting in soil erosion and decline in soil/land productivity
• Limited arable land is limiting the scope of expansion of agriculture
• Deforestation in fragile watershed areas is causing soil erosion and mass movements
resulting in sedimentation downstream
• Indiscriminate use of land for urbanization and industrialization leading to the risk of
wasting good arable land
• Anthropogenic activities exacerbate the natural degradation processes and accelerate
land degradation.
Table 3: Distribution and Extent of land degradation in Bhutan
Severity
Light
Area (km2)
Percentage of area
680
1.69
Moderate
1,667
4.15
Very Severe
1,018
2.54
Total
3,365
8.39
Source: FAO/AGL, 2005
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Strategies for Arresting Land Degradation in Bhutan
5. Types of land degradation
Four types of land degradation in Bhutan have been listed (Table 4).
Table 4: Types of land degradation processes in Bhutan
In Situ
Chemical
In Situ
Physical
Water erosion
Non-water
erosion
Others
Depletion of
soil organic
matter
Top soil
capping
Surface erosion Wind erosion Tectonic natural hazards
(Splash, Sheet, of soil
(earthquakes)
Rill)
Depletion of
soil nutrients
Sub soil
compaction
Piping erosion
Wind erosion Urban & industrial
of ash
(encroachment, pollution,
spoil tipping, riverbed
mining)
Water logging
Gully erosion
Cultivation or Mass movement caused by
tillage
gravity and slope instability
erosion
factors
Ravines
Glacial
erosion
(Nutrient
mining)
Soil
Acidification
Over
fertilization
Flash flooding by GLOF and
landslide-dammed lakes
outburst floods
Ravines
Bank erosion
Flooding
Water-induced degradation e.g. through soil erosion (splash, sheet and rill erosion),
gullies, ravines and flash floods is the most prominent and devastating form of land
degradation in the country. This form of degradation has resulted in the decline in soil
and land productivity through the removal of fertile top soils or loss of land physically
through concentrated erosion in rills, gullies and ravines. Mass movements, triggered by
gravity, acts as the second main degradation process in the Bhutan Himalayas, through
landslides (fall, slide and flows processes). In many parts of the country, water induced
degradation is mainly caused by poor management of water often at the tail end of
irrigated rice fields. Wind induced degradation is also extensive especially when the
fields are kept bare. Although it is difficult to quantify, this form of degradation is
assessed as being quite substantial and contribute to reduction in soil fertility status
through the removal of the fertile topsoil (SFU, 2005). Deep (up to 2m) aeolian deposits
are seen at many places between 2500 to 3500 m asl. (SSU, 2000) indicating some extent
of wind erosion.
In-situ chemical degradation, such as depletion of soil organic matter and nutrient
mining, and in-situ physical degradation, such as topsoil capping and subsoil compaction
are observed throughout Bhutan. These are some concealed but important forms of land
degradation contributing to the reduction of land productivity and crop yields.
Strategies for Arresting Land Degradation in Bhutan
63
Other land degradation processes such as the cultivation or tillage erosion is
predominant especially in steep dryland cultivation of maize in Eastern Bhutan and
potatoes in West-central regions. River or stream bank erosion and flash flooding are
extensive in the low lying areas of southern Bhutan and usually concentrated in
productive valleys. Salinization and waterlogging occur in pockets only, no reliable data
for which are available. Urban and industrial related degradation processes are more
severe is fast growing areas.
6. Factors contributing to land degradation
6.1. Unsustainable Agriculture
On the rugged and steep slopes, the proportion of agricultural land on slopes between
50-100 percent is about 29.4 percent and about 1.6. percent is on slopes greater than 100
percent. Cultivation in most cases is practised without proper soil and water management
measures. Improper management of irrigated paddy fields on steep slopes, shortening of
fallow period of tseri (slash and burn), burning crop residues, and lack of cover crop
establishment when necessary contribute to land degradation in numerous places. Further,
intensification of agricultural production as farmers move from traditional subsistence
farming to market based farming, introduction of high yielding improved crop varieties
and increased use of inputs especially of chemical pesticides and fertilizers have added to
the problem. With rising population, the land is increasingly used more intensively to
meet the food demand and under such condition, the imbalanced use of inorganic
fertilizers and nutrient mining are the main contributing factors to land degradation.
6.2. Forest degradation
Loss of vegetation due to pressure on forests, which occupy about 70% of the total
land area, is one of the main factors of land degradation. Over harvesting of the trees
beyond permissible limits, unsustainable fuel wood extraction, shifting cultivation,
encroachment into forest land, leaf litter extraction, forest fires and overgrazing are the
main factors leading to forest degradation.
6.3. Forest harvesting
To meet the demands for timber and fuel wood of the rapidly growing Bhutanese
population, the forest is increasingly being harvested in an unsustainable manner. The
Department of Forest and the Natural Resources Development Corporation Limited
(NRDCL) are supplying 284,800 m3 of wood annually. However, the estimated wood
demand is about 769,000 m3 per year, indicating a huge demand against the allowable
supply and one of the highest consumption rate per capita in the world. The excess
demand is somehow met from adhoc sources operated often without following the
sustainable forest management planning or system (mainly from rural timber allowances
brought into urban areas). Such unplanned extraction of wood from forests leads to
excessive extraction causing forest degradation.
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Strategies for Arresting Land Degradation in Bhutan
6.4. Forest Fires
Occurrence of frequent forest fires has been a major cause of degradation in many
parts of the country especially in the eastern region. Nearly half of the forest area burnt
between 1999/00-2006/07 in this region. Between 1992/93 and 2004/05, the Department
of Forest recorded 870 incidents of forest fires, affecting more than 128,000 hectares of
forest land. Between 1999/2000 and 2006/07, 476 incidents of forest fires were recorded,
affecting about 65,000 hectares of forest. Most forest fires are deliberate or man-made to
invigorate the growth of pasture or commercially valuable grasses such as lemon grass, or
sometimes due to general public carelessness. However, the formulation of more
stringent legislation and vigorous public awareness programmes and campaigns have
helped in reducing forest fire incidents and area burnt in recent years.
Apart from the destruction of vegetation, high intensity forest fires alter the physical,
chemical and biological attributes of the soil and leave the land prone to wind and water
erosion and also lower its productivity. Surface erosion often increases dramatically from
severely burnt forest areas in the initial year after a fire. Forest fires are concentrated in
the dry winter season.
6.5. Livestock Rearing and Grazing
Livestock rearing, especially of cattle, is an important activity among the rural
communities, particularly in the temperate and subtropical regions of the country. Almost
every household rear a certain number of cattle mainly for dairy products, meat, draught
power and production of dung and urine for farmyard manure. In the alpine and subalpine
regions, the rural semi-nomadic communities subsist largely on yak-herding. Yaks are
reared for dairy products, meat and transportation. Cattle population has increased from
320,509 in 2000 to 338,847 in 2005 and yak population from 34,928 to 45,538 during the
same period. Based on 1,737 km2 of pasture land in the country, the density of animal
(cattle and yak) per km2 of pasture land is 221. Grazing of this huge number, far beyond
the carrying capacity may lead to decline in plant species, land productivity and soil
erosion. With limited pasture land and land holding size of rural households, grazing is
usually on forest land and where grazing is extensive, forest regeneration is hampered
and change in vegetation induced. Severe forest degradation and land degradation is
reported from those areas that are commonly used for winter grazing by yak and summer
grazing by low land cattle.
6.6. Land use intensification and competition
With rapidly increasing population and socio-economic development, the limited
land resource is increasingly being competed for by various sectors, especially between
agriculture and urban development. Conversion of agricultural and forest land is
occurring each year to accommodate various development activities. These conversions
often take place with very little or no consideration of the land capability or suitability.
Between 1998 and 2007, about 161 hectares of prime agricultural land have been
converted to other forms of land use (Fig.1). Between 2003 and 2006, more than 3,600
Strategies for Arresting Land Degradation in Bhutan
65
hectares of forest land have been cleared for various infrastructure development activities
such as roads and power transmission lines. Further, as most of the land area suitable for
agriculture has already been utilized, marginal land areas are being brought under
cultivation to meet the food demand of the increasing population. At the same time, a lot
of land is being left fallow because of rural-urban migration, labour shortages, and lack of
irrigation facilities or assured irrigation water sources.
6.7. Mining and quarrying
Mining and quarrying in Bhutan are not very extensive and are operated mainly to
meet the domestic demand and for nearby markets in India and Bangladesh (marble,
gypsum, talc). Mines are located in few districts only and there are strict guidelines for
their operation. All mines are required to prepare a mine feasibility report along with an
environmental management plan before its operation is approved. Mining, however, has
been known to contribute to land degradation wherever it is being practised. The very
nature of the operation requires the disturbance of the soil and vegetation, and hence soil
erosion and siltation down slope are inevitable. As Bhutan has significant deposits of a
number of mineral resources such as limestone, coal, graphite, gypsum, slate and
dolomite, mining would become extensive in the coming years. As of October 2007,
there were 60 mines and quarries operating in the country.
6.8. Infrastructure development
With rapidly increasing population and modernization, the need for infrastructure
development has grown. Among others, roads and electrification are the two major areas
of infrastructure development being spread out rapidly and widely across the country.
The road network increased from 3,215 km in 2001 to 4,349 km in 2007. With the
establishment of several hydro power plants, the electrification programme targets to
electrify most rural areas of the country and hence an extensive network of power
transmission grids is being constructed across the country. While the development of
such infrastructure is inevitable and necessary, on a rugged terrain with fragile geologic
conditions it is environmentally challenging. Infrastructure development could leave
adverse impacts on landscapes through loss of vegetation, landslides and landslips due to
slope instability or geologic disturbances. Clearing of vegetation along transmission lines
and road corridors and road cuttings along steep and unstable slopes lead to a whole
range of land degradation processes. Road development and in particular farm road
construction, with less scope for mitigation works, are main causes of anthropogenic land
degradation. Efforts have been undertaken to develop an environmental friendly road
construction (EFRC) methodology, but cost concerns have prohibited a general
implementation of these guidelines.
66
Strategies for Arresting Land Degradation in Bhutan
Road
29.5%
Power
transmission line
50.8%
Government
building
19.7%
Fig. 1: Types of forest land conversion by percentage, 2003-2006
6.9. Policy gaps
Besides the very obvious aforesaid, natural and anthropogenic factors contributing to
land degradation, there are certain policy gaps in addressing land degradation. According
to Bhutan: State of the Environment 2000, the policy gaps encompass the following:
•
Absence of a well defined land and land use polices, leading to haphazard and
unsustainable use of land;
•
Absence of adequate land suitability and capability information, leading to improper
use of the limited land resource;
•
Lack of adequate inter-sectoral linkages to decide policies, strategies and practices
for resource conservation and their sustainable utilization;
•
Lack of adequate focus on a combined land and water (inter-dependent resources)
management strategy to make effective development plans; and
•
Lack of proper assessment and understanding of linkages between poverty and
sustainable land management.
7. Current Strategies to address land degradation
7.1. Overall policy support
Although there are policy gaps in addressing land degradation problems directly or
specifically, policy support towards the environment protection in general are being
strengthened rapidly. Bhutan’s Vision 2020 document emphasizes ecologically sensitive
approaches to its natural resources such as forest management. Bhutan’s constitution
requires a minimum of 60% of the land under forest cover, always. As Bhutan’s
development process is guided by the philosophy of “Gross National Happiness’ (GNH),
the non-material aspects of development is considered equally if not more important than
the gross national product. The conservation of environment is one the four pillars of
GNH, the other three being (i) equitable socio-economic development, (ii) preservation
and promotion of culture and (iii) promotion of good governance. Under the overall
umbrella of the “Conservation of Environment” pillar, protection of land from
degradation would also feature as an important area.
Bhutan’s development programs and activities are implemented through FYPs and
the current Tenth FYP document addresses environment as a cross cutting theme.
Strategies for Arresting Land Degradation in Bhutan
67
Sustainable land management has been mainstreamed in the Tenth FYP though in a
sectoral manner. As compared to the past FYPs, the current Tenth FYP has more SLM
elements.
Preparation and finalization of policies, strategies such as the land policy, land rules
and regulations, water act, and wetland protection framework are all underway that would
protect the land directly or indirectly from degradation. Within the Land Act 2007 of
Bhutan, there are provisions for land allotment and land swapping with government
reserved forest (GRF) land. With susceptibility to land degradation as one of the criteria,
one can qualify for land swapping with GRF or for resettlement to a better land.
7.2 Institutional setting for land and environmental management
The National Environment Commission (NEC) is the overall environmental advisor
to the Royal Government of Bhutan (RGoB). It prepares environmental legislation,
oversees compliance monitoring of the Environmental Assessment Act, and associated
regulations and guidelines. It coordinates the implementation of the National
Environment Strategy and national obligations to international environmental
conventions. The National Land Commission (NLC) is an independent authority and the
highest decision making body to exercise the jurisdiction and powers and discharge the
functions conferred by the Land Act of Bhutan. It lays down the policies, programmes,
regulations and guidelines related to land. Land acquisition, allotment, compensation and
conversion are also guided by the NLC.
7.3 Bhutan – party to the United Nations Convention to Combat Desertification
(UNCCD)
As in many countries around the world, land degradation is also seen as a major
environment and sustainable development issue in Bhutan. Its connection to rural
poverty, livelihood and climate change is a fairly well understood subject in the country,
especially with various studies being conducted on land degradation and its linkages to
other areas like poverty and environment. Recognizing this as an important issue, Bhutan
joined the UNCCD after ratifying it during the 81st National Assembly session in 2003.
As of July 2008, Bhutan is one of the 193 countries party to this international treaty.
The National Soil Services Centre (NSSC) of the Ministry of Agriculture and Forests
(MoAF) is the national focal agency for the UNCCD. The NSSC with its four units – Soil
Survey Unit, Soil Fertility Unit, Soil Microbiology Unit, and Soil and Plant Analytical
Laboratory (SPAL) has the mandate to coordinate land and soil management research
activities of the Renewable Natural Resources (RNR) sector and provide analytical
services. It functions as a referral agency for soil survey, soil and plant analysis, soil
fertility management and other soil related programs and projects. In addition, as the
UNCCD focal agency, it is also required to shoulder the responsibilities of combating
land degradation. The Centre manages two Sustainable Land Management Projects
through a multi-sectoral approach involving stakeholders at various levels (national,
district and local). The Centre coordinates and provides core technical advisory services
to all land management programs and activities in the country.
68
Strategies for Arresting Land Degradation in Bhutan
7.4 Sustainable Land Management (SLM) Projects
The NSSC executes two Global Environment Facility (GEF) funded SLM projects.
The projects are expected to put in place more permanent and workable strategies to
address land degradation problems in the country. The objective of these projects is to
strengthen institutional and community capacity for anticipating and managing land
degradation through enhancement of human resource capacity, policies, incentives,
technologies and knowledge for better management of land resources in the country. On
the whole, the projects aim to mainstream SLM in government policies and plans for
greater political and community support in combating land degradation.
7.4.1 SLM planning tools
In order to implement sustainable land management programs and projects
effectively, an effective participatory SLM planning method has been developed and
implemented successfully in the field. Unlike other planning processes, SLM planning is
a complete participatory planning at a community level and it is found to be very
effective. The SLM planning process makes use of tools like satellite images,
participatory natural resource maps, sketches, group discussions to help farmers come up
with simple, realistic, achievable plans. These SLM action plans contain prioritized SLM
interventions based on ranked land-based problems and identified causes of these
problems. A simple manual on participatory SLM planning has been prepared and a
separate manual for participatory natural resource mapping for SLM planning is being
prepared.
7.5 National Action Program (NAP)
As a member country to UNCCD, Bhutan has developed a National Action Program
(NAP) for land degradation along with an Integrated Financing Strategy (IFS) to help
implement the NAP and secure funding. The overall goal of the NAP is to “prevent and
mitigate land degradation and its impacts through systems and practices of sustainable
land management that protects and maintains the economic, ecological and aesthetic
values of our landscapes.” The overall goal will be pursued through the following set of
objectives: (a) conservation, rehabilitation and sustainable use of forest resources to
maintain well functioning forest landscapes; (b) development and promotion of
sustainable agricultural practices that enhances local livelihoods whilst maintaining the
productivity and stability of agricultural land; (c) integration of environmental
management measures in development activities that pose significant risks of land
degradation; (d) strengthening of systemic and institutional capacity to combat land
degradation and its impacts; and (e)information, advocacy and education to create
increased policy and public support for sustainable land management. The NAP analyses
the current policies and legislations of various organizations in relation to land
degradation and sustainable land management. It recommends approaches in addressing
land degradation issues in the country. This document will be a living document, updated
regularly based on the changing scenarios and will be the guiding document for the
country to deal with land degradation issues. The Integrated Financing Strategy identifies
the three possible sources of financing, i.e. internal, external and innovative, to help in
implementing the NAP.
Strategies for Arresting Land Degradation in Bhutan
69
7.6 Land Management Campaign (LMC)
With the calamitous impacts of land degradation becoming more and more visible
over the years, the Ministry of Agriculture and Forests initiated a national level land
management campaign (LMC) in 2005 and since then this has become an annual event.
The campaigns are conducted with the following objectives:
a. To create awareness on the importance of protecting land resources in a community
living in a fragile ecosystem
b. To be able to understand what are the anthropogenic factors responsible for land
degradation and soil erosions in particular
c. To introduce improved land management technologies that would include,
agronomic, vegetative and structural measures;
d. To mainstream land management activities into the regular institutional plans at all
levels (community, regional and national)
Thus, once a year event, seeks the participation of farmers, community leaders, students,
teachers, civil servants, non-governmental organizations, private entrepreneurs and
donors. Involvement of people from almost all occupations contributes to enhanced
awareness and mainstreaming of SLM. The campaign involves live demonstration of
various land management technologies on both private and government land. The
campaign sites are maintained, monitored and evaluated to see the impacts.
7.7 National Land Management Coordination Committee (NLMCC)
A National Land Management Coordination Committee (NLMCC) was established
in 2005 to support, oversee and coordinate land management activities at the national
level. The functions of the NLMCC has been awareness creation by mobilizing relevant
stakeholders particularly the local people in the implementation of land management
campaigns in the country. The NLMCC is represented by all relevant agencies within the
Ministry of Agriculture. As land degradation is an issue which cuts across various sectors
dealing with land, there is a need to establish a multi-sectoral land management
coordinating body in the country.
7.8 Other programs to strengthen SLM to combat land degradation
Programs to strengthen SLM directly or indirectly includes the following:
(Mainstreaming of SLM, 2008):
•
Establishment of the National Organic Program (NOP) within the Ministry of
Agriculture and Forests (MoAF) with the aim to work towards the development
and/or exploration of more scientific methods of organic farming and promoting
them among the farmers.
•
Soil fertility and land management program of MoAF aims to create and strengthen
data and information for SLM decision-making and mainstreaming into development
policies and plans, develop and I mplement SLM practices in the field and develop
the capacity of local communities for SLM.
70
Strategies for Arresting Land Degradation in Bhutan
•
Feed and fodder development promotes better pasture management on both
government and private land and help frame and implement national pasture land and
grazing management policies and strategies.
•
Promotion of environment-friendly construction techniques and improvement of
national highways, feeder roads and farm roads.
•
Capacity enhancement in Geo-scientific investigation and mineral development
program under the Ministry of Economic Affairs (MoEA) such as systematic
mapping, digital creation of database on geology, geomorphology, hydrogeology and
lithology and studies on slope stability, landslide mapping and geo-hazard assessment
which could enhance SLM.
•
Assessment and monitoring of climate change induced geological hazard program
under MoEA that focuses on time-series monitoring of glaciers and glacial lakes,
implementation of mitigation measures against glacial lake outburst floods, and
seismic risk assessment.
•
Development and sustainable management of forests through community
participation program of MoAF includes activities such as community and private
forest management, watershed management, soil conservation, and creation of forest
plantation and nurseries.
•
Forest resources development and management program of MoAF includes activities
such as creation of Forest management Unit (FMU), inventories of FMUs,
development of management plans for sustainable use of timber and other forest
resources and restocking of forests in the FMUs.
•
Forest protection and utilization program of MoAF protects forests from
encroachment and illegal use, and promoting the utilization of forest resources for
socio-economic development based on sustainable practices.
•
Nature conservation program of MoAF focuses on establishment and management of
protected areas and biological corridors.
•
Conservation of environment program of NEC which focuses on mainstreaming
environmental conservation needs in development plans and programs through
environment impact assessment (EIA) and strategic environment assessment (SEA)
processes, developing environmental legislations, guidelines and standards,
strengthening of environmental information, monitoring and reporting systems (State
of Environment, Bhutan, 2001).
•
The National Land Commission’s cadastral surveying and mapping is being
conducted across country in accordance with the relevant policy and legislative
framework provided by the Land Acts (1979 and 2007) of Bhutan. This would
provide accurate information on household land holding sizes and land use categories
for informed planning and decision making;
•
Land cover data and maps being updated for better information on land use types and
coverage in the country;
Strategies for Arresting Land Degradation in Bhutan
71
•
A Dynamic Information Framework (DrukDIF), is being developed, a simulation
model with time series data set (biodiversity, land cover, land use, & hydrology) with
climatic data to predict scenarios and develop appropriate interventions; and,
•
Curriculum on SLM for the non-formal education system developed with the aim to
develop it further and incorporate into the formal education system, later on.
8. Conclusion
Land degradation in Bhutan constitutes a serious challenge. The dynamic and often
extreme Himalayan landscape, with its steep and long slopes, inherently is prone to
natural degradation processes. Loss of agricultural land and decline in productivity
through degradation are serious constraints for the almost 70% of the Bhutanese who are
dependent on land for their subsistence and livelihoods. Since only 8% of the country’s
total land area is arable, any further loss of land or decrease in productivity would have
serious implications.
Land degradation is dominated by water as a degrading agent through surface erosion
(splash, sheet and rill), gully formation, bank erosion and (flash) flooding. Mass
movement driven by gravity is a secondary, but often very destructive process, often
interacting closely with water-induced degradation. Other land degradation processes
identified are in-situ chemical and physical degradation, wind and glacial erosion,
seismic events, flash flooding by GLOF and landslide-dammed lake outburst floods and
cultivation or tillage erosion on the steep Bhutanese slopes. Anthropogenic activities,
closely related to the strong growth in developmental activities over the last decades,
such as road construction and urban growth, have exacerbated and accelerated the
existing natural land degradation processes.
A number of factors that contributes to land degradation in Bhutan are:
•
Unsustainable agriculture as a result of cultivation on steep slopes without proper
water and soil conservation measures, poor water management of irrigated paddy
land, imbalanced use of fertilizers leading to nutrient mining, and persistent slash and
burn activities resulting in depletion of organic matter and soil erosion.
•
Deforestation, unsustainable management (excessive harvesting of timber and fire
wood) encroachment by developmental activities, overgrazing and forest fires are
resulting in land degradation.
•
Increase of cattle and yak population has led to an increased pressure on grazing land
(both pastures and forest areas). Forest and pasture degradation deserve serious
attention as livestock rearing is an important source of livelihood for many rural
households.
•
Rapid socio-economic development has resulted in an increased “scramble” for land
with various stakeholders competing for land. As a result prime forests and
productive agricultural land have been converted for other usages. This process
would indirectly lead to more intense use of the limited arable land. This is
accompanied by agriculture that becomes more oriented towards cash crops and
higher yields with the risk of developing a trend towards unsustainable use of land.
72
Strategies for Arresting Land Degradation in Bhutan
•
Mining activity in the country has increased drastically. This has led to severe
environmental impacts on and off site, although the total area under mining is
relatively limited.
•
Infrastructure development along the fragile slopes of Bhutan has led to acceleration
of land degradation processes. The strong policy focus on rural access has resulted in
a fast extension of the road networks, both feeder and farm roads. Road cuts induce a
range of slope instability problems and are an important cause of land degradation in
Bhutan. The process of rural electrification has seen a rapid increase of power and
transmission lines with negative impact on forest cover and related land degradation
along clear cut corridors.
The above mentioned factors contributing to land degradation should be tackled by a
comprehensive and targeted government policy to reduce the impact of these factors and
to screen and formulate policies that have less impact on the land. At present policy gaps
exist and there is a need to improve policies to address land degradation more
comprehensively.
The Royal Government of Bhutan is addressing land degradation through different
initiatives, policies and institutions. After disastrous floods and landslides in the monsoon
season of 2004 the Ministry of Agriculture and Forests started Land Management
Campaigns to create awareness, introduce SLM interventions and mainstream SLM
activities at all levels of government. A separate National Land Management Committee
was established to support, oversee and coordinate land management campaigns. As
party to the UNCCD, Bhutan has recognized the serious implication that land degradation
has on sustainable development. The National Soil Services Centre under the department
of Agriculture is the national focal agency for UNCCD and has the mandate to coordinate
land and soil management research. The Centre is the host to two GEF funded SLM
projects focusing on strengthening institutional and community capacity to anticipate and
address land degradation. The projects have developed participatory tools to identify and
map land-based problems and to prioritize, at grass-root level, SLM interventions to
mitigate land degradation (as a member country of UNCCD), a National Action Plan for
land degradation, along with an Integrated Financing Strategy. The NAP will function as
a guiding document for the country to deal with land degradation.
In a broader context it is recognized that land degradation affects mostly the rural
poor, who depend on access to and use of natural resources for their livelihoods. It is a
real challenge to maintain the delicate balance between the needs of the rural
communities and
sustainable use of natural resources without depletion and
accompanied land degradation. To encourage more sustainable land use by the rural
communities it is necessary to combine long-term environmental benefits of proper SLM
interventions with short-term gains in income and food security. At policy level there is a
need for a comprehensive land use and land planning policy to achieve a more balanced
and rational land use approach to steer proper land use and to protect the vulnerable land.
As there is so little land available for agriculture and economic development, a more
balanced land use policy is essential.
Strategies for Arresting Land Degradation in Bhutan
73
Land degradation results in increased sediment transport by the mountain streams of
Bhutan posing a risk to turbines and reservoirs of the hydropower installations upon
which Bhutan is increasingly dependent. Integrated watershed management to improve
sustainable land use and safeguard the natural resources is therefore also an economic
imperative.
Furthermore, with only 8% of Bhutan’s total land area identified as arable and almost
70% of its population deriving their livelihood from it, it is felt imperative for the Royal
Government to put in place a comprehensive strategy, outlining a well integrated
framework, requiring the involvement of all key stakeholders in addressing land
degradation issues. Such a strategy will not only ensure the sustainable management of
land for safeguarding the livelihood of our rural masses but also prevent degradation of
the ecosystem and help maintain a minimum of sixty percent of the country’s total land
under forests cover for all times to come, as required by the Constitution of Bhutan.
9. References
Bhutan Environment Outlook (2008). National Environment Commission, Royal Government of
Bhutan.
Chencho et. al. (2003). Types of Land Degradation in Bhutan. Journal of Bhutan Studies. Centre
for Bhutan Studies. Royal Government of Bhutan.
Facts and Figures of RNR Sector (2003). Policy and Planning Division. Ministry of Agriculture.
October 29, 2003.
Karma D Dorji (2008) Agriculture and Soil Fertility Management in Bhutan: An Overview. A
country paper presented in the meeting of Asia-Pacific Net on Integrated Plant Nutrient
Management (APIPNM) & International Workshop on Sustainable Nutrient Management:
Technology & Policy. Shijiazhuang, Hebei, China.
National Action Program (NAP) of Bhutan for Land Degradation (2009). GEF/UNDP Medium
Sized Project on Sustainable Land Management. National Soil Services Centre (NSSC),
Ministry of Agriculture and Forests. Thimphu, Bhutan.
Poverty Analysis Report (2007). National Statistics Bureau. Royal Government of Bhutan.
Review of Mainstreaming of Sustainable Land Management in Government Policies and
Plans in Bhutan (October 2008). National Soil Services Centre (NSSC), Department of
Agriculture, Ministry of Agriculture and Forests, Ryyal Government of Bhutan.
RNR Compendium 2008. Ministry of Agriculture & Forests. Royal Government of Bhutan.
SFU (2005). Report on the long term study on soil fertility trend of the major farming systems in
Bhutan. Report of Soil Fertility Unit, National Soil Fertility Management, Ministry of
Agriculture and Forests, Thimphu, Bhutan.
SSU (2000). Technical Report on semi-detailed soil survey of Radhi geog, Trashigang. Report
SS7(a), Soil Survey Unit, National Soil Services Centre (NSSC), Ministry of Agriculture
and Forests, Thimphu, Bhutan.
State of the Environment-Bhutan (2001). National Environment Commission. Royal Government
of Bhutan.
Statistical Yearbook of Bhutan, (November 2008). National Statistics Bureau, Royal Government
of Bhutan.
Statistical Yearbook of Bhutan (2007). National Statistics Bureau. Royal Government of Bhutan.
74
Strategies for Arresting Land Degradation in Bhutan
76
Land Degradation: Status, Impact and Strategies in India
Content
Page
1. Introduction
77
2. Unculturable Wastelands
80
3. Causes
81
3.1. Water Erosion
82
3.2. Wind Erosion
86
3.3. Waterlogging, Salinization and Acidification
87
3.4. Soil Physical Constraints: Compaction and Scaling
91
3.5. Floods and Droughts
92
3.6. Vegetation Degradation
94
3.7. Nutrient Mining
95
3.8. Depletion of Soil Organic Matter
96
3.9. Over Exploitation of Ground Water
98
3.10. Use of Poor Quality Ground Water
101
3.11. Degradation due to Urban and Industrial Wastes and
Excessive Use of Agro-Chemicals
104
3.12. Coastal Erosion
106
3.13. Gullies and Ravines
107
3.14. Mass Erosion Problems
109
3.15. Landslides
109
3.16. Minespoils
110
3.17. Torrents
111
4. Impacts of Land Degradation
111
5. Soil Physical Constraints
115
6. Strategies for Arresting Land Degradation
125
7. References
126
Land Degradation: Status, Impact and Strategies in India
77
1. Introduction
Land degradation is a global phenomenon caused by a variety of factors or processes
which include soil erosion by water/wind, deterioration in physical, chemical and
biological or economic properties of the soil and long-term loss of natural vegetation. It
is estimated that about 2 billion ha area in the world that once was biologically
productive is now affected by various forms of land degradation (Oldeman, 1991). About
5-7 million ha of arable land of the world is lost annually through land degradation (Lal
and Stewart, 1992). Globally, land degradation affects about one-sixth of the world’s
population, 70 percent of all dry lands (about 3.6 billion ha) and one-quarter of the total
land area of the world. The continental percentage of land degradation is highest in Asia
(37%) followed by Africa (25%), South America (14%), Europe (11%), North America
(4%) and Central America (3%), the world total being 15 percent.
In India, the estimates of land degradation by different agencies vary widely from
about 53 Mha to 188 Mha, mainly due to different approaches adopted in defining
degraded lands and/or differentiating criteria used (Table 1).
Table 1: Estimates of soil degradation in India by various agencies
Agency
Estimated
area (Mha)
Criteria for delineation
National Commission of
Agriculture (1976)
148.09
Based on secondary data collection
Ministry of Agriculture (1978)
175.00
Based on NCA estimates
Society for Promotion of
Wastelands Development
(1984)
129.58
Based on secondary data collection
National Remote Sensing
Agency (1985)
53.28
Mapping on 1:1 million scale based (1980-82)
on remote-sensing techniques (**)
Ministry of Agriculture (1985)
173.64
Land degradation statistics for the states (a)
Ministry of Agriculture (1994)
107.43
Elimination of duplication of area at (a) above
NBSS&LUP (1994)
187.70
Mapping 1:4.4 million scale at country level and
then deducting at state level based on Global
Assessment of Soil Degradation (GLASOD)
guidelines
NRSA (2000)
63.85
Based on satellite data (1986-1996)
NRSA (2005)
55.27
Based on satellite data (LISS-III sensor data
of 2003)
NBSS&LUP (2005)
146.82
Mapping of all the states at 1:250,000 scale.
Global Assessment of Soil Degradation
(GLASOD) guidelines
78
Land Degradation: Status, Impact and Strategies in India
As per estimates of NBSS&LUP, Nagpur employing GLASOD technique, an area of
187.8 Mha is affected by various land degradation problems with water erosion
contributing a maximum of 45.3% followed by chemical deterioration (4.2%), wind
erosion (4.1%) and physical deterioration (3.5%) (Sehgal and Abrol, 1994). These
estimates were revised to 146.8 Mha on 1:250,000 scale in 2005. The National Remote
Sensing Agency (NRSA) estimated that 80 Mha out of about 142 Mha under cultivation
and 11 Mha of pasture lands are substantially degraded while 40 Mha out of 75 Mha of
forest land has a canopy of less than 40%. Thus a total of 131 Mha (40% of country’s
total land mass) has productivity well below its actual potential. According to Wasteland
Atlas of India (2005) prepared by Ministry of Rural Development using IRS-LISS III
data, 55.27 Mha or 17.45% area of the country is degraded (Table 2) (DES, 2007).
Table 2: Degraded lands in India
Type
Gullied lands
Land with or without scrub
Area (M ha)
1.90
18.80
Waterlogged
0.97
Saline/alkali
1.20
Shifting Cultivation
1.88
Degraded forest and agricultural land under forest
12.66
Degraded pastures/plantation
2.15
Sands
3.40
Mining and industrial wastelands
0.20
Barren/stony/snow covered
12.11
Total
55.27
Realising the need to harmonize the area statistics on land degradation in the country,
the National Academy of Agricultural Sciences (NAAS) took a major initiative in 2006
to evolve a consensus among concerned organizations, viz; NBSS&LUP, Nagpur,
CS&WCR&TI, Dehradun, CAZRI, Jodhpur, CSSRI, Karnal, FSI, Dehradun and NRSA,
Hyderabad by adopting a common methodology and procedure for synthesizing the
datasets on land degradation/wastelands. Fig. 1 presents the harmonized area distribution
of degraded/wastelands of India on arable and non-arable lands and the statistics is
presented in Table 3 (Maji, 2007).
Land Degradation: Status, Impact and Strategies in India
79
Fig. 1: Wastelands/land degradation map of India
Table 3: Harmonized Area Statistics of Degraded Lands/ Wastelands of India (Mha)
Sl.
No.
Type of Degradation
Arable
land
(in Mha)
Open forest
(<40%
Canopy)
(in Mha)
1
Water erosion (>10 t/ha/yr)
73.27
9.30
Soil loss map, CSWCRTI
2.
Wind erosion (Aeolian)
12.40
-
Wind erosion map, CAZRI
Sub total
85.67
9.30
a) Exclusively salt affected
soils
5.44
-
b) Salt-affected and water
eroded soils
1.20
0.10
c) Exclusively acidic soils
(pH< 5.5)#
5.09
-
3.
Data source
Chemical degradation
National salt-affected soil
map, CSSRI, NBSS&LUP,
NRSA and others
Acid soil map of
NBSS&LUP
80
Land Degradation: Status, Impact and Strategies in India
d) Acidic (pH < 5.5) and
water eroded soils #
5.72
7.13
Sub total
17.45
7.23
4. Physical degradation
a) Mining and industrial
waste
0.19
b) Water logging
(Permanent surface
inundation) $
0.88
Sub total
1.07
Total
Grand total (Arable land
and Open forest)
Wasteland map of NRSA
104.19
16.53
120.72
Note: Forest Survey of India map (1999) was used to exclude degraded land under dense fores
2. Unculturable Wastelands
•
Barren rocky/stony waste: 6.46 Mha, They are the source for runoff water and
building material.
•
Snow covered/ Ice caps: 5.58 Mha, They are the best source of water and cannot be
treated as wastelands.
Note: # For acid soils areas under paddy growing and plantation crops were also
included in total acids soils $ Sub-surface waterloging was not considered.
As evident from the table, erosion by water constitutes a major form of land
degradation (68.4%) followed by chemical degradation (24.68 Mha), wind erosion (12.40
Mha) and physical degradation (1.07 Mha). The area under physical degradation
accounts for only waterlogging due to permanent surface inundation and does not include
sub-surface waterlogging. Similarly, barren/stony wastes which are the sources of runoff
water and building materials and snow covered/ice caps which are the best sources of
water availability were not considered as wastelands/degraded lands. For acid soils on
arable lands, areas under paddy growing and plantation crops were also included.
The perusal of area statistics on land degradation provided by NBSS&LUP, Nagpur
on three different time scales, viz; 1994, 2005 and 2007 indicates that during 1994 and
2005, the affected area reduced by 41 Mha from 187.8 to 146.8 Mha at a rate of 3.7
Mha/year. It has further reduced by 26 Mha to 120.72 Mha as per harmonized data base
during 2005 and 2007. It is ascribed to large-scale watershed development programmes
undertaken in the country since 1991. The salt affected area which initially increased
from 7.0 Mha in 1976 to 11.0 Mha in 1997 due to expansion of canal irrigation system
subsequently declined to 6.0 Mha in 2005 due to many soil reclamation schemes in the
last decade (Fig. 2).
Land Degradation: Status, Impact and Strategies in India
81
12
10
NBSS & LUP
Lok Sabha Q 256 (GOI)
Lok Sabha Q 256 (GIO)
TERI
Sehgal & Abrol
2
NBSS & LUP
4
NCA, MoA
6
NCA, MoA
Area (Mha)
8
0
1976
1985
1990
1994
1997
2 001
2 002
2005
Years
Fig. 2: Area (M ha) under salt affliction, 1976-2005
The area under waterlogging, shifting cultivation and degraded forest has declined at
an average annual rate of 1.79, 4.74 and 3.78%, respectively during 1994 and 2007. The
reduction in degraded forest area is attributed to launch of special schemes like Joint
Forest Management (JFM) and National Afforestation Programme under Ministry of
Environment and Forests and IWDP (Hills) under Ministry of Rural Development of
Govt. of India. Though the area degraded due to mining has declined at a rate of 6.9%
during 1994 and 2007, no change has been reported in area affected by ravines and
gullies during this period. It is envisaged to treat the remaining 53% degraded area by
the end of XIIIth Plan.
3. Causes
Degradation of land is a consequence of either natural hazards or direct causes or
underlying causes. Natural hazards are the environmental conditions which lead to high
susceptibility to erosion such as high intensity storms on steep slopes and soils having
less resistance to water erosion, high speed winds, soil fertility decline due to strong
leaching in humid climates, acidity or loss of nutrients, waterlogging etc. The direct
causes are human induced which result from unsustainable land use and inappropriate
land management practices such as deforestation and over-exploitation of vegetation,
overgrazing, cultivation on steep slopes and marginal/fragile lands without adoption of
soil conservation measures, shifting cultivation, improper crop rotations, imbalanced
fertilizer use or excessive use of agro-chemicals, over-exploitation of ground water and
improper management of canal water. The underlying causes are the factors indirectly
responsible for land degradation such as population pressures, land shortage, tenancy
82
Land Degradation: Status, Impact and Strategies in India
rights, economic pressures and poverty. Land shortage and poverty together lead to nonsustainable land management and consequently land degradation.
A study in Western Himalayas indicated that 70% of the rainfed and 41% of the
irrigated bench terraces were constructed on land slopes of 51-70% with 10% outward
slope and 8% longitudinal slope and a riser batter of 0.5:1 to 0.25:1 thus leading to
enormous runoff and soil loss (Juyal, 1987). In mountainous region of Nepal, common
specifications are 12% outward slope, 8% longitudinal gradient, 50 m length of bench,
vertical interval of 1-3 m with batter of 2:1 to 0.5:1 have been observed. In Bhutan,
cultivation on terraces is being practiced on mountain slopes ranging from 25% to 100%.
Clearing of vegetation for cultivation purposes on steep slopes and faulty management
practices are the major factors contributing to severe land degradation problems in the
hilly regions.
3.1. Water Erosion
Dhruvanarayana and Ram Babu (1983) estimated that about 5334 million tonnes of
soil is lost annually which is equivalent to 16.35 t/ha/yr. About 10% of the total eroded
soil gets deposited in the reservoirs thereby reducing their storage capacity by 1-2%
every year. The data on 17 medium and small reservoirs under river valley projects in
India have shown that the rate of inflow of sediments is about 3 times (9.17 ha-m/100
km2/year) as compared to the designed rate of 2.93 ha-m/100 km2/year, thus reducing the
life expectancy and hydro-electric power generation to one-third of the planned capacity.
Of the remaining, 61% is displaced from one place to another while 29% is permanently
lost into the sea causing irretrievable loss of the soil resource.
Among different land resource regions, highest erosion rate occurs in the black soil
region (23.7 – 112.5 t/ha) followed by Shiwalik region (80 t/ha), north-eastern region
with shifting cultivation (27-40 t/ha) and the least in north Himalayan forest region (2.1
t/ha). Singh et al. (1992) reported that annual erosion rates vary from less than 5
t/ha/year for dense forest, snow-clad cold deserts and arid regions of Western Rajasthan
to more than 80 t/ha/year in Shiwalik region. Sheet erosion affects red soils comprising
alfisols, ultisols and oxidols (4-10 t/ha/year) and black soils constituting vertisols and
vertic soils (11-43 t/ha/year). Gully erosion seriously affects hilly areas (> 33 t/ha/year)
while hill slope erosion is more than 80 t/ha/year.
Recently, the Central Soil and Water Conservation Research and Training Institute,
Dehradun, in collaboration with National Bureau of Soil Survey and Land Use Planning,
Nagpur computed the potential erosion rates for different states of the country using 10
km x 10 m grid size data from the parameters of Universal Soil Loss Equation (USLE).
Considering 10 t/ha as the permissible soil loss limit (Mandal et al., 2009), the analysis
revealed that on the whole, about 39% area in India has potential erosion rate of more
than the permissible limit while 11% area falls in very severe category with erosion rate
of more than 40 t/ha (Fig. 3).
Land Degradation: Status, Impact and Strategies in India
83
Fig. 3: Soil loss map of India (water erosion) (>10t/ha/yr)
The states of Nagaland, Meghalaya, Arunachal Pradesh, Assam, Chhatisgarh and
Jharkhand have more than 60% of their total geographical area beyond the permissible
rate of 10 t/ha. Similarly, more than 40% area in the states of Uttar Pradesh, Uttarakhand,
Madhya Pradesh and Manipur is affected by erosion rate exceeding the permissible limit
(Table 4) (Anonymous, 2008). About 125 Mha area in the country suffers from water
erosion rate of more than 10 t/ha either exclusively or in conjunction with other land
degradation problems like salinity, acidity etc.
84
Land Degradation: Status, Impact and Strategies in India
Table 4: Area (%) affected by potential soil erosion rates in different states of India
Sl.
No.
TGA
Moderate
(10-15)
(t/ha/yr)
Area
(sq km)
Area
(%)
State
1 Andhra Pradesh
Extra
Moderate
Total
Severe Very Severe
Severe (>
Severe
(>10)
(40-80)
(20-40)
80)
(15-20)
(t/ha/yr)
(t/ha/yr) (t/ha/yr)
(t/ha/yr)
(t/ha/yr)
Area
(%)
Area
(%)
Area
(%)
Area
(%)
Area
(%)
275045
13.16
7.54
12.50
6.53
0.00
39.73
Arunachal
2 Pradesh
83743
5.10
5.42
23.65
27.31
11.17
72.65
3 Assam
78438
4.58
18.08
14.83
28.30
--
65.79
4 Bihar
93979
6.23
3.43
2.73
0.58
--
12.97
134805
7.99
6.45
18.22
13.62
19.02
65.30
1483
9.18
5.27
6.64
1.15
--
22.24
5 Chhattisgarh
6 Delhi
7 Gujarat
196024
7.00
3.00
5.00
1.00
--
16.00
8 Haryana
44212
2.57
1.25
1.83
0.95
--
6.60
9 Himachal Pradesh
55673
5.43
3.75
7.40
5.74
10.08
32.40
222236
0.63
0.53
1.66
2.73
10.21
15.76
11 Jharkhand
79898
15.55
11.44
20.95
12.20
4.63
64.77
12 Karnataka
191791
27.00
11.00
9.00
2.00
--
49.00
Jammu &
10 Kashmir
13 Kerala
38863
10.21
2.59
2.36
0.09
--
15.25
14 Madhya Pradesh
308641
12.92
9.53
18.93
9.31
8.56
59.25
15 Maharashtra
307713
9.77
5.74
8.19
4.90
5.61
34.21
16 Manipur
22327
15.25
11.43
26.61
0.00
--
53.29
17 Meghalaya
22429
14.78
10.21
26.25
13.86
12.80
77.90
18 Nagaland
16579
4.09
3.80
15.96
28.48
34.94
87.27
19 Orissa
155707
10.28
6.69
9.54
4.22
1.04
31.77
20 Punjab
50362
2.52
0.90
1.79
1.48
--
6.69
342239
7.67
4.62
8.12
3.90
1.92
26.23
7096
0.90
1.19
7.82
10.93
16.02
36.86
130058
10.78
4.65
4.15
0.15
--
19.73
10486
7.10
7.00
6.50
8.60
9.20
38.40
25 Uttar Pradesh
241046
27.58
9.95
8.26
13.44
--
59.23
26 Uttarakhand
53365
7.71
7.04
9.24
34.23
--
58.22
27 West Bengal
88752
11.89
4.24
3.67
0.39
--
20.19
11.22
6.46
9.92
7.14
3.99
38.73
21 Rajasthan
22 Sikkim
23 Tamil Nadu
24 Tripura
Total
Source: Anonymous, 2008
Land Degradation: Status, Impact and Strategies in India
85
As per harmonized area statistics on land degradation, an area of 73.27 Mha on
arable land and 9.30 Mha under open forests (<40% canopy) is exclusively affected by
water erosion of more than 10 t/ha/year (Table 3). In addition, salt-affected area of 1.20
Mha on arable land and 0.10 Mha under open forest is also affected by water erosion.
Similarly, 5.72 Mha area on arable land and 7.13 Mha in open forest is affected by both
acidity and water erosion. Thus, a total of 96.72 Mha (80.19 Mha on arable land and
16.53 Mha under open forest) area is affected by water erosion either exclusively or in
conjunction with salinity/acidity which is about 80% of 120.72 Mha total degraded area
in the country. The trend analysis indicated that the area affected exclusively by water
erosion has declined from 148.9 Mha in 1994 to 93.68 Mha in 2005 and 73.28 Mha in
2007 at a rate of 3.91% (Fig. 4). Considering water erosion on arable lands in
conjunction with open forest and salt-affected soils, the rate of decrease during 1994 to
2007 works out to be 3.33% (Table 5).
S a lt a f f ic t io n
12
10
NBSS & LUP
NBSS & LUP
Lok Sabha Q 256 (GOI)
Lok Sabha Q 256 (GIO)
MoRD
1990
TERI
1985
Sehgal & Abrol
2
NBSS & LUP
4
NCA, MoA
6
NCA, MoA
Area (Mha)
8
2005
2007
0
1976
1994
1997
2000
2001
2002
Ye ars
Fig. 4: Area (M ha) under salt affliction, 1976-2007
Table 5: Percent change over 1994 and 2005 in each category of land degradation
Type of degradation
Area (M ha)
1994
Area (M
ha) 2005
Area (M ha)
2007
% change
over 1994
% change over
2005
Water erosion
148.9
93.68
73.28
-50.78 (-3.91) -21.77 (-10.88)
Water erosion +
open forest
148.9
-
82.57
-44.54(-3.42)
-
Water erosion + open
forest + salt affliction
148.9
-
84.41
-43.31(-3.33)
-
Wind erosion
17.5
9.48
11.55
-34.00(-2.61)
21.83 (10.91)
Ravines
3.97
-
3.97
0.00(0.00)
-
86
Land Degradation: Status, Impact and Strategies in India
Type of degradation
Area (M ha)
1994
Area (M
ha) 2005
Area (M ha)
2007
% change
over 1994
% change over
2005
Salt affected
9.4
5.94
8.22
-12.55(-0.96)
38.38 (19.19)
Waterlogging
11.6
14.30
14.3*
23.27(1.79)
0.0
Mining wasteland
2.53
-
0.26
-89.72(6.90)
-
Shifting cultivation
4.9
-
1.88*
-61.63(-4.74)
-
Degraded forest
24.9
-
12.66*
-49.15(-3.78)
-
Values in the parenthesis are AGR(%); * = based on 2005 data
The reduction is largely attributed to massive integrated watershed development
programmes launched in the country since 1991. Up to the end of Xth Five Year Plan
(2002-07), 47% (56.54 Mha) degraded area has been treated under various watershed
schemes and soil and water conservation programmes at an investment of about Rs.
19.5 billion (Sharda et al., 2008).
3.2. Wind Erosion
Wind erosion is prevalent in arid and semi-arid regions of the country covering an
area of about 28,600 km2 in the states of Rajasthan, Haryana, Gujarat and Punjab. About
68% of the affected area is covered by sand dunes and sandy plains. It has been estimated
that out of 208751 km2 mapped area of Western Rajasthan, 30% is slightly affected by
land degradation, while 41% is moderately, 16% severely and 5% very severely affected
(Narain and Kar, 2006). Decreasing rainfall gradient and increasing wind strength from
east to west are responsible for the spatial variability in sand reactivation pattern.
According to recent estimates, about 75% area of Western Rajasthan is affected by wind
erosion hazard of different intensities (Table 6) (Narain et al., 2000) besides 13% area
under water erosion and 4% under waterlogging and salinity/alkalinity. Fig. 5 presents
the wind erosion map of the country with erosion rate of more than the permissible rate of
10 t/ha/yr.
Table 6: Wind erosion deposition in western Rajasthan
Erosion/deposition
Very severe
Area
(km2)
% of total area
5800
2.78
Severe
25540
12.23
Moderate
73740
35.32
Slight
52690
25.24
Negligible
50981
24.43
208751
100.00
Total
Land Degradation: Status, Impact and Strategies in India
87
Fig. 5: Wind erosion map of India (>10t/ha/yr)
The spatial extent of the problem is increasing in the recent decades, especially due to
increased cultivation and grazing pressures on the erstwhile stable sandy terrain (Narain
and Kar, 2006) leading to depletion of vegetal cover. However, under desert
development programme (DDP) and watershed development projects, affected areas are
being rehabilitated along with stabilization of sand dunes through appropriate soil
conservation measures. The harmonized area statistics on land degradation in the country
shows that 12.4 Mha area on arable lands is affected by wind erosion of more than 10
t/ha/yr (Maji, 2007).
3.3. Waterlogging, Salinization and Acidification
The problems of waterlogging and salinization in the irrigated command areas of arid
and semi-arid regions are a global phenomenon, mainly associated with canal irrigation
systems. About 10-33 percent of irrigated lands in various countries are adversely
affected by the problems of waterlogging and salinization. An area is said to be
waterlogged when water table rises to such an extent that soil pores in the crop root zone
become saturated, resulting in restriction of the normal circulation of air, decline in level
of oxygen and increase in level of carbon dioxide. An area with water table within two
metres is called waterlogged though safe limit is beyond 3 meter depth. The major factors
88
Land Degradation: Status, Impact and Strategies in India
contributing to waterlogging and salinity include seepage from the canal distribution
network, excessive irrigation of agricultural crops, impediments in natural drainage
systems and topographical and climatic features.
Salt affected soils are grouped into two classes, namely saline and alkali soils
depending upon nature of soluble salts, physico-chemical characteristics and management
practices for their reclamation. Saline soils have EC higher than 4 dsm-1 but pH less than
8.5 and ESP below 15. Alkali soils, on the other hand, have pH higher than 8.5 and ESP
>15 with variable electrical conductivity. The soils which are both waterlogged and salt
affected are called waterlogged saline soils.
About 4.5 Mha area in India is affected by waterlogging, half of which occurs in
canal commands and the remaining half in other regions (Anonymous, 2004a).
Maximum area lies in Uttar Pradesh followed by Gujarat, Rajasthan, Andhra Pradesh and
Bihar (Table 7). Similarly, salt affected soils occur in 8.55 Mha, out of which 41 percent
lies in canal command areas. Though salt affected soils occur all over the country, they
are mainly concentrated in arid, semi-arid and sub-humid regions (Fig. 6). The states
most affected are Uttar Pradesh, Gujarat, Rajasthan, West Bengal and Andhra Pradesh
(Singh, 1992). Area in the range of 1.5 to 20 percent of total irrigated area is affected by
the problem of soil salinization in different states.
Table 7: Extent and distribution of waterlogged and salt affected soils in India (000,
ha)
State
Waterlogged area
Canal
commands
Unclassified
Salt affected area
Total
Canal
Commands
Outside
canal
Total
Coastal
Andhra Pradesh
266.4
72.6
339.0
139.4
390.6
283.3
813.3
Bihar
362.6
NA
362.6
224.0
176.0
Nil
400.0
Gujarat
172.6
311.4
484.0
540.0
372.1
302.3
1214.4
Haryana
229.8
45.4
275.2
455.0
NA
Nil
455.0
Karnataka
36.0
NA
36.0
51.4
266.6
86.0
404.0
Kerala
11.6
NA
11.6
NA
NA
26.0
26.0
Madhya Pradesh
57.0
NA
57.0
220.0
22.0
Nil
242.0
6.0
105.0
111.0
446.0
NA
88.0
534.0
Orissa
196.3
NA
19.3
NA
NA
400.0
400.0
Punjab
198.6
NA
198.6
392.6
126.9
NA
519.5
Rajasthan
179.5
168.8
348.3
138.2
983.8
NA
1122.0
18.0
109.9
127.9
256.5
NA
83.5
340.0
455.0
1525.6
1980.6
606.0
689.0
Nil
1295.0
NA
NA
NA
Nil
NA
800.0
800.0
2189.4
2189.4
4528.1
3469.1
3027.0
2069.1
8565.2
Maharashtra & Goa
Tamil Nadu
Uttar Pradesh
West Bengal
Total
Source: Anonymous 2004a
Land Degradation: Status, Impact and Strategies in India
89
Fig. 6: Salt affected soils in India
It is estimated that waterlogging and soil salinization is increasing at the rate of 3000
to 4000 ha per annum in various command areas. Rate of water table rise in Haryana has
been 0.14 to 1.0 m/year and about 0.4 Mha area has water table within 3 m of soil
surface. Similarly, in South Punjab and all irrigation commands of Gujarat, a steady rise
in water table is reported with corresponding increase in salt affected area. Area affected
by waterlogging in Tungbhadra Command in Karnataka increased from 16000 ha to
80000 during 1975 to 1997 (Fig. 7). Similarly, in Nagarjuna Sagar Project Command
area, nearly 25000 ha of the 140000 ha under irrigation have been affected by
waterlogging and salinity in a period of 14 years.
Land Degradation: Status, Impact and Strategies in India
Area (ha)
90
90000
80000
70000
60000
50000
40000
30000
20000
10000
0
80000
54000
35000
24475
16458
20200
1975-76 1977-78 1979-80 1984-85 1991-92 1996-97
Years
Fig. 7: Increase in waterlogged area under Tungbhadra Project, Karnataka
Acid soils cover an area of 49 Mha in India out of which 25 Mha have pH below 5.5
and 24 Mha between 5.5 and 6.5 (Misra, 2004). These soils have been classified under
soil orders Ultisol, Alfisol, Mollisol, Inceptisol and Entisol representing laterite, red, hill
brown forest, alluvial and peat soils, respectively. They are found in Himalayan region,
eastern and north eastern plains, peninsular India and coastal plains, covering states of
north eastern region, West Bengal, Bihar, Orissa, Andhra Pradesh, Kerala, Madhya
Pradesh, Karnataka, Maharashtra, Tamil Nadu, Himachal Pradesh, Jammu and Kashmir
and Uttarakhand (Fig. 8). Table.8 presents percentage of total geographical area under
acid soils in each state.
Fig. 8: Distribution of acid soils in India
Land Degradation: Status, Impact and Strategies in India
91
Table 8: Extent of occurrence of acid soils
State
% of TGA
State
% of TGA
Assam and North East
80
Karnataka
50
West Bengal
40
Kerala
90
Bihar
33
Maharastra
10
Orissa
80
Uttar Pradesh
10
Madhya Pradesh
20
Himachal Pradesh
90
Andhra Pradesh
20
Jammu & Kashmir
70
Tamil Nadu
20
Source: Misra, 2004
As per harmonized data base on land degradation in the country, an area of 5.09 Mha
is exclusively affected in arable lands by acidity in addition to 5.72 Mha affected by
acidity in conjunction with water erosion of more than 10 t/ha/year. An area of 7.13 Mha
also suffers from acidity in the open forest lands (< 40% canopy). Thus an area of 17.94
Mha is degraded in India due to strong (pH < 4.5) and moderate (pH between 4.5 – 5.5)
acidity either exclusively or in combination with water erosion on arable and non-arable
lands.
3.4. Soil Physical Constraints: Compaction and Scaling
Shallow depth, soil hardening, slow and high permeability, sub-surface compacted
layer, surface crusting, and temporary waterlogging are the major physical constraints of
Indian soils. Soil compaction is a management problem resulting from movement of
heavy machinery and repeated tillage operations accompanied with reduction in organic
matter and destruction of soil aggregates. Soil is said to be compacted if resistance to
penetration exceeds 2 Mega Pascal (Mpa). Compaction causes deterioration in soil
structure and impedes root growth and biological activity besides generating high amount
of runoff during intense storms.
Out of 141 Mha cultivated area, about 89.5 Mha suffers from one or another form of
physical constraint in the country as shown in Table 9 (Painuli and Yadav, 1998).
Maximum area is affected by shallow depth followed by soil hardening and the least by
temporary waterlogging.
92
Land Degradation: Status, Impact and Strategies in India
Table 9: Distribution of area (million ha) affected by various physical constraints in
India
Physical constraint
Area
Main states affected
Shallow depth
26.40
Andhra Pradesh, Maharashtra, West Bengal,
Kerala and Gujarat
Soil hardening
21.57
Andhra Pradesh, Maharashtra and Bihar
High permeability
13.75
Rajasthan, West Bengal, Gujarat, Punjab and
Tamil Nadu
Sub surface hard pan
11.31
Maharashtra, Punjab, Bihar, Rajasthan, West
Bengal and Tamil Nadu
Surface crusting
10.25
Haryana, Punjab, West Bengal, Orissa and
Gujarat
Temporary waterlogging
6.24
Madhya Pradesh, Maharashtra, Punjab, Gujarat,
Kerala and Orissa
Source: Painuli and Yadav (1998)
Soil scaling due to surface hardening and crust formation together affect 31.82 Mha
area in the country. Major factors are construction of houses, roads and other land
development activities and physico-chemical properties of the soil. They obstruct
movement of rainwater into the soil thus leading to high runoff and soil losses. The
deterioration in physical, chemical and biological functions of the soil due to compaction
and scaling adversely affects the productivity of agricultural crops. The technologies for
treating the soil affected by sub-surface mechanical impedance and compaction include
chiseling, chiseling plus amendment application, construction of ridges and raised and
sunken bed technology.
3.5. Floods and Droughts
Occurrence of floods, droughts and other climatological extremes is a common
feature in many parts of the country. These natural disasters cause widespread land
degradation apart from heavy monetary losses and a serious setback to economic
development of the country. It has been estimated that 8 major river valleys spread over
40 Mha area of the country covering 260 million population are affected by floods.
Besides environmental degradation, poverty and marginalization are other major factors
which force the poor to live in threatened and exposed conditions. About 60% of total
flood prone area in the country lies in Indo-Gangetic basin which supports 40% of India’s
population with 60 Mha cultivable land. The Brahmaputra basin is also critical as it
experiences frequent floods within the same year thus seriously affecting all
developmental activities. The incidence of floods is not restricted to humid and subhumid regions but have also caused extensive damage in the desert districts of Rajasthan
and Gujarat in the recent years.
Land Degradation: Status, Impact and Strategies in India
93
Drought occurs over an extended period of time and space, making it unpredictable
and the losses are not quantifiable easily (Samra, 2002). Therefore, the impact of drought
on the techno-economic and socio-economic aspects of agricultural development and
growth of the nation is severe and results in huge production and monetary losses. It is
estimated that about 68% of total sown area and 23% of total area of the country spread
in 16 states, viz; Andhra Pradesh, Bihar, Chhatisgarh, Gujarat, Himachal Pradesh, Jammu
and Kashmir, Jharkhand, Karnataka, Madhya Pradesh, Maharashtra, Orissa, Rajasthan,
Tamil Nadu, Uttar Pradesh, Uttarakhand and West Bengal covering a total of 183
districts and 12% of population are accounted as drought prone (CESI, 2006). In a state
like Rajasthan (arid), about 56% of the total area and 33% of the total population are
chronic drought prone affected followed by Andhra Pradesh, Gujarat and Karnataka with
corresponding figures as 30 and 22%, 29 and 18% and 25 and 22%, respectively. Except
Kerala, Punjab and north-eastern region, every state has one or more drought prone areas.
Drought is said to have occurred in an area when the annual rainfall is less than 75% of
the normal in 20% of the years examined. Any Taluk or equivalent unit having 30% or
more area under irrigation is considered to be reasonably protected against drought.
Apart from floods and droughts, cyclones frequently occur in the entire 5700 km long
coast line of Southern and Peninsular India besides Islands of Lakshadweep and
Andaman and Nicobar islands affecting 10 million population. Nearly 56% of the total
area of the country is susceptible to seismic disturbances affecting 400 million people.
Fig. 9 shows the areas affected by natural disasters in India (CPCB, 2005).
Fig. 9: Natural hazards in India
94
Land Degradation: Status, Impact and Strategies in India
3.6. Vegetation Degradation
The areas which are most affected by vegetation degradation include pasture lands
and open forests. The states which have considerable proportion of permanent pastures
and grazing lands include Himachal Pradesh (32%), Sikkim (10%), Madhya Pradesh
(including Chhatisgarh) (6%), Karnataka (5.1%), Rajasthan (5%), Gujarat (4.5%) and
Maharashtra (4%). Madhya Pradesh and Chhatisgarh account for about 23% of all India
acreage under pasture and grazing lands. The common grazing lands around the villages
which include Gochar (cultivable waste), Oran (permanent pasture) and Agro (pasture
around the pond) have been highly exploited and neglected. In India, with about 500
million livestock population, more than 50% of fodder demand is met from grasslands.
The average grazing intensity in India is about 42 animals per ha of land against the
threshold level of 5 animals per ha (Sahay, 2000). An estimated 100 million cow units
graze in forest lands against a sustainable level of 31 million per annum (MoEF, 1999)
affecting approximately 78% of India’s forests.
The land use statistics indicated that forests occupy 22.8% (69.67 Mha) area in the
country which together with permanent pastures comes out to 26.2% (80.1 Mha) (DES,
2007). Though the area under forests increased significantly during 1950-51 to 1970-71 by
about 7% to 63.91 Mha, the increase has been only marginal thereafter till 2004-05. The
total perennial cover comprising of forests, permanent pastures and other grazing land, and
miscellaneous trees and groves together has increased just by 0.5% since 1970-71 showing
an annual growth rate of 0.017%. Per capita forest area in India is only 0.07 ha which is far
below the world average of 0.8 ha. Dense forests are losing their crown density and
productivity continuously, the current productivity being one-third (0.7 t/ha) of the actual
potential. The combined availability of green fodder from pasture lands and grazing lands,
agricultural lands and forest (899.33 Mt) is far short of the actual demand of 1820 Mt
(DES, 2007). It causes indiscriminate grazing on forest lands leading to large scale
degradation thereby seriously affecting natural regeneration of forests. The present forest
cover of 20.6% (FSI, 2005) is far below the 33% cover recommended by National Forest
Policy of 1988, the proportion being 60% in the hill regions and 20% in the plains. Out of
this, 5.46 Mha (1.66%) is very dense forest (>70% canopy), 33.26 Mha (100.12%) is
moderately dense (40-70% canopy) and the rest 28.99 Mha (2.82%) is open forest (<40%
canopy) including 0.44 Mha mangroves. Including 3.85 Mha of scrub forest and 9.17 Mha
under tree cover outside the recorded forest area, the total forest cover comes to be 76.88
Mha which is only 23.40% of the total geographical area of the country.
The net annual loss of forest areas is put at 74000 ha which is attributed to
overgrazing and over-extraction of firewood from 78% of the forest areas and fire
hazards in 71% of forest lands. The State of Forest Reports (SFR) 2001 and 2005
indicate that while the area under dense forest cover declined by 7.1% (from 416809 to
387216 sq km), the area under open forests increased by 12.0% (from 258729 to 289872
sq km) with overall increase of 0.2% during the 4 years period. The Joint Forest
Management (JFM) programme launched in 1991 has the major objective of protecting,
developing and managing forests particularly in degraded areas by bringing together
State Forest Departments and village communities.
Land Degradation: Status, Impact and Strategies in India
95
3.7. Nutrient Mining
Excessive nutrient mining and inadequate replenishment of primary, secondary and
micro-nutrients are the major factors responsible for declining nutrient use efficiency,
deterioration of soil health and consequently decline or stagnation in agricultural
productivity. The decline in factor productivity and compound growth rates of major
crops under intensive cropping systems and low nutrient use efficiency is attributed to
deterioration of chemical, physical and biological functions of the soil due to imbalanced
supply of plant nutrients (Lal, 2004). Most of the Indian soils are low in nitrogen, 6570% are deficient in phosphorous content and 50% are either low or medium in
potassium content. In addition, about 48, 30, 12, 4 and 3% soils are reported to be
deficient in zinc, sulphur, iron, copper and manganese, respectively. Major crop rotations
based upon cereal-cereal or cereal-legume cropping sequence remove more than 500 kg
of NPK annually from the soil and/or added nutrients (Table 10).
Table 10: Nutrient uptake by some intensive cropping systems
Cropping system
Yield
(t ha-1)
Nutrient uptake kg ha-1 yr-1
N
P2O5
K2O
Total
Maize-wheat
7.7
220
87
247
554
Pigeon pea-wheat
4.8
219
71
339
629
7.7
260
85
204
549
Pigeon pea-sorghum
0.8+1.1
185
19
299
503
Pigeon pea-pearl millet*
0.7+1.3
203
14
336
553
0.9+0.2
154
26
132
312
Soybean wheat
*
Pigeon pea-urd bean
*
* Intercropping systems
Similarly, annual removal of micro-nutrient is in the range of 287-744 g for Zn,
1224-7296 g for Fe, 488-2980 g for Mn, 144 – 710 g for Cu, 120 – 252 g for B and 16 g
for Mo (Takkar, 1996).
In Indian agriculture, there is little resemblance between the pattern of NPK removal by
crops and their addition through fertilizers (Tiwari, 2007). In general, nitrogen (N) is the
dominant addition while potassium is the dominantly removed nutrient. Potassium is the
lowest applied nutrient though it accounts for 55% removal of total NPK. Nitrogen
contributes to only 31%, while P accounts for the remaining 14% of the total NPK uptake.
Use of site specific nutrient management practice based on positive nutrient balance can yield
about 15-17 t/ha/yr of grain production.
At the present level of crop production, crops remove 27 Mt of NPK against
application of 16.8 Mt, thus resulting in a gap of 10.2 Mt. The gap is expected to
increase up to 11 Mt by 2010 and 13.3 Mt by 2025 when the removal would reach a level
of 31.7 Mt and 40 Mt, respectively. As a result of inadequate and imbalanced fertilizer
96
Land Degradation: Status, Impact and Strategies in India
use, production response of chemical fertilizers has reduced from about 15 kg of food
grains per kg of fertilizers in 1970 to only 5-6 kg per kg of fertilizer in 2005.
Consequently, the annual compound growth rate of major crops has declined from 3.33%
in 1981-85 to 0.11% in 2001-05, with a similar trend in pulses and oilseed crops also.
The fertilizer consumption in India is grossly imbalanced and is more inclined
towards N followed by P. The imbalanced consumption ratio of N:P:K which was
6.2:4:1 in 1990-91 widened further to 7:2.7:1 in 2000-01 as against favourable ratio of
4:2:1. With the increase in foodgrain production, the number of elements deficient in
Indian soils increased from one (N) in 1950 to 9 (Mo, B, Mn, S, K, P, Zn, Fe and N) in
the year 2005-06 which may further increase due to imbalanced fertilizer use.
The gap between consumption and removal of nutrients by 2025 is expected to be
bridged by use of crop residues, cattle dung, sewage-sludge and other organic sources.
Crop residues offer most favourable alternative and have the capacity to supply 3.39 Mt
of nutrients followed by cattle dung and human excreta (Table 11).
Table 11: Some projections on availability of plant nutrients from organic sources
for agriculture in India during 2000-2025
Resource
N + P2O5 + K2O
2000
2010
2025
Crop residue
2.05
2.34
3.39
Cattle dung
2.00
2.10
2.26
Human excreta
1.60
1.80
2.10
Total
5.50
6.24
7.75
3.8. Depletion of Soil Organic Matter
The organic matter content in India varies with soil texture, climate, rainfall,
moisture, tillage, crop residue management, land use, application of fertilizers and
cropping systems. The organic matter content is generally low under Indian conditions
due to tropical and sub-tropical climate. Comprehensive data on status of organic matter
during different time scales is largely missing. In Tamil Nadu state, organic matter
reduced from 1.20 in1971 to 0.78 percent in 2002. In the cultivated fields, it rarely
exceeds 1 percent except in few soils of hilly region (Table 12). High soil organic carbon
(SOC) (> 1 percent) can be accumulated in red and laterite soils of humid tropical and hill
and mountain soils having humid temperate climate. Desert soils are the poorest in SOC
contents.
Land Degradation: Status, Impact and Strategies in India
97
Table 12: Organic carbon in surface layer of important soil groups of India
Sl.No.
Soil group
Organic carbon (%)
1
Deep black soils
0.3 – 0.8
2
Red and laterite soils
0.7 – 6.5
3
Alluvial Soils
0.3 – 1.1
4
Hill and mountain soils
4.0 – 8.0
5
Desert Soils
0.3- 0.6
6
Coastal alluvial soils
0.5 –0.9
Bhattacharyya et al. (2000) reported that among the five physiographic regions of
India (Fig. 10), the Northern Mountains cover 55.3 Mha area and have SOC reserve in
the range of 7.89 to 18.31 Pg in first 30-150 cm depths. The Great Plains covering 72.4
Mha have SOC stocks of 3.2 to 10.53 Pg. For Peninsular India, The Peninsular plateau
and Coastal Plains and Islands covering 54.7, 105.7 and 40.9 Mha area, SOC ranges from
3.64 to 13.34, 3.62 to 10.11 and 2.24 to 10.90 Pg, respectively.
Fig. 10: Soil organic carbon (SOC) stocks in different physiographic
regions of India based on 1000 soil samples
98
Land Degradation: Status, Impact and Strategies in India
It is estimated that 300, 375 and 16.5 Mt of crop residues, livestock dung and human
excreta are available annually in India. Of this, about one-third of crop residues, half of
the livestock dung and 80% of human excreta are available for use in agriculture. Every
million tones increase in food grain production can produce 1.2 – 1.5 Mt of crop residues
and every million increase in cattle population can provide additional 1.2 Mt of dry dung
per annum. Thus NPK supply can be supplemented through all the wastes to the extent
of 6.25 and 9.25 Mt by 2010 and 2025, respectively to sustain productivity and keep the
fertilizer related pollution under control (IISS, 2007).
3.9. Over Exploitation of Ground Water
The annual replenishable ground water resource in India has been estimated as 433
BCM, of which rainfall contribution is 67% (290 BCM) and the remaining 33% (143
BCM) is contributed by other sources that include return flow from canal irrigation,
seepage from water bodies and artificial recharge from water storage structures (CGWB,
2006). Presently, about 53% (231 BCM) ground water resource has been developed
which meets 70% of the irrigation and 80% of the drinking water needs of the country.
Due to subsidized power and pump sets in rural areas and absence of any regulatory
mechanism, the number of ground water abstraction structures has increased by more
than 3 times since 1982-83, thus causing over-exploitation of ground water resource
(Table 13).
Table 13: Growth of ground water extraction structures
Number of structures
Type of structure
Dug wells
Shallow tubewells
Deep tubewells
Total
1982-83
1993-94
2000-01
5384627
7354905
9617381
459853
3944724
8355692
31429
227070
530194
5875909
11526699
18503267
About 70 percent area in Punjab, 50 percent in Haryana and a major part in lower
Himachal Pradesh and Uttarakhand, Uttar Pradesh and Northern Rajasthan is being
irrigated by tube wells. Over the last four decades, number of tube wells have increased
twenty folds (6 lakhs) in Haryana and thirty folds in Punjab (14 lakhs) and still there are
no legislative measures to control their numbers or regulate withdrawal of ground water.
While area under canal irrigation has decreased from 1.3 to 1.0 Mha in Punjab, the area
under tube well irrigation increased from 0.8 to 3.1 Mha during 1965-66 to 2003-04 (Fig.
11). Similarly, in Haryana area under tube well irrigation increased from 0.2 to 1.59 Mha
(Fig. 12).
Land Degradation: Status, Impact and Strategies in India
99
3500
Area (000'ha) irrigated
3000
Canal
Tube wells
2500
2000
1500
1000
500
0
1965-66
1975-76
Period
1993-94
1998-99 2003-2004
Fig. 11: Area (000’ha) irrigated by canals and tube wells in Punjab
1800
1600
Canal
Area (000'ha) irrigated
Tube wells
1400
1200
1000
800
600
400
200
0
1965-66
1975-76
1993-94
Period
1998-99 2003-2004
Fig. 12: Area (000’ha) irrigated by canals and tube wells in Haryana
Due to declining ground water table, 90 percent farmers in rice-wheat cropping
system of Punjab and Haryana are replacing centrifugal pumps with submersible pumps
causing further exploitation of ground water (Kaledhonkar et al., 2006).
The Central Ground Water Board (CGWB) is monitoring ground water fluctuations
in various blocks of the country which are classified as white, grey, dark and overexploited depending upon the net draft as percentage of net recharge of <65, 65-85, 85100 and >100 percent, respectively. The analysis of data indicates that out of 7928
blocks in the country, 425 fall in the dark/critical zone and 673 are over-exploited (Table
14).
100
Land Degradation: Status, Impact and Strategies in India
Table 14: Groundwater development levels in India
Sl.
No.
States
Number of
assessment
units
No. of assessment units
Over-exploited
Dark/Critical
No.
%
No.
%
1157
118
10.20
79
6.83
59
0
0.00
0
0.00
1.
Andhra Pradesh
2.
Arunachal Pradesh
3.
Assam
219
0
0.00
0
0.00
4.
Bihar
394
6
1.52
14
3.55
5.
Chhattisgarh
145
0
0.00
0
0.00
6.
Delhi
6
3
50.00
1
16.07
7.
Goa
12
0
0.00
0
0.00
8.
Gujarat
180
41
22.78
19
10.56
9.
Haryana
111
30
27.03
13
11.50
10.
Himachal Pradesh
69
0
0.00
0
0.00
11
Jammu & Kashmir
69
0
0.00
0
0.00
12
Jharkhand
193
0
0.00
0
0.00
13
Karnataka
175
7
2.00
0
5.14
14
Kerala
151
3
1.99
6
3.97
15.
Madhya Pradesh
312
2
0.64
1
0.34
16
Maharashtra
2316
154
6.65
72
3.11
17
Manipur
29
0
0.00
0
0.00
18
Meghalaya
39
0
0.00
0
0.00
19
Mizoram
12
0
0.00
0
0.00
20
Nagaland
52
0
0.00
0
0.00
21
Orissa
314
0
0.00
12
8.70
22
Punjab
138
81
58.70
48
33.76
23
Rajasthan
237
86
36.29
0
0.00
24
Sikkim
4
0
0.00
37
9.61
25
Tamil Nadu
385
138
35.84
0
0.00
26
Tripura
38
0
0.00
20
2.44
27
Uttar Pradesh & Uttarakhand
819
2
0.24
61
7.45
28
West Bengal
275
0
0.00
61
22.18
Total states
7910
671
8.48
424
5.36
18
2
11.11
1
5.56
7928
673
8.49
425
5.36
Union Territories
Grand Total
Land Degradation: Status, Impact and Strategies in India
101
In Punjab, Haryana and Western U.P., the situation is really alarming as 40% of the
total over-exploited and dark zones are located in these states. In Punjab and Haryana,
there is steady decline of water table in areas having good quality aquifers while the
water table is rising in regions having saline ground water. In fresh water areas of
Haryana, water level has gone down by 2.5 to 11.0 m during thhe last two decades
whereas it has increased by 0.5 to 6.0 m in saline ground water areas. Similarly, Punjab
is experiencing fall of water level in 75% of the good quality water zones and rise in
remaining 25% areas having poor quality. The ground water extraction in states
experiencing decline in water table ranges from 98.3% in Punjab to 75.6% in Haryana,
72.1% in Rajasthan, 62.6% in Tamil Nadu, 49.3% in Gujarat and 41.9% in Uttar Pradesh.
The CGWB has drafted a model bill that can be adopted by various states to ensure
sustainable and equitable development and use of groundwater resources. It envisages
compulsory registration of bore-well owners, compulsory requirement of statutory
permission to sink a new bore-well, creation of a groundwater regulatory body, restriction
on the depth of bore wells, establishment of protection zones around drinking water wells
and other measures. So far about 11 states and UTs have implemented the groundwater
legislation based on the model bill of CGWB.
3.10. Use of Poor Quality Ground Water
From management point of view, ground water may be classified into good, saline
and alkali water depending upon the restriction imposed (Table 15).
Table 15: Grouping of poor quality water
EC
(dSm-1)
SAR
(mmol l-1)1/2
RSC
(meq l-1)
<2
<10
<2.5
i. Marginally saline
2-4
<10
<2.5
ii. Saline
>4
<10
<2.5
iii.High SAR saline
>4
>10
<2.5
i. Marginally alkali
<4
<10
2.5-4.0
ii. Alkali
<4
<10
>4.0
Variable
>10
>4.0
Water quality
A. Good
B. Saline
C. Alkali waters
iii High-SAR alkali
As per estimates of Ministry of Water Resources, Govt. of India, only 231 BCM
(53.3%) of ground water has been utilized out of the 434 BCM annual utilizable ground
water. About 31% of the utilized ground water is of poor quality particularly to meet the
high irrigation demand. Maximum utilization of poor quality ground water in the range
of 32 to 85% is in the arid and semi-arid regions of India. Fig. 13 presents the distribution
of poor quality ground water in the country.
102
Land Degradation: Status, Impact and Strategies in India
Fig. 13: Distribution of saline and alkali water in India
Based upon salinity alone, ground water is classified as good (EC < 2dsm-1),
marginal (2-6 dsm-1) and poor (EC >6 dsm-1). A major portion of ground water is unfit
for irrigation due to salinity (Table 16).
Table 16: Distribution of groundwater in different states based on ground water
quality
State
Groundwater quality (%)
Good
Marginal
Poor
Haryana
37
8
55
Punjab
59
22
19
Uttar Pradesh
37
20
43
Gujrat
70
20
10
Rajasthan
16
16
68
Karnataka
65
10
25
Source: Anonymous, 2004a
Land Degradation: Status, Impact and Strategies in India
103
Rajasthan state has maximum area under high salinity followed by Haryana and Uttar
Pradesh. Based upon ground water quality survey, a comprehensive ground water quality
map of the country on 1:6 million scale has been developed (Fig. 14). The map provides
distribution of different kinds of ground water quality, viz; good, saline, high SAR saline
and alkali water.
Fig. 14: Ground water quality and quantity map of India
Poor quality alkali water zones occur in parts of U.P., Haryana, Punjab and
Rajasthan. In Peninsular India, poor quality water is present in coastal belt and few
isolated pockets. As per standards of Central Pollution Control Board (CPCB), a good
quality irrigation water should have pH between 6-8.5, EC less than 2250 micro mhos
cm-1, SAR less than 26 and Boron less than 2 mg/l.
Ground water quality is polluted either due to geological factors (arsenic, iron,
fluoride etc.) or due to excessive use of agro-chemicals. The occurrence of arsenic in
ground water is reported in West Bengal, Bihar, Chhatisgarh and Assam while high
concentrations of iron have been observed mainly in Assam, West Bengal, Orissa,
Chhatisgarh and in Karnataka. Similarly, high levels of fluoride occur in about 200
districts in India. Nitrate pollution occurs in intensively irrigated and high productivity
regions due to excessive use of chemical fertilizers in India, especially in states like
Punjab, Haryana and Western U.P. Use of agro-chemicals has increased from 56114 Mt
in 1996-97 to 413,504 in 2004-05 (TERI, 2004-05) resulting in pollution of surface and
ground water resources. Similarly, about 18.4 million m3 of waste water produced per
day in India through sewage and industrial effluents is contaminating the water resources
(Minhas and Samra, 2004). It is estimated that between 103 and 177 km3/year of waste
waters that are discharged from municipalities, industries and irrigation can be recycled
and reused after proper treatment for various purposes (Gupta and Deshpande, 2004).
104
Land Degradation: Status, Impact and Strategies in India
3.11. Degradation due to Urban and Industrial Wastes and Excessive Use of AgroChemicals
Rapid urbanization, industrialization and agricultural intensification are accompanied
by generation of large amounts of solid and liquid wastes. Soil and surface bodies have
become logical sinks for Urban Solid Waste (USW), sewage-sludge and industrial
effluents (Minhas and Samra, 2004). The per capita generation of solid wastes in India
varies from 0.2 to 0.6 kg per day depending upon population size of the city (MUD &
PA, 2000). Thus over 450 class I and II cities in India are generating about 57 Mt of
solid wastes which are expected to increase to 107 Mt per annum by 2030 (Anonymous,
2003) (Table 17).
Table 17:
Year
USW generation from urban areas and estimated quantity of compost
production in India
Urban population (Million)
USW (Mt/annum)
Compost (Mt/annum)
2005
315
57.5
8.1
2010
355
64.8
9.1
2015
402
73.4
10.3
2020
456
83.2
11.7
2025
517
94.4
13.2
2030
586
107.0
15.0
Source: Anonymous, 2003
The treatment of USW would not only clean the environment but also help in
augmenting the supply of organic manures. As present, 8 Mt of compost can be
generated from 57 Mt of urban wastes (Jewan Rao and Shantaram, 1999). The untreated
compost has N, P2O5 and K2O contents in the range of 0.5 to 0.9 percent but the amounts
of heavy metals are very high (Table 18).
Table 18: Heavy metal contents in USW (mg/kg dry weight)
Heavy
metal
Bangalore
Nagpur
Fe
Range
4291-22291
Average
972.0
Range
6634-100244
Average
36539
Mn
34-161
98.4
210-3074
971.0
Cu
40-736
296.5
23.5-878
235.9
Zn
275-1341
808.0
29-3095
358.1
Pb
122-678
346.5
30.0-477.6
159.7
Cd
5-12
7.7
4.9-42.9
19.0
Ni
24-115
51.6
1.8-262.7
44.3
Cr
21-184
64.5
17.5-373.5
66.1
Land Degradation: Status, Impact and Strategies in India
105
Sewage water and industrial effluents are the major sources of waste water. India
produces 18.4 million m3 of waste water per day (Patnakar, 2001). Studies have shown that
use of waste water in peri-urban areas has resulted in soil fertility and organic matter build
up. However, harmful effects result from accumulation of heavy and toxic metals.
Industrial effluents are even more harmful and pollute the surface water bodies. All the
lakes around Coimbatore have been polluted by effluents produced from 30000 small,
medium and large industries of textiles and foundaries. Surface water bodies loaded with
effluents may ultimately pollute the ground water. Water samples collected from Hussain
Lake, polluted by over 400 industrial units and also ground water samples collected from
bore wells recorded higher degree of contaminations (Table 19). Heavy metal
contaminations in ground water, 1-2 km away from the lake were many times less than
those closer to the lake (Minhas and Samra, 2004).
Table 19: Metal contaminations in and around Hussain Sagar Lake (Hyderabad)
Zn
Cd
Pb
Ni
Source
Lake water
Range
Mean
Range
Mean
Range
Mean
Range
Mean
48-271
181
4-8
5
38-62
42
16-31
24
36-617
106
8-27
14
7-28
14
20-74
40
0.35
17
1.7
4
1.9
7
0.20
11
Ground water from
0.2–1.0 km around lake
1-2 km from lake
Source: Minhas and Samra, 2004
The consumption of pesticides has increased from 2.35 thousand tonnes in 1950-51 to
37.95 thousand tonnes in 2006-07 and is still increasing (DES, 2007). Pesticides and heavy
metals generally reduce soil respiration, microbial activity and enzyme activity, inhibit
crucial processes such as ammonification and nitrification, reduce earthworm population
and suppress algal population thus adversely affecting crop yields and quality. These
pollutants may also enter the food chain and cause health problems like blood pressure,
kidney problem, cancer etc. if threshold limit exceeds. Recent studies conducted by
CCSHAU, Hisar (2003) have shown alarming levels of pesticide contamination in human
food and water resources (Table 20).
106
Land Degradation: Status, Impact and Strategies in India
Table 20:
Sl.
No.
Pesticide residue persistence in food, fodder and irrigation waters as seen in
2001
Commodity
Samples
(nos.)
Contamination
Major residues
1.
Feed & fodder
126
81.0
HCH, DDT, Chloropyri-phos,
Endosulphan
2.
Milk
537
52.0
HCH (94%), Endosulphan (9%)
DDT residues
3.
Butter
184
64.7
-do-
4.
Irrigation waters
(a)
General water
258
60.0
HCH, DDT
(b)
Surface water
251
73.0
Endosulphan, Chloropyri-phos
(c)
Canal water
10
100.0
-do-
(d)
Pond water
11
100.0
-do-
Source: CCS Haryana Agricultural University (2003)
3.12. Coastal Erosion
The coastline in India extends from Tamil Nadu to West Bengal in the east and from
Kerala to Gujarat in the west. The total coastal length has been reported to vary from 5708
km to 5996 km by various workers (Singh et al., 2004; Joshi, 1995; Ramachandran, 2001).
The tidal waves in the Indian Ocean cause considerable soil erosion. Nearly 250 million
people live within a distance of 50 km from the coast with a population density of about
880 persons per sq km.
In the west, about 80 percent (400 km) of the entire coast line of Kerala is affected by
erosion while in Karnataka, about 73 km coastline is affected (Joshi, 1995). In some
parts of coastal Kerala, erosion is so high that shoreline is receding at the rate of nearly 5
cm per year (Sundar, 2001). At some places, sea advances as much as 30 to 50 m during
the monsoon and recedes by 25 to 40 m during the dry months thus resulting in a loss of
5 to 10 m of valuable land every year (KSLUB, 1996). Shoreline fluctuations over a
period of 55 years (1910-1965) based on Survey of India toposheets shows a loss of 22
km2 through erosion (Thirvikramaji et al., 1983) and a gain of 41 km2 by accretion.
Another study showed that about 600 m wide belt of land was lost during 120 years from
1850 to 1970 (KERI, 1971).
On the east coast, the region between Point of Climere and Vishakhapatnam has been
identified as cyclone prone zone. Due to any storm of depression centered in the Bay of
Bengal, whether it crosses the land or not, the equilibrium of east coast shoreline gets
affected, resulting in sporadic coastal erosion of very severe nature (Natarajan et al.,
1991). In Tamil Nadu, about 80 km coastline, in Orissa about 30 to 40 km and in West
Bengal about 180 km coast stretching from confluence of river Hooghly in the west to
confluence of river Jagdal in the east are affected. The rate of erosion is as high as 30 m
per year (Joshi, 1995).
Land Degradation: Status, Impact and Strategies in India
107
The coastline of Tamil Nadu is more affected by storms and depressions especially
during November to January (north east monsoon). The state has lost many villages and
towns in the past due to sea intrusions. A study of coastal processes indicated that a total
extent of 158.52 acres of land has been lost to the sea on the coastal front of Tamil Nadu
state during 1978 to 1988, within a stretch of 77 km. Therefore, the total erosion would
amount to 1950 acres in 10 years period as a generalized estimate for the entire coastline
of Tamil Nadu (Natarajan et al., 1991). By and large, cyclonic erosion and accretion is
experienced along the entire east coast. The most vulnerable coastal erosion sites are
presented in Fig. 15.
Fig. 15: Major coastal erosion sites
3.13. Gullies and Ravines
Gullies result from continuous non-judicious use of the land and are defined as
advanced form of rill erosion. They generally originate on sloppy lands due to improper
management and concentration of flowing water leading to severe erosion hazards. They
are visible in the plateau region of Eastern India, along the foothills of Himalayas and in
extensive areas of Deccan plateau. Ravines, on the other hand, are a network of gullies
almost parallel to each other and generally associated with some river system. The major
factors responsible for formation and development of ravines include severe misuse and
management of rainwater and faulty agricultural practices in the upper river catchments
resulting in heavy siltation rates and meandering of rivers and backflow of water from
adjoining porous strata into the river system leaving behind a network of gullies.
In India, ravines (gullies) occur along the rivers Beas, Yamuna, Ganga, Chambal,
Kalisindh, Mahi, Narmada, Sabarmati and their tributaries in the States of Punjab, Uttar
Pradesh, Bihar, West Bengal, Rajasthan, Madhya Pradesh and Gujarat (Fig. 16).
108
Land Degradation: Status, Impact and Strategies in India
Fig. 16: Extent of ravines in India
An area of about 3.7 Mha is affected by ravines in the country (Table 21). As already
discussed, there is no change in the status of ravine area since 1985.
Land Degradation: Status, Impact and Strategies in India
109
Table 21: Statewise distribution of ravines (Gullied area) in India
State
Uttar Pradesh
Gullied area
(lac ha)
12.30
Madhya Pradesh
6.83
Rajasthan
4.52
Gujarat
4.00
Maharashtra
0.20
Punjab
1.20
Bihar
6.00
Tamil Nadu
0.60
West Bengal
1.04
Total
36.69
Source: Anonymous, 1972
The CSWCRTI, Dehradun established three Regional Centres at Agra (U.P.), Kota
(Rajasthan) and Vasad (Gujarat) during First Five Year Plan to tackle the problems of
ravines and develop appropriate technologies for their reclamation and productive
utilization in the Yamuna, Chambal and Mahi river systems, respectively.
3.14. Mass Erosion Problems
Landslides, minespoils and torrents are the major mass erosion problems prevailing
in various regions of the country, especially in the hill and mountain agro-ecosystems
covering Himalayas and Shiwalik region. Due to precipitous slope and high intensity
rains, they lead to enormous sedimentation rates affecting productive lands besides loss
to life and property. Apart from causing disruption to traffic, they also impair the quality
of water resources and in turn the aquatic life in streams and reservoirs.
3.15. Landslides
The hilly regions having steep slopes, fragile ecology, high seismic activity and
intense rainfall conditions are highly susceptible to landsliding. The problem gets further
aggravated by excessive deforestation, unscientific cultivation on steep slopes and
developmental activities like road construction, buildings construction, mining etc.
Occurrence of landslides is a regular feature along nearly 44000 km roads constructed in
the Himalayan region. National Highway No. 31A (Ranipur-Rangpur) in Sikkim state is
a veritable live museum of landslides. Krishnaswamy and Jain (1975) identified 31
major landslides in northern and north-western Himalayas spread over 1,20000 km2. As
many as 369 landslides have been recorded in the Alaknanda, Bhagirathi and Ganga
basins of U.P. Himalayas by the Geological Survey of India.
110
Land Degradation: Status, Impact and Strategies in India
A study conducted along the roads in Tehri Garhwal and Dehradun districts indicated
that, on an average, there are about 10 medium size landslides in each kilometer of the road,
each depositing about 500 hundred cubic metres of debris on the road (Bansal and Mathur,
1976). Small and medium size landslides (5-100 cubic metre) contributed 63 percent by
number and 30 percent by volume of the debris clearance problem on Mussoorie-Tehri road
(Haigh, 1979). The hill roads have been observed to suffer from about 4-10 landslides and 820 slumps per km, engulfing an area of about 15-20 ha (Saxena et al., 1995). Major
landslides in Himalayas are estimated to cause an annual loss of more than 50000 man hours
and 5000 vehicle hours per km on hill roads entailing an annual loss of Rs. 150 crores
towards removal of debris for road clearance.
3.16. Minespoils
Mining industry plays a vital role in Indian economy and is spread over an area of
9,43380 hectares covering 7365 mine leases (Anonymous, 1992). The Himalayas in
India, covering an area of nearly 50 million ha, are bestowed with a large variety of
mineral resources such as limestone, dolomite, phosphorite, magnesite, gypsum etc. An
area of about 25000 ha has been estimated under mining activity, mainly limestone
quarrying in the Himalayan region (Table 22) (Soni, 1994). Limestone mining has been
found to reduce food production by 28%, water resources by 50% and livestock
production by 35% in the upstream reaches of Doon Valley (Anonymous, 1988). The
unscientific mining on steep slopes often using excessive explosives causes huge damage
to the fragile ecosystem leading to environmental degradation due to heavy soil erosion,
drying of water resources, loss of land area, disruption to communication systems, floods
and consequent decline in food and milk production.
Table 22: Distribution of mined lands in Himalayas
State
Mining area
(in ha)
Uttarakhand
Garhwal region
6832
4820
Kumaon region
610
Meghalaya, Assam & West
Bengal
11471
Mineral
Limestone, Phosphorite
Limestone, Dolomite, Copper,
Silica, Gypsum, Magnesite
Chromite
Dolomite, Silica, Coal, Limestone,
China Clay, Quartz, Mica
Jammu & Kashmir
886
Limestone, China Clay, Gypsum,
Magnesite, Bauxite, Sapphire
Himachal Pradesh
438
Limestone
Total
25057
Land Degradation: Status, Impact and Strategies in India
111
The sedimentation rate from unreclaimed minespoils of limestone mining in Doon
Valley of North-West Himalayas has been recorded as 550 t/ha/yr (Katiyar et al., 1987).
A reduction of about 50% in spring flow during the lean period has been reported due to
mining activity in the Baldi valley (Katiyar et al., 1990). The torrents emanating from
the mined headwater regions are damaging about 100 ha of forest land every year in the
valley and destroying trees worth Rs. 10 million (Juyal et al., 1995). Due to
communication failures, the Public Works Department was spending an amount of more
than Rs. 1 lakh every year to clear the debris from a 64 ha limestone quarry at
Sahastradhara, a tourist spot near Dehradun (Katiyar et al., 1987). The CSWCRTI,
Dehradun has developed a bio-engineering technology for rehabilitation of degraded
minespoil areas (Juyal et al., 2007).
3.17. Torrents
Torrents are ephemeral streams characterized by flash flows accompanied with high
debris load during monsoon season. They originate from the hill slopes, descend to the
mildly sloping foothills and valleys and finally drain into a river system. The area
affected by seasonal torrents in Hoshiarpur district of Punjab increased from 192 sq km in
1852 to 286 sq km in 1886 to 2000 sq km in 1939 and to 3000 sq km in 1988 (Grewal,
1995). Latest estimates of Soil Conservation Division of Ministry of Agriculture, Govt.
of India revealed that about 2.73 Mha area in the country is affected by the problems of
torrents and riverine lands, a major part of torrents lying in the Shiwalik region
(Mukherjee et al., 1985). The problem of meandering rivers is very acute in Bihar and
Uttar Pradesh as many flood prone rivers flow through these states. The Kosi river alone
has shifted over 167 kms from the east to the west over a period of over a century and a
quarter (Das, 1985).
Recent studies have indicated that 1517 sq km area in the Shiwaliks lies directly
under the course of torrents affecting about 7500 sq km area in the states of J&K, H.P.,
Uttarakhand, Punjab, Haryana and Union Territory of Chandigarh (Sharda et al., 2007).
The torrent training measures include spurs, protection walls, embankments and
biofences. A cost effective technology for training of torrents comprising of appropriate
mix of engineering and vegetative measures has been developed by CSWCRTI,
Dehradun (Juyal et al., 2005).
4. Impacts of Land Degradation
Land degradation has both on-site and off-site impacts which apart from lowering the
productive potential also results in deterioration of soil health, impairment of water
quality, pollution of surface and ground water resources, loss of storage capacity of
reservoirs, loss of biodiversity, landlessness, poverty, food insecurity and several types of
environmental hazards. A brief description of the impacts of various forms of land
degradation is presented in the following sections:
Water Erosion: Erosion removes soil containing organic matter and other plant
nutrients thus causing loss of productivity which has been estimated to vary from 5 to
50% depending upon type of soil and crop and the intensity of erosion (Sehgal and Abrol,
1994). It has been estimated that nearly 5.37 to 8.4 Mt of plant nutrients are lost every
112
Land Degradation: Status, Impact and Strategies in India
year from Indian soils due to water erosion. The annual loss in production of major crops
due to soil erosion has been estimated to vary from 7.2 Mt (UNEP, 1993) to 13.5 Mt
(Bansil, 1990). The loss in production for 11 major crops varied from 1.7% to 4.1% of
total production (Brandon et al., 1995). Experimental studies in lower Himalayan region
indicated that removal of 1 cm of top soil caused 76 kg/ha reduction in maize grain yield
and 236 kg/ha in straw yield (Khybri et al., 1988). The reduction was observed to be 103
kg/ha in Shiwalik region of Punjab (Sur et al., 1998). Vittal et al. (1990) recorded losses
of 138, 84 and 51 kg/ha/cm removal of top soil for sorghum, pearlmillet and casterbean,
respectively.
Recently, CSWCRTI Dehradun systematically computed the production losses of 27
major cereal, oilseed and pulse crops under rainfed conditions. The experimental data
collected on loss of productivity in different agro-ecological regions was integrated with
potential erosion rates in five categories, viz; <5, 5-10, 10-20, 20-40 and >40 t/ha/yr
under three major soil groups i.e. alluvium derived, black and red by evolving a uniform
procedure and methodology. From the analysis, it is concluded that in India, a loss of
1344.8 Mt occurs in cereal, oilseed and pulse crops due to water erosion which is
equivalent to Rs. 111.6 billion. The cereals contribute 68.3% to total loss followed by
oilseeds (20.9%) and pulses (12.8%). Among oilseed crops, groundnut and soybean
occupying 26.5 and 36.5% of total area, contribute 12.3% and 10.4% to total monetary
loss. Similarly, in pulse crops, gram (6.4%) and pigeonpea (2.9%) are the main
contributors to total monetary loss as compared to other crops.
Apart from reducing productivity, sediment laden runoff water carries toxic
substances and organic compounds such as pesticides which cause wide range of
environmental hazards in the downstream reaches such as degradation of adjoining
agricultural lands, meandering of river courses, smothering of crops and vegetation,
pollution of water in streams, canals and rivers and flooding. Satellite imagery of
Himalayan torrents shows that between 1990 and 1997, the width of torrents has
increased by 106 percent and that of rivers by 36% resulting into flooding of downstream
reaches.
The data on 17 medium and small reservoirs under river valley projects in India have
shown that the rate of inflow of sediments is about 3 times (9.17 ha-m/100 km2/year) as
compared to the design rate of 2.93 ha-m/100 km2/year, thus reducing the life expectancy
and hydro-electric generation to one-third of the planned capacity. The loss of natural
vegetation due to water erosion and deforestation is a major cause of natural disasters
such as landslides and floods. In the Himalayan foothills, landslides killed more than 300
people within a week in August, 1999 (GoI, 1999). Occurrence of landslides has become
a common feature due to clearance of forests for agriculture and road building. India is
one of the top 10 countries in the world, which are highly vulnerable to droughts, floods,
cyclones and earthquakes though landslides, avalanches and bush fires also occur
frequently in the Himalayan region.
Wind Erosion: Wind erosion causes decrease in land productivity at both the sites
from where the finer particles are blown away and at sites where they are deposited.
Raina (1992) reported that decrease of organic carbon content in the soils of degraded
sites was more in oran (50.7%) followed by cultivated (50.3%) and pasture lands (39.4%)
while the decrease in potassium was more in cultivated soils (55%) followed by oran
Land Degradation: Status, Impact and Strategies in India
113
(35.2%) and pasture land (12%). Maximum decrease in phosphorous was recorded in
pasture soils (72.4%) followed by cultivated lands (52.9%). Deep ploughing of sand
plains lost more than 3000 tonnes of soil per ha during a sand storm of 1987 while areas
with 10-12% plant cover or with higher cloddy surface suffered negligible soil loss
(Samra and Narain, 2006).
Waterlogging, Salinization and Acidification: Waterlogging causes reduction in
oxygen supply to the root zone resulting in excess accumulation of toxic organic
constituents and reduced forms of metallic ions such as iron and manganese thus causing
complete failure of crops. It is estimated that India loses 1.2 to 1.6 million tones of food
grain production every year due to waterlogging resulting from temporary submergence
of soils by floods as well as rise in water table (Brandon et al., 1995). Reclamation of
waterlogged saline soils is a costly affair and the progress is very slow. So far about
22000 ha barren waterlogged saline soils have been reclaimed (Table 23).
Table 23: Extent of salt affected and waterlogged saline soils reclaimed in different
states
Salt affected area
(m ha)
Area affected
Area reclaimed
Waterlogged saline area
reclaimed
(ha)
Punjab
0.530
0.366
250
Haryana
0.700
0.547
1650
Uttar Pradesh
1.200
0.140
-
Rajasthan
-
-
15000
Karnataka
-
-
5000
State
Reclaimed waterlogged saline soils have the potential to produce 4.0 to 9.5 t/ha of
wheat with a benefit cost ratio of 1.26 to 3.99, where nothing was growing (Anonymous,
2004a). Reclaimed area is contributing nearly 6 million tonnes of paddy and wheat
annually in Punjab, Haryana and Uttar Pradesh.
The loss in productivity due to salinity in India is estimated to vary from 6.2 million
tonnes (UNEP, 1993) to 9.7 million tonnes (Bansil, 1990). The difference is attributed to
the fact that UNEP takes into account only the agricultural lands while Bansil includes
other non-wasteland and other non-forest land as well. The annual loss in production of 11
major crops varied from 1.5% to 3% for UNEP and Bansil data, respectively. It is
estimated that reclamation of 8.5 Mha salt-affected soils in India with suitable technology
can produce additional 50-55 Mt of food grains annually with a benefit cost ratio of 4.6
without government subsidy on gypsum and between 6 and 7 with 50-70 percent subsidy
(Yadav, 2007). The reclamation and management package for waterlogged, saline and
alkali soils consist of land leveling and construction of bunds (field dykes), adequate
drainage provision for removal of excess salt and horizontal sub-surface drainage to control
114
Land Degradation: Status, Impact and Strategies in India
water table, assured source of good quality irrigation water, application of amendments
(gypsum/pyrite) in alkali soils, leaching of excess salts, selection of suitable crops and
cropping sequences and nutrient and water management (Tyagi, 1998).
Depending upon level of acidity, type of soil, crop grown and climatic conditions,
acid soils can reduce productivity by 10-50% (Velayutham and Bhattacharyya, 2000).
The reduction is attributed to low base saturation (20-25%), deficiency of calcium,
magnesium, molybdenum, boron and zinc, low cation exchange capacity of Kaolinitic
clay and poor nutrient retention, poor organic matter build up and nitrogen availability,
high P fixation and its low availability, and excess/toxicity of iron, aluminium and
manganese. A long-term study conducted in Typic Hapudalfs acid soil for 29 years
(1972-2001) indicated that even 100 percent application of recommended NPK fertilizer
dose without amendments (lime or FYM) failed to check the decline in maize (Fig. 17)
and wheat (Fig. 18) yields (Subehia et al., 2005). The higher yields of maize to the tune
of 0.85 and 1.27 t/ha over 100% NPK were obtained with application of lime @ 0.9 t/ha
and FYM @ 10 t/ha, respectively. Similarly, 100% NPK with FYM yielded highest
wheat grain yield of 2.4 t/ha followed by 2.3 t/ha with 100% NPK + lime as against 1.6
t/ha with 100% NPK without amendments.
6
Grain yield of maize (t/ha)
1973-82
1983-92
1993-01
5
4
3
2
1
0
Control
100% NPK
100%
NPK+lime
100%
NPK+FYM
Fig. 17: Impact of nutrient and amendment on yield of maize in acid soil
Land Degradation: Status, Impact and Strategies in India
Grain yield of wheat (t/ha)
4
1973-82
115
1983-92
1993-01
3.5
3
2.5
2
1.5
1
0.5
0
Control
100% NPK
100%
NPK+lime
100%
NPK+FYM
Fig. 18: Impact of nutrient and amendment on yield of wheat in acid soil
Organic amendments like FYM, coir pith and press mud in conjunction with lime
have been found quite effective. Depending upon their sensitivity to pH, high responsive
crops (pigeonpea, soybean, cotton), medium responsive crops (gram, lentil, pea, maize
and sorghum) and low responsive crops (paddy, small millet, mustard) can be grown.
5. Soil Physical Constraints
The impact assessment of technologies developed for soils having sub-surface
mechanical impedance under field conditions show spectacular increase in production of
major crops varying from 12 to 63% (Table 24) (Painuli and Yadav, 1998).
Table 24: Field evaluation of technologies for soils having sub-surface mechanical
impedance
Technology
Chiesel technology
(chiseling up to 45
cm at 50 cm
interval)
Soil type
(location)
Mode of
evaluation
Red soil
(Coimbatore)
ORP- rainfed
(8 acres)
No. of
years
1
1
1
1
ORP irrigated
(8 acres)
1
Crop
Sorghum (1 crop)
Maize (II crop)
Groundnut (1 crop)
Tomato (II crop)
Black gram (1 crop)
Samai (II crop)
Maize (I crop)
Maize (II crop)
Maize
Increase (%)
in yield over
farmer’s
practice
18.6
21.6
62.7
26.9
64.1
28.9
55.7
28.2
34.4
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Land Degradation: Status, Impact and Strategies in India
Chiesel technology
(chiselingupto 30cm
interval)
Black soil
(Nizamabad)
Farmer’s
field
1
Sugarcane
12.0
Chisel technology
(chiseling up to 40
cm depth at 50 cm
interval)
Sandy loam
(Hisar)
Farmer’s
field
-
Wheat
Cotton
Raya
14.0
17.0
41.0
Chisel +
amendment
(gypsum @ 5 t/ha
or FYM @ 25 t/ha)
technology
Black soil
(Nizamabad)
Farmer’s
field
1
Sugarcane
25.4
Ridge technology
Sandy loam
(Hisar)
Farmer’s
field
-
Mustard
33.0
The raised and sunken bed (RSB) technology for vertisols having high clay content
has been found to be highly remunerative on sustainable basis (Painuli et al., 2002).
Soybean on raised bed produced 2.28 t/ha against 1.0 t/ha on flat bed while paddy yielded
2.6 t/ha in the sunken bed on net cropped area basis (Table 25). The technology is
equally effective in sub-surface compacted soils as effective rooting depth is increased by
30 cm in raised beds. The technologies for checking sub-surface mechanical impedance
and compaction also help in conserving soil and water besides increasing productivity.
Table 25: Productivity of soybean-rice cropping sequence in raised and sunken
bed system of cultivation (t ha-1)
Selected year
Soybean seed yield
Raised bed
Flat bed
Paddy grain
yield in sunken
bed
Annual
rainfall (mm)
1980
2.96
2.23
5.10
1432
1985
2.25
1.00
2.50
1380
1990
2.43
0.58
3.00
1624
1995
1.76
1.11
4.47
1153
Mean of 16 yrs.
2.28
0.96
2.61
1397
Horti-pastoral system of aonla + hybrid napier was found to be more effective than
pure aonla in reducing compaction in 10-30 cm soil depth from 1890 to 284 kpa (Yadav
et al., 2005).
Poor Quality Ground Water : Long term use of poor quality water makes EC of top
60 cm of soil equal to that of irrigation water and high ESP in upper soil layer. It causes
breakdown of structure in alkali soils and salt induced water stress in saline soils. The
Land Degradation: Status, Impact and Strategies in India
117
strategies for minimizing the impact of poor quality water on crop productivity include
the following:
•
Application of less amount of poor quality water
•
Conjunctive use with good quality water by blending alkaline/saline water with canal
water, rotational use of saline/fresh water and management of shallow saline water
table
•
Application of gypsum to neutralize RSC of irrigation water. Add 12 kg gypsum per
hectare to neutralize 1 meg/l RSC for 1 cm of irrigation water.
•
Appropriate water and nutrient management to prevent adverse impact of salts
•
Selection of suitable crops, varieties and rotations.
Pollution due to Urban Industrial Wastes and Excessive Use of Chemicals : The use
of waste water from Nag river in India for 20 years was found to have no effect on
morphological and physical properties of soil (Bhise et al., 2007). In fact it improved the
availability of Ca, Mg, K, Zn, Cu, Mn and Fe under five land use systems tried.
However, it had adverse impact on EC, ESP, soluble cation ratio (Na/K and Na/Mg) and
heavy metal (Pb, Cd, Co and Ni) contents thus causing accumulation of toxic elements.
The impact assessment of wastes utilization in agriculture can be visualized in terms
of soil quality, plant growth and human and animal health. Type of soil and organic
matter contents play a crucial role in the amount of heavy metal that can be adsorbed.
Detailed study on adsorption of Cd in sewage irrigated Haryana soils revealed that Cd
adsorption was positively correlated with clay content, CEC, pH and organic matter (Lal
and Minhas, 2005).
Use of solid and liquid wastes has risk of transfer of heavy metals and their
accumulation in edible parts of vegetable and meat products. Sewage flowing through
Musi river near Hyderabad has shown that Cd, Cr, Ni, Pb, Co, Zn, Cu, Fe and Mn get
accumulated in milk produced by animals fed on fodder grown with sewage
(Anonymous, 2004b). All these metals exceeded the safe limit in the milk produced
(Table 26).
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Land Degradation: Status, Impact and Strategies in India
Table 26: Relationship between heavy metal contents in water, soil, plant and
milch animals along Musi river draining Hyderabad city
Elem
ent
Sewage
Mean
Cd
Soil
PSE
0.025
Mean
90
(5)
Cr
Plant
High
0.37
27.0
PSE
Mean
10
--
0.062
85
(1.3)
1.32
12.2
--
90
(1.3)
2.79
46.3
22
12.50
60.9
32
100
0.52
4.9
--
0.003
Nil
0.011
10.96
87.8
--
Nil
5.83
60.9
56
Tr
PSE
0.062
100
92
36
0.226
0.140
4.34
19.22
2.39
0.780
100
(15.6)
100
24
0.224
0.029
0.497
100
(3.9)
100
100
0.850
0.385
0.730
100
(14.9)
68
--
0.345
0.077
--
--
--
75.9
--
--
44.88
88
32
0.074
0.496
6.300
62.5
12.76
(1.3)
92
56
0.060
0.302
0.420
--
84
60
0.370
24.16
11.900
100
(2.1)
92.7
65
(7.6)
Mn
4.90
(2.2)
(3.2)
Tr
0.022
Mean
(1.2)
(2.2)
Fe
0.053
(3.9)
(10.6)
Cu
4
Mean
(2.2)
(2.5)
0.053
Zn
Mean
(2.5)
(1.4)
0.210
Co
20
PSE
Milk
12.4
(0.7)
Pb
0.79
High
Serum
(0.7)
Tr
Ni
Urine
4.59
(3.1)
--
--
92.86
(1.8)
(39.7)
68
24
0.058
0.04
0.920
100
(9.0)
Source: Anonymous, 2004b
Figures in parentheses are number of times more than the normal limits; tr-traces;
PSE- percent samples having excessive amounts than the prescribed limits.
The pesticides use in India may increase in the coming years due to intensification of
modern agriculture which may have serious repercussions on soil and human health.
Some of the negative impacts include excessive mortality and reduced reproductive
potential in organisms, a reduction in number of species and diversity of ecosystems,
deterioration of soil health and development of resistance to pesticides in the target and
non-target species (TERI, 1998). Recent studies conducted by CCS HAU, Hissar (2003)
have shown alarming levels of pesticide contamination in human food and water
resources (Table 27).
Land Degradation: Status, Impact and Strategies in India
119
Table 27: Pesticide residue persistence in food, fodder and irrigation waters as
seen in year 2001
Sl.
No.
Commodity
Samples
(nos.)
Contamination
Major residues
1.
Feed & fodder
126
81.0
HCH, DDT, Chloropyri-phos,
Endosulphan
2.
Milk
537
52.0
HCH (94%), Endosulphan (9%) DDT
residues
3.
Butter
184
64.7
-do-
4.
Irrigation
waters
(a)
General water
258
60.0
HCH, DDT
(b)
Surface water
251
73.0
Endosulphan, Chloropyri-phos
(c)
Canal water
10
100.0
-do-
(d)
Pond water
11
100.0
-do-
Source: CCS Haryana Agricultural University, 2003
Nutrient Mining: Studies have established that it is not possible to obtain economical
yields of major crops in different regions of the country on long term basis (Swarup and
Wanjari, 2000). Unfertilized exhausted soils can produce wheat, rice and maize yields
only in the range of 0.8-1.1, 1.5 – 1.6 and 0.3 – 0.7 t/ha (Table 28). The yields can be
increased and also sustained at higher levels of 4.0 – 5.0, 2.4 – 4.6 and 2.5 – 3.0 for rice,
wheat and maize, respectively if deficient nutrients are brought to sufficiency levels
through chemical fertilizers.
Table 28: Mean grain yield of crops under long term fertilizer application and
manuring
Mean grain yields
(t ha-1)
Location & Duration
Crops
Barrackpore (27 yrs)
Bhubneswar (22 yrs)
Unfertilize
d
100%
NPK
100%
NPK+FY
M
150%
NPK
Rice
1.6
3.9
4.1
4.3
wheat
0.8
2.4
2.5
2.9
Rice
1.6
2.8
3.5
3.0
Wheat
1.4
3.0
3.7
3.3
120
Land Degradation: Status, Impact and Strategies in India
Coimbatore (28 yrs)
1.0
3.0
3.5
3.2
0.7
3.0
3.4
3.2
Maize
0.4
2.6
3.2
2.5
Wheat
1.0
4.8
5.0
4.9
Finger
millet
Maize
Ludhiana (29 yrs)
Jabalpur (20 yrs)
Pantnagar (28 yrs)
Palampur (26 yrs)
Soybean
0.9
2.1
2.2
2.1
Wheat
1.1
4.2
4.6
4.4
Rice
3.1
5.3
6.0
5.3
Wheat
1.5
3.8
4.5
4.1
Maize
0.3
3.2
4.6
4.0
Wheat
0.3
2.5
3.3
3.0
Studies under Integrated Plant Nutrients Supply (IPNS) system proved that various
types of organic sources of nutrients like FYM, crop residues and green manuring not
only maintain the yield but also reduce input cost, enhance profit and improve soil health
(Yadav et al., 2000). Nutrient studies for more than a decade have shown non-significant
differences in yield of rice grown by 50 percent nutrient substitution by FYM, crop
residues or green manure (Table 29). However, no nutrient balances need to be worked
out to ensure the sustainability of the system. A system which is sustainable improves
soil organic and fertility build up, increases yield and economic returns without causing
adverse effect on environment.
Table 29: Grain yield (tha-1) for rice under long term application of NPK along or
on substitution with organic sources
Control
50%
NPK
100%
NPK
50%
NPK +
FYM
50% NPK
+ CR
50%
NPK +
GN
Ludhiana (15 yrs)
2.05
3.95
6.08
5.57
5.06
6.05
Panthnagar (15 yrs)
2.80
3.39
4.56
4.03
3.84
4.29
Kanpur (13 yrs)
1.76
3.04
4.47
3.80
3.65
4.22
Faizabad (14 yrs)
1.66
2.91
4.20
4.03
3.78
3.88
Sabour (12 yrs)
1.58
2.78
4.11
4.08
3.87
3.90
Kalyani (13 yrs)
1.37
2.53
3.32
3.37
3.46
3.68
Jabalpur (12 yrs)
2.51
3.62
5.09
4.78
4.37
5.20
Mean
1.96
3.18
4.59
4.24
4.00
4.46
Location &
Duration
CD (P=0.05), Treatment (T) 0.21, Location (L) 0.21, Interaction(T x L) 0.53
Land Degradation: Status, Impact and Strategies in India
121
Depletion of Organic Matter: Projection for 60 years (1970-2030) data showed that
SOC could be maintained at the base level of 0.45 percent in Alfisols with conjunctive
use of chemical fertilizers and FYM while it reduced to 0.30 and 0.36 percent under no
fertilizer and chemical fertilizers treatments, respectively (Fig. 19) (Vision 2025, IISS,
Bhopal).
RANCHI (ALFISOLS)
100%NPK
100%NPK+ FYM
Control
0.5
0.4
0.3
0.2
0.1
0.0
1970
1980
1990
2000
2010
2020
2030
Years
Fig. 19: Projected level of soil organic carbon under different nutrient
management practices under soybean-wheat rotation
The SOC can be improved through Integrated Nutrient Management (INM) by
applying NPK in conjunction with FYM. Long-term studies in Mollisols indicated that
INM helped in maintaining the SOC at the same level after 31 years of cropping cycles
(Sharma et al., 2007). Addition of FYM with 100% NPK maintained the SOC at around
1.54 percent.
Land uses like agroforestry and agri-horticulture increased the soil organic content by
about two folds compared to sole cropping within a short span of 6 years (Table 30) (Das
and Itnal, 1994). Different species vary in their capacity to build up organic carbon under
similar soil and climatic conditions. In salt-affected soils, organic carbon content
increased many times in soil profiles under differet plant species, the maximum being
under Prosopis juliflora and lowest under Eucalyptus tereticornis.
Table 30: Organic carbon content in soils after six years under different land uses
Land use
Sole cropping
Agro-foresry
Agri-horticulture
Agri-silviculture
Organic carbon (%)
0-15 cm
0.42
15-30 cm
0.37
0.71
0.73
0.38
0.73
0.74
0.56
122
Land Degradation: Status, Impact and Strategies in India
The SOC in the degraded soils can be improved by adopting the following measures:
•
Conservation tillage utilizing crop residues
•
Growing leguminous cover crops to enhance biodiversity and produce quality residue
for incorporation in soils
•
Adding N, P, K and all deficient nutrients to accelerate the process of humification to
convert organic residues to humus besides optimizing production.
•
Adding organic manures (FYM, Compost and vermin-compost) under IPNS.
•
Adopting soil conservation measures, viz; contour cultivation, contour and graded
bunding, terracing etc. to hold humified organic residues along with the soil.
•
Maintaining microbial biodiversity which is inherently important to the concept of
soil health and transformation of soil organic matter through various soil processes.
Floods and Droughts: Average flood damage to houses, crops and public utilities
during 1953-02 has been estimated as Rs. 13,760.8 million affecting an area of 7.38 Mha
and a population of 32.97 million (CESI, 2006). Human and cattle loss has been put at
1560 and 91555 affecting 3.48 Mha of cropped area in the country (Table 31). The
maximum damage to area, human and livestock population, crops and public utilities
occurred during the years 1977, 1978, 1979, 1988 and 1998. Due to high erosion rates
and excessive sedimentation, the storage capacity of major reservoirs is lost at the rate of
1-2% every year.
The ideal solution for flood control is the creation of adequate storages in flood prone
river systems. The best example is the construction of storages in the Damodar river
basin by DVC which have made the floods a matter of history in the region. Floods can
be prevented or significantly moderated by watershed management in the catchment
areas of river basins. For international rivers originating in Nepal and Bhutan, a joint
mechanism for watershed management needs to be evolved. The total area reasonably
protected against floods in India by the end of Tenth Plan (2002-07) is 18.22 Mha
(Planning Commission, 2007).
Table 29: Flood affected area and flood damages
Sl.
No.
Item
Unit
Av. flood
damage during
1953-02
Maximum
damage (with
year)
Damage
during 2002
(tentative)
1
Area affected
million ha
7.38
17.50 (1978)
2.87
2
Population
affected
million
32.97
70.450 (1978)
22.41
3
Human lives lost
Number
1560
11316 (1977)
640
4
Cattle lost
Number
91555
618248 (1979)
3647
5
Cropped area
affected
Million ha
3.48
10.15 (1988)
1.27
Land Degradation: Status, Impact and Strategies in India
Sl.
No.
Item
Unit
Av. flood
damage during
1953-02
123
Maximum
damage (with
year)
Damage
during 2002
(tentative)
6
Value of damage
to crops
Million Rs
5969.70
25109.00 (1988)
5471.30
7
Houses damaged
Million
1.19
3.51 (1978)
0.45
8.
Value of damage
to houses
Million Rs
1891.00
13078.00(1988)
4551.70
9
Value of damage
to public utilities
Million Rs
5662.40
31714.00 (1998)
4864.90
10
Value of damage Million Rs
to houses, crops
and public utilities
13760.80
58459.80 (1998)
14887.90
Note: Figure for the years 1998, 1999, 2000, 2001 and 2002 are tentative and are being finalized in
consultation with State Govt.
Source: 1. Central Water Commission; 2. Compendium of Environment Statistics India, 2006, Central
Statistical Organization, Ministry of Statistics and Programme Implementation, Govt. of India (Website:
http://www.mospi.gov.in).
India has experienced 40 major droughts in the past 200 years (1801-2002) with 10
years under severe drought category (> 39.5% area affected) and 5 years under
phenomenal drought (>47.7% area affected) (Subbareddy et al., 2008). Since
Independence, India has experienced 15 droughts out of which 3 were of severe, 7 of
moderate and 5 of slight intensity affecting 13.3 to 49.2% of total geographical area of
the country (FAI, 2006-07). Drought prone areas are more vulnerable to land
degradation. In a good or normal rainfall year, they substantially contribute to agriculture
production particularly for groundnut, bajra and jowar crops where they account for onethird to one-fourth of the total national production. Similarly, one-sixth to one-tenth of
other important crops like ragi, maize and cotton and 12% of rice production is realized
from these areas besides sizeable contribution to the production of pulses and oilseeds.
The severe drought in 2002 was widespread affecting 14 states. In Andhra Pradesh
alone, crop loss of Rs. 5227 crores was estimated. About 75% of the districts received
rainfall less than normal till July and 64% till the end of monsoon. The late sowing resulted
in significant reduction in production of crops like rice (-12.5 Mt), wheat (-6.5 Mt), coarse
cereals (-7.52 Mt), oilseeds (3.37 Mt), cotton (-2.61 M bales) and sugarcane (-15.82 Mt)
(Subbareddy et al., 2008).
Climate Change Impacts: The analysis of monthly rainfall data for all the 36 subdivisions of the country indicates that contribution of June and August rainfall exhibited
significantly increasing trend while contribution of July rainfall showed a decreasing
trend (Guhathakurta and Rajeevan, 2006). Thus, a major shift in rainfall pattern both
spatially and temporarily has been recorded in the recent years. Analysis of long-term
rainfall data for over 1100 stations across India show pockets of deficit rainfall over
eastern Madhya Pradesh, Chhatisgarh and North-east region in Central and Eastern India
124
Land Degradation: Status, Impact and Strategies in India
(Subba Rao et al., 2007), especially around Jharkhand and Chhatisgarh. In contrast,
increasing trends (+ 10 to 12%) in rainfall are observed along the west coast, northern
Andhra Pradesh and parts of NW India (NAPCC, 2008). In the Southern Peninsular
region, a shift in peak monthly rainfall by 20-25 days from September to October is
recorded.
The intensification of hydrologic cycle due to global warming may result in more
intense rains, frequent floods and droughts, shifting of rainy season towards winter and
significant reduction in mass of glaciers causing more flow in the initial few decades but
substantially reduced flow thereafter. Analysis of rainfall data with intensities of 10,100
and above 100 mm revealed that in the recent period, the frequency of rain events of
more than 100 mm intensity have increased while the frequency of moderate events over
central India has significantly decreased during 1951 to 2000 (Goswami et al., 2006).
Thus high intensity storms would cause high erosion losses leading to severe land
degradation problems.
The deforestation, desertification and soil erosion are also disrupting the carbon cycle
between pedosphere and atmosphere resulting in decline of carbon stock especially of
soil organic carbon thus deteriorating chemical, hydrological and biological environment
of the soil. India is the lowest contributor of the GHG compared to North America and
many other industrial and developed countries (0.29 tonnes per capita consumption
compared to 5.37 and 4.63 by USA and Australia at 1996 level). However, with growing
industrialization and economic development, India may become the second fastest
growing GHG contributor in the world (increase in per capita consumption to 1.02 tonnes
by 2004) next to China (NAPCC, 2008). While the CO2 emissions at 1997 level had
been 237 Mt, it is projected to increase to 775 Mt by the end of the century if coal
consumption continues at the present rate (Ravi Sharma, 2007).
The average increase in temperature in India during 1901 and 2005 has been 0.51oC
compared to 0.74oC at global level. The increase was in the order of 0.03oC per decade
during 1901-1970 while it was around 0.22oC per decade for the period from 1971 to
2004 indicating greater warming in the recent decades. The projected increase in the 21st
century is expected to vary between 3 to 6oC with southern regions registering 2-4oC
increase while the increase (> 4oC) would be more pronounced in the northern states and
eastern peninsular region. The rainfall from the normal period (1961-1990) till the end of
21st century has been projected to increase in India by 15 to 40 percent by different
models.
The climate change would have serious impact on agriculture, water resources,
forests, national ecosystems, fisheries and energy sectors. The yields of both rabi and
kharif crops are expected to be adversely affected due to deficient and erratic distribution
of rainfall. Potential yields of major cereal crops especially wheat is likely to be reduced
due to probable increase in minimum temperature during the reproductive period. A
simulation study on the impact of high temperature on irrigated wheat in north India
indicated that grain yield can decrease by 17% if the temperature increased by 2oC
(Aggarwal et al., 2001).
Land Degradation: Status, Impact and Strategies in India
125
The climate change would disturb the water balance in different parts of India and
ground water quality would be affected due to intrusion of sea water. Thermal expansion
of sea water due to global warming coupled with melting of glaciers and snowfields
would result in the rise of sea level by 0.1 to 0.5 metres by the middle of 21st century
(IPCC, 2001). It is expected that by the end of the century, 68 to 77 percent of the forest
areas are likely to experience shift in forest types with corresponding reduction in forest
produce and livelihood prospects. Coastal wetlands would have serious impact due to
change in the composition of plant species and expected sea level rise. The marine and
aquatic life would be significantly affected due to rise of sea water temperature and sea
level resulting in their migration to favourable regions, thus affecting livelihood of
coastal people. The energy requirements in summers in plains would increase more than
being compensated by saving in energy due to increased temperature in winter in
northern mountainous regions. The demand for energy would also increase for irrigation
needs due to high evaporative demands in cropped areas.
6. Strategies for Arresting Land Degradation
For evolving effective strategies to check land degradation, it is imperative to assess,
characterize and classify different types of degradation problems and develop appropriate
technologies to reclaim the degraded areas for their productive utilization. In India,
participatory watershed management has been accepted as a tool for all developmental
activities with a focus on socio-economic aspects apart from biophysical attributes
following ‘bottom up’ participatory approaches. Common guidelines for watershed
development projects have been formulated and implemented since April 1, 2008 for all
the concerned ministries. Under the guidelines, 50% of the total budget is earmarked for
natural resource management with special emphasis on treatment of degraded/wastelands
and water resource development. It involves adoption of appropriate resource conserving
technologies on arable and non-arable lands for holistic development of rainfed areas and
wastelands for sustained productivity and environmental security. The following issues
need to be addressed on high priority for efficient management of natural resources:
• Integrated land resource management policy is needed to meet the projected
phytomass/ biomass demand by accounting for the reclamation of degraded lands and
involving all the concerned ministries.
• For sustainable land use management, methodologies need to be developed for
optimal land use planning at different scales using modern tools and procedures.
• There is a need to develop and evaluate integrated farming systems in different agroecological regions of the country to maximize productivity and profitability, input
use efficiency, cropping intensity, resource conservation, employment generation,
environmental security and poverty alleviation. It would encompass optimal
combination of various enterprises, viz; agriculture, horticulture, livestock, fishery,
forestry etc. for different categories of farmers and farming situations to achieve
efficient utilization of land and water resources and prevent over exploitation of land.
• For productive utilization of waste/degraded lands, location specific alternate land use
systems, viz; agri-horti, horti-pastoral, agri-horti-silvi, agri-silvi-medicinal and silvipastoral need to be developed for scientific planning of land resources following
watershed approach.
126
Land Degradation: Status, Impact and Strategies in India
•
Soil quality deterioration is attributed to wide gap between nutrient demand and
supply, imbalanced fertilizer use and emerging deficiencies of secondary and micronutrients in soils. The nutrient use efficiency can be increased by integrating and
balancing the nutrient dose in relation to nutrient status and crop requirements to
achieve higher partial and total productivity. Soil health cards should be prepared
based upon modern soil testing tools or test kits depicting fertility status of
agricultural lands for balanced use of fertilizers.
•
The problem soils such as saline and alkali soils should be managed by leaching of
excess salts, improving drainage systems, application of gypsum, growing green
manures or mulches and tolerant crops and trees as per packages developed and
recommended by research organizations.
•
Soils polluted by heavy metals or toxic substances and excessive use of agrochemicals can be ameliorated through phytoremediation, bioremediation,
manipulating microbial catabolic genes and growing resistant crops.
•
To prevent land degradation, conservation agriculture should be promoted to ensure
minimum disturbance to the soil, provide permanent cover to the land surface and
select appropriate cropping systems and rotation to achieve higher profitability and
environmental security.
It would include zero-tillage, residue management,
mulching, cover crops and various soil and water conservation measures.
•
Soil management practices like residue incorporation, manuring, reduced tillage and
mulching play a vital role in sequestering carbon in the soil and check CO2 emissions.
Reclamation of degraded soils and ecosystems following watershed approach can
enhance the terrestrial C pool, microbial population and soils net C sinks for higher and
sustained productivity.
•
Suitable soil quality indicators need to be developed to sustain hydrological,
biological and production functions of the soil and prevent deterioration of land
resource due to physical, chemical and biological factors.
•
Enabling policy framework is essentially required by enacting suitable legislations to
provide for remediation of damaged soils, trans-boundary impact of pollution and
cost of land degradation to tax-payers. The polluters must pay for abuse of the land
resource through dumping of industrial or domestic wastes, irrigation with poor
quality water, excessive use of agro-chemicals, intensive use and over-exploitation of
land especially the marginal and fragile ecosystems and non-adoption of appropriate
conservation measures during mining and related activities.
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Land Degradation and Rehabilitation in Nepal
Content
1. Introduction
2. Land Degradation
3. Causes of Land Degradation in Nepal
3.1 Geomorphology and Land form
3.2 Population Pressure
3.3 Land use
3.4 Soil Acidification and Soil Fertility Depletion
3.5 Shifting Cultivation
3.6 Torrential Rainfall and Glacial Lake
3.7 Livestock
3.8 Pressure on Forest
3.9 Infrastructural Development
3.10 Earthquake
4. Types of Land Degradation and Its Extent
4.1 Erosion
4.2 Flooding
4.3 Water logging
4.3 Stone Quarrying
5. Status of Land Degradation in Nepal
5.1 High Himalayas
5.2 Middle and High Mountains
5.3 Inner Terai/ Siwalik
5.4 Terai (Plain area)
6. Impact of Land Degradation in Nepal
7. Government Policy, Strategies and Programs
7.1 Agriculture
7.2 Forestry
8. Conclusion and Recommendations
9. References
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1. Introduction
Nepal is a mountainous country, sandwich between of China on the North and India
on the East, South, and West. It lies between 8004' to 88012' longitudes toward east and
26022' to 30027' latitudes toward north along the southern slope of great Himalayan
between the Tibetan plateau in the north and Genetic plain in the south. The altitudinal
variation of this country ranging from 67 meter in the south and 8848 meter amsl in north
within less than 200 km distance. The country comprises of an area of 147,181 square
kilometers. Nepal has divided into five physiographic regions, namely: the High
Himalayas, the High Mountains, the Middle Mountains, the Siwalik and the plain Terai
covering 22.7, 20.1, 30.1, 12.8, and 14.3 per cent of the total area of the country,
respectively (LRMP, 1986).
Soil, water and vegetation, the basic natural resources of the life support system in
Nepal, are under intense pressure due to natural and human accelerated factors. With
different landform and climatic variation, different soils types prevail in Nepal. The hills
soils are of medium to light texture with dominance of coarse-grained sand and gravel
having very high permeability. The soils in the hills slopes tend to loss topsoil because of
their erosive nature. The soil originating from weathered soft rocks are characterized by a
high degree of porosity and poor slope stability is a common problem, particularly in the
Siwalik. The soil reaction is moderately to strongly acidic. The organic matter, nitrogen,
phosphorus and potassium content vary from low to medium, representing low to
medium soil fertility (Joshy, 1997). The major soil orders of Nepal according USDA
taxonomy system are Entisols, Inceptisols, Spodosols, Mollisols, Alfisols, and the soil
orders occasionally found are Ultisols, Aridisols and Histosols (LRMP, 1986).
The major land use of Nepal namely agriculture, forests, grazing and shrub land
covers about 26.8, 38.1, 11.9 and 4.7 per cent of the country, respectively. Similarly,
perpetual snow, rock and sand, gravel and boulders cover about 3.5, 13.3 and 1.4 percent
of the country and others cover 0.3 percent (LRMP, 1986). Land use distribution pattern
in Nepal in different physiographic region is given in Table 1.
The country lies within the subtropical monsoon climate region, but because of its
varied elevation and topography, it has a wide range of climates varying from Tropical to
Arctic regions. About 60 to 80 percent of the total rainfall occurs in four months from
June to September. With the wide range of temperature, altitude, slope and rainfall, Nepal
has a rich in biodiversity. The distribution of vegetation generally follows the altitudinal
zones.
Nepal has drained by three major river systems, the Koshi, Gandaki, and Karnali
along with more than their 6000 tributaries (MoPE, 2004). All the rivers of the country
ultimately flow to the Bay of Bengal.
Agriculture is the mainstay of the national economy, which accounts for about 40 per
cent of the GDP and 70 per cent of the employment. Food grain production constitutes 82
per cent of the total agriculture production and among them cereal crops viz. rice, wheat,
maize and millet occupy 61 per cent of that part. Total cultivated agricultural land is 2.97
millions hectare.
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Table 1: Topographical Distribution of Land
(Area ‘000 ha)
Physical
Condition
Agricultural
Cultivated
Noncultivated
Grazing
Forest
Others
Total
Hill Himalayas
7.7
1.7
884.4
221.5
2233.9
3349.2
High Mountain
244.8
146.9
509.9
1813.1
244.7
2959.4
Mid Mountain
1222.3
665.5
292.7
2202.4
60.7
4443.6
258.9
55.2
20.8
1476.6
74.3
1885.8
1234.3
117.5
49.7
592.9
116.0
2110.4
21.1
6.7
11.9
42.8
18.5
100
2968.0
986.8
1757.5
6306.5
2729.6
14748.4
Siwalik
Terai
Percentage
Total
Source: Rimal and Rimal, 2006
Steep hills and mountains comprise approximately 86 percent of the area. The rate of
natural and anthropogenic erosion in the geologically young and seismically active
mountains is high. The rapidly increasing infrastructural development like roads,
irrigation canals, and dams create ecological disturbance provide the grounds to erosion
and land degradation. Moreover, erosion and mass wasting in the high land and flooding
and sedimentation in the lowlands have become a regular phenomenon in this region.
Consequently, land degradation of mountain ecosystems is becoming increasingly
widespread.
2. Land Degradation
Land degradation has generally defined as the temporary or permanent decline in the
productivity capacity of the land (Stocking and Murnaghan, 2001). Land degradation
may also be defined loss of utility or potential utility of land or to the reduction, loss, or
change of features of land or organisms that cannot be replaced (Barrow 1991). Land
degradation is one or more processes of reducing its current and potential capability to
produce goods and services. It mainly reduces the biological productivity therefore the
carrying capacity of the land. Thus, it reduces the production of fuel, fiber, food, and
fodder thereby threat to the survival of the human kinds.
Land degradation is a serious environmental issue in Nepal leading to socioeconomic
instability because the country is unable to supply adequate food and others basic
requirements. In addition, the natural resources such as water, forest and land are also at
declining state to support the livelihood of the hill and mountain people. Nepal is
basically agricultural based whose important components are forestry, livestock and
agriculture and the socio-economic status of the people determines the sustainable
management of these resources. In recent year, government and other institutions and
personnel involved in research and development have shown a great concern that there
has been over exploitation and mismanagement of land resources. The hilly and
Land Degradation and Rehabilitation in Nepal
137
mountainous landscape itself is very vulnerable posing land degradation because of
inherent geological and topographic properties. The climate and human pressure
eventually further accelerate the land degradation processes. The ever growing
population determines the sustainable management of these resources.
3. Causes of Land Degradation in Nepal
Local geology, soil type, landform, land use, rainfall intensity, and human
activities/population pressure are root causes of the land degradation in Nepal (Figure 1).
The causes of land degradation can be visualized as:
Population Growth
Food Deficit
Fodder Deficit
ƒ Cultivation of Marginal
Lands
ƒ Intensive Agriculture
ƒ Overgrazing
ƒ Excessive Lopping
of Fodder
Less Manure
Wood Deficit
Over Deficit
Grassland Degradation
Forest
Degradation
Soil Erosion
Reduced Fertility
Land Degradation
Natural Causes
Fig. 1: Causes of Land Degradation and their Relationships, Nepal (UNEP, 2001)
3.1 Geomorphology and Land form
Nepal is a diverse country with complex geomorphology, landform and climate with
a short span in width. Physiographically, Nepal has divided into five regions viz. High
Himal, High Mountains, Middle Mountains, Siwalik and plain Terai. About three
quarter’s of the Country’s topography is rugged comprising high Himal, High Mountains,
Middle Mountains and the part of Siwalik region and remaining part is plain terai in
south of the country (Figure 2). The rugged hills are geologically young and fragile
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Land Degradation and Rehabilitation in Nepal
including Siwalik are more prone to landslide, mass movement, and soil erosion in the
intense monsoon period. Consequently, frequent flooding in terai region causes loss of
human life, agricultural product and washing away of infrastructure every year.
Fig. 2: Physiographic Division of Nepal
3.2 Population Pressure
The population of the country reached 18.49 million in 1991 (CBS, 1994) with a
growth rate of 2.08 percent and in the fiscal year of 2005/06 the population has reached
26 million with a growth rate of 2.25 (CBS, 2009). The population density per square
kilometers of total land is 176. Land has been one of the major natural resource available
for economic development of the country. Agriculture has been basis in fulfilling basic
needs for subsistence living of the major population of the country. Majority of the
population deriving their livelihood from land resource is definitely not a favorable
situation for the stability of hilly environment. The constant increase in the population
depending on agriculture has many implications. One consequence is that the process of
fragmentation of agricultural land parcels has continued because of an increase in the
number of farming households, turning landholding parcels into uneconomic sizes in
terms of modern agricultural practices. Secondly, there is a skewed distribution of
landholdings among farmers, and this has hindered agricultural land development. The
number of marginalized and small farmers with landholdings below one-hectare accounts
for 69.4 % but these farms covers only 30.4 % of the total landholding area. Shifting
cultivation has persistently existed in scattered form in the remote hills, encroaching upon
forests. The impacts of land degradation such as landslides, soil erosion, and flash floods,
are the most pressing problems particularly in Mid-hills of Nepal. These are every year
phenomena that take place particularly during the rainy season. While landslides and soil
erosion occur oven the hills and mountains, flash floods occur in the valleys and the Terai
plains.
Land Degradation and Rehabilitation in Nepal
139
For the subsistence living, one family in the Mountain needs more than 1 hectare in
the Hills and 0.5 hectare in Terai. However, 43 percent of all land holdings were less than
0.5 hectare in size in 1991/92 (CBS, 1994). Therefore, those fraction of people are forced
to seek additional land or other employment for their subsistence living. Since most of
the arable lands are already under cultivation, the expansion of agriculture land will be
mostly on fragile and marginal lands resulting land degradation. The farming of sloping
areas especially in the hills and mountains without adequate conservation measures is
another major cause responsible for the erosion of fertile topsoil.
3.3 Land use
Land use beyond its capabilities or suitability is the root cause of land degradation in
Nepal. The soil conservation and watershed management plans prepared by the
Department of Soil Conservation for some areas indicate that 19 percent of currently
cultivated land should not be cultivated. Similarly 33 percent of forest, 51 percent of
shrub land and 56 percent of grass land need permanent protection. Proper drainage is
essential for 61 percent of agriculture lands and of which proper terracing is essential for
23 percent of agriculture land to continue cultivation. Land use beyond its capability or
suitability and without due consideration of the conservation measures is the root cause
of land degradation in Nepal.
3.4 Soil Acidification and Soil Fertility Depletion
Topsoil degradation and loss are possibly the most serious processes affecting
sustainability of farming systems in the hills and mountains of Nepal. Throughout the
hill regions, particularly at lower elevation where rainfall intensity is highest, erosion is a
major contributor to the decline of soil fertility. Increased degradation of marginal
upland soils results in the loss of nutrients. The estimated soil and nutrient loss are given
for major production systems of Nepal below 1,000-m elevation in Table 2 (Carson,
1992).
Soil acidification degrades land, lower crop productivity and increase soil
vulnerability to contamination and erosion. Soils are often initially acidic because their
parent materials were acidic and initially low in the basic cations (Ca, Mg, K, and Na).
Acidification occurs when these elements are removed from the soil profile by normal
rainfall or the harvesting crops. The pH of the Nepalese soils usually ranges from 4.0-8.0.
Most of the soils are formed from the acidic and neutral parent materials; they are slightly
acidic to neutral in reaction. Soil of the middle and High mountains regions are acidic in
reaction (Joshy, 1997). Continuous use of acidifying nitrogenous fertilizers like
ammonium sulfate and urea has contributed to the development of high acidity in the
agricultural land causing land degradation. It is even worse when there is unbalanced use
of these fertilizers. Similarly, it has been reported that in the high mountain and mid hill
area due to growing scarcity of broad leaf species intensive use of compost prepared from
pine needles has helped in developing high acidity in the soils and thereby enhances the
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land degradation.
Land Degradation and Rehabilitation in Nepal
Land Degradation and Rehabilitation in Nepal
141
Table 2: Estimated nutrient loss by rainfall erosion associated with different
production systems
Rain fed Agriculture
Soil loss Depth in mm
-1
Soil loss tons ha yr
-1
OM loss kg ha yr
-1
-1
-1
Nitrogen loss kg ha yr
-1
-1
Phosphorus loss kg ha yr
-1
Potassium loss kg ha yr
-1
-1
Bench terrace
Marginal land
Grazing
(degraded)
0.4
1.0
8.0
5.0
20.0
100.0
75.0
300.0
1500.0
3.8
15.0
75.0
5.0
20.0
100.0
10.0
40.0
200.0
Source: Carson, 1992
3.5 Shifting Cultivation
Other forms of land degradation such as shifting cultivation whose extent and
coverage is not known clearly. Shifting cultivation is practiced in the mid-hills of Nepal
in different intensity and is one of the causes of land degradation in many parts of the
areas. Shifting cultivation had been a sustainable agro ecosystem in the past, but, it
cannot serve as a model for the future. Regeneration of forests is crucial for the long-term
productivity and sustainability of shifting practices. However, many farmers are no
longer able to leave their fields fallow for the necessary period of time (Partap and
Watson, 1994). Soil erosion during the monsoon due to high run-off is a serious problem
and this process has further been accelerated due to the practice of shifting and sloping
terrace cultivation in the hills and mountains of Central Nepal.
3.6 Torrential Rainfall and Glacial Lake
Nepal being hilly and mountainous country with monsoon rain, major land
degradation is caused by the surface erosion, mass movement, river cutting and flooding.
The hectic monsoon rains with localized cloud bursts pouring tremendous amount of rain
in short period is one of the main reasons for the disastrous erosion with devastating
damage to the land's quality therefore causing land degradation.
Glacial lakes are found above the snow line of the Eastern and Central Region of
Nepal. Sudden breaks of these glacial lakes bring surges of debris laden floods and
generally known as glacial lake outburst floods. The surge strips out the valley slopes
causing unstable slopes to degrade.
3.7 Livestock
Livestock, an integral part of agriculture production system are kept principally for
manure and all the draft power. Its milk, meat and wool production contributes as cash
income for the owners. The cattle population of 7.36 million (2005/06) with its growth
rate of 13 percent for the decade exerted tremendous grazing pressure on rangeland,
grassland and forest. In addition, lot of fodder, bedding materials for cattle are collected
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Land Degradation and Rehabilitation in Nepal
from the forest for the cattle feed, and biomass for the manure, which is the essential
component for the subsistence farming system. There is a clear relationship between
livestock, soil fertility and natural resources in the mountain farming system.
Livestock sector is a major performer in the agriculture. Therefore, sustainable
management is an important aspect. The land available for raising livestock and feed
availability according to the requirements is unbalance. The current stocking density is
exceeding the carrying capacity except in the alpine meadows region. The situation is
more alarming in the mid hills and open grassland (Tables 3), which are more vulnerable
to land degradation.
Table 3: Stock density and carrying capacity in grassland in Nepal
Grass land
Carrying capacity LU/ha
Stocking density LU/ha
Mid-Hills
0.31
4.08
Steep grasslands
0.01
0.19
Open grass land
0.54
7.07
Alpine meadows
1.42
0.64
3.8 Pressure on Forest
Heavy pressure on the forest for the additional agriculture lands and over-exploitation
of the fuel wood, timber and fodder to meet the demands of the fast growing population,
the forest have been reduced and depleted the trees. Based on the aerial photographs the
crown cover of the forest has been reduced at the rate of 2.1 per cent. For 1978/79 to
1990/91 period in the Terai districts, the annual deforestation rate has been estimated to
be 1.3 per cent (FRISP, 1994). Resettlement program of the Government for hill migrants
in Terai is also responsible for most of the deforestation in Terai. The rapid deforestation
situation has increased soil erosion and mass movement in the hills and mountains and at
the same time, there is widespread flooding and sedimentation in the plains and valleys.
Because of rapid deforestation, it has become increasingly difficult for the people to meet
their basic needs for forest products. Pressure on the remaining forests is further
intensified, creating a vicious circle and aggravating the already serious problems of
deforestation and therefore land degradation.
3.9 Infrastructural Development
The rapidly increasing construction of infrastructures like roads, irrigation canals,
and dams residential house construction without due consideration of the conservation
measures has encouraged soil erosion and landslides aggravating directly or indirectly
land degradation.
3.10 Earthquake
Nepal being seismically active, earthquake also aggravates land degradation by
setting the geology weak and triggering the mass movement. The earthquake in eastern
Nepal occurred at the 6.7 Richter scale on 21 August 1988 took a heavy toll of 730
human lives and triggered several landslides.
Land Degradation and Rehabilitation in Nepal
143
4. Types of Land Degradation and Its Extent
Almost all types of land degradation exist in Nepal. However, erosion, flooding and
water logging are the three major types of land degradation processes most prevalent in
Nepal. Its extent has been broadly assessed as follows:4.1 Erosion
Erosion, mainly water, is one of the major land degradation processes most prevalent
in Nepal due to its steep slopes and hectic monsoon. Almost all of Nepal is affected by
water erosion mainly by surface erosion, mass movement (slumping, gulling, landslides
and rock fall) and riverbank cutting, and some areas are affected by deposition and water
logging (LRMP, 1986).
Table 4: Estimates of Soil Erosion Rates
Land use categories
Soil erosion rate (tons/ha/yr)
Well-management forest land
5-10
Well-management paddy terraces
5-10
Well-management maize terraces
5-15
Poorly-managed slopping terraces
20-100
Degraded rangelands
40-200
Source: UNEP, 2001
The extent of area mainly affected by riverbank slumping and gulling is about 16398
sq. km., slumping and gulling is about 4244 sq. km. mass wasting (slumping, landslides
rock fall and avalanches) is about 116566 sq. km. Expressing watershed condition at the
district level, it is estimated that 5, 7 and 13 districts are under very poor, poor and
marginal condition, respectively. There are 25 districts each under fairly good and good
watershed condition (Shrestha et. al., 1983). The productivity of the land has been
significantly reduced in 34 and 20 percent of the areas of Siwalik and the Middle
Mountain region respectively.
Owing to the complex features of the mountain terrain, the nature of soil degradation
varies greatly. However, information on soil degradation is scattered and sketchy. Table 4
provides information on the soil erosion rates for different lands-use categories. The soil
erosion rate appears to be higher in the unmanaged land-use category and on steep slopes
than in the managed land-use category.
The impacts of soil degradation are many and all are closely related to environmental
degradation. One of the direct impacts of soil degradation is the loss of fine topsoil. There
is also depletion of organic matter and plant nutrients along with the topsoil, which
ultimately affects soil fertility. The average annual weight of sediment per unit area
affected deposited by various rivers in Nepal is shown in Table 5.
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Land Degradation and Rehabilitation in Nepal
Table 5: Sediment Yields from Some of the Main Rivers
River
Location/Regions
Rate (tones/ km2/yr)
Tamor
East
8,200
Sun Koshi
Central and East
3,970
Bagmati at Chovar
Kathmandu Valley, Central
3,030
Trisuli
Betrawati, Central
2,750
Karnali
Chisapani, Far West
5,100
Source: CBS, 1998
Landslides are another important factor in soil degradation. Landslides occur almost
every year in every part of the country, resulting in the loss of land and lives. Several
people’s life has loss and effect on land and families due to erosion, landslides, and flood
in different years. Roads, trials, bridges, and property are also damaged or destroyed.
4.2 Flooding
High intense rain has been main reason for the flooding during the monsoon in the
low-lying valleys and Terai plains. The floods can cause serious damage to infrastructure,
houses, agriculture land and the environment along the flood path. The area affected by
the floods accounts about 8977 square kilometers. These areas are flooded with different
frequency damaging the fertile plains by scouring and sediment deposition.
4.3 Water logging
Water logging is mainly problem during the monsoon period in depression of the
Terai region, where drainage has been disturbed due to some man made reasons such as
embankment, dams, roads etc. Also, marshy land is observed in the Terai region, south of
Bhabhar zone where two lithological units having different porosity and permeability
meet along with the change of elevation resulting mainly spring lines, pond, lakes etc.
The area affected by water logging during the monsoon is about 7297 square kilometers
and has been mainly used for the rice cultivation.
4.3 Stone Quarrying
Stone quarrying for construction materials has been one of the major causes of
landslides in the accessible areas. The flood and debris flow due to cloud bursts in 19-20
July 1993 were strongly influenced by unmanaged stone quarrying mainly along the high
ways. In the year 2007-2010, the construction companies are quarrying stones and
boulders from Siwalik range aggravating further land degradation.
5. Status of Land Degradation in Nepal
Up to date status of the land degradation in Nepal has not well documented.
However, general remarks about the land degradation in the different physiographic
zones can be stated as follows:-
Land Degradation and Rehabilitation in Nepal
145
5.1 High Himalayas
In the High Himalayas, areas rockslides, avalanches and glacial lake outbursts are the
main erosion types resulting disastrous floods therefore land degradation.
5.2 Middle and High Mountains
High population density, coupled with intensive land use and tourism enhanced
erosion in these regions. The predominant erosion processes in these regions are mass
wasting and gully erosion. Surface erosion (rill and inter-rill) on sloping agriculture land
is prevalent in the Middle Hills and to some extent in the High Mountains. A majority of
the sediment load contribution to the rivers are derived from surface erosion. However,
compared to mass wasting and gully erosion the contribution to in-stream sediment from
erosion of agriculture land is considered to be less.
5.3 Inner Terai/ Siwalik
This region lies at the foot of the Mahabharat range. In this region, there are several
inner valleys or Duns, which are densely populated. Because of the alluvial deposition by
the rivers, these valleys are very fertile and are potential places for good agriculture.
Siwaliks consists of weakly consolidated Tertiary sediments with gentle to strongly
dipping slope. Its soils are unstable to retain high precipitation that frequently occurs
resulting to flash floods in the river systems of the region. The Siwaliks areas are highly
vulnerable to water erosion and flash floods occur frequently in the low-lying areas. The
rivers flowing in the Siwalik region transport tremendous volumes of debris during the
monsoon season causing land degradation by vast sedimentation of the fertile plains.
5.4 Terai (Plain area)
This region is the flat plain area and is an extension of the southern Indio-Gangetic
Plain. The Terai regions are known as the granary of Nepal. Wherever irrigation water is
available, the land is intensively cultivated. The Terai region, a gently sloping plain of
alluvial deposits is subject to severe flooding, river shifting and riverbank cutting
threatening the stability of agriculture in many areas of this region. The middle Terai is
an undulating terrain with isolated pockets of water logging and marshy condition.
6. Impact of Land Degradation in Nepal
The impact of land degradation are the loss of top soil and organic matter; plant
nutrients; landslides; siltation; loss of biodiversity and so on. It is estimated that a loss of
soils at the rate of 5 tons per hectare, which is equivalent to loss of 75, 3.8, 10 and 5 kg
per hectare of organic matter, Nitrogen, potassium and phosphorus, respectively (Carson,
1992). Similarly, Nepalese river systems drain thousand tons of soil per year, example of
which is given in Table 5. Erosion estimated from some of the watershed indicated more
than 70 tons per hectare of soil loss. Landslide is another example of land degradation in
Nepal. As Nepalese landscape is relative young and rainfall pattern in Nepal is intense
during summer monsoon period, event of landslide is higher during June to September.
The loss of human life, agricultural land, livestock and soil have directly influence in the
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Land Degradation and Rehabilitation in Nepal
ecology and economy in Nepal. Washing away of top soil and landslides in the hills
cause frequent flooding in the terai region, which again temper national economy as well
as life of human, livestock and other flora and fauna.
7. Government Policy, Strategies and Programs
Extensive Land Degradation is caused mainly by the excessive land use. There are
numerous government and non-government sectors and agencies related with land
degradation and working to rehabilitate degraded lands. Ministries of Agriculture, Forest
and Soil Conservation and Water Resource are the three main line agencies and there are
several non-governmental agencies involved in the land use and rehabilitation of
degraded lands. However, agriculture, forestry and water resource are priority sectors of
the government as well.
7.1 Agriculture
Agriculture is mainly run by the private sector. Agricultural development is
determined by changes in prices, technologies, infrastructure and institutions. Role of
government in the agricultural development is important for controlling agricultural land
degradation. Government provides support service to ensure the delivery of the
agriculture inputs and through extension provide the technical know how. In addition,
government provides credits for the agriculture development through different banks.
Due to duel, ownership and land tenure system in Nepal neither the landlord nor the
tenants are willing to invest for land improvement.
The National Planning Commission in its 20 years Agriculture Prospective Plan
(APP, 1995) has given top priority to soil fertility management for achieving increased
agricultural productivity in Nepal which is not driven by physical targets, but is directed
to meet Government's more general long term developmental goals of poverty
alleviation, sustainable economic growth and resource conservation.
Ministry of Agriculture carry-out the upgrading of livestock by providing the basic
inputs and technical services in different districts. It also provides extension services to
carry out the agriculture development in integrated way. For the cultivation and
rehabilitation of degraded lands, it also provides irrigation facilities. To mitigate the land
degradation with perennial crops horticulture program has been extensively adopted at
the district level activity.
Nepal Agricultural Research Council (NARC), a leader agricultural research in
Nepal verified and promotes various technologies for achieving conservation agriculture.
NARC promotes Sloping Agricultural Land Technology (SALT), Integrated Plant
Nutrient Management System (IPNS), terrace and contour farming during past three
decades in hills and terai of intensely cultivation region. However, adoption of these
technologies is restricted and further dissemination is needed.
7.2 Forestry
Master Plan for the Forestry Sector (MPFS, 1988) emphasized on people
participation in the forestry development through the implementation of community
forestry, private forestry and leasehold forestry and prevention and control of erosion is
Land Degradation and Rehabilitation in Nepal
147
the main forestry policy of the government in order to manage the land and rehabilitation
of degraded lands. Role of government in the management of forestland and
rehabilitation of degraded lands through the people participation will be catalytic
(community organization, mobilization and facilitating) and technical advisory. The
strategic policy to manage forest and rehabilitate degraded lands is to produce basic
needs for forest products with due consideration of soil conservation measures and
promote alternative energy resource and energy efficient devices.
Under the guidance of the forestry development policies of the government, the
Forestry Sector Master Plan has recognized four main programs related with the land use
and rehabilitation of degraded lands.
7.2.1 Community and Private Forestry Program
Aims to develop and manage forest resources through the active participation of
individuals and communities to meet their basic needs for fuel wood, timber, and fodder.
The main components of the program are:
Mobilize, organize and support user groups to manage the scattered natural and or
degraded forest, which is required to meet their basic needs within the communities.
Government plays catalytic, advisory and technical supervisory roles in the management
of the forest. The user groups prepare operational plans with the help of forestry field
staff. District Forest Office hand over the forest to the user groups to protect, manage and
get the total benefit from the forest as per the plans.
So far, there are more than 3000 user groups actively engaged in managing about
125000 hectares of the community forests. Impact of this program has shown
encouraging results. Because of popularity of this program, there is high demand for the
establishment of community forests. In Nepal, 61 percent (About 5.8 million hectares) of
the national forest (5.5 million hectares) is potential for community forestry. About 27
percent of the total forest area is covered by grazing and barren lands. Planting trees is
one of the main activities to rehabilitate degraded lands.
7.2.2 National and Leasehold Forest
Aims to develop and manage the national forests through government agencies and
private sector lessees, and complement community and private forestry as a means to
increase the supply of forest products. The main focus of the program is to establishment
and management of national forests in suitable places to supply wood and timber to urban
and wood deficit areas for development and leasing of forestland that is available and
suitable for industrial plantations.
So far 34730 hectares of national forest has been under intensive forest management
and about 165 hectares and 342 hectares of forest are under leasehold forest managed by
industries/institutions and people below poverty level respectively.
7.2.3 Soil Conservation and Watershed Management Program
In continuing endeavor to mitigate land degradation and increase productivity
through the mobilization of national and local resources, the Department of Soil
Conservation and Watershed Management (DSCWM) has implemented four major subprograms natural hazard prevention, land productivity conservation, development
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Land Degradation and Rehabilitation in Nepal
infrastructure protection, and community soil conservation extension programs. The main
roles of the department are to mobilize, organize and formulate user groups to manage
the land resources against the degradation and implement conservation measures to
rehabilitate the degraded lands for the betterment of the local peoples. Department plays
catalytic, advisory and technical supervisory roles and provide constructional materials
which are not locally available and skill labors.
Department of Soil Conservation had carried out rehabilitation of degraded lands of
about 7000 hectares, on-farm conservation on 1335 hectares and about 1000 hectares of
land had been planted with fodder, fruit, and or grass and 458 number of gullies, 169
number of landslides had been treated. Similarly, stream bank protection had been carried
out in 16 kilometers and road slope stabilization in 58 kilometers.
7.2.4 Conservation of Ecosystems and Genetic Resources
In continuing endeavor to conserve the ecosystems, currently there are eight national
parks covering 10,174 square kilometers, five reserves covering 2298 square kilometers
and two conservation areas covering about 7830 square kilometers mainly managed by
the Department of National Parks and Wildlife Reserve.
7.2.5 River Training Program
Department of Irrigation under the Ministry of Water Resource carry out the river
training program regularly to check the damage to land and settlements from the river
bank erosion and floods and to mitigate the land degradation caused by the flooding and
river shifting. River training works are carried out by encouraging local people's
participation. Local people will be involved from appraisal to implementation in the river
training works. Main government role in river training will be to deliver the materials
mainly galvanized crates at site and to provide the technical guidance and supervision in
implementation.
8. Conclusion and Recommendations
Land degradation is a serious problem in Nepal as Nepalese economy is based on
agriculture with about 70 percent of the population engaged in it. Land is the basis of
subsistence, farm incomes and source of employment in Nepal. The root cause of land
degradation in Nepal is the poor economic condition, lack of knowledge/awareness and
inefficient government policies. Assessment of soil erosion and its associated factors is
necessary for scientific planning and carrying out soil and water conservation land
management practices for sustainable use of land. However, the findings on the
assessment of erosion are very much inconsistent and difficult to draw conclusion. The
main reasons are complex terrain, soils, and geology, climate and land management
practices. At the same time the application of methodology to quantify the erosion rate
and its extent vary greatly that make difficult task.
It is observed that there is a lack of study on land degradation at the national level.
This could due to inadequate logistic support and trained human resources available or
low priority of the government. However, to acquire information on land degradation in
short period of time the application of remote sense technique could be an alternative
which has been considered suitable for the difficult terrain and remoteness.
Land Degradation and Rehabilitation in Nepal
149
The program at watershed or sub watershed as a lowest management unit could be
most appropriate. Both the combination of indigenous and modern management
initiatives through people participation could be an ideal approach. Thus, the following
measures are suggested for utilization of land resource sustainably:
Policies
•
Study on land degradation and its trends at the national and regional level
•
Awareness of land degradation and incorporation of environmental education in
school education
•
Implement integrated package programs that include vegetative, agronomic, and
water management measures to tackle soil erosion problems with watershed
management approach
•
Involvement and mobilize local people in the implementation of soil and land
conservation activities
•
Formulate the clear policy, strategies and programs, which should be given high
priority to tackle the rehabilitation of degraded lands
•
Formulate the proper land use policy, which direct people to use according its
suitability
•
Establish and maintain linkages and networking with all other related sectors such as
forestry, agriculture, livestock, water resources, roads and so on
•
Mobilize people’s participation in the implementation of soil conservation activities
•
Preparing a national action program to address the issues of land degradation and
desertification
Technical
•
Afforestation on degraded forest and establish and maintain linkages and networking
with all other related sectors such as forestry, agriculture, livestock, water resources,
roads and other infrastructure
•
Land gradation and land consolidation
•
Mulching on dry degraded lands
•
Liming on acidic lands
•
Integrated Plant Nutrient Management, conservation tillage, fallowing, and scientific
management techniques (such as use of legumes in the cropping systems, strip
cropping, cover cropping etc.)
•
Promotion of Sloping agricultural land technology (SALT) in sloping land
•
Promotion of erosion control techniques such as contouring, terracing or other
bioengineering approach in sloping land
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Land Degradation and Rehabilitation in Nepal
9. References
APP, 1995. The National Planning Commission (NPC), Twenty Years Agriculture Perspective
Plan (APP), Singhdarbar, Kathmandu, Nepal.
Barrow, C.J. 1991. Land Degradation: Development and Breakdown of Terrestrial Environments.
Cambridge University Press, London.
Carson, B. 1985. Erosion and Sedimentation Process in the Nepalese Himalaya, ICIMOD
Occasional Paper N. 1, Nepal.
Carson, B. 1992. The Land, The Farmers and The Future, ICIMOD Occasional Paper N. 21,
Kathmandu, Nepal.
CBS, 1994. National Sample Census of Agriculture Nepal (1991/92) Highlights. Central Bureau
of Statistics, Kathmandu, Nepal.
CBS, 1998. A Compendium on Environmental Statistics: 1998. Central Bureau of Statistics,
Kathmandu, Nepal.
CBS, 2009. Statistical Pocket Book, Nepal. Central Bureau of Statistics, Kathmandu, Nepal.
FRISP, 1994. Deforestation in The Terai Districts 1978/79-1990/91. Forest Resource Information
System Project. Forest Research and Survey Centre, Kathmandu, Nepal.
Joshy, D. 1997. Soil Fertility and fertilizer Use in Nepal. Soil Science Division, Khumaltar,
Lalitpur, Nepal.
LRMP, 1986. Land System Report. Land Resource Mapping Project, HMG/N and Government of
Canada, Kenting Earth Science Limited.
MoPE, 2004. Nepal: National Action Program on Land Degradation and Desertification in the
Context of the UN Convention to combat Desertification. Ministry of Population and
Environment, Kathmandu, Nepal.
MPFS, 1988. Master Plan for the Forestry Sector (MPFS) Nepal. Ministry of Forests and Soil
Conservation, Kathmandu.
Partap, T. and H. R. Watson, 1994. Sloping Agricultural Land Technology (SALT): A
Regenerative Options for Sustainable Mountain Farming, Occasional Paper No. 23,
ICIMOD, Kathmandu.
Rimal, S. and R. Rimal, 2006. Nepal district profile. Nepal Development Information Institute
(NIDI), Kathmandu
Shrestha, B.D, P. Van Ginneken and K.M. Sthapit; 1983. Watershed Condition of the Districts of
Nepal. FO:DP/NEP/80/029, Field Document no. 9. Watershed Management and
Conservation Education Project, Department of Soil Conservation, Kathmandu.
Stocking, A. M. and N. Murnaghan. 2001. Handbook for the Field Assessment of land
Degradation. Earthscan Publication Ltd. UK.
UNEP, 2001. Nepal: State of Environment. United Nation Environment Program (UNEP),
Regional Resource Center for Asia and the Pacific, Pathumthani, Thailand.
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Strategies for Arresting Land Degradation in South Asian Countries – Sri Lankan Experience
Content
Page
1. Abstract
153
2. Introduction
153
3. Severity of Land Degradation in Sri Lanka
158
3.1. Soil Erosion and Sedimentation
158
3.2. Coastal Erosion
162
3.3. Economic Estimations of Soil Loss
162
3.4. Soil Fertility Decline
163
3.5. Acidification
163
3.6. Salinity and Alkalinity
164
3.7. Iron toxicity
164
3.8. Leaching of Toxic Substances to Groundwater
165
3.9. Pollution
165
3.10. Gaps in the Knowledge Base
166
4. Policy Issues
167
5. Arresting Land Degradation: Some Recommendations
167
6. References
169
Strategies for Arresting Land Degradation in South Asian Countries – Sri Lankan Experience
153
1. Abstract
Sri Lanka consisting of a land area of 65,525 ha with a population of 19 million is
ranked 19th in population density representing one of the densely populated countries in
the world. Among SARRC countries it is ranked as no. 4 on population density. The land:
man ratio for arable land is around 0.15 ha showing the pressure on land resources. With
increasing pressure on land, population growth and slow growth rate of the economy,
land degradation has become a major problem in the country. The land degradation
factors identified are soil erosion and sedimentation, soil fertility decline, acidification,
increase in salinity and alkalinity, accumulation of toxic substances, eutrophication due to
over use of fertilizers, leaching of groundwater, iron toxicity, pollution and soil
compaction. It is reported that the loss of land productivity due to degradation to be
about US $ 36 /ha/yr while the loss due to nutrient depletion to be about US $ 51 /ha/y.
The existing knowledge on land degradation is mostly limited to studies of soil erosion
with less information available with other processes The knowledge gaps are mainly on
the absence of a proper national data base on natural resources, specially on soil.
Eventhough data on soil erosion and sedimentation are available, there is no data on
fertility decline, salinity and eutrophication. A database should be developed in these
lines and recommendations for arresting land degradation are highlighted in the paper.
Key words: Arresting Land Degradation, Sri Lanka
2. Introduction
The democratic socialist republic of Sri Lanka which was formally known as Ceylon
comprises of one large island and several very small islets lying east of the southern tip of
the Indian subcontinent. It stretches from 50 55’ to 90 50’ North latitude and from 790 42’
to 810 53’ East longitude. The maximum north-south length of the island is 435 km and
its greatest width is 224 km surrounded by the Indian ocean. The coastline of the island is
1920 km long. The Bay of Bengal lies to its north and east and the Arabian Sea to its
west. The country including adjacent small islands consist of a land area of 65,610 km2
(6,56 million ha) with a population of 20.2 million. For administrative purposes the
country is divided by 9 provinces and 25 districts. The administrative structure extends to
319 divisional secretary/assistant government agent divisions and 38,259 villages. The
country profile of socio economic data is shown in table 1.
Sri Lanka covers a land area of 65,610 km2 (6.56 million ha) with a population of 19
million. When compared with other countries in the world, Sri Lanka ranks 118th in area,
47th in population size and 19th in population density, making it one of the densely
populated countries (Madduma Bandara. 2000). This is an indication of pressure on land
154
Strategies for Arresting Land Degradation in South Asian Countries – Sri Lankan Experience
Table 1: The socio-economic data-country profile of Sri Lanka
2005
2006
2007(a)
19,668
19,886
20,010
Population Growth (%)
1.0
1.1
1.1
Population Density (persons per sq.km)
314
317
319
Labour Force ('000 persons)
8,141
7599
7,49
Employed Population ('000 persons)
6788
7,105
7,042
524
493
447
Male
67.3
68.1
67.8
Female
32.6
35.7
33.4
Total
49.3
51.2
49.8
Mid Year Population ('000 )
Unemployed Population ('000 persons)
Labour Force Participation Rate%)
Unemployment rate (% of Labour force)
7.2
Agriculture labour force employed (%)
30.7
32.2
3 \.3
Agriculture Contribution to GDP (% )
11.8
1\.3
11.9
6.2
7.7
6.8
1,241
1,421
1,617
Real GDP growth rate (% )
Per capita GDP at market price (US$)
6.5
6.0
Source: Central Bank of Sri Lanka
(a) Provisional resources creating human induced land degradation. The pressure on
land will keep growing with the annual population growth rate of 1.1% where the total
population is estimated to be 23 million by 2050 .The land area, population and
population density in SAARC countries is given in table 2. (Survey Department, 2007).
Among SAARC counties, Sri Lanka is ranked as 4th highest in population density.
Topographically, the country has two distinct features, a central highland area rising
above 2500 m and the lowland plains surrounding it extending to the coastal region. The
climate is tropical and maritime, with two distinct monsoonal seasons, the southwest
monsoon during May to September locally called Yala season and the northeast monsoon
during October to January, the Maha season. The rainfall varies from 3175 mm per year
in the wettest parts of the Wet Zone Up-country down to 500 mm per year in the driest
parts of the Dry Zone Low Country. The variation of mean annual rainfall in Sri Lanka is
shown in figure 1.
Strategies for Arresting Land Degradation in South Asian Countries – Sri Lankan Experience
155
Table 2: Land area, population and population density among SARRC countries
Country
Pakistan
Land Area
(km2)
Population
(millions)
Population Density
per km2
Rank
803,940
165.803
206.2
5
3,287,590
1,025.351
332.2
3
300
0.359
1196.7
1
65.610
20.222
308.2
4
Nepal
140.800
28.287
201.0
6
Bhutan
47,000
2.273
46.5
7
144,000
147.365
1021.4
2
India
Maldives
Sri Lanka
Bangladesh
Source: Survey Department, 2007
Based on the rainfall patterns three
major climatic zones are identified. The
Wet Zone covers the area where the
mean annual rainfall > 2500 mm
without any dry period while the
Intermediate Zone is the area receiving
mean annual rainfall of 1750-2500 mm
with a short and less prominent dry
season. The Dry Zone which covers
more than 1/3 rd of the land area,
receives <1750 mm rainfall per year
with a distinct dry season from May to
September. Even though the Dry Zone
experiences a considerable total rainfall,
the distribution is not even where more
than 80% falls within a three months
period. In addition to rainfall, the
country
is
dividing
to
three
physiographic regions based on the
height from mean sea level as Low
Country < 300 meters from mean sea
level, Mid Country 300-900 m and Up
country >900 m msl . In combination
with the rainfall and physiographic
regions the country is divided to 46
Agro-ecological regions. Each AER is
denoted by a four character code
consisting of letters and numbers
(Example: WL1a). These denote the
mean annual rainfall, elevation category
Fig. 1: Variation of mean annual rainfall (mm) in Sri
Lanka (Domros, 1973)
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Strategies for Arresting Land Degradation in South Asian Countries – Sri Lankan Experience
and distribution of rainfall. In addition the AER map gives information on the terrain and
soil types
The total land area of Sri Lanka amounts to 65,610 km2 (6.56 million ha) where about
130,300 ha is covered by water bodies as irrigation and hydropower reservoirs which
reduces the exposed surface area. According to the land balance sheet shown in table 1.7,
only 1/3rd of the land area is used for agriculture while another 1/3rd is under forest and
wild life conservations. Urban areas and areas of infrastructure development consist of
the balance 1/3rd of the country (Somasekaram, 1996). The pressure on land which is
shown by the land/man ratio (per capita land area) is a major factor contributing to land
degradation. As shown in table 4 the land:man ratio of Sri Lanka in 1871 when the
population was 2.4 million was 2.7 ha which reduced to 0.32 ha in 2007 with population
increasing to 20.2 million. This gross land:man ratio of 2.7 ha is misleading as it does
not make an allowance for lands unsuitable for human use. When the topographically
unsuitable lands and lands set apart for conservation are excluded the total land area
available for agriculture decreases to 2.85 million ha decreasing the land:man ratio to
0.14 ha indicting the heavy pressure on agricultural land.
The first provisional soil map of Sri Lanka was compiled by A.W.R. Joachim
(Joachim, 1955) and later revised by De Alwis and Panabokke (1972). This was the most
used soil map in the past decade. This soil map which was at the scale of 1: 100,000
shows the soil mapping units. Soil mapping units of this map consist of soil associations,
soil complexes and miscellaneous land units. When two or more Great Soil Groups occur
in the same pattern in the centenary landscape they were called soil associations. When
they do not occur in the same pattern the mapping unit is called a soil complex. The land
pockets not suitable for agriculture as eroded remnants and rock knobs were called
miscellaneous land units. A Great Soil Group was defined as a soil with similar
sequences of genetic horizons, even though the depths of each horizon may vary. This
map consist of a total of 31 mapping units, where 18 mapping units belongs to the soils
of the dry zone and semi dry intermediate zone, 9 mapping units belonging to the wet and
semi-wet intermediate zone and 4 were miscellaneous mapping units.
Table 3: Land balance sheet of Sri Lanka
Land Type
Reserved Land (Reservoirs, streams, roads, etc.)
Forest and Catchment Areas
Steep Lands
Lands above 1500m (5000ft) contour
Barren Lands
Marshes and Mangroves
Presently Used Lands
Sparsely Used Land (Shifting cultivation, Patana etc.)
Total
Area (ha)
585,300
2000,000
380,000
76,400
77,000
70,000
2,635,000
728,800
6,552,500
Strategies for Arresting Land Degradation in South Asian Countries – Sri Lankan Experience
157
Table 4: Changes of the land/man ratio (per- capita land area) in Sri Lanka
Year
Land area
Population (million)
(million ha)
Land/man ratio
(ha)
1871
6.5
2.4
2.7
1900
6.5
3.5
1.8
1953
6.5
8.1
0.8
1986
6.5
16.5
0.4
2000
6.5
19.0
0.35
2007
6.5
20.2
0.32
With the advancement of Soil Science, to be at par with other countries, the need to
classify and map the soils of Sri Lanka according to international systems in more detail
was required. The Soil Science Society of Sri Lanka characterized the soils of Sri Lanka,
classified them according to Soil Taxonomy and FAO-UNESCO legend under the
SRICANSOL Project with assistance from Canadian Society of Soil Science. By this
time, a transitional intermediate zone has been demarcated in-between the dry and wet
zones which were identified mainly from proper interpretation of available climatic data.
The most recent characterization, classification and mapping of soils were done in
different stages for the three climatic zones. Wet zone, Intermediate zone and Dry zone,
and maps in more detail scale were produced. The soil maps thus produced/consisted of
the Wet Zone of Sri Lanka (Mapa et al, 1999) the Intermediate zone of Sri Lanka (Mapa
et al., 2005) and Dry zone of Sri Lanka (Mapa et al., 2009). In addition, these soils were
classified according to Soil Taxonomy (USDA, 2003) and FAO-UNESCO legend, and
further to Soil Series level.
The United Nations Convention to Combat Desertification (UNCCD), defines land
degradation as the reduction or loss of the biological or economic productivity and
complexity of rain fed cropland, irrigated cropland or range, pasture, forest and
woodlands resulting from land use or from a process or a combination of processes
including processes arising from human activities and habitation patterns. Land
degradation is the process that diminishes or impairs productivity of land which reduces
its future capacity to support human life. When used in such a manner, 'Biological
Potential of the Land' will decline irreversibly which ultimately reduce its ability to
produce food and fibber, a process known as soil degradation. This can take place due to
natural as well as human induced (anthropogenic) processes.
The reasons for soil degradation are reflected from the pressure on land resources of
Sri Lanka. From the total land area of about 6.5 million ha, only about 3 million are
arable due to unsuitable terrain, forest reserves and inland water bodies.The gross
land/man ratio, which was 2.7 ha in 1871 with a population of 2.4 million, has been
reduced to 0.35 ha with about 19 million people in 2000. According to Maddudma
Bandara (2000), the arable land available for human use is estimated to be at 0.15 ha per
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Strategies for Arresting Land Degradation in South Asian Countries – Sri Lankan Experience
person. The pressure on land is also reflected from the forestry perspective where the
forest cover declined throughout the years. The forest cover of the country which was
90% during 1900 when the population was 3.5 million, declined to less than 20% at
present with the increase of population to 20.2 million. Out of this, only 9% are in the
sensitive watershed areas showing the importance of relocating them with proper
planning. Main reasons for soil degradation in Sri Lanka are listed as soil erosion due to
water, fertility decline resulting from reduction of organic matter and plant nutrients,
salinization resulting from improper water management and soil compaction.
Therefore, the objective of this study was to evaluate the extent of land degradation
in Sri Lanka and the steps taken to arrest such degradation using available literature.
3. Severity of Land Degradation in Sri Lanka
Nayekekorale (1998) reported soil erosion as the major soil degradation processes in
Sri Lanka where more than 33% of the land is exposed to erosion. The Central
Environmental Authority of Sri Lanka, which is the major body dealing with
environmental issues, listed soil erosion as the major cause of soil degradation in Sri
Lanka. They documented that soil erosion resulted from encroachment of forests,
disturbing the hydrologically critical areas, shifting cultivation, inadequate attention to
lands higher than 1500 meters from mean sea level. They also highlighted that the
fragmentation of responsibilities of soil conservation among different agencies is a
drawback in controlling this problem.
3.1. Soil Erosion and Sedimentation
Soil loss by sheet erosion and subsequent sedimentation are the major soil
degradation process as shown in figure 2. Even though the major cause of soil
degradation is soil erosion, not much published data are found on erosion rates and
related soil conservation. The tolerable soil erosion rate, which is the allowable soil
erosion rate without declining the soil productivity was estimated by Krishnarajah (1984)
and is given in table 5. These were estimated using the existing rooting depth, soil
organic matter contents and soil formation rates and served as guidelines to understand
the need for establishing soil conservation methods. Anandacoomaraswamy et al. (2001)
documented that tea yields have an inverse relationship down to 350 mm of top soil depth
Strategies for Arresting Land Degradation in South Asian Countries – Sri Lankan Experience
159
Fig. 2: Sheet erosion and associated reservoir sedimentation in Sri Lanka
and it is necessary to have at least 200 to 250 mm of top soil for successful tea
cultivation. How the actual soil erosion rates exceeded the tolerable limit in most land use
systems are given in table 6, as documented by Stocking (1992). These data also
highlight the importance of simple agronomic conservation measures such as mulching
and planting on the contour in decreasing the soil loss below tolerable limits. The lowest
soil loss rates were observed in the mixed home gardens in Mid Country Wet zone which
is a mixture of crops producing canopies at different levels in taking off the erosive
power of raindrops at different heights. One of the major catchments of the up country Sri
Lanka is the upper Mahaweli catchment area. This feeds the Mahaweli river which is the
longest and most useful. The land use types and soil erosion associated with the upper
Mahaweli watershed is given in table 7. As shown before, the highest erosion rates are
associated with Tobacco cultivation, and slash and burn cultivation (shifting cultivation).
Normally Tobacco is cultivated in fertile areas with high slopes and the open canopy type
of the crop accelerates soil erosion.
Table 5: Estimated rates of tolerable soil loss for different soils of Sri Lanka
Agro-Ecological
Region
Soil
Order
Potential
Rooting Depth (cm)
Tolerable
Soil Loss t/ha/y
Up Country
Wet Zone
Ultisols
180-240
13.2
Mid Country
Wet zone
Ultisols
120-150
9.0
Low Country
Dry Zone
Alfisols
90-150
6.7
The soil erodibility (K) factor, which shows the inherent susceptibility or resistance
to soil erosion by water was worked out for selected soils by Joshua (1977). These
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Strategies for Arresting Land Degradation in South Asian Countries – Sri Lankan Experience
erodibility values are related to the clay and organic matter contents of soil, soil structural
types and aggregate stability. These values are given in table 8. The Sandy Regosol great
soil group which is classified as Entisols in Soil Taxonomy showed the highest
susceptibility to erosion, while Reddish Brown Latosolic soils showed more resistance to
erosion by water. This highlights the fact that soils with lower soil erodibility values
could be cultivated with less hazards of soil erosion, while soils with high erodibility
values need extensive soil conservation methods to be used for agricultural activity in a
sustainable manner.
Most of the eroded soil causes sedimentation of reservoirs down stream causing
siltation, while the finer particles interfere with power generating equipment. This water
is subsequently released for irrigation in the dry zone where these finer particles causes
many off-site environmental problems. It is documented that in the Mahaweli irrigation
system the Polgolla reservoir has silted to 40% of its capacity in 12 years after its
commissioning. Dhramasena (1991) reported that nearly 60% of the capacity is lost in
most of the village tanks in the dry zone due to siltation by soil erosion. The sediment
yields from selected sub catchments of the Upper Mahaweli watershed as reported by
Wallingford (1995) are shown in table 9. As seen from these data, sediment yields are
higher in lands which are disturbed annually for vegetable and potato cultivation than in
permanent vegetation such as tea and home gardens.
Table 6: Soil loss in different land use systems in Sri Lanka
AgroEcological
Region
Location
Land use
Seedling tea without
conservation
Well managed tea in contour
Mixed home gardens
Soil Loss
(t/ha/y)
40.00
0.24
0.05
Mid
Country
Wet Zone
Peradeniya
Up Country
Wet Zone
Talawakele
Clean weeded VP tea
VP tea with mulch
52.6
0.07
Mid
Country
Intermediat
e Zone
Hanguranketha
Tobacco no conservation
Capsicum no conservation
Carrots no conservation
70.0
38.0
18.0
Strategies for Arresting Land Degradation in South Asian Countries – Sri Lankan Experience
161
Table 7: Land use and soil erosion rates in the Upper Mahaweli catchment of Sri
Lanka
Land Use Type
Area
2
(km )
Soil Loss
-2
-1
(t km yr )
Bedrock Erosion
Rate*
(mm k yr-1)
Dense Forest
356.6
100
37
Degraded forest & shrubs
435.7
2500
925
Degraded grasslands
141.9
3000
1110
Poorly managed seedling tea
454.8
5200
1924
Seedling tea with conservation
252.7
1500
555
Vegetatively propagated tea
114.9
200
74
Paddy
285.7
300
111
Home gardens
537.7
100
17
Shifting cultivation & Tobacco
484.6
7000
2590
Market gardens
163.6
2500
925
These results give a clear picture of soil erosion in the country as the major soil
degradation process. The worst affected area is the mid country, which ranges from 3001,000 m elevation due to steep slopes, high rainfall intensities and more erodable soils.
Not much work has been conducted in measuring soil erodibilities other than a value of
0.31 reported for tea soils by Greenland and Lal (1977) and the values reported by Joshua
(1977) (Table 8).
Table 8: Soil erodibility values (K factor) for selected soils of Sri Lanka
Station
Great Soil Group
Soil taxonomic
equivalent
Soil Erodibility
Factor (K)
Ratnapura
Red Yellow Podzolic
Rhodudults
0.22
Katugasthota
Reddish Brown latosolic
Ultisols
0.17
Katunayake
Sandy Regosols
Entisols
0.48
Anuradhapura
Reddish Brown Earths
Rhodustalfs
0.27
Kankasanthurai
Red Yellow Latosols
Oxisols
0.33
Batticaloa
Noncalcic Brown soils
Haplustalfs
0.35
(Soils with higher values show relatively higher susceptibility to erosion)
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Strategies for Arresting Land Degradation in South Asian Countries – Sri Lankan Experience
Table 9: Sedimentation of selected catchments in the mid county wet zone of Sri
Lanka
Sub Catchment
Area (km2)
Land Use
Sediment
Yield
(t ha-l yr -l)
Above Peradeniya
1,160
Tea, grassland
4.2
Above Plogolla
1,300
Tea, townships
3.4
Tea, home gardens
0.6
Nilembe oya
61
Victoria
1,800
Tea
3.4
Mahaoya
476
Vegetables
9.4
Uma oya
94
Vegetables
10.6
3.2. Coastal Erosion
Sri Lanka also experiences severe coastal erosion as it is an island and the coastline
extends to 1920 km around the country. The coastline is shared by five provinces while
covering urban areas and 33% of population in these areas. With the development of
tourism the coastal areas will become more economically important in the future. The
mean annual recession of the coastline of Sri Lanka is estimated as 1.1 m (Madduma
Bandara, 2000). The most severe coastal erosion is in the coastal belt of 685 km
extending from Kirinada to Kalpitiya.
Coastal erosion is of two types, seasonal in nature during monsoonal times and
constant long term erosion. The erosion or deposition levels at the coast depend on the
rates of sand deposition from the rivers and removal from the tide. In addition winds
move sands off shore creatings and dunes. Coastal erosion is presently further
aggravated by sand mining, due to shortage of river sand used for construction work.
As pointed out by many environmental economists the estimation of losses due to
environmental degradation is a very complicated process (Gunathilaka, 2003). The most
recent estimates about losses due to soil erosion in Sri Lanka is documented by Griggs
(1999), where on site and off site add up to about Rs 3000 to 4000 million (Us $ 30-40
million) annually. The adverse impacts on irrigated agriculture mainly due to
sedimentation are estimated to be equivalent to Rs 320 million (US $ 3.2 million)
annually. These are only conservative estimates, as the intangible off site events as
flooding, detrimental impacts on human health and recreation are not taken into account.
3.3. Economic Estimations of Soil Loss
The National Report on Desertification/Land Degradation in Sri Lanka (Anonymous,
2000) estimated the on-site costs of soil erosion of the country as productive losses of Rs.
3529 (US $ 35) ha/y, loss of nutrients amounting to Rs 5068 (US$ 51) ha/y and estimated
nutrient losses from the major watershed in Sri Lanka, the Upper Mahaweli watershed as
Rs 953 million (US $ 9.5 m). The off site economic costs of soil erosion estimated were
Rs. 3952 (US $ 40) ha/y, loss of nutrients as Rs 5481 (US $ 55) ha/y and loss due to
reduction of hydropower and irrigation in the Upper Mahaweli watershed as Rs 15
million (US $ 1.5m) per annum.
Strategies for Arresting Land Degradation in South Asian Countries – Sri Lankan Experience
163
The next level of soil degradation associated with edaphic changes is represented by
transformation of the chemical composition of soil. This takes place in the form of
depletion of soil nutrients, increase of the salinity and alkalinity of soil acidification and
accumulation of toxic substances in the soil (Peiris, 2006).
3.4. Soil Fertility Decline
Part of the soil fertility decline is associated indirectly with soil erosion as the most
active colloid particles are lost in the erosion process. The clay particles and organic
matter affect the specific surface of soil effecting the nutrient and water holding capacity
of soils. Fertility decline may take place due to reduction of soil depth, depletion of soil
nutrients and organic matter. The removal of most fertile topsoil can reduce the yields of
crops drastically. It is shown that removal of the first five cm of topsoil reduces the yield
from 40% to 50% in many crops. Basnayake (1985) documented that during a five month
observation period the N, P and K losses from a tea land on a 30% slope in the up country
wet zone were 0.37, 0.87 and 0.045 kg /ha/t yr respectively.
The cation exchange capacity in some of the selected cultivated srilankar soils was
found to be to mainly due to their highly weathered nature. Mapa (1992) showed that
most of the soils of Sri Lanka have a kaolinitic and oxidic clay mineralogy and show low
clay activity values. In such soils the only practical way to increase the CEC is by
maintaining a higher amount of soil organic matter. The organic matter contents of
cultivated soils are low due to its rapid decomposition in these tropical environments. In
addition the soils in the wet zone are mostly acidic, affecting the availability of essential
plant nutrients. Nayakekorala and Prasantha (1996) showed that the nitrogen content of
most cultivated soils is within a range of 0.19% to 0.14% while the exchangeable K
values varied from 27 to 75 ppm.
The ways to overcome the degradation of soils by fertility decline include application
of fertilizers to replenish nutrients lost by plant uptake and leaching, and maintaining a
healthy organic matter content together with application of soil amendments and liming
material for the acidic soils. Maintaining a higher organic matter level is beneficial in
increasing soil physical, chemical and biological properties. While providing a part of
plant nutrient requirements, organic matter improves CEC and aggregate stability,
reduces erosion by wind and water. Instead of application of organic matter from external
sources as straw or compost, agro-forestry systems in which nitrogen fixing trees are
grown alongside crops to enrich the soil have become sustainable farming systems in
countries as Sri Lanka.
3.5. Acidification
When rainfall is high, as in countries like Sri Lanka, the bases get leached from the
soil and H+ ion replace the sites occupied by the cations in the exchange complex. Soils
in mid-country and up-country of Sri Lanka become acidic by natural leaching and
applications of ammonium sulphate as N fertilizers to tea plantations (Wickramasinghe et
al., 1985). Analyzing two degraded tea soil of Sri Lanka Botschek et al. (1994) showed
that Al-saturation fluctuated between 61 and 74% where CEC and P-availability were
extremely low and the soils were strongly acidic throughout the profile. They also
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Strategies for Arresting Land Degradation in South Asian Countries – Sri Lankan Experience
documented that the potential acidity of these soils were between 0.5 to 2.17 cmol/kg.
The zero point of net charges fluctuated around 3, and in many soils is below the field
pH. H showed that About 1-2 t ha-1 CaCo3 is required to reduce the Al-saturation of these
topsoils by up to 30%.
Acid sulphate soils are found in poorly drained areas in the southwest of the low
country Wet Zone. These are developed due to Dystrification whereby soil pH is lowered
by increase of acidic compounds in soils. Tokutome (1970) reported that pH of these
soils decreased on drying from 6.5 to 2.5. The occurrence of Typic Sulfaquents in Sri
Lanka where the Sulphate-S is high as 3100 to 3900 mg/kg of surface soil have been
reported by several workers. These soils are found in the Nilwala River flood plain close
to the coastal sand plain where flooded rice is the main crop. Yellow coloured jarocite
mottles could be easily observed along the cracks formed in the dry season due to
oxidation of iron pyrite. These soils have high acidity and salinity, iron toxicity, hydrogen
sulphide toxicity, aluminium toxicity and low P availability.
3.6. Salinity and Alkalinity
Lathiff and Nayakakorala (1993) reported about 160,000 ha of salt -affected soils in
Mannar, Puttlam and Jaffna and around 15,000 ha in Galle and Kaluthara regions These
are mainly the poorly drained areas along the sea cost consisting of Natraqualfs. In
addition there are some inland salinity patches formed due to improper management of
irrigation water. Most of the original drainage channels of major irrigation schemes are
encroached by the farmers making drainage impossible. When drainage water is used to
re-irrigate, this brackish water causes soil salinity. The available data for Sri Lanka
indicates that large scale development of soil salinity is not a major problem due to high
rainfall and sloping topography. Any soil salinity built-up during the dry season could be
easily washed away using high rainfall water during the wet season if proper drainage is
provided. Even though salinity is periodically flushed away by monsoon rains and
cleaning of drainage channels, the rise of ground water level in irrigated areas of arid
zone contributes to an upward movement of salts during drier periods.
3.7. Iron toxicity
Iron toxicity is the major soil constraint in the wet zone paddy lands causing an
average yield loss of about 43 kg/ha (Herath et al., 1998). Iron toxicity causes bronzing,
yellowing or orange colouration of the plant and is regarded as a major physiological
stress. This is caused by higher solubility of iron compounds after submerging the soil.
The standing water in paddy fields deprive the movement of oxygen into the soil where
anaerobic conditions occur. These will reduce iron oxides ie ferric compounds are
reduced to ferrous compounds, making them more soluble.
In soils with high organic matter content this condition may be more severe.
According to Ponnamperuma (1972) the concentration of water soluble iron is around 20
parts per million (ppm) in a neutral well aerated soil and it may increase by 30 times to
about 600 ppm, one to three weeks after submergence in an acid soil with high organic
matter content. This higher solubility will result in higher uptake of iron by plants which
will cause disorders that reduces the growth. When the soil is deficient in other nutrients
Strategies for Arresting Land Degradation in South Asian Countries – Sri Lankan Experience
165
the iron toxicity is aggravated. Therefore, supplying the essential nutrients by fertilizer
application, breeding for varieties of well developed root systems, higher oxidizing and
nutrient extracting mechanisms has potential for the future. Liming of soils using
dolomite to increase other ions as calcium and magnesium in soil solution also can reduce
the ill effects of iron toxicity. Shallow submergence due to occasional flooding also effect
paddy production in the internal lowland valleys. With prolonged submergence of soils
with high organic matter content make them boggy, deficient in phosphorus as well as
make tillage and water management difficult. Better flood protection mechanisms and
drainage facilities have to be implemented to overcome the constraints due to flooding.
3.8. Leaching of Toxic Substances to Groundwater
Leaching of plant nutrients and agro-chemicals to ground water can pollute water
resource and when this water is used for irrigation it causes land degradation. In Sri
Lanka ground water is used for irrigation in the North and areas as in Kalpitiya in North
Western Province. Jinadasa (1987) reported that in Red Latasols of the Northern region
of Sri Lanka leaching rate of 10-28 kg N/ha during a 81 day period. In addition
Nagarajah et al. (1988) reported that NO3-N in agricultural wells in iaffna and
Kilinochchi districts were higher that the WHO drinking water standards of 11.3 mg/l.
Kuruppauarchi et al. (1990) reported that the NO3-N levels of the ground water in
Talawila, Kalpitiya area showed profound seasonal variation. The values increased to 70
mg/l in the wet season with the rise of the water table. He also documented that the
potassium leached from use of higher doses of fertilizers increased the K concentration to
about 60 mg/l in the ground water. Using such water for irrigation will definitely cause
land degradation
3.9. Pollution
Pollution leading to land degradation could be from effluents from industrial fields as
well as impurities in fertilizer as heavy metals. In addition extensive use of agrochemicals lead to pollution of soils and water bodies. Soil pollution by toxic metals is one
of the serious problems of the environment. In addition to the natural sources, the
anthropogenic sources such as addition of fertilizers, agro-chemicals and manures are the
major sources of heavy metals to the agricultural lands.
Sri Lanka is neither an industrialized country nor does it has any natural metal
deposits. However use of chemical fertilizers, manures and pesticides more than the
recommended doses as well as frequent and long-term cultivations could contribute to the
heavy metal accumulations in soils. Jayathilake and Bandara, (1989) reported that most
of Sri Lankan farmers apply two to eight times more fertilizer than the recommended
dosage. Many researches have documented that, synthetic fertilizers and pesticides
contain heavy metals as an impurity or as an active ingredient. Wood et al (1996) and
Han et al. (2000) have shown that short and long-term applications of poultry litter
increased Cu and Zn concentrations in soil especially in the top 5 to 10 cm. Hence, long
term fertilizer and manure applied soils may accumulate these heavy metals over the
time.
Heavy metal concentrations in Up Country and Low Country-Wet zone of Sri Lanka
were determined by Premarathne (2006) in different vegetable growing soils, vegetables,
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Strategies for Arresting Land Degradation in South Asian Countries – Sri Lankan Experience
and in fertilizers and manures used in their agricultural activities. Crop, soil, and
fertilizer/manure samples were collected from Kandapola, Sita-Eliya, Bogahakumbura,
Haputale and Rahangala for the Up Country (Wellampitiya, Sedawatta, Welewatta and
Kotuvila) and Bandaragama (Bandaragama and Kahathuduwa) selected as the Low
Country areas. Soil, fertilizer and manure samples were analyzed for total heavy metals
(Cd, Cu, Ni, Pb, and Zn). The Pb concentrations in the Low Country vegetable growing
fields were similar to the control soil indicating either geological or non-agricultural
activities as the source of Pb. Significant increase in Cd, Cu, Ni, Pb and Zn
concentrations were observed in cultivated lands than the control. Values observed in
Sedawatta fields were higher than the European Community Set Standards for Cd, Zn, Pb
and Cu and was lower than that of the United State Set Standards. Farmers of these areas
have been used higher amount of synthetic fertilizers and pesticides. It could also result
from accumulation of heavy metal in soil as observed in many counties before (Williams
and David, 1976). Fertilizers and pesticides contain some heavy metal as impurity or as
an active ingredient. Therefore, fertilizers and pesticides could also be a source of heavy
metals to the soils of the area. Further, the studied fields are located in flood plain of
Kelani River and frequently subjected to flooding. Therefore, polluted water can enter in
to these fields. thereby contributing to accumulation of heavy metals in these lands
Premaratne (2006) also measured the heavy metal contamination (Cd, Cu, Ni, Pb and
Zn) of a range of phosphate fertilizers, manures and liming materials used by up country
and low country vegetable farmers. The results indicated that rock phosphate mined from
Sri Lanka (Eppawala rock phosphate) contains relatively low concentration of Cd and
other heavy metals compared to imported rock phosphates and Triple super phosphate
(TSP). Out of all fertilizers measured, the TSP contained the highest Cd concentrations
and it was 23.5 mg/kg. Except for Cd in phosphate fertilizers, other heavy metals were
well below the maximum levels of the standards setup by Sri Lanka Standard Institute
(SLSI) for compost that can be applied to the agricultural lands. The standards for
compost were used as at present there are no such standards imposed for heavy metals for
commercial fertilizers. Application of TSP, poultry manure, and other amendments in
high rates for a long period of time can increase soil Cd and other heavy metal
concentrations significantly.
3.10. Gaps in the Knowledge Base
The existing knowledge on land degradation is mostly limited to studies of soil
erosion with less information available with other processes of human induced land
degradation. These data are available according to the regional elevation pattern as Up
country, Mid country and Low country of Sri Lanka. Based upon spatial distribution of
soil erosion index values for Sri Lanka showing the most sensitive areas for soil erosion,
five areas were gazetted by the government as sensitive areas for soil erosion. In addition,
soil erosion hazard maps constructed using soil erodibility and rainfall erosivity factor for
districts in the central province are also available.
The knowledge gaps are mainly on the absence of a proper national data base on
natural resources, specially on soil. Even though data on soil erosion and sedimentation
are available, there is no data on fertility decline, salinity and eutrophication. Even in soil
Strategies for Arresting Land Degradation in South Asian Countries – Sri Lankan Experience
167
erosion, field plots are used to monitor runoff and soil loss which give a set of process
reflecting site condition, but they say little about whether the land use can be sustained
and where the sediment depositsion will occur. In addition, the findings of these
researches are limited to the soil type, slope and climatic zones and therefore, there is a
need to study these factors covering all the soil types so as to increase the applicability of
research findings.
Research should result in technologies that promote environmentally sound
agricultural practices while increasing productivity, and policies that strengthen property
rights, correct tenurial anomalies, discourage fragmentation, and promote land markets
that operate more freely. The National Environmental Action plan proposed by the
Government of Sri Lanka considering nine key sectors of the economy prioritizing the
key issues related to land and water resource management provide guidelines to arrest
land degradation due to each of these factors.
South Asian countries as Sri Lanka will have to manage their water resources on a
long-term, integrated basis. The imperatives of such planning are particularly critical as
withdrawals will increase to about 71 percent of available water. Seasonal water
shortages can severely affect agricultural output. The use of water for agriculture in the
region can be made more efficient through improved practices, such as water
management regimes with user participation, and the application of new technologies,
such as sprinkler irrigation. Incentives for economizing in the use of water must come
from reasonable pricing policies. The pricing of irrigation water, however, remains a
controversial issue in many Asian countries. The research and development initiatives
should integrate in preventing land degradation resulting in increase of water quality and
quantity.
4. Policy Issues
The policy issues related to land degradation is strongly related to landlessness and
land tenure. If farmers do not own land they will be not interested or invest in long term
sustainability but just mine the land until it is degraded. In Sri Lanka many land
commissions have documented the historical aspects of land ownership. If some of the
legislation related to land such as the Soil Conservation Act were properly implemented
by the government, the land resource of Sri Lanka would have been more productive at
present. Most of the policy for combating land degradation is prepared by the land Use
Policy Planning Division (LUPPD) of the land Ministry while their implementation is
done mostly through the Ministry of Environment and Natural resources.
Land use planning is the best long term tool to prevent land degradation. There are
many sound land use planning examples as the Kandyan mixed home garden where the
soil erosion is less as 0.05 t/ha/y.
5. Arresting Land Degradation: Some Recommendations
The following recommendations are proposed to arrest land degradation of Sri
Lanka.
168
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Strategies for Arresting Land Degradation in South Asian Countries – Sri Lankan Experience
There is a good understanding about human induced land degradation, especially the
soil erosion and sedimentation problem. Still, the remediation measures are taken in
ad-hoc basis by many different ministries and government departments. There should
be coordination of these activities through a central body as a soil conservation
authority.
The long term arresting of land degradation depend on implementation of land use
planning based on sound and long term land use policies formulated to fulfill national
priorities. Crop zoning initiated by the Department of Agriculture is a good
beginning. The lands best suited for selected crops have to be farmed intensively,
while unsuitable lands have to be released for non-agricultural activities and for
conservation.
Rehabilitation of degraded land should be seen as an investment and Rs. 250,000/=
(US $ 2500) per ha which is the approximate value loss due to complete degradation.
This could be arrested by investing a fraction of this amount.
Future land use policies should be developed on the basis that the population of Sri
Lanka will which stabilize at 23 million by 2020 and out of this 70% will live in
urban areas.
Distribution of land for political reasons among the poor as an alternative for
employment should be discouraged.
Detailed information on soils is limited as well as scattered among many agencies.
This data should be used to prepare a collective database and the data gaps should be
identified and filled. A proper and complete database is a pre-requisite in making
policies to arrest land degradation.
Steps should be taken to stop slash and burn (shifting) agriculture and these lands
should be made more productive by developing the soil organic matter levels using
systems such as alley cropping and conservation farming techniques.
A major shortcome in soil conservation programs is the laxity in respect of
enforcement. Strict enforcement of regulations is necessary especially with the soil
conservation act. In addition prohibition of cultivation of land exceeding 60% slope
and above 1525 meters (5000 feet) contour line should be strictly enforced.
New institutional mechanisms involving farmer organizations and the community
should be developed at grassroots levels. Community based participatory approaches
should receive high priority in future programs.
Trade liberalization have positive effects on soil conservation. For example, trade
restrictions for potatoes increase the price of potatoes which encourages cultivation in
erosive upcountry lands. This is a large economic loss by degrading valuable land
resource.
New research programs emphasizing adaptive research should be initiated in
collaboration with universities, and budgetary provision should be made for the
research as well for dissemination of research findings. Farmers, plantation
managements and the community should be closely involved in the exercise. Existing
organizations such as the LUPPD, NRMC of the Department of Agriculture and the
Tea Research Institute, already engaged in related activities should be strengthened
by providing the required resources
Strategies for Arresting Land Degradation in South Asian Countries – Sri Lankan Experience
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169
The Department of Agriculture should develop appropriate cropping systems
incorporating ecological, social and economic goals for specific locations and
landscapes. The Natural Resource Management Center of the Department of
Agriculture has an important and leadership role to play for collecting available data
and propose suitable of soil conservation measures to arrest land degradation in
different agro-ecological regions of Sri Lanka.
The Tea, Rubber, Coconut research institutes, departments of Forest, Export
Agriculture and Coast conservation should be able to provide leadership in proposing
and implementation of arresting land degradation with respect to their disciplines.
The Central Environmental Authority is geared to provide leadership in arresting land
and water degradation due to pollution from industries which can ruin these resources
in a very short time.
Soil conservation units of Provincial Councils need to be strengthened in
implementing soil conservation measures in the provinces.
Carefully targeted government assistance should be provided for land conservation.
Land conservation should be made mandatory to qualify for government subsidies as
fertilizer subsidies and subsidies for replanting perennial crops.
6. References
Anonymous, 1998 National Environmental Action Plan. Ministry of Environmental and
Parliamentary Affairs, Government of Sri Lanka.
Anandacoomrasamy, A, Ekanayake, A.A.B, Ananthacumaraswamy, S., Chishom, A.H. and
Jayasuriya, S. 2001. Effects of land degradation on tae productivity of Sri Lanka. Proc.
International Symposium on soil erosion research for 21st century, ASAE publication 75-78.
Dharamasena, P.B. 1991. Present use of land and water resources in village tank farming. Journal
of Soil Science Society, Sri Lanka 7, 1-17.
De Alwis, K.A.. and Panabokke, C.R. 1972. Handbook of Soils o Sri Lanka. Soil Sci. Soc. Sri
Lanka 2:1-95
Domros, S. 1974. The Agro-Climate of Ceylon. Franz Steiner Verlag Gmbh.
Griggs T 1998 Solutions to Sri Lankan erosion woes. Partners in Research for Development 11:
1-7.
Gunathilake H.M., 2003 Environmental Valuation. Theory and Applications. 373 p Han, F.X.,
Kingery, W.L., Selim, H.M. and Gerard, P.D. (2000). Accumulation of heavy metals in a
long-term poultry waste amended soil. Soil Science. 165(3): 260-268
Herath, B.R.M., Dhanapala, M.P., De Silva, G.A.C., and Hossain, M. 1998. Constraints to
increase paddy production in Sri Lanka. Paper presented at the workshop on prioritization
of rice research, IRRI, Phillipines, 20-22 April 1998.
Jayathilake, J., and Bandara, J.M.R.S. 1989. Pesticide management by the hill country vegetable
farmers. Trop. Agri. Res.1:121-131
Joachim, A.W.R. 1955. The Soils of Ceylon. Tropical Agriculturist 111:161-172.
Joshua, W.D. 1977. Soil erosive power of rainfall in the different climatic zones of Sri Lanka.
Proc. Symposium on deposition and soil matter transport in inland waters. Paris. AISI
Publication no. 1222, 1977.
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Strategies for Arresting Land Degradation in South Asian Countries – Sri Lankan Experience
Kabir,W. and Akter, N. 2007. Statistical data book for agricultural research and development in
SAARC countries. SAARC Agricultural Centre, Dhaka, Bangladesh. 403
Krishnarajah P.1984. Erosion and degradation of environment. Proc. Annual Sessions of the Soil
Science Society of Sri Lanka
Lathiff, M.A. and Nayakekorale, H.B. 1993. Problem soils of Sri Lanka. SAARC Workshop on
Problem Soils, 23-24 Nov. Kandy, Sri Lanka.
Madduma Bandara, C.M. 2000. Land Resources: Conditions and Trends. (Ed.) PG Cooray.
Natural Resources of Sri Lanka. National Science Foundation of Sri Lanka 53-73
Mapa RB 1992 Clay mineralogy of six Sri Lankan soils in relation to weathering sequences. J.
Geological Soc. Sri Lanka 4:41-49.
Mapa, R.B. ,Somasiri, S. and Dassanayake, A.R. 2007. Soils of the Dry Zone of Sri Lanka.
Morphology, Characterization and Classification. Special Publication No. 9. Soil Science
Society of Sri Lanka. 357 pp
Mapa, R.B., Dassanayake, A.R. and Nayakekorale, H.B. . 2005. Soils of the Imtermediate Zone
of Sri Lanka. Morphology, Characterization and Classification. Special Publication No. 4.
Soil Science Society of Sri Lanka. 225 pp
Mapa, R.B., Somasiri, S. and Nagarajah, S. 1999. Soils of the Wet Zone of Sri Lanka.
Morphology, Characterization and Classification. Special Publication No 1, Soil Science
Society of Sri Lanka 191 pp
Nagarajah, S and Hindagala, C.B. 1993. Report of the SAARC Workshop on problem soils. 23-24
November 1993, Kandy Sri Lanka.
Nayakekorale HB 1998 Human induced soil erosion status in Sri Lanka. J. Soil Sci. Soc. Sri Lanka
10: 1-35.
Nayakekorala, H.B. and Prasantha, B.O.R. 1996. Physical and chemical characteristics of some
eroded soils in the mid country of Sri Lanka. Journal of Soil Science Society, Sri Lanka 9,
16-31.
Ponnamperuma, F.N. 1972. The chemistry of submerged soils. Advances n Agronomy
Premarathne, H.M.L.P. 2006. Soil and Crop Contamination by Toxic and Trace
Elements, M.Phil. Thesis, Postgraduate Institute of Agriculture, University of Peradeniya, Sri
Lanka
Somasekaram, T. 1996. Facts About Our Land. Arjuna Consulting Co. (Ltd.) Dehiwala.
Stockings M. 1992. Soil erosion in the upper Mahaweli catchment. Technical report No. 14,
Report submitted to the environment and forestry division of Mahaweli authority of Sri
Lanka.
Survey Department. 2007. National Atlas of Sri Lanka. Published by the Survey Department of Sri
Lanka pp
USDA. 2003. Keys to Soil Taxonomy. 9th Ed. Natural resources Conservation Service, United
States Department of Agriculture. 325 p
Wood, B.H., Wood, C.W., Yoon, K.H., and Delancy, D.R. (1996). Nutrient accumulation and
nitrate leaching under broiler litter amended corn fields. Commun. Soil Sci. Plant Anal. 27:
2875-2894.
172
Acid Soil Management in India-Challenges and Opportunities
Acid Soil Management in India-Challenges and
Opportunities
D. Jena
Professor IFFCO Chair & Former Head
Department of Soil Science & Agriculture
OUAT, Bhubaneswar-751003
Email: [email protected]
Acid Soil Management in India-Challenges and Opportunities
173
Abstract
Acid soils are base unsaturated soils developed under drastic weathering, influenced
by hot and humid climate and heavy precipitation. Acid soils constitute about 30 % of the
total cultivated area in India. The productivity of acid soils is low due to low pH,
presence of toxic levels of Al, Fe and Mn, nutrient imbalance, deficiency of Ca, Mg, S, P,
B and Mo and poor microbial activity .Amelioration of acid soil by liming enhances
availability of several plant nutrients and increases crop yield. Agriculture can not afford
to use industrial grade lime as it is cost prohibitive. Alternative sources of lime like paper
mill sludge, steel mill slag, blast furnace slag, pressmud are recommended for acid soils.
Amending soil with full dose of lime should be replaced by 0.10 to 0.20 LR dose.
Phosphorus management in such soils is done economically by using powered indigenous
rock phosphate mixing with highly active imported rock. Deficiency of Ca and Mg can
be corrected by using dolomite or other liming materials. Modest dose of lime should
find a place in integrated nutrient management system for acid unbunded and bunded
uplands. Balance use of lime and micronutrients is recommended for vegetables, cereals,
pulses and oilseeds in acid soils. Growing acid tolerant species and cultivars is the
alternative.
Keyword : Acid soil, liming material, lime requirement, nutrient availability, acid tolerant
crop.
Acid soils are base unsaturated soils constitute about 30% of the total cultivable area
in India. They occur in the Himalayan region, the eastern and north-eastern plains,
peninsular India and coastal plains under varying topography, geology, climate and
vegetation. Most of these soils belong to the soil orders, Ultisols, Alfisols, Mollisols,
Spodosols, Entisols and Inceptisols. The acid soils are mostly distributed in Assam,
Manipur, Tripura, Meghalaya, Mizoram, Nagaland, Sikkim, Arunachal Pradesh, West
Bengal, Jharkhand, Orissa, Madhya Pradesh, Himachal Pradesh, Jammu & Kashmir,
Andhra Pradesh, Karnataka, Kerala, Maharastra and Tamilnadu. Acid soils of Himalayan
region are occupied by acid podozols in association with brown forest soils. Acid soils of
alluvial region occur in West Bengal, Bihar, Assam and Orissa.
Acid soils in marsh areas are found in Assam, Kerala, West Bengal, Coastal districts
of Orissa,south-east coast of Tamilnadu, tarai regions of Utter Pradesh, Bihar and West
Bengal. Acid sulphate soils are found in Sunderban area of West Bengal and Kuttand
area of Kerala. The extent of occurance of acid soils in different states of India is given in
table 1. It is estimated that about 12% soils are strongly acidic (pH < 5.0), 48%
moderately acidic (pH 5.0-5.5) and 40% mildly acidic (pH 5.6-6.5).
Formation of Acid Soils
Acid soils in India are formed due to drastic weathering under hot humid climate and
heavy precipitation. Laterization, podzolization and accumulation of undecomposed
organic matter under marshy conditions contribute to the development of soil acidity.
Acid soils are formed mainly due to acidic parent materials (granite) and leaching of
bases from the surface soils due to high rainfall. Nitrogenous fertilizers like ammonium
sulphate, mmonium nitrate, ammonium chloride and urea create soil acidity.
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Acid Soil Management in India-Challenges and Opportunities
Table 1: Acid soils regions
State
Area under acid
Soils (m ha)
Percent
Cultivated area (mha)
with pH < 5.5
Assam and Northeastern states
20.0
80
3.5
West Bengal
3.5
40
2.0
Erstwhile Bihar
5.2
33
0.4
Orissa
12.5
80
1.8
Madhya Pradesh
8.9
20
-
Andhra Pradesh
5.5
20
-
Tamilnadu
2.6
20
-
Karnataka
9.6
50
-
Kerala
3.5
90
2.1
Maharastra
3.1
10
0.3
Erstwhile Uttar Pradesh
2.9
10
-
Himachal Pradesh
5.0
90
0.1
Jammu & Kashmir
15.5
70
-
Source: Mandal (1997), Sarkar (2005)
Chemistry of Acid soils
In acid soils, the concentration of H+ ions exceeds that of OH- ions. For the long
time, it has been considered that the soil acidity is owing to exchangeable H+ ions only.
Mukherjee and Chatterjee (1942, 1945) found the dominance of Al in the soil acidity in
early thirties. Most of the clay particles interact with H+ ions. Hydrogen saturated clay
undergoes a spontaneous decomposition. In the octahedral layer, hydrogen ions replace
the Al ions. The Al released is then absorbed by the clay complex and a H-Al-Clay
complex is formed rapidly. The trivalent aluminium hydrolyses to monomeric and
polymeric hydroxy-aluminium complexes (Chernov 1947) and contribute to soil acidity.
Soil acidity is of three kinds
(i) Active acidity refers to H+ ions soil solution
(ii) Exchange acidity includes exchangeable H+ and Al3+
(iii) Non-exchange or residual acidity comprising of weak acids caused by organic
matter and bound Al. The total acidity estimated by BaCl2 – TEA comprises of pH –
dependent or residual and exchange acidity. Different types of soil acidity in different soil
orders is presented in table 2.
Acid Soil Management in India-Challenges and Opportunities
175
Table 2: Forms of acidity [c mol(p+) kg-1] in soils under different soil orders
Location
Total
acidity
pH
dependent
acidity
Total
exchange
acidity
Acidity
due to H
Acidity due
to Al3+
+
Inceptisols
West Bengala
5.98
5.50
0.48
0.19
0.29
Orissab
2.29
2.19
0.10
0.08
0.02
Mizoramc
12.50
11.08
1.41
0.23
1.18
Alfisols
West Bengala
3.20
3.1
0.10
0.03
0.07
Orissab
10.3
8.7
1.60
0.45
1.15
Entisols
West Bengala
5.15
4.93
0.22
0.11
0.11
Orissab
10.76
10.65
0.11
0.11
-
Mizoram
12.24
11.63
1.64
0.32
1.32
Ultisols
Orissab
5.30
4.70
0.60
0.30
0.30
Mizoramc
13.19
11.67
1.52
0.29
1.23
Source: a- Chand & Mandal (2000)
b- Misra et al. (1989)
c- Misra & Saithantuaanga (2000)
Studying different forms of acidity in major soil groups of India, Sharma et al (1990)
reported that exchangeable H+ and exchangeable Al 3+ comprises 21 and 79% of
exchange acidity, whereas pH dependent and exchange acidity accounted for 71% of the
total acidity. The acidity unaccounted for were probably due to hydrolysis of Fe and Mn
on the exchange sites of the soil complex. The important soil factors that control the
different kinds of soil acidity are pH organic matter, exchangeable and extractable Al.
Crop Production constrains in Acid Soils
The upland acid soils have coarse soil texture with high infiltration rate, low water
holding capacity, high permeability, soil crust formation, excessive leaching of nutrients
and high bulk density. Seed germination is affected by surface soil crust. Application of
organic matter (Biswas and Khosla 1971), tank slit, conservation tillage, contour and strip
176
Acid Soil Management in India-Challenges and Opportunities
cropping, intercropping of cereals with legumes or oilseeds and insitu rainwater
harvesting are some of the suitable methods for crop yield in such soils.
Common problems of acid soils in respect of chemical properties are low pH, low
CEC (due to dominance of 1;1 type of clay),low level base saturation percentage, high
Fe, Al, and Mn saturation percentage, a high P fixing capacity, clay fractions consisting
of rather low surface active minerals. These problems could be managed by amelioration
with liming which improve soil pH, base status and CEC, inactivates Fe, Al and Mn soil
solution, reduce acidity and P fixation in soil (Panda and Koshy 1982, Misra et al. 1989,
Sahu and Patnaik 1990, Jena 2008 (Fig.-).
Acid soils are deficient in Ca. Exchangeable Mg content of such soils is also poor.
High concentration of Fe and Al results in Fe and Al toxicity. Sulphur deficiency is
common in upland coarse textured soils. Micronutrients such as B and Mo are often
deficient in acid soils. Acid soils of India have generally low organic carbon and nitrogen
status.
Crop production in acid soils suffer due to poor availability of plant nutrients,
toxicity of Fe and Al, poor biological activity and low and imbalanced fertilizer use.
Ameliorating these soils with liming materials, using balanced nutrients, organic manure,
growing acid tolerant crops and crop species, use of biofertilizers will definitely increase
crop productivity in acid soil regions of the country.
Liming- Source, Efficiency, Response and Limitations
Liming is a widely accepted practice for ameliorating acid soils. It decreases
exchange acidity and increases soil pH. It improves base saturation percent of soils,
inactivates Al, Fe and Mn, reduces P fixation and stimulates microbial activity leading to
the mineralization of organic nitrogen. Availability of major, secondary and
micronutrients due to liming of acid soils have been reported.
Among the naturally occurring lime sources, calcite, dolomite and stormatolitic lime
stones are important. Since calcite and dolomite have industrial use, its application in
agriculture is not economical. In India, the total reserve of all categories of lime stone is
about 76,446 million tones (mt) out of which 11,562 mt are under proved category,
16,463 mt under probable category and 48,419 mt under possible category (Panda 2007).
Deposits of lime stone in North-Eastern states are in the order of 4522 mt in Meghalaya,
703 mt in Assam, 309 mt in Nagaland, 140 mt in Arunachal Pradesh and 46 mt in
Manipur. Orissa has a reserve of 1683 mt. Deposits of about 40 mt of stormatolitic lime
stone, a poor grade lime containing 28-32% CaO, 12% MgO and 0.5% P2O5 is found in
Orissa. Its use in acid soils needs detailed study.
Several industrial wastes such as paper mill sludge (PMS) from paper mills, basic
slag from steel industry, pressmud from sugar mills using carbonate process have been
tested successfully in acid soil regions of India as amendments which are ecofriendly.
Depending on the availability and cost of the materials, several types of liming materials
are used in acid soil regions of India (Table 3). Liming material must be locally available,
properly ground and should have high neutralizing value and low cost for use by small
and marginal farmers. Although huge amount of basic slag (100 mt per annuum) is
Acid Soil Management in India-Challenges and Opportunities
177
generated from steel mills located in Bhilai, Rourkela, Bokaro, Durgapur Burnpur, its use
is limited due to high grinding cost. On an average Indian slag contains 1 to 7 of P2O5,
24 to 50% CaO and 2 to 10% MgO.
Table 3: Availability of liming materials in India
Acid soil region/state
Liming material
Quantity available
(million tones)
Assam
Lime stone
Himachal Pradesh
Marketable lime
Jharkhand
Lime stone/basic slag*
1.0
Kerala
Lime shells
4.0
North-Eastern Hill region
Lime stone
14.0
Orissa
Paper mill sludge/ basic slag*/
stromatolytic / lime stone*
0.2
West Bengal
Basic slag
0.3
Others
Basic slag
3.0
15.0
-
*prices not available
Source: Sharma and Sarkar (2005)
Crop Response to Liming and Fertilization
Effect of lime on crop yield in acid soil regions has been reported by several workers.
Based on past studies on liming (Table 4), the crops have been grouped into
(a) High response group (pigeon pea, soyabean, cotton),
(b) Medium response group (gram, lentil, groundnut, maize, sorghum, wheat, pea)
(c) Low response group (barley, minor millet and paddy). Generally the crops
responded to liming are legumes, cotton, maize, sorghum, wheat and linseed etc.
Table 4: Relative response of different crops to liming
Crop
Control
Lime alone
NPK alone
NPK + lime
Arhar
100
1133
394
1927
Soyabean
100
503
207
788
Cotton
100
1083
2270
3887
Group-I High Response
Group II- Medium Response
Gram
100
223
256
606
Lentil
100
266
301
627
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Acid Soil Management in India-Challenges and Opportunities
Groundnut
100
304
197
333
Maize
100
202
429
660
Sorghum
100
196
139
346
Wheat
100
109
215
267
Pea
100
295
313
596
Group III- Low Response
Barley
100
102
265
327
Minor millet
100
132
283
319
Paddy
100
173
280
266
Source: Sharma and Sarkar (2005)
Sharma and Sarkar (2005) reported that application of lime @ 2-4 q/ha increased the
yield of rape seed mustard, wheat, green gram, maize, pigeon pea, field pea, black gram,
groundnut by 14 to 52% over farmer’s practice. The recommended application of
fertilizers (100% NPK) increased yield by 15 to 99% over farmer’s practice at different
places. On the otherhand application of lime with 100% NPK resulted in 49-189% higher
yield over farmer’s practice. The response to combined application of lime and fertilizers
was more than fertilizer or lime alone, indicating synergy or complementarity between
fertilizer use and liming. The yields recorded with 50% NPK + lime @ 2-4 q/ha were
equal or slightly higher to the yield with 100% NPK (Table 5).
Jena (2008) studied the effect of different levels of lime (calcite) on pH,
exchangeable Al+3 and H+ in an acidic laterite soil of Dhenkanal. The data revealed that
application of lime @ 0.2 LR increased the pH from 5.1 to 6.9 (Fig 1) and decreased
exchangeable Al+3 from 0.62 to 0 cmol(p+) kg-1 within seven days of incubation (Fig 2).
Based on the study, several field trials were conducted in farmer’s field covering several
crops and soil types 5.5 6 6.5 7 0 7 15 22 30 3 Incubation Period (Days) P.
Fig. 1: Effect of Lime application on soil pH
Acid Soil Management in India-Challenges and Opportunities
179
Fig. 2: Effect of Lime application on Exch. Al
Table 5: Yield (q/ha) of crops in acid soils with recommended fertilizer and half the
recommended fertilizer + lime
State
Assam
Crop
100% NPK
50% NPK +
lime
Yield
deviation (%)
Rapeseed
9.7
10.1
+ 4.1
Summer green gram
4.4
5.2
+18.1
Himachal
Pradesh
Maize
34.0
33.1
- 2.6
wheat
27.9
23.7
- 15.0
Jharkhand
Maize + pigeon pea (maize
equ. yield)
69.0
65.0
- 5.8
Pea
38.4
50.8
Cowpea
8.6
10.6
+ 23.2
Blackgram
6.4
8.1
+ 26.6
Maize
30.5
30.3
- 0.7
Grundnut
14.2
21.3
+50.0
Groundnut
22.5
23.6
+ 4.9
Pigeonpea
12.0
12.2
+ 1.7
Kerala
Meghalaya
Orissa
West
Bengal
+ 32.3
Mustard
8.2
8.4
+ 2.4
Wheat
16.7
17.1
+ 2.4
Source: Sharma and Sarkar (2005)
The data revealed that liming @ 0.2 LR through PMS (paper mill sludge) increased
the yield of groundnut by 17-36%, green gram 5-21 %, cabbage 15-16 %and cauliflower
22% over farmer’s practice (Table 6).
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Acid Soil Management in India-Challenges and Opportunities
Organic amendments reduce exchangeable Al in soils due to precipitation of Al ions
by OH ions released from exchangeable ligand (Hue 1992; Lyamuremye et.al 1995).
Several workers have suggested for application of organic amendments (FYM) either
alone or in combination with lime for controlling the acidity as well as nutrient
availability (Table 7). Liming also stimulates microbial activity leading to mineralization
of organic N and fixation of N2 (Raychaudhuri et al 1998).
Table 6: Response of different crops to liming in red and laterite soils of Orissa
Yield (q/ha)
Crop
District
pH
FP
FP +lime
Yield
Response (%)
Groundnut
Greengram
Cabbage
Dhenkanal
4.0-6.3
8.40
11.43
36
Mayurbhanja
Nayagarh
4.8-5.2
15.05
17.55
17
5.5-5.7
10.70
12.70
19
Ganjam
5.6-6.1
19.05
23.87
25
Khurda
5.5-6.5
8.10
8.95
5
Dhenkanal
3.8-6.0
8.20
9.90
21
Kandhamal
5.9-6.6
111.70
130.00
16
Koraput
5.8-7.3
224.00
256.90
15
6.0-6.1
99.50
121.0
22
Cauliflower
Source: Jena (2008)
Table 7: Effect of lime and FYM on soil properties after 30 days of application in
acid Inceptisols of Bhubaneswar
Acidity (cmol (p+) kg-1)
Treatments
Available (kg ha-1)
pH
Total
Exch.
Al
N
P
K
Control
5.8
3.0
0.17
0.06
349
50
138
Lime
6.9
1.9
0.16
0
359
66
148
FYM
5.9
2.4
0.16
0
384
70
160
Lime +
6.8
1.9
0.14
0
370
60
160
-
-
-
-
-
-
-
FYM
Source: Mohanty (2000)
Lime requirement value of varies with soil properties. Lime requirement of acid soils
of India varied from 2.6 to 24.0 t CaCO3 ha-1 and was significantly related to soil pH
and organic matter content (Sharma and Tripathy 1989). But liming at @ full LR dose is
Acid Soil Management in India-Challenges and Opportunities
181
often not economical. For laterite soil of Bhubaneswar 0.5 LR was enough for maize
(Pradhan 1978), although exchangeable Al was neutralized with 0.25 LR. Application of
lime @ 10-20% of LR in furrows increased the yield of greengram, groundnut,
blackgram, soyabean, lentil, pea and gram over ‘no lime’ control (Mathur et al. 1985,
Mathur 1997). In an experiment on direct and residual effect of liming in different
cropping system conducted in acid sandy loam soil at G. Udayagiri in Orissa, grain yield
of mustard, wheat and cowpea increased by 41, 28 and 21%, respectively due to direct
effect of liming @ 0.25 LR and maize yield increased by 7-13% under residual condition
(Table 8).
Result of long-term experiment conducted in acid soil regions at Ranchi,
Bhubaneswar, Palampur and Bangalore over a period of 9-24 revealed that soil pH was
decreased by 0.2-0.9 units with application of chemical fertilizer (NPK) but the pH was
almost maintained or increased by 0.3-0.6 units with NPK + lime (Table 9). Average crop
yield of soyabean, wheat, rice and maize increased by 0.3-0.7 t ha-1 due to application of
NPK + lime over NPK. The crop response to lime application at Bangalore was negative
because the initial pH was higher than 6.
Table 8: Effect of liming on field pea, wheat and mustard and its residual effect on
succeeding maize crop
Crop
Field pea
Wheat
Mustard
Direct effect (t/ha)
Residual maize (t/ha)
L0
L1
L0
L1
F1
1.02
1.30
2.00
2.21
F2
1.34
1.56
2.16
2.21
Mean
1.18
1.43
2.08
2.21
F1
0.75
0.90
1.00
1.02
F2
0.89
1.15
1.09
1.35
Mean
0.82
1.02
1.04
1.18
F1
0.18
0.24
1.18
1.27
F2
0.29
0.34
1.14
1.31
Mean
0.23
0.29
1.16
1.29
L0: No lime, L1: 0.25 LR F1: 50% RDF, F2: 100% RDF (Recommended dose of fertilizer)
Source: Jena (1996)
B:C Ratio
4.25
1.33
1.68
182
Acid Soil Management in India-Challenges and Opportunities
Table 9: Long term effect of liming on soil pH and crop yield in acid soil regions
Location/cropping
system
Initial
Soil pH after 9-36
years
Grain yield (t/ha)
NPK
NPK+Lime
NPK
NPK+Lime
Response
5.3
4.8
5.8
1.6
3.4
1.9
3.7
0.3
0.3
5.6
5.4
5.5
2.8
3.0
3.3
3.4
0.5
0.4
Maize
Wheat
5.8
5.3
6.4
3.5
3.0
4.1
3.3
0.6
0.3
Bangalore
Finger millet
Maize
6.1
5.2
6.4
4.0
3.7
-0.3
2.0
- 0.1
Ranchi
Soyabean
Wheat
Bhubaneswar
Rice
Rice
Palampur
2.1
Source: Singh & Sarkar (1998); Sahoo et al (1998); Sharma et al (1998); Sudhir et al (1998)
Agro-techniques for Reducing Phosphate fixation and Improving Fertilizer use
Efficiency
Attempts have been made by several workers to reduce the cost of P fertilizers in acid
soils by direct use of rock phosphate or rock phosphate and single super phosphate
mixture in 1:1 ratio. The total phosphate rock deposit in India is estimated as 200 million
tones of which only 18.5 m ton can be rate as high grade (> 30% P2O5). Crop response
to phosphate is strongly dependent upon the rate of dissolution of rock. Partial acidulation
of phosphate has been reported to be the possible means for economic and efficient
utilization.
Panda et al. (2007) reported North-carolina rock phosphate of 35 mesh was superior
to 100 mesh size of Indian phosphate rocks such as Udaipur, Musoorie, Hirapur,
Kasipatnam, Maton and Purulia. Udaipur rock phosphate containing dolomite and calcite
was found economical for maize-mustard cropping system in alfisol. (Jena et al 2004).
Mixture of imported phosphate rock with indigenous phosphate rocks works good for
crops in acid soils since former one could act as a starter dose. The effectiveness of low
reactivity phosphate rock can also be increased by applying it to green manure crop
preceeding the main crop or by inoculation of the field with either phosphate solubilizing
micro-organisms or Mycorrhiza (Misra 2004). Rice grown in iron toxic soils can be
benefited from application of Udaipur rock phosphate containing substantial amount of
dolomite and calcite. (Misra 2004).
Acid Soil Management in India-Challenges and Opportunities
183
Management of Secondary Nutrients in Acid Soils
Most of the acid soils are deficient in Ca, Mg and S except acid sulphate soils which
contain high amount of S. Soils having Ca saturation less than 25% of the total cation
exchange capacity require Ca application to most of the crops. Deficiency of Ca and Mg
can be corrected by using lime or liming materials @ 4-5 q/ha.
Coarse textured acidic upland soils low in organic matter show S-deficiency. Sulphur
deficiency of 17-87% was recorded in acid soil regions of the country (Singh 2007).
Results of long term fertilizer experiments on maize-wheat sequence of Palampur (pH
5.8), soyabean-wheat sequence in Ranchi (pH 5.6), and finger millet-maize sequence in
Bangalore (pH 6.0) showed the necessity of S application. Continuous depletion of S lead
to significant decline in crop yields compared to the yields achieved in NPK + S
treatment. Deficiency of S can be corrected by use of various S sources such as gypsum
(15-18% S), SSP (12%S), ammonium sulphate (24% S), ammonium phosphate sulphate
(15% S), sulphate of potash (18%), gromor sulphur bentonite (90% S) in acid soils. The
efficiency of gromor bentonite S pastille can be compared with SSP on yield of ricecowpea sequence in alfisol of Bangalore and rice-groundnut and hybrid rice-potato
sequence in acid soils of Bhubaneswar (Jena et al 2006).
Phosphogypsum is a byproduct of diammonium phosphate factory located at Paradip
of Orissa state. When rock phosphate is treated with sulphuric acid, gypsum and
phosphoric acid is produced. Phosphogypsum contains 16% S and 20-21% Ca. It also
contains about 0.2 to 1.2% phosphorus. Since Ca in phoshogypsum can leach down faster
as compared to lime in light textured soils, sub-soil acidity could be ameliorated with
resultant reduction of aluminium toxicity and calcium deficiency. Jena (2008) reported
that about 10 million tones of phoshogypsum is dumped around fertilizer industry at
Paradip and it has been found equally efficient source for correcting S deficiency in
various crops.
Table 10: Crop response to phoshogypsum application in Orissa
Crop
Soil
Yield (q/ha)
% Response
NPK
NPK + S
laterite
5.08
6.95
36.8
Rice
laterite
25.50
29.73
16.6
Hybrid rice
laterite
43.13
52.33
21.3
Rice
alluvial
52.30
63.30
21.0
Potato
laterite
178.00
212.70
19.5
Greengram
laterite
6.30
8.53
35.4
Groundnut
(Rabi)
alluvial
17.50
29.50
68.6
Groundnut
(kharif)
Source : Jena (2008)
184
Acid Soil Management in India-Challenges and Opportunities
Management of Micronutrients in Acid Soils
Data complied by Singh (2007) for different states representing mostly acid soils
indicate the deficiency of Zn, Cu, Fe and Mn is 31, 3, 4, and 3% samples, respectively in
comparison to 47, 4, 14 and 6% for non-acidic soils of India. Taking DTPA extractable
micronutrient levels as 0.6 ppm Zn, 0.2 ppm Cu, 4.5 ppm Fe, 2 ppm Mn, 0.5 ppm hot
water soluble B and 0.15 ppm ammonium oxalate extractable Mo as the critical levels,
out of 33000 and 4268 soil samples 45 and 12% samples were found to be deficient in B
and Mo, respectively. Wide spread Zn deficiency ranging from 23 to 54% has been
reported from the states like Assam, Jharkhand, Chattisgarh, Uttarakhand, Orissa and
West Bengal. The deficiency of Zn and B may be attributed to a number of factors such
as high rainfall, high acidity, coarse texture, low oxidation of organic matter etc.
Deficiency of B can be corrected by applying various boron fertilizers like borax
decahydrate (Na2B4O7.10H2O; 10.5% B), boric acid (H3BO3, 17% B), granubor II
(Na2B4O7.5H2O; 14.6% B). Boron is generally applied through broadcast and mixed
properly prior to sowing or transplanting of crops @ 0.75 to 1.5 kg/ha. Band placement
1-2 kg B/ha was superior to broadcasting in increasing cud yield of cauliflower (Singh
2007). Productivity of cereals, chickpea, pigeonpea, groundnut, sunflower, sesame,
linseed and mustard increased significantly with application of 12.5 kg B/ha (Sakal and
Singh 1995). Application of granubor significantly increased the yield of caulifliower in
Kullu, Himachal Pradesh (Sharma 2006) and alfisols of Tamilnadu, maize and
cauliflower in Alfisols of Ranchi (Mohapatra 2006), maize-groundnut in acid soil of
Srikakulam (Bhupalraj et al 2005) and rice-groundnut laterite soil of Bhubaneswar (Jena
et al 2006).
Recovery of applied B in acid soils is about 36-54% due to higher precipitation with
hydrous oxide of Al and Fe ( Mandal and Mandal 1992). Mandal (1995) and Jena (2008)
found that combined application of B with lime together had significant effect on
increasing the yield of wheat and cauliflower, respectively. Singh (2007) reported that the
soil application of B @ 2 kg/ha was superior to foliar spray of 0.2% borax + lime twice
for increasing tuber yields of potato in acid soils of Garhwal, but for crops like soyabean
both soil and foliar spraying were equally efficient.
Zinc deficiency is wide spread in Assam and North-Eastern hill regions due to high
organic matter content. In terai soils, the deficiency was about 49-51% as compared to
20-46% in red and laterite soils. Zinc deficiency has been reported from tea orchard soil
of north-eastern hill region soils. Basal application of ZnSO4 is the common practice to
correct Zn deficiency. Application of ZnSO4 @ 25 kg/ha in coarse textured soils and
37.5 kg/ha in fine textured soils was found optimum for rice, wheat, maize and other field
crops. If soil application is missed at sowing/planting, top-dressing up to the preflowering stage in rice, wheat and other crops is recommended. The spraying of ZnSO4
@ 0.5% neutralized with lime @ 0.25% on standing crops correct Zn deficiency in
cereals, pulses, oilseeds and plantation crops.
Seed treatment with teprosyn zinc phosphate (slurry containing 300g Zn + 200g
P2O5 per litre at the @ 8 mL/kg seed) increased the yield of maize, groundnut, sunflower
and was comparable to that of basal application of Zn @ 5 kg/ha (Singh 2003). Seed
treatments to the crops having smaller size was found ineffective.
Acid Soil Management in India-Challenges and Opportunities
185
Organic manures raise the use efficiency of synthetic materials due to higher
chelation and subsequently slow release (Singh 2007, Jena et al. 2006). Zinc @ 2.5 kg/ha
was thoroughly mixed with 200-300 kg of fresh cowdung or well decomposed FYM and
incubated for 20-25 days under optimum moisture condition to facilitate chelation of Zn.
At the end, the material was dried under shade, finely ground for uniform distribution on
the field. The result revealed that Zn-enriched organic manure @ 2.5 kg Zn/ha recorded
similar yield of groundnut, mustard, sesame, bengalgram, pea as compared to 5 kg Zn/ha.
Thus the Zn-enriched organic manure increased the use efficiency of Zn by saving 2.5 kg
Zn/ha without causing any loss in crop productivity.
Limited information is available on rate and method of application of Mo
fertilization. Among Mo sources, molybdic acid (80%), ammonium molybdate (54%) and
sodium molybdate (39%) were equally efficient in correcting Mo deficiency in
groundnut, lentil, cauliflower and other crops (Singh 1993). Pre-soaking of potato tubers
in 0.01% ammonium molybdate solution increased the tuber yield by 2 t/ha in hill, 1.3
t/ha in red and lateritic and 0.2 t/ha in alluvial soils (Grewal and Trehan 1990).
Integrated nutrient management
The basic principle of integrated nutrient management (INM) is the maintainace of
soil health, sustenance of agricultural productivity and increasing farm profitability
through judicious use of chemical fertilizer, organic manure, green manuring, residue
recycling and biofertilizers. Though biofertilizers are ecofriendly and can increase farm
productivity in economically backward acid soil regions, their benefit is limited.
Rhizobium is beneficial for pulses and oilseeds crops like soyabean, groundnut. But their
growth in acid soils is affected due to poor availability of nutrients. Blue green algae
perform poorly when the soil is highly acidic. Azolla could not be popularized due to
poor management of water in high precipitation regions. Azospirillum is good for cereals,
where as Azotobacter can benefit crops like sugarcane, cotton, potato etc. A good amount
of organic manure like FYM or paddy straw are not available because a large proportion
of cattle dung is used for fuel. There is no escape to accept a small dose of lime as a
component in acid soils. Integrated application of lime and FYM further improves in
yield of several crops. Mishra (2002) reported the yield of cowpea, groundnut, pigeonpea
and maize in Alfisols of Bhubaneswar significantly increased with application of lime
@10% LR and FYM @5 t/ha.
Long term experiment conducted at Ranchi, Bhubaneswar, Palampur and Bangalore
over a period of 9-24 years showed that average grain yields of crops such as soyabean,
wheat, rice and maize increased by 0.4 to 1.5 t/ha due to application of NPK + FYM over
NPK (Panda et al 2007). Integrated use of chemical fertilizer with lime and organic
manures has shown higher nutrient use efficiency compared to inorganic sources alone.
In acid soils, crop response to liming was more than chemical fertilizers and liming along
with NPK fertilizer imparted sustainability to the crop yields. Green manuring with
fertilizers use have shown excellent results in rice-based cropping systems in the irrigated
areas.
In a long term experiment conducted over more than 10 years in an acidic red soils of
G-Udayagiri, Orissa with rice-horse gram cropping system, Jena et al (2000b) observed
186
Acid Soil Management in India-Challenges and Opportunities
that, water stable aggregates, porosity, available water capacity, organic C, available P
and K content of the soil were higher with Gliricidia green leaf manure or FYM
application either alone or in combination with 50% RDF over control or 100% RDF.
While full dose of NPK gave higher yield in years of favourable distribution of rainfall,
the INM practice recorded higher yield in the years of uneven distribution of rainfall,
suggesting the sustainability of crop production with INM in rainfed acid soil regions.
Combined application of chemical fertilizer, FYM @ 5 t/ha and lime @ 0.25 LR to maize
crop in acid red sandy loam of Phulbani district of Orissa gave significantly one (Jena et
al 2000 ).
Management of Iron toxic soils
Iron toxicity occurs in hill bottom red and lateritic soils (Alfisol, Oxisol, Ultisol)
under undulating topography and impeded drainage condition. These soils are
characterized with poor base saturation and limited supply of available nutrients like K,
Ca, Mg, P, Zn and Cu. Iron toxicity symptoms in rice is seen as bronzing symptoms when
Fe2+ concentration in soil solution goes up to 250-500 mg/kg due to reduce conditions
under prolonged submergence (Jena et al. 2008). The concentration of Fe2+ further
increases due to lateral flow of Fe from an adjacent upland to low land rice fields during
rainy season (Sureshkumar 1999). In most of the rice soils the concentration of Fe2+
increases upon flooding and attains peaks after 2-5 weeks (Mandal 1961).
In iron toxic soils, substantial amount of iron is oxidized and get deposited on the
active roots making physical barrier for absorption of plant nutrients from soil solution.
Under extreme conditions, more number of roots become blackish in colour and only a
few remain as whitish to brownish in colour. Plants get stressed and forced to produce
more new roots at the expense of shoot growth. Production and decay of roots continue
throughout the plant growth period. Iron toxicity in plants promotes sterility and the grain
yield is reduced by 20-80% depending upon the situation.
Iron toxicity can be corrected by providing intermittent drainage. It reduces uptake of
iron and increases availability of other plant nutrients. Liming of soils @ 1-2 t/ha along
with K application had beneficial effect on alleviating Fe toxicity in rice by 27% over
lime control in soils of Orissa (Mitra and Sahu 1992). Application of fresh cowdung @ 5
t/ha increased grain yield by 9.31 q/ha over control (19.04 q/ha). Application of lime @
0.5 LR or potash @ 40 kg/ha or Zn @ 10 kg/ha increased grain yield by 8.25, 11.41 and
11.63 q/ha, respectively over control (Jena et al 2007). Foliar application of MnSO4 @
0.6% had no beneficial effect on rice in iron toxic soil. Balanced fertilization helps in
alleviating iron toxicity in rice. Singh et al (1993) reported application of 90 kg P2O5 /ha
to iron toxicity soil at Barapani farm of Meghalaya resulted in reduction of Fe2+ from
3.60 to 1.63 mg/kg. Dipping rice seedling in boronated SSP and FYM slurry before
transplanting helped to increase rice yield by reducing Fe toxicity.
Jena (2007) evaluated several rice genotypes in iron toxic laterite soils of
Bhubaneswar over three consecutive years and reported rice genotypes like Kalinga III,
Udayagiri, Panidhan and Tulasi are good tolerant to iron toxicity and IR 36, Konark,
Birupa, Gajapati, Samalai and Indrabati are moderately tolerant to iron toxicity. Savithri
and Sree Poongodevi (1980) evaluated rice varieties in iron toxic acid soils (pH 4.7;
Acid Soil Management in India-Challenges and Opportunities
187
DTPA Fe- 31 ppm, Aquic Hapludalf) in Kanyakumari district. Genotypic difference in
the degree of susceptibility to excess Fe was confirmed by changes in the content of
metabolically active Fe2+, chlorophyll and enzymatic activity in plant parts.
Metabolically-active Fe2+ contents in the leaves, stems and roots of tolerant genotype
(ASD-16) was 212, 392 and 4674 ppm as compared to highly susceptible rice genotype
(ADT36) having 281, 442 and 5933 ppm Fe content, respectively. Genotypic differences
in degree of susceptibility to excess Fe were attributed to leaf tissue tolerance of high
level of Fe, reduced translocation from root to shoot and ability of roots to resist its entry
inside the plant system.
Epilogue
Acid soils are formed due to drastic weathering accompanied by hot humid climate
and heavy precipitation. Inherent soil characteristics pose macro, secondary and
micronutrient deficiency as well as toxicity problems. These soils have poor physical
properties, low pH, poor base saturation and high sesquioxides contents which affects the
transformation and availability of nutrients. These soils are generally deficient in Ca, Mg,
S, B, Zn and Mo and adequate in Fe, Mn and Cu. These soils have not been considered
problematic and hence neglected.
Deficiency of Ca and Mg can be corrected by using locally available low cost liming
materials at the rate of 0.1 to 0.2 lime requirement. Phosphorous management in such
soils is done economically by using powdered indigenous rock phosphate by mixing with
highly active imported rock. Partial acidulation is also recommended. Locally available
phosphogypsum offers a cost-effective and cheaper option for correcting Ca and S
deficiencies. Application of 25kg zinc sulphate/ha in coarse textured soils efficiently
corrects the Zinc deficiency and leaves residual effect for 3-4 crops. Seed treatment with
Zinc phosphate is beneficial for bold and big-sized seed crops like maize, sunflower etc.
Application of 0.5-1.5 kg B/ha corrects the boron deficiency in most of the crops.
Application of 0.5 kg sodium molybdate /ha annually has been found to be optimum in
maize, niger, groundnut, rice and vegetable crops. Balance use of lime and micronutrients
produces higher response than either lime or micronutrient application alone. Integrated
use of lime and FYM @ 5 t/ha is beneficial in ameliorating Zn, B and Mo deficiencies as
well as correcting Al and Fe toxicities in acid soils. Toxicity of iron can be alleviated by
using lime, high dose of P, K and Zn fertilizers, FYM and pressmud etc.
Several crops and cultivars tolerant to acidity has been suggested. Horticultural and
plantation crops suffering from micronutrients deficiencies can be benefited by foliar
spraying of micronutrients. The technology generated requires to be operationalized on
about 25 mha of cultivated acid lands having pH < 5.5. About 10 mha of cultivated lands
have been identified for amelioration in the agriculturally-important districts of states in
the first instance. The central and state Governments should facilitate the availability,
marketing and distribution of locally available liming materials to the farmers at cheaper
rates. The participation of KVKs and ATMAs in this regard would go a long way in
popularizing the technology in the acid soil regions.
188
Acid Soil Management in India-Challenges and Opportunities
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Issues and Strategies for Managing Degraded
Lands in Rainfed Ecosystem in India
B. Venkateswarlu and J.V.N.S. Prasad
Central Research Institute for Dryland Agriculture, Hyderabad 500 059, India
Email: [email protected]
192
Issues and Strategies for Managing Degraded Lands in Rainfed Ecosystem in India
Abstract
Land degradation is steadily increasing due to the growing pressure on land and
unsustainable land use in India. Land degradation and the associated loss of soil
productivity and quality is of great concern both from food production perspective and
environmental conservation. Land degradation due to water erosion is the most
widespread, the extent of the area affected is to the tune of 82.5 m ha. constituting about
78 % of the total degraded area of the country. Water erosion is prevalent in all the
agroecological zones of the country. Various technologies for arresting land degradation
have been tested across the country in research stations and farmers fields through a large
number of developmental programmes. Some of the most effective technologies for
arresting water erosion induced land degradation in rainfed agro-ecosystems are
discussed in this chapter.
Keywords: land degradation, water erosion, engineering measures, agroforestry,
vegetative measures, rainfed agro-ecosystem.
Introduction
Land degradation can be defined as lowering of land productivity due to the
deterioration of land’s physical, chemical and biological condition. Physical land
degradation is due to water erosion, wind erosion, compaction, crusting and water
logging and chemical degradation is due to the processes of salinization, alkalization,
acidification and nutrient depletion. Biological degradation is due to the reduction of soil
biota and organic matter, degradation of vegetation and impairment of activities of microflora and fauna. Worldwide about 1,900 M ha of land is suffering from various forms of
land degradation.
In India, land degradation assessment has been undertaken by various organizations
in the past. Recently, efforts were made to harmonize the data bases of different
categories of degraded lands estimated by various organizations. The total degraded area
in India is about 120.72 M ha of which 104.19 M ha is under arable land use and 16.53 M
ha is under forest land use with less than 40% canopy (Table 1). Among the different
types of land degradation, water erosion (with soil loss of more than10 t/ha/yr) is the
predominant form of degradation affecting an area about 73.27 M ha in the arable land
and 9.30 M ha in the open forest. About 78% of the total degraded area in the country is
due to water erosion (ICAR, 2010). As the country’s burgeoning population places
multifarious demands on the land for food, fodder and fuel, besides the growing demands
on land for habitat, industries, infrastructure development including roads and other
public amenities, the pressure on the land is growing continuously. Due to the growing
pressure and the unsustainable use, land degradation is continuously on rise. Land
degradation and the associated loss of soil productivity and quality is thus a great concern
not only from the perspective of food production but also for protecting the environment.
Issues and Strategies for Managing Degraded Lands in Rainfed Ecosystem in India
193
Table 1: Harmonized area statistics of degraded and wastelands of India (M ha)
Degradation type
Arable land
(Mha)
Open forest (<40% canopy)
(Mha)
Data source
Water erosion (>10
tonnes/ha/yr)
73.27
9.30
Soil Loss Map of India
CSWCRT&TI
Wind erosion
(Aeolian)
12.40
-
Sub total
85.67
9.30
Exclusively Salt
Affected Soils
5.44
-
Salt Affected and
Water Eroded Soils
1.20
0.10
Exclusively Acidic
Soils (pH< 5.5)
5.09
-
Acidic (pH < 5.5) and
Water Eroded Soils
5.72
7.13
Sub-total
17.45
7.13
Wind erosion map,
CAZRI
Chemical degradation
National Salt Affected
Soils Map, CSSRI,
NBSS&LUP, NRSA
and others
Acid Soil map of India
NBSS&LUP
Physical degradation
Mining and Industrial
Waste
0.19
Waterlogging
(permanent surface
inundation)$
0.88
Sub-total
1.07
Total
Grand Total (Arable
land and open forest)
Wasteland Map of the
NRSA
104.19
16.53
120.72
Source: ICAR (2010)
Water Erosion
Land degradation due to water erosion is the most widespread in India and occurs
widely in all the agro-climatic zones. Soil displacement by water can result either in loss
of top soil or terrain deformation or both through the processes of splash erosion, sheet
erosion, rill erosion and gully erosion. Soil erosion starts with the falling of the raindrops
onto the bare soil surface. The impact of the raindrops breaks-up surface soil aggregates
and splashes particles into the air. On sloping land, detached soil material flows with
runoff down the slope, resulting in soil loss. The extent and the severity of erosion is a
function of the intensity of rainfall, land slope, soil types and land use.
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Issues and Strategies for Managing Degraded Lands in Rainfed Ecosystem in India
Water erosion is the most predominant form of degradation affecting a large number
of states. Madhya Pradesh is the worst affected state owing to water erosion, consisting of
16% of the total geographical area, followed by Uttar Pradesh, Andhra Pradesh,
Maharashtra, Rajasthan and Karnataka covering 15%, 10%, 11%, 10% and 9% of the
total area of these states (Table 2). Orissa, with 4% affected area ranks seventh and
Jharkhand with 3.8% ranks eighth in terms of the area affected by water erosion. Water
erosion in agricultural and open forest areas has affected almost all agro ecological
regions (AERs) of the country. The AERs affected by water erosion are those regions
which are primarily semi arid and where rainfed agriculture is predominant. AERs where
large areas affected by water erosion are: AER-4 (13.1 M ha), AER-6 (10.6 M ha), AER5 (7.4 M ha), AER-12 (6.4 M ha), AER-14 (5.0 M ha), AER-7 (4.8 M ha) and AER-8
(4.8 M ha, Table 3). Apart from the above, AER-9, AER-10and AER-11s has substantial
area affected by water erosion. The nine above mentioned areas have about 56.5 M ha.
area affected by water erosion which constitutes about 76% of the total area affected in
the country (Table 3). Severely degraded lands are mostly inhabited by marginal farmers
and tribal populations, who are poor and less literate. They are devoid of land-based
amenities and infrastructure in comparison with the other farmers who cultivate better
lands. Besides, soil erosion and land-degradation processes lead to nutrient depletion thus
reducing soil quality. Studies have been carried out to examine implications of land
degradation in terms of the resulting economic losses. The total economic losses to the
country at current prices have been estimated to be a staggering sum of over Rs 285
billion, which is about 12% loss as per the total value productivity of these lands (Vasisht
et al., 2003). Conservation of natural resources and rejuvenation of the degraded and the
wastelands, therefore, offer a potentially enormous means of poverty alleviation and
sustainable livelihoods (Srivastava et al., 2002).
Table 2: State wise area statistics of water eroded lands of India
Water erosion
(000'ha)
(>10 t/ha)
Total
geographical area
of the state (%)
Madhya Pradesh
11,881
16
14,095
Uttar Pradesh
12,370
15
14,405
Andhra Pradesh
8,050
11
9,193
Maharashtra
8,400
11
9,728
Rajasthan
7,436
10
20,424
Karnataka
7,450
9
8,093
Orissa
2,176
4
3,722
Jharkhand
2,825
4
3,943
Chhattisgarh
2,347
3
4,786
Asom
1,929
3
4,571
Tamil Nadu
2,063
3
2,997
State
Source: ICAR (2010)
Total degraded
area of the state
(000'ha)
Issues and Strategies for Managing Degraded Lands in Rainfed Ecosystem in India
195
Table 3: Area affected by water erosion under different AERs of India
Description of the AER
AER
no.
4
5
6
7
8
9
10
11
12
Area
affected
(,000 ha)
Total
degraded
area (,000 ha)
Northern plain and central highlands including Aravallis,
hot semi-arid eco region, with alluvium derived soils
12,109
14,961
Central (Malwa) highlands, Gujarat plains and Kathiawar
peninsula, hot semi-arid ecoregions, with medium and
deep black soils
6,455
7,700
Deccan plateau, hot semi-arid eco regions, with shallow
and medium (with inclusion of deep) black soils
10,374
11,270
Deccan (Telangana) plateau and Eastern Ghats, hot semiarid eco regions, with red and black soils
4,376
4,986
Eastern Ghats, Tamil Nadu uplands and Deccan
(Karnataka) plateau, hot semi-arid eco regions with red
loamy soils
4,412
5,685
Northern plain, hot sub-humid (dry) eco regions with
alluvium derived soils
3,122
4,271
Central Highlands (Malwa, Bundelkhand and Eastern
Satpura), hot sub-humid eco regions, with black and red
soils
6,934
8,289
Eastern plateau (Chattisgarh), hot sub humid eco region,
with red and yellow soils
3,843
5,925
Eastern (Chhotanagpur) plateau and Eastern Ghats, hot
sub humid eco region, with red and lateritic soils
4,917
8,194
Total of the 9 AERs
56,542
(76%)
Total area
74,020
120,410
Source: ICAR (2010)
Technologies for controlling of water erosion and improving soil productivity
Based on the outputs from various research institutes and experiences from watershed
development programs in India, technologies for arresting water erosion have been
identified for different agro climatic zones of India. The details are furnished in Table 4.
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Issues and Strategies for Managing Degraded Lands in Rainfed Ecosystem in India
Table 4: Soil and water conservation measures for various rainfall zones in India
Seasonal rainfall (mm)
< 500
500-750
• Contour
cultivation with
Conservation
furrows
•
• Ridging
•
•
750-1000
Contour cultivation •
with
conservation
furrows
•
Ridging
Broad bed furrow
(vertisols)
• Broad bed furrow
(vertisols
Conservation
furrows
• Field bunds
•
Sowing across slope • Sowing across
slope
Tied ridges
•
Mulching
•
Zingg terrace
•
Off season tillage
•
• Small basins
Broad bed furrow
•
• Field bunds
Inter row water
harvesting system
• Vegetative bunds
•
Small basins
•
Modified Contour
bunds
• Contour bunds
•
Field bunds
• Field bunds
•
Khadin
• Sowing across
slope
• Mulching
• Scoops
• Tied ridges
•
Off season
tillage
• Inter row water
harvesting
system
• Small basins
>1000
• Tillage
• Lock and spill
drains
• Vegetative bunds
• Graded bunds
• Choes
• Level terraces
• Graded bunds
• Nadi
• Zingg terrace
• Khadin
Source: Pathak et al. 2009
The choice of measures to be implemented depends on the predominant problems
and resource endowments of the region. Earlier, efforts were concentrated on the
construction of mechanical structures like bunds across the slope in various soil and
water conservation programs. They helped in controlling erosion and reducing soil loss
rather than increasing crop yields through moisture conservation. Current emphasis is
more on improving moisture through various field and community based moisture
conservation practices (Pathak et al. 2009) and contribute towards improvement of crop
yields. Some of the promising soil and water conservation interventions for improving
the productivity and reducing the land degradation are described below.
Broad bed and furrow (BBF)
This technology is suitable for the rainfall range of 700 - 1300 mm and for medium
to deep black soils (Vertisols) with slope up to 5%. The BBF system consists of a
relatively raised flat bed or ridge approximately 95 cm wide and shallow furrow about 55
cm wide and 15 cm deep. The BBF system is laid out on a grade of 0.4 - 0.8% for
Issues and Strategies for Managing Degraded Lands in Rainfed Ecosystem in India
197
optimum performance. It is important to attain a uniform shape without sudden and sharp
edges because of the need to plant rows on the shoulder of the broad-bed. The BBF
formed during the first year can be maintained for the long term (25-30 years). The raised
bed portion acts as an in-situ 'bund' to conserve more moisture, ensures soil stability and
the shallow furrows provides good surface drainage to promote aeration in the seedbed
and root zone and prevents water logging of crops on the bed. It is suitable for many
crops and cropping systems and mechanized operations and reduces the water erosion
and conserves moisture effectively.
Conservation furrows
This technology is suitable for the rainfall range of 400-900 mm for alfisols and
associated soils with a slope of 1-4%. This practice is highly suitable for soils with severe
problems of crusting, sealing and hard setting where early runoff is quite common. In this
practice, a series of furrows are opened on contour or across the slope at 3-5 m apart.
These furrows harvest the local runoff water and improve the soil moisture to the
adjacent crop row, particularly during the period of water stress. To improve its
effectiveness further it is recommended to use this system along with contour cultivation
or cultivation across the slope (Rao et al. 1981). The spacing between the furrows and its
size can be chosen based on the rainfall, soils, crops and topography. The furrows can be
made either during planting time or during interculture operation using a country plough.
Two to three passes in the same furrow may be needed to obtain the required furrow size.
Modified Contour Bunds
This technology is suitable for the rainfall range of 500-900 mm for alfisols and
moderate to deep black soils with slope of 1-8%. The modified contour bunds with gatedoutlets have shown good promise because of the better control on ponded runoff water.
Modified contour bunding involves constructing embankments on contours with gatedoutlet at the lower end of the field. This gated-outlet allows the runoff to be stored in the
field for a desired period and then released at a predetermined rate through the spillway,
thus reducing the time of water stagnation behind the bund, which will have no adverse
effect on crop growth and yield and also facilitates the water infiltration into soil to its
optimum capacity.
Contour cultivation
A simple practice of farming across the slope has many beneficial effects. The ridges
and the rows of the plants placed across the slope form a continual series of miniature
barriers to the water moving over the soil surface. The barriers are small individually, but
as they are large in number, their total effect is great in reducing run-off, soil erosion and
loss of plant nutrients. Apart from conserving the water and soil, contour-farming
conserves soil fertility and increases crop yields. This technology is suitable for the
rainfall up to 1000 mm for almost all soil types with a slope of 1.5-4.0%. Contour
cultivation or cultivation across the slope are simple methods of cultivation, which can
effectively reduce the runoff and soil loss on gentle sloping lands (Figure 1). In contour
cultivation, all the field operations such as ploughing, planting and inter-cultivation are
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Issues and Strategies for Managing Degraded Lands in Rainfed Ecosystem in India
performed on the contour. It helps in reduction of runoff by impounding water in small
depressions and reduces the developments of rills. In some situations it is desirable to
provide a small slope along the row (cultivation a cross the slope), to prevent runoff from
a large storm breaking over the small ridges formed during the contour cultivations. On
long slopes, where bunding is done to decrease the slope length, the bunds can act as
guidelines for contour cultivation. On the mild slopes where bunding is not necessary,
contour guidelines may be marked in the field (Rao et al. 1981).
Fig. 1: Contour farming using vegetative hedge
Community-based Water Harvesting and Soil Conservation Structures
The community-based soil and water conservation are playing a key role in
improving surface and groundwater availability and controlling soil erosion in the
watershed programs in India. Some of the most promising community based soil and
water conservation measures are discussed.
Masonry Check Dam
These structures are popular in watershed programs in India. Masonry check dams
are permanent structures used for controlling gully erosion, water harvesting and
groundwater recharging. The cost of construction is generally quite high. These structures
are preferred at sites where the velocity of runoff water flow in gullies/streams is very
high and stable structure is needed to withstand the velocity. Proper planning and design
are needed for construction of masonry check dam. The basic requirements for designing
the masonry check dams are: hydrologic data, information on soils and geology, the
nature and properties of the soils in the command area and profile survey and crosssectional details of the stream or gully. A narrow gorge should be selected for erecting
the dam to keep the ratio of earthwork to storage at minimum. Runoff availability for the
Issues and Strategies for Managing Degraded Lands in Rainfed Ecosystem in India
199
reservoir should be computed on the basis of rainfall runoff relationship. Depending upon
the assumed depth of structure and the corresponding area to be submerged, suitable
height of the dam may be selected to provide adequate storage in a given topographic
situation (Katyal et al. 1995). The cross-section of dam and other specifications are
finalized considering the following criteria: there should be no possibility of the dam
being over-topped by flood-water, the seepage line should be well within the toe at the
downstream, the upstream and downstream faces should be stable under the worst
conditions, the foundation shear stress should be within safe limit, proper spillway should
be constructed to handle the excess runoff and the dam and foundation should be safe
against piping and undermining (Pathak et al. 2009).
Low-cost earthen check dam
Earthen check dams are those water harvesting structures that have an embankment
constructed across the waterway. The size of the dam depends on the site conditions.
Earthen check dams are very popular in the watershed programs in India for controlling
gully erosion and for harvesting runoff water. These are constructed using locally
available materials. The cost of construction is generally quite low. This technology is
suited for all soil types in the rainfall range of 350-1300 mm. In some cases, the stone
pitching may be required to protect the bund from scouring. The earthen check dams are
used for multiple purposes. They are used as surface water storage structures as well as
for recharging groundwater.
Khadin System
Khadin is a land-use system developed centuries ago in the Jaisalmer district of
western Rajasthan. This system is practiced by a single larger farmer or by group of small
farmers. It is highly suitable for areas with very low and erratic rainfall. This technology
is suitable for sandy and other light soil types in the rainfall range of 250-700 mm. In
khadin system, preferably an earthen or masonry embankment is made across the major
slope to harvest the runoff water and prevent soil erosion for improving crop production.
Khadin is practiced where rocky catchments and valley plains occur in proximity. The
runoff from the catchment is stored in the lower valley floor enclosed by an earthen/stone
'bund'. The water stands in the khadin throughout the monsoon period. It may be fully
absorbed by the soil during October to November, leaving the surface moist. If standing
water persists longer, it is discharged through the sluice before sowing. Wheat, chickpea
or other crops are then planted. These crops mature without irrigation. The soils in the
khadins are extremely fertile because of the frequent deposition of fine sediment, while
the water that seeps away removes salts. The khadin is, therefore, a land-use system,
which prevents soil deterioration. This practice has a distinct advantage under saline
groundwater condition, as rainwater is the only source of good quality water in such area.
Farm Ponds
Farm ponds are very age old practice of harvesting runoff water in India. These are
bodies of water, either constructed by excavating a pit or by constructing an embankment
across a water-course or the combination of both. Farm pond size is decided on the total
200
Issues and Strategies for Managing Degraded Lands in Rainfed Ecosystem in India
requirement of water for irrigation, livestock and domestic use. If the expected runoff is
low, the capacity of the pond will only include the requirement for livestock and
domestic use. Once the capacity of the pond is determined, the next step is to determine
the dimensions of the pond. High-storage efficiency of the farm pond can be achieved by
locating the pond in a gully, depression, or on land having steep slopes. This design will
considerably improve the storage efficiency of the structure. Reduction in seepage losses
can be achieved by selecting the pond site having sub soils with low saturated hydraulic
conductivity. As a rough guide, the silt and clay content of the least conducting soil layer
is inversely linked with seepage losses. Therefore, it is best to select the site having
subsoil with higher clay and silt and less coarse sand. Also, reduce the pond wetted
surface area in relation to water storage volume. This can be achieved by making the
pond of a circular shape or close to circular shape.
Gully checks with loose boulder wall
Loose boulder gully checks are quite popular in the watershed program for
controlling gully erosion and for increasing groundwater recharge. These are very low
cost structures and quite simple in construction. These gully checks are built with loose
boulder and may be reinforced by wire mesh, steel posts, if required for stability. Often it
is found on the land and thus eliminates expenditure for long hauls. The quality, shape,
size and distribution of the boulders used in the construction of gully checks affect the
life span of the structures. Obviously, boulders that disintegrate rapidly when exposed to
water and atmosphere will have a short structural life. Further, if only small boulders are
used in a dam, they may be moved by the impact of the first large water flow. In contrast,
gully checks are constructed of large boulders that leave large voids.
Important vegetative measures for controlling water erosion
Crops and vegetation cover the ground surface substantially and have extensive root
system to prevent soil erosion. Plant canopy protects the soil from the adverse effect of
rainfall. The grasses and legumes produce dense sod which helps in reducing soil erosion.
The vegetation provides organic matter to the soil. As a result, the fertility of soil
increases and the physical condition of soil is improved which will enhance infiltration.
Following are some of the key technologies which can be used for arresting the water
erosion at field level.
Intercropping systems
Intercropping systems are intensification of cropping systems in space and time.
These systems cover the soil during the early crop growing season and continue to cover
the soil for longer period unlike the normal cropping pattern. Due to the differential
canopy, these systems provide vegetative cover for longer periods than the mono
cropping system. A good intercropping system should include densely planted small
grain crops, spreading legume crop etc. which will check soil erosion. Integration of
legumes in to the intercropping systems will supply nitrogen to the associated crop
resulting in better growth and economic benefits. Different types of intercropping
systems with various row ratios were developed for rainfed situations in the country. The
best performing intercropping systems and their adoption for rainfed situations in
different agro climatic regions was reported by Rao and Khan (2003).
Issues and Strategies for Managing Degraded Lands in Rainfed Ecosystem in India
201
Mulching
Mulches of different kinds such a leaves, straw, stubbles, etc. minimize evaporation
and increase the infiltration of moisture and protect the surface of the land against the
beating action of rain drops and reduces the erosive velocity. Later on they decay to form
humus which improves the physical condition of soil. Mulches involving the leguminous
materials provide substantial quantities of nitrogen for the crop growth. Various types of
mulches are used and plastic mulches are being used for high value crops.
Strip Cropping
It consists of growing erosion permitting crop (e.g. Jowar, Bajra, Maize etc.) in
alternate strips with erosion checking close growing crops (e.g. grasses, pulses etc.). Strip
cropping employs several good farming practices including crop rotation, contour
cultivation, proper tillage, stubbles mulching, cover cropping etc. It is very effective and
practical means for controlling soil erosion, especially in gently sloping lands. It may be
of different types such as contour strip cropping, which is growing of erosion permitting
and erosion resisting crops alternately in strips across the slope and on the contour line.
This practice is useful as it checks the flow of run-off, increases the infiltration and
prevents soil erosion. In buffer strip cropping, the eroded portion of land is permanently
kept under grass and contour strip cropping is practiced in the rest of the area.
Vegetative hedges or strips
Vegetative barriers or vegetative hedges or live bunds are effective in reducing soil
erosion and conserving moisture. In several situations the vegetative barriers are more
effective and economical than the mechanical measures viz. bunding. This technology is
suitable for alfisols, vertisols, vertic-inceptisols and associated soils with slope more than
2.5%. Vegetative barriers can be established either on contour or on moderate slope of
0.4 to 0.8%. The vegetative hedges act as barriers to runoff flow, which slow down the
runoff velocity resulting in the deposition of eroded sediments and increased rainwater
infiltration. These hedges can increase the time for water to infiltrate into the soil, and
facilitate sedimentation and deposition of eroded material by reducing the carrying
capacity of the overland flow. It is advisable to establish the vegetative hedges on small
bund. This increases its effectiveness particularly during the first few years when the
vegetative hedges are not so well established. If the main purpose of the vegetative
barrier is to act as a filter to trap the eroded sediments and reduce the velocity of runoff
then the grass species such as vetiver, sewan (Lasiurus sindicus), sania (Crotolaria
burhia) and kair (Capparis aphylla) could be used. But if the purpose of vegetative
hedges is to stabilize the bund then plants such as Glyricidia or others could be
effectively used.
Afforestation and grassland management
Sod forming crop such as lucern (Medicago sativa L), Egyptian Clover, Berseem
(Trifolium alexandrinum), ground nut (Arachis hypogea L), Sunhemp (Crotolaria
juncea), etc. cover the surface of the land and their roots bind the soil particles to form
202
Issues and Strategies for Managing Degraded Lands in Rainfed Ecosystem in India
soil aggregates, thus preventing soil erosion. Growing of trees in areas which are devoid
of vegetative cover substantially contributes towards the reduction of erosion. Infiltration
of water is favoured due to high porosity of soil under vegetation. Surface accumulation
of organic matter increases the water holding capacity of the underground soil. Root
system of vegetation holds the soil mechanically and provides stability of the
underground soil. The highly degraded soils can be brought under vegetative cover for
arresting further degradation.
Agroforestry
Agroforestry is a land-use systems in which trees or shrubs are grown in association
with agricultural crops, pastures or livestock, and in which there are both ecological and
economic interactions between the trees and other components. It is a traditional form of
dryland management and soil conservation measure that has been practiced in various
parts of the world. Agroforestry practices provide vegetative cover which reduces the
impact of rain drop and provide protection to the soil, enhance soil productivity and
contribute towards sustainable land management. There is experimental evidence that soil
loss can be greatly reduced by maintenance of a good ground surface cover (Young,
1989). Agroforestry systems are more effective in erosion control through supply of litter
to the ground surface than through the effects of the tree canopy. Reduction of runoff and
soil loss with tree species of leucaena and eucalyptus was reported when grown alone or
in combination with grass than growing of subabul or eucalyptus along with maize
(Narain et al., 1994). Based on research various agroforestry models suitable for different
regions of the country have been evolved (Figure 2). Important agroforestry options for
degraded lands in key agro climatic regions are furnished in Table 5.
Fig. 2: Different agroforestry systems for degraded lands
Issues and Strategies for Managing Degraded Lands in Rainfed Ecosystem in India
203
Table 5: Agroforestry systems for rainfed conditions in various agroclimatic regions
of the country
S Agroclimati
No
c region
1.
Eastern
plateau and
hills region
Arable land
Agrisilviculture
•
•
•
2
Central
plateau and
hills region
•
•
•
3
Western
plateau and
hills region
4
Southern
plateau and
Non arable lands
Agri horticulture
Silvi pasture
Hortipasture
Acacia nilotica • Annona squamosa + •
coarse cereals
+ coarse
cereals
• Emblica officinalis
+ pulses
Tectona
grandis +
•
• Psidium guava +
oilseeds
soybean
Gmelina
arborea+
•
soybean/lentil
Azadirachta
indica +
Panicum
maximum
Acacia nilotica
+ Pennisetum
pedicellatum
Hardwickia
binata + Setaria
• Tamarindus
indica/ Annona
squamosa +
Stylosanthes
hamata
Azadirachta
• Zizyphus mauritiana •
indica+
+Mustard
sorghum
• Anona squamosa
Acacia ni/otica
•
+ Groundnut/
+ Groundnut/
Sorghum
Sorghum
• Citrus/
Hardwickia
Pomegranate+
binata + coarse
Pigeon pea/Gram
cereals
Albizia lebbeck
+ Cenchrus
ciliaris
Hardwickia
binata+Sehima
nervosum/
Dichanthium
annulatum
• Zizyphus
mauritiana
Stylosanthes
hamata
• Psidium
guajava
+Panicum
maximum
• Emblica
officinalis +
Stylosanthes
hamata
•
Azadirachta
indica/
Acacia nilotica
+ oil seeds
• Hardwickia
binata
/Leucaena
leucocephala
+ Sorghum/ pulses
/soyabean
• Tamarindus
indica+
Block
plantation
•
•
•
•
+
•
•
• Zizyphus
•
mauritiana+
Groundnut/
Sorghum /Pigeonpea
• Anona squamosa
+ oil seeds
• Emblica
officinalis /
•
Citrus /
Pomegranate
+ Lentil
Mustard
Albizia lebbeck/ • Zizyphus
•
mauritiana
A. amara/ A.
/Psidium
procera+Cenchr
guajava+
us ciliaris
Stylosanthes
/Sehima
•
hamata
nervosum
• Emhlica
•
officinalis+
Hardwickia
Stylosanthes
binata
hamata / Panicum
+Dichanthium
maximum
annulatum
•
Citrus +
/Panicum
Stylosanthes
maximum
hamata /
Panicum
maximum
• Tamarindus indica/
Syzygium cumini
Acacia
leucophloea/
•
• Citrus
• Cocos nucifera
•
Leucaen
a
leucocep
hala,
Casuarin
a
equisetif
olia,
Eucalypt
us sps.
Leucaen
a
leucocep
hala
Acacia
nilotica
Acacia
tortilis
Leucaen
a
leucocep
hala
Acacia
nilotica
Acacia
tortilis
Prosopis
juliflora/
204
S Agroclimati
No
c region
Issues and Strategies for Managing Degraded Lands in Rainfed Ecosystem in India
Arable land
Agrisilviculture
hills region
5
Gujarat
plains and
hills region
•
•
•
Non arable lands
Agri horticulture
Silvi pasture
+Tomato/chilli
Tomato
/Chilli,/Curry
• nona squamosa /
leaf
Emblica officinalis
• Ailanthus
+ Tomato/curry leaf
excelsa
+
Cowpea/,
Sesamum/
Sorghum
/,PearmiIlet
• Albizia
lebbeck+
Cowpea/
Sesamum
/Sorghum
/Pearl miIlet
+Cenchrus
ciliaris /
Cenchrus
setigerus /
Local grasses
Azadirachta
indica+
groundnut
Acacia
nilotica +
cotton/ pulses
Hardwickia
binata
/Dalbergia
sissoo
+ castor
/onion
• Zizyphus
mauritiana+
groundnut
• Emblica
officinalis
+pulses,
• Punica granatum
+cotton,castor
Hortipasture
• Nutmeg
Block
plantation
•
•
•
•
•
•
Prosopis
cineraria
Ailanthus
excelsa
Acacia tortilis
Acacia nilotica
• Mangifera
indica+ Cenchrus
ciliaris
• Zizyphus
mauritiana
+Stylosanthes
hamata
• Emblica
officinalis
+Sehima
nervosum
•
•
•
•
A.
planiorm
is/
ferrugine
a
Borassus
flabellife
r
Casuarin
a
equisetif
olia
Leucaen
a
leucocep
hala
Prosopis
juliflora
Eucalypt
us hybrid
Issues and Strategies for Managing Degraded Lands in Rainfed Ecosystem in India
205
Community–based biomass production for improved soil health
This practice emphasizes on community approach for increasing the biomass
productivity and utilising the biomass produced for improving the fertility of the soil.
Trees such as Gliricidia are grown either on degraded lands or on bunds for producing
the biomass and the biomass thus produced is either used as mulch or incorporated in to
the soil. This practice contributes for arresting the water erosion through arresting the
impact of rain drop and increases the infiltration in to the soil and thus reduces the water
erosion. The tree has high coppicing ability and twigs and leaves are rich in nitrogen
(about 3%). Biomass production during the second year is about 1.3 kg dry matter/m2,
which will increase to 2.6 kg/m2 during the third year and about 3.6 kg /m2 during the
fourth year. The biomass production can reach up to 30 t/ ha from third onwards, which
has potential to contribute substantial quantity of nitrogen besides contributing towards
carbon sequestration and improvement in soil physical properties.
Tank silt as an organic amendment for rehabilitating degraded land
Tank silt is an important amendment which can be used for the development of
degraded lands affected by water erosion. Continuous exposure to water erosion leads to
loss of silt fraction which can be remedied by tank silt application. The tank silt by virtue
of higher silt and clay content retains substantial quantities of moisture and improves the
crop growth and yield. This is especially effective in light textures soils. The on farm
evaluation of silt application in various field crops under rainfed conditions at six centers,
viz. Anantapur (AP), Nalgonda (AP), Warangal (AP), Kolar (Karnataka), Solapur
(Maharashtra) and Bhilwara (Rajasthan) for two years was presented in Table 6. Silt
application has improved the crop yields, water productivity and profitability per
millimeter of water used [Osman, (2010), Figure 3].
Table 6: Water use efficiency of different crops as influenced by tank silt application
Sl.
No.
District
WUE (kg ha-1 mm-1)
Crop
2008-09 (year I)
2009-10 (year II)
With silt
Without silt
With silt
Without silt
1.
Anantapur
Groundnut
1.86
0.74
3.34
2.07
2.
Nalgonda
Castor
0.48
0.14
*3.89
*1.74
3.
Warangal
Cotton
2.57
2.17
3.35
2.00
4.
Kolar
Mulberry
0.52
0.50
0.33
0.29
5.
Solapur
Rabi sorghum
6.30
4.24
8.08
6.01
6.
Bhilwara
Maize
6.89
5.57
5.28
3.93
Note: * indicates yield accrued from cotton crop, castor was substituted with cotton during the second year
206
Issues and Strategies for Managing Degraded Lands in Rainfed Ecosystem in India
a) With tank silt application
b) without tank silt
Fig. 3: Effect of tank silt application in Maize at Bhilwara (Rajasthan)
Issues involved in arresting land degradation due to water erosion
Continued practice of unsustainable land use and management practices is
contributing towards the land degradation due to water erosion. The growing pressure on
land is leading to bringing more land under intensive use resulting in further degradation.
Any comprehensive program or action to arrest water erosion should be based on
assessment of the current land use, ownership and the severity of erosion. As watershed
development program is being implemented by the government in large scale throughout
the country effective implementation of the program will greatly contribute towards
arresting the further degradation. As the extent of area affected by water erosion is large
and difficult to cover the entire area, it is appropriate to inventorize the already treated
lands and their current status and prioritization of the remaining degraded lands needs to
be done for effective targeting of the program.
However, in recent years, large scale distribution of land to the weaker sections for
cultivation is being done without providing support for their improvement. As these lands
require substantial investments to control water erosion, suitable provision should be
made for providing resources for arresting degradation of such lands. Besides issues such
as overlapping jurisdiction of ministries, shortage of trained staff for implementation of
the watershed development programme, rampant encroachment, lack of control on open
grazing and lack of effective supervision and monitoring and evaluation inbuilt in the
program are contributing for the lack of desired impact of the program. There should be a
proactive approach for convergence among relevant programs, separate cost norms for
treatment depending on the severity of degradation and effective use of GIS and remote
sensing are necessary for the effective implementation of the watershed related
development programs aimed at arresting land degradation.
Issues and Strategies for Managing Degraded Lands in Rainfed Ecosystem in India
207
Conclusions
There is a need for convergence of different programmes aimed at land and water
resources development to tackle the problems of land degradation in arable and nonarable lands. A consortium approach in planning, implementation and monitoring of the
program is essential. There is a need for generating a sense of awareness and building of
ownership of the program by PRIs/SHGs/UGs and besides hand-holding by NGOs and
line departments.
References
ICAR (Indian Council of Agricultural Research) (2010). Degraded and wastelands of India.
Status and spatial distribution. ICAR, New Delhi.
Katyal, J.C., Shrinivas Sharma, Padmanabhan, M.V., Das, S.K. and Mishra, P.K. (1995). Field
manual on watershed management. Central Research Institute for Dryland Agriculture,
Santoshnagar, Hyderabad, India, 165pp.
Narain, P., Chaudary, R.S., and Singh., R.K.( 1994). Efficacy of conservation measures in north
eastern hilly regions. Indian journal of soil conservation, 22:42-62.
Osman, M. (2010). Final report on Tank silt as an organic amendment for improving soil and
water productivity. FPARP, Ministry of Water Resources, New Delhi, 98pp.
Pathak, P., Mishra, P, K., Rao, K.V., Wani, S.P. and Sudi, R. (2009). Best best options for soil and
water conservation. In: Best best options for integrated watershed management. (Ed. Wani,
S.P., Venkateswarlu, B., Sahrawat, K.L., Rao, K.V. and Ramakrishna, Y.S.). Proceedings
of the comprehensive assessment of watershed programs in India, 25-27 July 2007,
ICRISAT, Patancheru 502324.
Pathak, P.S. and Solanki, K.R. (2002). Agroforestry technologies for different agro-climatic
regions of India. ICAR, New Delhi, India, 42 pp.
Rao, J.V. and Khan, I.A. (2003). Research gaps in intercropping systems under rainfed conditions
in India, An On farm survey. CRIDA, Hyderabad, 132 pp.
Rao, M.S.R.M., Chittaranajn, S., Selvarajan, S. and Krishnamurthy, K. (1981). Proceedings of the
panel discussion on soil and water conservation in red and black soils, 20 March 1981,
UAS, Bangalore, Karnataka; Central Soil and water Conservation Research and Training
Institute Research Center, Bellary, Karnataka and University of Agricultural Sciences,
Bangalore, India, 127 pp.
Srivastava, S.K., Bandopadhyay, S., Meena Rani, H.C., Hedge, V.S. and Jayaraman, V. (2002).
Incidence of poverty, natural resources degradation and economic policies and
interventions: A study based on wasteland mapping. IAPRS & SIS, Vol. 34, Part 7,
Resources and Environmental Monitoring, NRSA, Hyderabad, India.
Vasisht, A.K., Singh, R.P., Mathur, V.C. (2003). Economic implications of land degradation on
sustainability and food security in India. Agropedology, 13:19-27.
Young, A. (1989). Agroforestry for soil and water conservation. CABI, 318 pp.
Land Degradation due to Selenium:
Causes, Implications and Management
K. S. Dhillon and S. K. Dhillon
Department of Soils, Punjab Agricultural University, Ludhiana, India
Email: [email protected]
Land Degradation due to Selenium: Causes, Implications and Management
209
Abstract
Selenium (Se) is not an essential element for plant growth, but its concentration in
plant tissues is important for animal and human health. Plants vary considerably in their
physiological response to Se. Intensive screening of cultivated agricultural plant species
have revealed that Se accumulation was the greatest in oilseeds followed by legumes and
cereals. The soils containing > 0.5 mg Se kg-1 are often associated with vegetation
accumulating > 5 mg Se kg-1 - the critical level for animal consumption and thus are
designated as Se-degraded or seleniferous soils. The presence of Se-degraded soils has
been reported from Haryana, Punjab, West Bengal, Assam and Meghalaya states of India.
The problem of selenium toxicity has been studied in detail during the last two decades in
Punjab where >1000 ha of Se-degraded land has been identified. This paper reports about
the sources of selenium, distribution in soil – plant system, toxicological impacts on
animal and human health and the management of seleniferous environments.
Introduction
Selenium (Se) was discovered by Jöns Jacob Berzelius and J. G. Gaham in 1817
while working with sediments of a sulphuric acid plant at Gripsholm, Sweden. The
element isolated from the red deposits on the walls of lead chambers was given the name
of ‘Selenium’ after the moon Goddess ‘Selene’. Since its discovery, Se continued to be
known as an environmental toxicant till it was discovered as an essential nutrient for
animal and human health (Schwarz and Foltz, 1957). In 1985, the United States
Environmental Protection Agency postulated that Se should receive closer scrutiny as a
potential contaminant of the food chain.
Perhaps, Marco Polo was the first to come in contact with probable Se poisoning
while traveling in the remote parts of Western China and eastern Turkestan in 13th
century. However, the first documented report describing Se poisoning in animals
(horses), as known to today’s scientists, was penned in 1856 by an army surgeon Dr.
Madison stationed at Fort Randal, South Dakota, USA. Loss of hooves and hair from
horses grazing on the “poisoned lands of Meath” was reported from Ireland as early as
1890. Later on, Se toxic areas were identified in Columbia, Ireland, Israel, Australia
(Rosenfeld and Beath, 1964). More recently, accumulation of Se in toxic levels in food
chain has been observed in San Joaquin valley of California, USA (Ohlendorf, 1989) and
northwestern India (Dhillon and Dhillon, 1991a). Selenium is increasingly becoming an
environmental threat and often has been described as the element with two faces of
toxicity and deficiency existing side by side. Selenium occurs naturally in soils varying
from 0.005 mg kg-1 in a deficient area in Finland to 8000 mg kg-1 in the Tuva area of
Russia.
Recently, a great loss of animal wealth due to some mysterious disease was reported
from some locations in northwestern India. The basic reason for this health problem was
identified in 1984-85 when chemical analysis of plant samples showing snow-white
chlorosis revealed the presence of excess selenium. Further investigations revealed the
presence of large amounts of Se in samples of soil, water, plant, animal and human
tissues collected from the affected area. Selenium is not an essential element for plant
210
Land Degradation due to Selenium: Causes, Implications and Management
growth, but its concentration in plant tissues is important for animal and human health.
The nutritional minimum level for animals and humans is about 0.05 to 0.10 mg Se kg-1
dry fodder / food. Toxic effects of Se may appear in animals and humans consuming feed
containing 2 to 5 mg Se kg-1 or more. A number of greenhouse and field experiments
were conducted to study the impact of selenium in soil - plant - animal - human system
and to develop a suitable technology for mitigating the toxic effects of selenium in animal
and human health. The results are discussed in the following sections.
Location of Se-degraded soils
Interpretation of data in terms of probability of occurrence of a particular
concentration of Se in soil-plant system (Dhillon et al., 1992a) has revealed that soils
containing > 0.5 mg Se kg-1 are, in fact, associated with vegetation accumulating Se more
than the maximum permissible level (MPL) of 5 mg kg-1 dry matter for animal
consumption. Thus, presence of 0.5 mg Se kg-1 soil was considered as the critical level
and the soils containing Se above the critical level were designated as Se-degraded or
seleniferous soils. The plant species, however, differ appreciably in their Se absorbing
capacity and thus the critical limit should be used cautiously in differentiating
seleniferous from nonseleniferous soils.
The presence of Se-degraded land has been reported from four different locations in
India: i) Initially, Se toxicity problem was reported from Haryana state (Arora et al.,
1975). A lot of research work was undertaken at National Dairy Research Institute,
Karnal and Haryana Agricultural University, Hissar; but the relationship of Se toxicity in
soil-plant-animal system was established only at one site near Karnal. The soils
containing excess Se were highly saline in nature. The problem of Se toxicity disappeared
when the affected soils were subjected to the process of reclamation; ii) In 1984-85, Se
toxicity problem was reported from Punjab (Dhillon and Dhillon, 1991a). Since then
detailed investigations have been undertaken and the results are discussed in the present
manuscript; iii) Selenium toxicity in cattle were reported from Jalpaiguri, West Bengal by
Ghosh et al., (1993); iv) Dey et al. (1999)) have reported that the dead remains of wild
animals collected from the forest areas of Assam and Meghalaya states contained Se
many times more than the normal level. Scientists concluded that the wild animals could
have died due to accumulation of excess Se in their body tissues. Forages containing
deficient as well as toxic levels of Se have been reported from different countries
including America, Canada, Australia, New Zealand, China, India, Israel, United
kingdom, Sweden, Finland.
Extent of Se-degraded Soils in Punjab, India
Periodic surveys were conducted to assess the status of Se in soils, grasses, forage
and grain crops commonly grown in Punjab and Se-related disorders in animals and
human-beings. In a survey conducted in 1970-72, only 1% of plant samples collected
from different blocks of Punjab contained Se in toxic levels and the toxic site was located
in Saroya block of Hoshiarpur district (Dhillon et al., 1977). The follow-up survey
undertaken in 1984-85 lead to the identification of selenium toxic areas in a number of
villages namely Panam, Nazarpur, Simbly belonging to Hoshiarpur and Barwa, Jainpur,
Mehindpur, Rakkara Dhahan, Jadla and Bhan Majara villages of Nawanshahar districts of
Land Degradation due to Selenium: Causes, Implications and Management
211
Punjab (Dhillon and Dhillon, 1991a and Dhillon et al., 1992a). The Se-contaminated
region that has been subjected to detailed investigation is enclosed by Garhshankar –
Balachaur road on the eastern side, Bist Doab Canal on the western side and
Nawanshahar – Balachaur road on the southern side. On the basis of Se content of soil
and plant samples, the soil maps have been prepared depicting highly toxic and
moderately toxic locations in Hoshiarpur and Nawanshahar districts (Fig 1). During a
recent survey of whole of the Kandi region of Punjab (Dhillon et al., 2004), some
additional Se-contaminated sites were identified and the comprehensive list is reported in
Table 1. There is need to undertake detailed investigations so as to ascertain the extent of
Se toxicity problem at the new locations also. Selenium-contaminated soils as shown in
Fig 1 constitute about 1000 ha and are sporadically distributed in different villages (Table
2).
Fig 1: Map showing severely and moderately Se-contaminated areas in Punjab
212
Land Degradation due to Selenium: Causes, Implications and Management
Table 1: Comprehensive list of seleniferous sites located in the Kandi region of
Punjab
Distric
Hoshiarpur
Nawanshahar
Ropar
Block
Village
Garhshankar
Simbly, Nazarpur, Dhamai, Panam, Binjon and Behbalpur
Mahilpur
Todarpur and Jandoli
Saroya
Jainpur, Mehindpur, Rakkar Dhahan, Bholewal, Bharapur,
Chandpur Rurki, Karimpur Chawala, Karimpur Dhianai,
Thandupur, Bachhauri, Kulpur and Katwara
Nawanshahar
Barwa, Bhan majara, Kishanpura and Daulatpur
Balachaur
Rurki khurd, Phirni majara, Karawar, Mazari and
Ghamour
Anadpur Sahib
Lodhipur
Table 2: Selenium-contaminated area (acres) at different locations in Punjab as
shown in Fig 1.
District
Hoshiarpur
Block
Garhshanker
Village
Simbly
Nawanshahar
Saroya
Moderately toxic
(0.5 - 2 mg Se kg-1
soil)
Total
180
488
668
25
56
81
Total
205
544
749
Barwa
175
355
530
Bhan Majara
16
45
61
Baghouran
21
60
81
Jadla
30
45
70
Total
242
505
742
Jainpur
150
310
460
Mehindpur
25
60
85
Rakkar
Dhahan
65
130
195
Total
240
500
740
Grand
Total
687
1549
2231
Nazarpur
Nawanshahar
Highly
toxic
(>2 mg Se
kg-1 soil)
Land Degradation due to Selenium: Causes, Implications and Management
213
Genesis of Se-degraded soils in Punjab
The factors responsible for the development of Se-degraded soils in Punjab are Parent material, Irrigation water and Adoption of rice based cropping sequences.
Parent material: The most important factor controlling the level of Se in geoecosystems is the parent material (Rosenfeld and Beath, 1964). Accumulation of Se in
toxic levels is a direct consequence of geological origin of soils. The soils that tend to be
seleniferous have developed like the normal soils as a result of so called active and
passive factors of soil formation. Change in topographical features and leaching / erosion
processes have played an important role in the development of seleniferous soils. Areas
containing toxic, adequate or deficient Se levels exist side by side in many parts of the
world. Most of the seleniferous soils lying in arid and semi-arid areas of the western
states of USA have developed in situ from weathering of underlying rocks. Toxic soils
are derived from Cretaceous sedimentary deposits of the Niobrara and portions of Pierre
shale. The chalky and calcareous marls and shales of Niobrara formation are the most
persistent seleniferous beds of the Great Plains region of USA.
In Punjab, Se-toxic sites are located at the dead ends of seasonal rivulets (Choes)
originating from the Shiwalik ranges (Fig 2). Identification of Se contaminated soils at
the dead ends of seasonal rivulets (choes) provides a valid reason to believe that Se-rich
material could have been transported through these rivulets along with flood water and
repeatedly being deposited at their endings. Exact nature of parent material of
seleniferous soils is not known, but it might resemble that of upper Shiwalik rocks. These
rocks are mainly composed of polymictic conglomerates of variable composition
containing many unstable materials (granite, basalt, limestone etc.) and derived from
metamorphic terrain of Himalayas (Karunakaran and Rao, 1979). In addition to this, Se
absorbed by natural vegetation from lower layers of soil got deposited in the surface layer
following countless cycles of growth and death. Under increasing population pressure,
when these sites were brought under cultivation, movement of Se in appreciable quantity
from soil through plants to animal and human system has resulted in serious health
hazards.
Selenium content of rock samples collected from Shiwalik range is reported in Table
3. Among the sedimentary rock samples, majority of the samples belonged to sandstone.
Selenium content of rock samples is also quite low and thus may not be considered as Serich materials at present. It is most likely that instead of transporting Se-rich materials as
such, the flood water moving through the materials in the Shiwalik range dissolved Se
from the materials which moved down stream along with water and got repeatedly
deposited at the dead ends. It is a well known fact that Se is highly soluble in water.
According to Krauskopf (1955), the processes responsible for enrichment of Se in
geological materials are: mechanical enrichment, precipitation, adsorption, substitution
and presence of organic material in deposits. Among the sedimentary rocks, shales
commonly contain more Se than sandstone, limestone and phosphate rocks. Sandstones
are usually more permeable than limestones and shales and their gross composition is
more variable. Local enrichment of sandstone may occur because of precipitation of Se
from ground waters moving through beds long after their deposition. Of the total Se in
214
Land Degradation due to Selenium: Causes, Implications and Management
sandstones, >80% is water soluble, whereas in pyritic phosphoric rocks only 0.6% is
water soluble (Rosenfeld and Beath, 1964). In Se-toxic regions of China, the leaching
conditions controlled by microtopography features are mainly responsible for the
distribution and redistribution of Se in soils and plants (Zhu and Zheng, 2001).
Fig 2: The lines depict the choes originating from the Shiwalik ranges and
transporting alluvial material along with flood water to the low lying araes.
● – Indicate location of Se-contaminated soils at the dead ends of choes
Table 3: Selenium content of rock samples collected from lower and upper Shiwalik
ranges
Sampling
period
No. of
sample
s
Location
Type of rocks
Se content
(µg kg-1)
Range
Mean±SD
November
2003
5
Cluster of rocks
near Pojewal, Distt
Hoshiarpur
Clay stone, Salt and
pepper sandstone,
Yellowish brown
sandstone and Light grey
sandstone
1864 2754
2341±
336
December
2004
25
Upper Shiwalik hills
along roads from
Hoshiarpur to Gagret,
Nurpur Bedi and Una
Shale, Sandstone,
Claystone, Siltstone,
Limestone,
Conglomerates
11 - 847
242±
190
April
2005
9
Along Chandigarh–
Basathu– Solan road
Sandstone, Claystone,
Siltstone, Wood coal
46 - 644
247±
211
Land Degradation due to Selenium: Causes, Implications and Management
215
Irrigation water: Wide variation in Se concentration of underground water was
observed in the affected region. In general, Se content of water samples ranged from 0.25
to 69.5 g L-1 with an average value of 4.7 g L-1 (Fig 2). However, the samples collected
from tubewells located at or near the toxic sites contained 2.5 to 69.5 g Se L-1 with an
average value of 24.6 g Se L-1. On the basis of the guidelines recommended by the NASNAE (1973), 88.9% of water samples contained Se in the safe range, 11.1% of the
samples were not suitable for drinking purposes; 4.4% of the samples exceeded the
irrigation water guidelines of 20 g Se L-1. Total Se in ground water, in the present
investigation, was higher than that observed by Robberecht and Grieken (1982) in ground
water from Italy, Australia, Belgium, Russia and Sweden and was 1 to 8 times lower than
that observed in France, Argentina and USA.
Adoption of rice based cropping sequences: The affected region was traditionally a
maize-wheat growing area. With the availability of electric power, the farmers installed
tubewells for pumping out underground water. Wherever the land was suitable, ricewheat system being more profitable was adopted by the farmers. After about 8-10 years
of regular cultivation of rice, Se toxicity symptoms started appearing on wheat crop that
followed rice. Underground water, the only source of water available for irrigation
purposes, was found to be contaminated with Se at certain locations. Depending upon the
amount of irrigation water required and the extent of Se contamination in water, Se
additions through water may range from 6 to 1155 g ha-1 under different crops.
Obviously, Se additions through the irrigation water were the highest in the case of rice.
Selenium inputs in soil through underground water under different cropping sequences
(Table 2), revealed that regular cultivation of crops with excessive requirements of water
is leading to significant accumulation of Se in the soil and is further accentuating the Se
toxicity problem.
Characteristics of Se-degraded soil
Se-degraded soils were alkaline in reaction ranging in pH from 7.3 to 9.4 and
electrical conductivity from 0.2 to 5.2 dS m-1. Except a few samples, all the soil samples
were calcareous in nature having free calcium carbonate 0.1 to 6.2%, organic matter 0.1
to 2.7% and cation exchange capacity 2.6 to 36.7 cmol kg-1. Soil texture varied between
silty loam to silty clay loam. Seleniferous soils did not differ significantly from
nonseleniferous soils with respect to their physical and chemical characteristics except in
calcium carbonate content. Average CaCO3 content of toxic soils (1.7± 1.01%) was
almost double than that of non-toxic soils (0.9± 0.83%). There was no difference in the
productivity potential of both the soil groups except that the farm produce obtained from
toxic soils is rich in selenium and is thus not fit for animal and human consumption.
216
Land Degradation due to Selenium: Causes, Implications and Management
Fig. 3: Se content of underground water - the only source of irrigation
and drinking water in the seleniferous region of Punjab, India
Table 4: Selenium additions in soil after irrigating different cropping sequences
with underground water in the seleniferous region of northwest India
Crop rotation
Se addition through underground
water after one year (g ha-1)
Range
Mean
Se addition through
underground after after 10
years
(g ha-1)
Rice - Wheat
50.6 – 1417
498
4980
Rice-Berseem
63.7 – 1785
627
6270
Rice -Sunflower
59.9 – 1680
590
5900
Maize-Wheat
18.8 – 525
184
1840
Sugarcane
22.5 – 630
221
2210
Rice - Oryza sativa; Wheat - Triticum aestivum; Berseem - Trifolium alexandrinum; Sunflower - Helianthus
annuus; Maize - Zea mays; Sugarcane - Saccharum officcinarum.
In a survey extended over whole of the Kandi region and its adjoining areas in
Punjab, Dhillon et al. (2004) have reported that total Se content in the surface soil ranged
from 0.02 to 4.55 mg kg-1 with an average value of 0.41±0.68 mg kg-1 (Table 5). Out of
184 soil samples, 18% of the samples contained Se more than the critical level of 0.5 mg
Se kg-1. On the basis of average values, maximum level of Se was present in soils from
Nawanshahar block followed by that from Garhshanker, Saroya, Anandpur Sahib, Nurpur
Bedi, Balachaur and Mahilpur blocks. Total Se content exhibited significant and positive
relationship with hot water soluble Se (r = 0.83**), Se content of plants (r = 0.78**),
Land Degradation due to Selenium: Causes, Implications and Management
217
CaCO3 content (r = 0.42**), electrical conductivity (r = 0.39**) and silt content (r = 0.31**)
of soils. Fractionation of native Se in seleniferous soils of Punjab, from where chronic
selenosis in animals has been reported, revealed that KCl extractable Se (selenate)
constitutes 6-14% of total Se, KH2PO4 extractable (selenite) 11-19%, 4M HCl extractable
Se 2-7% and residual Se ranged from 67-76% (Dhillon and Dhillon, 1999).
At the seleniferous sites, Se was present in the soil profile up to 2 m depth, but its
distribution in different layers of the soil profile did not follow any specific pattern
(Table 6). At all of the toxic sites, surface layer was found to be rich in Se as it contained
1.5 to 6.0 times more Se in comparison to the lower layers. Among the surface soil layers
at different sites, Se content was the greatest in Simbly followed by that from Nazarpur,
Barwa II, Jainpur and Barwa I sites. On the basis of physico-chemical characteristics of
surface and profile samples, it may be concluded that seleniferous soils belong to Order Inceptisol, Great group - Haplustept and Subgroup - Fluventic.
Among other states of India, soils with as high as 10 mg Se kg-1 exist in Haryana
(Singh and Kumar, 1976); but no relationship has been reported between high Se levels
and health of animal and humans. Only at one location near Karnal at village Chamar
Khera, symptoms resembling Se toxicity were observed by Arora et al. (1975) on some
buffaloes (Bubalus bubalis) feeding on fodders containing 0.9 to 6.7 mg Se kg-1. In the
sub-Himalayan region of West Bengal, Se content of soils from the toxic pastures ranged
from 1.45 to 2.25 mg kg-1. Se-rich soils have been identified in many parts of the world.
Selenium content of surface soils ranged from 1.5 to 20 mg kg-1 and a maximum of 98
mg Se kg-1 have also been recorded in the toxic region in Western United States
(Rosenfeld and Beath, 1964). In China, soils containing total Se >3.0 mg kg-1 and watersoluble Se >0.02 mg kg-1 are associated with Se poisoning and are located in Sangliao,
Weihe and Hua Bei plains (Tan et al., 1994). Acute poisoning and chronic selenosis has
been reported from the regions where total Se content in surface soils ranged from 0.3 to
0.7 mg kg-1 in Canada, 0.3 to 20 mg kg-1 in Mexico, 1 to 14 mg kg-1 in Columbia, 1.2 to
324.0 mg kg-1 in Ireland and up to 6.0 mg kg-1 in Israel (Rosenfeld and Beath, 1964).
Table 5: Selenium content (mg kg-1) of surface soil (0-15 cm depth) from different
locations in the Kandi region of Punjab
District
Hoshiarpur
Nawanshahar
Ropar
Selenium content (mg kg-1)
No. of
samples
Minimum
Garhshankar
35
0.09
2.92
0.69
0.76
Mahilpur
12
0.08
0.42
0.20
0.11
Saroya
69
0.02
4.55
0.41
0.68
Nawanshahar
16
0.08
2.41
0.83
0.84
Balachaur
25
0.06
0.74
0.25
0.16
Anandpur
Sahib
14
0.15
0.80
0.46
0.29
Nurpur Bedi
13
0.07
0.49
0.31
0.22
Block
Maximum
Mean
+ SD
218
Land Degradation due to Selenium: Causes, Implications and Management
Table 6: Distribution of Se in the soil profiles representing different seleniferous
sites in the Kandi region of Punjab
Profile
locations
Nazarpur
Simbly
Barwa I
Barwa II
Jainpur
Depth
(cm)
pH
EC
(dS m-1)
OC
CaCO3
Total Se
HWS-Se
(mg kg-1)
(%)
0-24
8.22
0.27
0.65
0.87
2485
70.7
24-87
8.08
0.15
0.46
0.75
1056
31.8
87-120
7.89
0.18
0.43
0.50
1695
10.9
120-157
7.73
0.28
0.41
0.50
593
12.0
157-170
8.55
0.20
0.37
7.50
402
15.5
0-27
8.45
0.25
0.63
2.25
3247
98.0
27-90
8.23
0.14
0.41
0.50
1044
30.8
90-146
8.59
0.17
0.34
9.92
1171
14.8
146-195
8.67
0.16
0.36
12.5
1235
8.9
0-22
8.78
0.23
0.53
2.65
1432
31.0
22-61
8.50
0.16
0.40
0.75
698
18.2
61-89
8.35
0.21
0.41
0.35
1104
9.8
89-111
8.41
0.18
0.33
0.30
859
11.9
111-166
8.70
0.20
0.31
9.30
1319
13.3
0-24
8.58
0.30
0.53
4.87
2322
26.8
24-62
8.56
0.23
0.39
1.75
1742
12.7
62-126
7.84
0.31
0.33
0.52
1012
10.1
126-163
7.89
0.34
0.32
0.35
507
5.6
0-17
8.56
0.27
0.58
4.75
1729
35.7
17-65
8.80
0.23
0.55
2.87
1091
13.9
65-124
8.10
0.30
0.40
0.32
294
9.6
124-155
8.06
0.32
0.39
0.40
460
8.3
Impact of selenium toxicity on plant, livestock and human health
Plant health: Typical symptoms of Se poisoning in plants i.e. snow-white or paperywhite chlorosis with pink colouration at lower side of leaves and sheath of wheat
(Triticum aestivum) were, at first, observed by Hurd-Karrer (1934) in a sand culture
experiment. But in the recorded history of Se research, similar symptoms have been
recorded for the first time on wheat growing under field conditions on naturally occurring
seleniferous soils of Punjab, India (Dhillon and Dhillon, 2003) and on lentil (Lens
culinaris) plant under greenhouse conditions at a level of 2.5 mg selenate-Se kg-1 soil.
The red colour indicates that excess Se has accumulated in elemental form. The above
Land Degradation due to Selenium: Causes, Implications and Management
219
ground portion of wheat plants showing varying degrees of toxicity symptoms may
contain Se ranging from 100 to 450 mg kg-1. Plant responses to different levels of
selenate -Se were recorded under greenhouse conditions. Progressive restriction in
growth was observed in all the plant species with increasing level of Se in the soil.
Among oilseed crops, complete mortality was observed in all the crops except toria
(Brassica compestris var toria) at a level of 5 mg selenate-Se kg-1 soil. Taramira (Eruca
sativa) proved the most sensitive and toria highly resistant to the presence of selenate-Se
in the soil. Among vegetables, only spinach (Spinacea oleracea) and potato (Solanum
tuberosum) plants could withstand the toxic effect of Se when applied as selenate up to 5
mg kg-1 soil. Complete mortality was observed in case of radish (Raphanus sativus) and
turnip (Brassica rapa) and fruit development did not take place in case of tomato
(Lycopersicum esculentum), brinjal (Solanum melongena), peas (Pisum sativum) and
cauliflower (Brassica oleracea var. botrytis). Tuber / bulb formation did take place to
some extent in potato, garlic (Allium sativum) and onion (Allium cepa). All the weed
plants proved very sensitive and their growth pattern was seriously affected due to the
presence of selenate-Se in soil. In some species flowering was delayed by about a week
and in others colour of leaves changed to light green. In case of wild oats (Avena sativa),
burning of tips and leaf margins was observed at 2.5 mg selenate-Se kg-1 soil. While
studying the impact of Se accumulation on consumability of leafy vegetables, it was
observed that Se uptake adversely affected the dietary parameters like total proteins,
vitamin C and crude fiber content (Sagoo et al., 2004a).
Animal health: Animals consuming Se-rich fodders and cereal straws grown on
seleniferous soils exhibited typical symptoms of Se poisoning (Dhillon and Dhillon,
1990, 1997a; Dhillon et al., 1992c). The most consistent clinical manifestations indicated
by all the affected animals were: loosing body condition and loss of hair, necrosis of the
tip of tail reluctance to move, stiff gate, overgrowth of hoof followed by cracks gradually
leading to detachment from the main hoof, abnormalities in horn growth and shedding of
horn corium. The animals may die depending on the severity of symptoms. Some of the
animals were showing hair loss from switch of tail and bilateral cataract. Complaints of
delayed onset of estrus, anestrus and premature abortion were also recorded. Farmers also
reported that animals brought from nonseleniferous areas start disliking even the
succulent green fodders within a short period of even 4-5 days. As a result of garlic like
smell emanating from toxic fodders, animals are able to differentiate between Se-toxic
and healthy fodders. There are cases where animals suffering from chronic selenosis have
recovered when fed with fodders brought from Se-free areas.
Epidemiological studies conducted on animals showing varying degrees of chronic
selenosis in the seleniferous region of Punjab (Atwal et al., 2003) have revealed that
anestrus condition was prevalent in all the age groups of buffaloes and was observed in
more than 50% of the animals. Delayed puberty was a prominent sign in 32% of the
heifers. Majority of anestrus animals in selenotic areas were found to be in low to
medium plane of nutrition and may be designated as major cause of reproductive failure
in seleniferous areas of Punjab. The animals affected with chronic selenosis had 35% less
haemoglobin and 15% less TEC and thus were also suffering from macrocytic and
hypochromic anaemia (Dhillon et al., 1992b). Further investigations on pathophysiology
220
Land Degradation due to Selenium: Causes, Implications and Management
of affected animals revealed that chronic selenosis results in chronic hepatitus and
impairment of hepatic and renal functions (Randhawa et al., 1992; Singh et al., 2002).
Selenium content in tissues of diseased animals was significantly higher than the critical
levels reported by Blood and Radostitis (1989) in cattle and thus confirming Se toxicity.
Average Se content of hair, hoof and blood samples of animals showing typical
symptoms of Se toxicity was 311 to 643, 34 to 37 and 38 to 83 times higher than that of
healthy animals feeding on plants grown in nonseleniferous areas of the state.
Human health: Selenium toxicity in human beings resulting from dietary intake of
Se was considered ‘unobserved’ up to as late as 1980 (FNB, 1980). The best evidence of
chronic Se toxicosis as a result of excessive dietary intake of Se was at first reported from
China by Yang et al. (1983). The authors have reported that a disease characteristic of Se
poisoning in human population occurred in some villages of Enshi County of Hubei
province. Corn containing markedly elevated levels of Se was identified as the main toxic
dietary constituent. Daily dietary intake of Se in the affected individuals ranged from
3.20 to 6.69 mg with an average value of 4.99 mg compared with 0.116 mg in Se
adequate areas. The population suffering from chronic selenosis exhibited prominently
the loss of hair and nails. In the affected individuals, hair was found to be brittle, easily
broken and the new hair lacked pigment. Nails were also brittle with white spots and
longitudinal streaks and eventually broke-off. Eruptive skin lesions occurred with reddish
pigmentation that frequently remained after the lesions have healed. Tooth mottling was
evident in approximately 1/3 of the affected population. Numerous neurological signs,
frequently accompanied by gastrointestinal disturbances were observed in one village that
had a particularly high prevalence of selenosis.
Humans residing in the seleniferous areas of Punjab and consuming Se-rich grains
and vegetables (Table 9) produced at their farms have developed typical symptoms of Se
poisoning (Dhillon and Dhillon, 1997a). Out of 20 humans studied, 55% showed loss of
hair from the body, particularly head, malformation of finger as well as toe nails and
progressive deterioration in general health. Others complained of occasional severe
headache and nausea. In some of the affected humans, fingernails got completely
detached and blood kept oozing out from the fingertips. Humans of all ages were affected
by Se poisoning. Selenium content of hair and nails of affected persons was 8 - 9 and 6 8 times, respectively, higher than the healthy persons (Dhillon and Dhillon, 1997a). In
addition to the symptoms described above, majority of the human population suffering
from chronic selenosis also exhibited tooth decay, black / brown stains on teeth and nails
showing longitudinal streaks, black stains and brittleness (Hira et al., 2003). Farmers in
the seleniferous region did observe that even leaving the region temporarily for 3 - 4
months resulted in a remarkable recovery from Se poisoning. Similar observations have
also been reported by Yang et al. (1983). Obviously, when source of food was changed
from seleniferous to nonseleniferous regions, intake of Se was reduced.
In a recent survey, Hira et al. (2003) compared the general growth pattern of humans
residing in endemic and nonendemic areas of Punjab. Data on anthropometric
measurements of 40 families from each region indicated that the height of men and
women in both areas was comparable, while the weight and body mass index (BMI)
calculated as weight/ (height)2 of men and women in nonendemic (low selenium) area
was significantly higher (P ≤ 0.01) than that of their counterparts in the endemic (high
selenium) areas.
Land Degradation due to Selenium: Causes, Implications and Management
221
Management of Se-degraded soils
The main thrust of the technology for the management of seleniferous soils is on the
production of forages/cereals containing the amount of Se which is safe for
animal/human consumption. This can be achieved either by reducing the movement of Se
from soil through plants to animal/human system or by lowering the level of Se in toxic
soils to safe levels. Efforts have been made to develop suitable technology for the
remediation of seleniferous soils and the results are discussed below:
Application of Gypsum: Selenium accumulation by plants is significantly influenced
by the presence of sulfate ions in the growth medium. The antagonistic interaction
between sulfate and selenate for plant uptake was initially observed by Hurd-Karrer
(1934) under greenhouse conditions. Recently, this relationship has been confirmed
under actual field situations in sugarcane (Dhillon and Dhillon, 1991b) and rice - wheat
cropping sequence (Dhillon and Dhillon, 2000). Reduction in Se absorption by 60-70% in
a number of crops has been achieved by application of gypsum in alkaline calcareous
seleniferous soils of northwestern India. Farmers of the region have adopted this practice
as a practical measure for reducing transfer of Se from soil to food chain crops.
Selecting plants with low Se absorption capacity: In order to reduce the movement of
Se into the food chain, plants absorbing the least amount of Se may be recommended for
cultivation in seleniferous regions (Dhillon and Dhillon, 1997b). Investigations on the Se
absorption capacity of fodder crops commonly grown in the seleniferous region revealed
that the differences in the Se content of fodders was negligible up to a level of 0.25 mg
Se kg-1 soil. At higher Se levels, the differences in Se accumulation became apparent. Oat
(Avena sativa) and sorghum (Sorghum bicolor) among cereals and senji (Melilotus
parviflora) among leguminous fodders absorbed the least amount of Se compared to
other fodder crops. In case of multi-cut fodders like berseem (Trifolium alexandrinum)
and lucerne (Medicago sativa), the first one/two cuts contain 2-3 times more Se than the
following cuts. The farmers are advised to avoid feeding of the first cut of berseem and
the first two cuts of lucerne to animals.
Cultivation of crops requiring less water: Excessive use of Se-contaminated
underground water for irrigation of crops in the seleniferous region, especially rice, has
contributed significantly to the development of seleniferous soils. Therefore cultivation
of crops requiring less water should be preferred over other crops in this region. The
farmers are advised to discontinue the cultivation of rice based cropping sequences.
Role of organic amendments: Application of sugar cane press mud at 15 to 20 t ha-1
and poultry manure at 10 to 15 t ha-1 proved equally effective in reducing Se content in
grain and straw of wheat and rapeseed. Reduction in Se content varied from 73 to 92% in
wheat and 45 to 96% in rapeseed. In case of wheat, Se content of grains and straw got
reduced to the levels considered safe for animal and human consumption. Positive
residual effect of these manures was also observed on the following crops of maize and
rice.
Phytoremediation: Although concept of phytoremediation is not new, yet it has
become the topic of extensive research only recently. Phytoremediation has been defined
as the use of green plants to remove pollutants from the environment or to render them
222
Land Degradation due to Selenium: Causes, Implications and Management
harmless. Chaney (1983) introduced the idea of developing a “Phytoremediation crop” to
decontaminate polluted soils emphasizing that value of metals in the biomass might offset a part or all of the cost of cleaning up the toxic site. Linking birth defects in waterfowl
to excessive Se build-up in Kesterson reservoir in California (Ohlendorf, 1989), provided
a strong incentive to the scientists to establish phytoremediation as a new technology for
the clean up of Se polluted soil and water. The development of technology and the
increased knowledge of the phytoremediation processes have led to the identification of
important mechanisms by which plants are believed to remove, degrade or stabilize the
environmental contaminants. The possible mechanisms are:
Phytoextraction
-
Plant uptake and assimilation of contaminants
Phytovolatilization -
Use of plants to volatilize contaminants absorbed from soil
Phytodegradation
-
Use of plants to make volatile chemical species of contaminants
Rhyzofilteration
-
Use of plant roots to remove contaminants from flowing water
Rhyzodegradation -
Biodegradation of environmental contaminants by plant
exudates
Phytost
Use of plants to transform soil metals so as to reduce their
bioavailability and prevent their entry into the food chain
-
Selenium hyper accumulating plants are known to exist even before the problem of
Se toxicity was recognized (Rosenfeld and Beath, 1964). However, the practicality of
including Se accumulators in remedial strategies is limited, because they are i)
genetically poor, ii) susceptible to pests and diseases ii) not responsive to fertilizer
application and iv) seed is not commercially available. In fact the plants that are the best
Se accumulators are small in size and thus do not produce high biomass. The ideal plant
species for phytoremediation of Se must be able to accumulate and volatilize large
amounts of Se; grow rapidly and accumulate large biomass on the contaminated soil;
tolerate salinity and other toxic conditions. Intensive screening of different cultivated
agricultural plant species (Dhillon and Dhillon, 2009a, 2009b)) under greenhouse (Fig 4)
and field conditions revealed that Brassica spp. have most of the desired attributes
compared to others and notable among them were Indian mustard (Brassica juncea czern.
L.) and canola (Brassica napus). As soon as plant roots absorb Se, it is translocated to
shoots and the harvested biomass can be removed away from the site; thus leading to
reduction in Se levels in the soil.
Land Degradation due to Selenium: Causes, Implications and Management
223
Fig. 4: Selection of crops for phytoremediation purposes
Selenium removal efficiency of different cropping systems:
i) Biomass production and Se content of different crops:
Field experiments were conducted at two different locations in the seleniferous
region of northwestern India from 2000-06. Cropping systems selected for the experiment
were: a) rapeseed (Brassica napus) (locally known as gobhi sarson) – arhar (Cajanus
cajan); b) rapeseed (Brassica napus) – sunn hemp (Crotalaria juncea), c) rapeseed
(Brassica napus) - cotton (Gossypium arboretum) and d) wheat (Triticum aestivum) –
rice (Oryza sativa). Total biomass (straw + grain) of all the crops at maturity (Table 7)
was greater than that at the peak flowering stage throughout the period of
phytoremediation experiments at both the sites (Dhillon and Dhillon, 2009c). At maturity,
the greatest biomass was obtained from rice followed by wheat and rapeseed, arhar,
cotton or sun hemp. At the peak flowering stage, the leaves of different crops contained
greater amounts of Se than stems (Table 8). By the time the crop matured, more Se was
translocated to grain than stems in leguminous and oilseed crops, but the reverse was true
for cereal crops. For the different crops, seeds of rapeseed contained the greatest amount
of Se at both sites. In the first year of phytoremediation experiments at site I, rapeseed
grains contained the greatest amount of Se (108.6±10.4 mg Se kg-1) followed by cotton
(67.5±7.7 mg kg-1), wheat (33.9± 4.1 mg kg-1), arhar (16.1±1.3 mg kg-1) and rice
(12.7±5.1 mg kg-1) (Table 8). The order of Se content in the straw portions of different
crops slightly changed with the highest value (70 mg Se kg-1) in rapeseed followed by
wheat, rice, cotton and arhar straw. These results are in line with those of Bañuelos et al.
(1997) who reported that among different plant species, Indian mustard absorbed the
highest amount of Se in comparison with other crops. Nevertheless shoots of different
crops evaluated by Bañuelos et al. (1997) absorbed only 0.36-2.15 mg Se kg-1 as
compared to 15-129 mg Se kg-1 in the present study. The biomass of different crops was,
however, comparable in the two studies.
224
Land Degradation due to Selenium: Causes, Implications and Management
Table 7: Total biomass accumulation by crops (q ha-1) in a year under different
cropping systems*
Site I
Cropping
systems
Site II
Crops
GSI
G S II
Cropping systems Crops
Rapeseed
- Cotton
Rapeseed
76.5±5.4
96.8±7.4
Cotton
59.5±1.6
63.2±2.4
Rapeseed
- Arhar
Rapeseed
74.2±6.6
94.0±9.8
Arhar
64.4±4.7
69.6±6.0
Wheat
–Rice
Wheat
85.0±12.1
103.6±3.5
Rice
95.7±6.5
129.7±3.7
GSI
G S II
Rapeseed-Sunn
hemp
Rapeseed
78.6±5.6
87.0±9.8
Sunn hemp 52.8±3.4
76.7±9.5
Rapeseed
- Arhar
Rapeseed
83.5±8.2
Arhar
103.8±20.3 123.8±25.6
Wheat
–Rice
Wheat
61.4±8.2
Rice
83.8±18.2 123.1±8.9
69.5±4.5
98.0±7.3
*Growth stage I (GS I) refers to peak flowering for rapeseed, Cotton, Sun hemp and Arhar; or Ear initiation
in wheat, or panicle initiation in rice and growth stage II (GS II) refers to maturity. Values are mean±SD.
Table 8: Representative contents of Se (mg kg-1 DM) in plant parts at different
growth stages of crops
Site I
Cropping
systems
Crops
Growth
stage I
Shoots
Rapeseed - Rapeseed 131±6
Cotton
Cotton
105±35
Rapeseed - Rapeseed 129±7
Arhar
Arhar
19±2
Wheat
Rice
Site II
Growth stage II
Stem
Grains
69±6
109±9
19±1
67±8
68±4
107±20
11±1
20±1
- Wheat
43±7
29±7
19±4
Rice
15±5
17±6
11±5
Cropping
systems
Crops
Shoots
Stem
Grains
153±19
70±18
185±21
44±10
27±6
48±8
177±22
62±19
201±18
Arhar
44±10
16±8
68±11
Wheat
60±7
46±5
53±7
Rice
27±14
20±13
Rapeseed-Sunn Rapeseed
hemp
Sunn hemp
Rapeseed
Arhar
Wheat – Rice
Growth stage I Growth stage II
- Rapeseed
3±10
Selenium removed by Brassica based cropping sequences at the peak flowering
stage was 2-3 times more than that removed by the wheat-rice rotation (Dhillon and
Dhillon, 2009c) (Table 9). The amount of Se added to the soil through leaf fall at
maturity was relatively more in the case of rapeseed-cotton than for the rapeseed-arhar
sequence. Selenium removal by different crops was higher at maturity than at the peak
flowering stage at site II compared to site I where redeposition of Se in soil through leaf
fall was almost twice that at site II. In a field experiment conducted for 4 years with
different crop rotations, Se removal ranged between 4 to 13 g ha-1 yr-1 (Bañuelos et al.,
1997). In contrast, Se removal by different crop rotations was many times higher in the
present investigation and varied between 435 to 1374 g Se ha-1 yr-1 at the peak flowering
stage and between 370 to 949 g Se ha-1 yr-1 at the maturity stage at the two experimental
sites. In both situations, Brassica based cropping sequences could remove 2 to 3 times
more Se than others.
Land Degradation due to Selenium: Causes, Implications and Management
225
ii) Net Se change in soil profile under different cropping sequences:
At site I, cumulative Se removed from seleniferous soil in two years by different crop
rotations (Table 9) varied from 984 to 2749 g Se ha-1 at the peak flowering stage (Dhillon
and Dhillon, 2009c). When harvested at maturity, the total amount of removed Se
decreased by 25 to 39% compared to that at the peak flowering stage. The amount of Se
removed by different crops at maturity was only 1.7 to 5.1% of total Se present in soil
down to 120 cm. Losses of soil Se under different crop rotations was 18.5 to 24.5% of the
total Se present as indicated by soil analysis after two years of experiment.(Table 9).
Similarly, different crop rotations at peak flowering removed 1306 to 2527 g Se ha-1 in 3
years at site II. When harvested at maturity, Se removal varied from 1551 to 2846 g Se
ha-1 and was equivalent to 4.8 to 13.2 % of total soil Se. But the results from soil analysis
indicate that Se loss varies from 21 to 33 % of total soil Se. Thus at both sites 15-20 % of
total Se lost from the soil cannot be explained. Appreciable differences between the two
estimates indicate that besides plant uptake, some other processes are responsible for soil
Se losses. These may include Se volatilization by plants (Terry et al., 1992) and soil
microorganisms (Frankenberger and Karlson, 1994), Se entrapped in the plant root
system (Dhillon and Dhillon, 2009d), leaching of Se below the sampling depth and
spatial variability of soil Se.
Selenium removal efficiency of different Agroforestry farming systems
Different agroforestry farming systems were evaluated for their Se absorption
capacity under greenhouse and field conditions in the seleniferous region of Punjab
(Dhillon et. al., 2008; Banuelos and Dhillon, 2010). Among different trees, poplar
(Populus deltoides) proved more efficient than eucalyptus (Eucalyptus hybrid) and
shisham (Dalbergia sissoo). Total removable biomass of poplar trees, when harvested
after 7 years of growth, was recorded as 272±2.34 Mg ha-1 y-1 (Table 10). Poplar trees get
completely denuded during winter season and thus 15 to 20 Mg ha-1 of leaf biomass was
re-deposited in the soil during its growth period of 7 years. Selenium removal through
poplar- sugarcane (Saccharum officcinarum) /wheat system was 1.5 times more than that
of poplar- menthe (Mentha viridis) /wheat system (Table 10). Including sugarcane as
intercultural crop improved the efficiency of Se removal by agroforestry farming
systems. Comparing Se removal efficiency of different farming systems in one year, the
Brassica-based cropping systems was 1.1 to 1.4 times more efficient than poplarsugarcane/wheat; 1.5 to 2.1 times more efficient than poplar-mentha/wheat system and
2.6 to 3.7 times more efficient than the cultivation of poplar alone. Cultivation of
agroforestry trees yielding 40 t ha-1 yr-1 dry matter containing 3.5 mg Se kg-1 can help in
removing 140 g Se ha-1 yr-1 (Cervinka, 1994). In addition to Se removal through
biomass, hybrid poplar can volatilize significant amounts of Se and the volatilization
rates are dependant upon the form of Se present in soil (Pilon-Smits, et al., 1998).
226
Land Degradation due to Selenium: Causes, Implications and Management
Table 9: Selenium balance in soil profile under different cropping systems after the
completion of phytoremediation experiments
Selenium balance in the soil profile (0-120 cm) at Site I
Cropping Sequence
Initial
On the basis of Se removed by harvested
biomass in 2 yrs
Se
level
Se removed in 2 yr
Se removed in
(g ha-1)
as % of initial soil
2 yrs (g ha-1)
Se
Rapeseed - Cotton
Rapeseed - Arhar
32627
48195
Rapeseed- Sunn hemp
Rapeseed - Arhar
Wheat - Rice
Initial
Se
level
(g ha-1 )
30830
21564
32076
Se lost from soil
Se left
in soil
(g ha-1)
Total
(g ha-1)
Per
cent
GSI
G S II
GSI
G S II
2749
2083
1665
1473
8.43
4.32
5.10
3.06
24633
37448
7994
10747
24.5
22.3
2.29
1.73
34957
7934
18.5
Wheat - Rice
42891
984
740
Selenium balance in the soil profile (0-120 cm) at Site II
Cropping Sequence
On the basis of soil analysis before &
after 2yr
On the basis of Se removed by harvested
biomass in 3 yr
On the basis of soil analysis before
after 3 yr
Se removed in
3 yrs (g ha-1)
Se removed in 3 yr
as % of initial soil
Se
Se left
in soil
(g ha-1)
GSI
2149
2527
1306
GSI
6.97
11.72
4.07
20625
15181
25407
G S II
2665
2846
1551
G S II
8.64
13.20
4.84
Se lost from soil
Total
(g ha-1)
Per
cent
10205
6383
6669
33.1
29.6
20.8
Table 10: Biomass and Se accumulation from Se-degraded soils by agroforestry
farming systems
Cropping
system
Poplar
Mentha/
Wheat
Trees/
Crops
- Poplar
Mentha
Wheat
Poplar
- SugarSugarcane/
cane
Wheat
Plant parts
Se content
(mg kg-1)
Leaves
32.6 ±3.79
Stem
Branches
Roots
Shoots
Oil
Straw
Grain
Cane
Green leaves
Dry leaves
Baggasse
Juice
5.2±1.25
7.3±2.13
18.7±2.35
32.1±2.45
2.3±0.44
38.4±7.24
44.3±9.87
7.8±0.9
21.8±6.2
13.4±2.2
9.5±1.9
0.11±0.03
Total
Se balance in soil
biomass Initial Se in Se removal
Se removal
(mg ha-1 ysoil
through
through
1
)
biomass
biomass as
(g ha-1)
% of initial
(g ha-1)
Se
17.2
17350
1959+
20.3
226+
220.7
1335
34.5
= 3520
29.3
3.6±1.4
6.5±0.5
81.2±6.2
13.7±1.2
3.0±0.5
-
17350
1959+ 2006+ 30.5
1335 =5300
Note: The intercultural crops grown in poplar plantation are: mentha / sugarcane was grown for the initial 2
yrs followed by wheat for the next 5 yrs.
Land Degradation due to Selenium: Causes, Implications and Management
227
Managing seleniferous soils through cultivation of flowers/fiber crops
Greenhouse and field experiments were conducted to quantify Se uptake by different
flowering and fiber plants (Banuelos and Dhillon, 2010). The flowering plants evaluated
under both the situations were able to absorb significant amounts of Se. On the basis of
the amount of Se accumulated per pot, different flowering plants can be ranked as:
Gaillardia > Kotchia > Dimorpothica ≥ Cosmos > Rose > Coreopsis > Holicrism. In the
field experiment conducted in the seleniferous soil containing 4.2 mg Se kg-1 in the
surface layer, Se removal was found to be the greatest in case of gaillardia followed by
calendula, African marigold, French marigold, coreopsis, dimorpothica and holicrism
(Table 11). Thus, cultivation of gaillardia, calendula and African marigold should be
encouraged in Se-degraded soil. Among the cultivated agricultural crops, sunn hemp - the
only cultivated fiber crop, does not constitute food item for animals/human consumption.
When grown in the seleniferous fields in the affected region, sunn hemp crop could
remove up to 240 g Se ha-1 when harvested at maturity.
Table 11: Efficiency of different flower / fiber crops for Se accumulation under
field conditions
Flower/ Fiber crops
Dry matter
yield (g m-1)
Se content (mg kg1
)
Total Se Removal
Flowers
Straw
(µg m-2)
(g ha-1)
Flower crops
Calendula (Calendula officinalis)
966
24.0
21.6
18828
188
Gaillardia (Gaillardia aristata)
364
26.2
59.6
23784
238
Coreopsis (Coreopsis gladiata)
102
57.6
30.1
2656
27
Dimorpotheca (Dimorpotheca
pluvialis)
123
17.4
24.7
2707
27
Helichrysum (Helichrysum
orientale)
250
13.8
10.3
2198
22
French marigold (Tagetes patula)
463
20.5
22.7
9982
100
African marigold (Tagetes erecta)
364
30.6
38.0
12760
128
767
48.2*
27.4
23930
239
Fiber crops
Sunn hemp (Crotalaria juncea)
Conclusions
More than 1000 ha of Se-degraded land has been characterized and mapped in
northwestern India. Consumption of plant based products grown on Se-degraded land is
seriously affecting health of animals and humans in the affected region. Phytoremediation
using Brassica or agroforestry based farming systems seem to be an important tool for
managing selenium affected soils. Brassica based systems can remove 0.8-1.0 kg Se ha-1
y-1 and agroforestry farming systems can remove 4-5 kg Se ha-1 in a growth period of 7
yrs. Selenium removal can further be increased by 1.5-2 times if Se-rich leaves after
228
Land Degradation due to Selenium: Causes, Implications and Management
senescence and root biomass are also removed away fom the soil. If this practice is
adopted as a regular strategy in the seleniferous region, it may require regular cultivation
of about 20-35 cycles of rapeseed -arhar sequence or 4-8 cycles of poplar based farming
systems to lower the level of Se in contaminated soils to < 0.5 mg kg-1 which is
considered safe for producing forages and grains without any potential danger to animal
and human health. The time needed for effective remediation becomes less important if
Se-rich biomass (grain + straw) produced by the process of phytoremediation is
considered as harvestable resource of economic value.
Although Se removal by flower and fiber crops is quite low as compared to the cereal
and oilseed crops; yet it is considered to be the highly remunerative system. The major
advantage of cultivation of flowers or fiber corps lies in the fact that these crops do not
constitute food items for animals and humans. Thus, adoption of floriculture or fiber
crops will help in achieving the ultimate objective of the phytoremediation technology,
i.e. a complete ban on the entry of Se in the food chain and thereby avoiding any
potential dangers to animal and human health.
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234
Strategies for Arresting Land Degradation In South Asian Countries
Appendix-A
Concept Note
Strategies for Arresting Land Degradation
in the South Asian Countries
1. Background and justification
1.1. Importance of the land resources
LAND is Nature’s most precious gift to mankind. Some 12000 years ago, an ancient
man (or, probably, a woman), the first “farmer”, consciously sowed seeds on a piece of
land. It was a unique incident, the most important turning point in human history that
marked the beginning of agriculture, and, with this, mankind’s first step, or more
precisely put in, the first leap toward civilization. Land with all its attributes as a versatile
resource base played the key role here. For about ten thousand years now, farmers, a most
hardworking and productive section of the human population, have been working up land
to produce food, the most basic necessity of life, not only for themselves but also for their
fellow human beings.
With time, human needs increased in diverse ways. Demands for a mix of cereals,
vegetables, fruits, meat, fish, etc. instead of a simple cereal in the food bowl grew. The
need for plant fibre for clothing instead of crude animal hide was felt. The caves were
abandoned as people moved into huts and finally to today’s multistoried buildings to live
in. Land, in some way or other, provided all of these, food, feed, fibre and shelter, for the
human race and its civilization to thrive on this planet. As civilization progressed, great
advances in the art and science of agricultural production came about — the “Green
Revolution” consisting of quality research-derived seed-fertilizer-pesticide-irrigation
technology could be cited as a good example. Farmers were able to reap increasingly
better harvests, cautious optimism about wiping out hunger and poverty from the planet
was there.
However, while the Green Revolution was doubling or tripling the food output from
the land resources, an undesirable development was taking place — the human
population boom. This threatened to negate the gains from the Green Revolution.
Population experts now estimate world population had doubled four times within the first
10000 years following the advent of agriculture. The population growth rate increased
fast so that the time taken for the doubling of the population was becoming shorter for
each doubling. It took about 2000 years for the doubling of the world population from
250 million in 350 B.C. to about half a billion (500 million) in the year 1650 A.D. With
ever increasing population growth rates, it took only 325 years for the world population
to reach a figure of 4 billion in 1975. The estimate is that, the world will have more than
8 billion people in the year 2020 (IUPAC/IRRI, 1983). The population growth rate was
high, around 2% per annum in the impoverished, developing nations of Asia. For
Strategies for Arresting Land Degradation In South Asian Countries
235
example, in the SAARC countries, the total population was 1418.5 million in 2004 which
is estimated to be about 1800 million by the year 2020 (SAARC Statistical Data Book,
2006-2007). About 22% of the world’s human population live in the eight SAARC
countries. Obviously, pressure on land resources intensified to meet increasing demands
for food by a burgeoning population.
The food demand and internal supply situations in most SAARC countries have not
been satisfactory as the scope of horizontal expansion of agriculture almost exhausted
and crop yields began to stagnate or even decline in many cases. The recent food price
hikes and limited availability of food in the international markets have further
complicated the issues related to achieving food security in the SAARC countries and at
the same time maintaining the pace of their socio-economic development. The
implication, then, is that, countries must produce enough food for their present
populations and check population growth rates to ensure that food shortages do not occur
in the future. Virtually all of the food increase will have to come from land. It is now
time, therefore, for policy makers, researchers, farmers and the general public to pay
attention to these crucial points: (1) Land is a FINITE resource, (2) No science or
combination of sciences related to agriculture offers infinite prospects for increasing the
supply of food (IUPAC/IRRI, 1983), (3) Population growth rates must be substantially
and quickly checked, and (4) Quality of land resources, especially when under pressure
from natural processes and phenomena and indiscriminate human interventions, WILL
deteriorate.
It is in the above context that the issue of land degradation has to be addressed. Land
degradation as an issue is not something new, but recent developments in the food sector
do not bode well for the South Asian countries striving to provide food security and
improve the quality of life for their teeming millions. A fresh assessment of the status of
the land resources and evaluation of the land degradation processes to close the
knowledge and awareness gaps and develop ways and means for SAARC national and
regional technological and policy level interventions to halt, and wherever possible,
reverse land degradation are necessary. This Concept Note seeks to attract the attention of
policy makers and agricultural scientists to the issues stated above.
1.2. Land degradation: Causes, processes, extent in South Asia
Land is a complex, multi-component natural entity that becomes a resource base
when used for a specific purpose or purposes. In light of this, land degradation has been
defined as “The reduction in the capability of the land to produce benefits from a
particular land use under a specified form of land management” (Blaikie and Brookfield,
1987). Thus, when agricultural use of land is concerned, land degradation would
essentially mean losses in production of crops, plantations, livestock and inland fishery.
There are a number of interrelated land degradation components, as follows, all of which
may contribute to a decline in agricultural production (FAO, 1999):
•
Soil degradation: Decline in the productive capacity of the soil
236
Strategies for Arresting Land Degradation In South Asian Countries
•
Vegetation degradation: Decline in the quantity and quality of the natural biomass
and loss of vegetative cover (A very recent example from Bangladesh: The hurricane
“Sidr” caused a 5% loss of the Sundarbans, the largest mangrove forest of the world,
Bangladesh lost a portion of the “green wall” against cyclones)
•
Water degradation: Decline in the quantity and/or quality of the surface and
groundwater resources
•
Climate deterioration: Changes in climatic conditions that increase the risk of crop
failure
A big difficulty in studying these components of land degradation and their impacts
on agricultural production separately is that, they are caused by both natural factors and
human interventions mostly in overlapping ways. For example, soil degradation may
occur due to fertility decline caused by loss of nutrients through erosion (natural cause)
and simultaneously, intensive cropping without appropriate fertilization (human factor)
and if some adverse climatic condition (e.g., too little or too much rain) sneaks in, what
expectedly would result is a huge crop loss, the ultimate impact. Here, while the crop loss
could be measured, it would be almost impossible to determine exactly which factor
contributed how much in causing yield loss! Such attempts would not be practical either.
For the practical purpose of assessment of land degradation in SAARC countries and
determination of the needs for technological and policy interventions, the following list
showing the causes of land degradation, natural or human induced, should suffice:
1.
Natural hazards e.g flood, drought, tidal surge, snow melt, etc. (some or the other
in all SAARC countries---e.g., floods and tidal surges in Bangladesh, drought in
Pakistan and India, snow melt and landslides in Nepal and Bhutan)
2.
Erosion by water and wind (e.g. serious land erosion from riverwater currents in
Bangladesh during recurrent floods, wind erosion in the semi-arid regions of India
and Pakistan)
3.
Salinization and acidification (natural and anthropogenic e.g tidal flooding, shrimp
culture in crop land in Bangladesh, faulty irrigation and drainage in India and
Pakistan, arid and semi-arid conditions in India and Pakistan, draining and drying
of potentially acid sulphate soils, etc.)
4.
Formation of hardpan, compaction and waterlogging (mostly human induced in all
SAARC countries)
5.
Deforestation, shrinkage of vegetation cover on land, overgrazing (natural and/or
human induced----in India, Pakistan for example)
6.
Inappropriate management in cultivation of land on steep slopes (human induced--e.g., in Nepal)
7.
Nutrient mining and inadequate nutrient replenishment (human induced----all
SAARC cpountries)
8.
Soil organic matter depletion (mostly human induced----e.g., serious problem in
Bangladesh)
Strategies for Arresting Land Degradation In South Asian Countries
237
9.
Over-exploitation of ground water in excess of natural recharge capacity (faulty
irrigation practice, human induced)
10.
Use of poor quality irrigation water (e.g. use of groundwater containing high
arsenic concentrations for irrigation in Bangladesh and West Bengal of India, risk
of toxic levels arsenic accumulation in soils and foodstuff)
11.
Pollution of soil and surface water bodies (rivers, ponds) by urban industrial waste,
excessive use of agrochemicals, oil spills etc. (human induced----e.g., in India, the
most industrialized SAARC country)
12.
Global warming and consequent sea level rise, an impending calamity? (mostly
human induced, mainly responsible are the industrialized countries of North
America and Europe, but the SAARC are under the of severe consequences).
An important question is: What is the status of the latest information and statistics
about the nature and extent of the different land degradation components in the SAARC
countries? There are limited data, varying in content and precision from country to
country. However, what is known to date may be largely qualitative and not always
precise but these do provide food for thought for policy makers and agricultural scientists
of the region for future action plans to protect the region from the ill effect of land
degradation.
Some statistics gleaned from various sources (SAARC Statistical Data Book, 20062007) are given below as references:
1.
Water erosion and chemical degradation are the most devastating land degradation
pathways in the SAARC region. Erosion risk is the highest (53% of the total area)
in Bhutan, followed by 42% in Sri Lanka, 31% in Nepal, 29% in India, 15% in
Bangladesh and 13% in Pakistan.
2.
Soil salinity/sodicity are problems in Pakistan (20% of the total area), India (8%)
and Bangladesh (6%).
3.
Land with shallow soils (poor fertility and physical properties): 24% in Pakistan,
21% in Nepal, 13% in Bhutan, 10% in Sri Lanka, 9% in India and 1% in
Bangladesh.
4.
Soil fertility decline due to organic matter depletion is a growing problem in all
countries. In Bangladesh about 60% of the soils have a low organic matter content,
often less than 1%.
5.
In India 41% of the land area is without major soil constraints, the figures for Sri
Lanka, Bangladesh, Nepal, Bhutan and Pakistan are 37%, 29%, 26%, 22% and 9%,
respectively.
6.
On a SAARC regional basis, only 24% of the total land area is without major soil
constraints.
An irony is that, while farmers toil hard to increase production and as countries
struggle to eradicate hunger and alleviate poverty, land degradation is accelerated. “Land
mismanagement, whether for crop, livestock or tree production purposes, consists usually
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Strategies for Arresting Land Degradation In South Asian Countries
of removing too much, returning too little, and cultivating, grazing or cutting too often.
Such mining of land beyond its limits results in degradation with decreasing productivity,
and is not sustainable” (FAO, 1999). Estimates of human induced land degradation in the
SAARC countries are rather disquieting. Land degradation through human activities is
progressing at a fast pace in all South Asian countries. Human induced land degradation
in India is the highest (58% of the total degraded area) followed by Sri Lanka 54%,
Bangladesh 27%, Nepal 27% and Pakistan 24%. It is in this aspect of land degradation,
i.e., human induced land degradation, where there is the greatest scope and
necessity to intervene with national and regional policy measures and technological
innovations.
1.3. Impacts of land degradation
Estimating the impacts of land degradation is a very difficult task as this would
involve not only the biophysical and agro-ecological issues but also socio-economic and
development issues. However, this is very important since policy makers, donor agencies
and international development partners would be more interested in quantitative estimates
of the impacts of land degradation than just qualitative statements about what could
happen. A concerted effort by agricultural and social scientists is very much needed. A
study of the effect of land degradation in south Asia concluded that land
degradation was costing countries in the region an economic loss of the order no less
than US$ 10 billion, equivalent to 7% of their combined agricultural GDP (FAO
1994). The current figures could be much higher.
An estimate of losses from land degradation in Bangladesh is given in Table 1 below:
Table 1. Estimates of economic losses from different types
of land degradation in Bangladesh.
Type of
degradation
Degraded
area
(million ha)
Degree of
degradation
Water
erosion
(mostly
floods and
riverbank
erosion)
1.70
Light to Strong
Cereal production loss:
1.06
Nutrient loss: 1.44
140.72
544.18
Fertility
Decline
3.20
Light to
Moderate
Cereal production loss:
4.27
Additional input need :
1.22
566.84
461.04
Salinization
3.10
Light to Strong
Total production loss:
4.42
586.75
Source: Z. Karim and Anwar Iqbal, 2001
Loss estimate
(million ton/year)
Financial loss
(million US$/yr)
Strategies for Arresting Land Degradation In South Asian Countries
239
A more recent estimate-projection on the impact of land degradation in Bangladesh is
quite frightening (Kholiquzzaman, 2007) :
•
Loss of 180 ha arable land/day, 7.5 ha/hr due to building of homes, industries, roads
and other structures.
•
Loss in food production estimated at 5000 t/day or 1.6 million t/yr.
•
At this rate of loss of arable land, not even a sq inch would be available for
agriculture 50 years hence.
•
In 1974, 59% of the net land area of the country was under agriculture; decreased to
53% in 1996. During the period 1983-1996, the rate of decrease in arable land area
was 87,000 ha/yr.
•
During 1983-1996, food production suffered a loss of about 2.1 million t/yr due to
continuously decreasing arable land area
•
Since 1996:
o
In 10 years the number of families increased by 5.015 million, an additional 0.18
million ha arable land was lost for housing, at the rate of 18,200 ha/yr
o
For other purposes, additionally, 0.05 million ha arable land was lost every year
o
In total since 1996, the loss of arable land over the next 10 years was 0.65 million
ha/yr.
Bangladesh faces another hazard, that from sea level rise due to global warming. The
losses could be really colossal:
•
Inundation of the whole coastal belt
•
Displacement of some 30 million people who will become refugees in their own
country
•
Huge loss of agricultural production will result in widespread hunger and poverty
•
More than 10% of the GDP could be lost.
The above are some examples of the present and potential impacts from one SAARC
country only (Bangladesh). Land degradation in almost all its known forms is in progress
in all other SAARC countries. The extent and intensity of the various land degradation
processes would differ, however, from country to country. For example, arsenic
contamination of the irrigation water-soil-crop systems is known to be quite a serious
water quality/soil degradation problem in Bangladesh and West Bengal of India, but this
is not much of a problem in Pakistan, other parts of India and other SAARC countries.
Again, sea level rise due to global warming could be a very serious threat to Bangladesh
and Maldives, but Nepal and Bhutan are not supposed to be directly affected. Since no
generalization can be made regarding the causes and effects of land degradation, it is
imperative that dependable data for each country be available so that scientists, policy
makers and farmers can take appropriate measures to face the problem nationally and
regionally. This Concept Note calls for relevant information generation.
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Strategies for Arresting Land Degradation In South Asian Countries
2. Benefits of the proposed project
Considering the importance and urgency related to land degradation, the Governing
Board of SAC at its very first meeting approved to undertake a study on “Strategies for
arresting land degradation in the South Asian Countries”. It is expected that, this
important study findings would help to (a) formulate policy issues (b) draw strategies and
(c) undertake joint projects and also national programs projects in order to address the
issues of major concern and collectively find out measures to minimize the impact of land
degradation on the millions of affected people in the SAARC nations.
The purpose of this concept note is to initiate an assessment and review of the land
degradation situations in the different SAARC countries, collect and sort out information
and following this prioritize strategies and actions for the SAARC countries individually
and identify needs and scopes of regional collaboration to tackle the problem of land
degradation.
3. Target beneficiaries
Beneficiaries will include policy makers in the governments of the SAARC
countries, agricultural and social scientists, environmental scientists, NGOs, donor
agencies and ultimately the farmers.
4. Goal
Understand and quantify the impacts of natural and anthropogenic land degradation
on agriculture and socio-economic development in SAARC countries and develop
strategies to prevent further land degradation at national and regional levels.
5. Objectives
The objectives of the project/programme will be to:
a. Collect information on the factors and processes and nature and extent of land
degradation in each SAARC country.
b. Assess the impacts of land degradation on agriculture and socio-economic
development at the SAARC national and regional levels.
c. Review existing technical knowledge and evaluate knowledge gaps in the field of
management of land degradation.
d. Prioritize R&D initiatives to address the specific needs of the SAARC countries and
suggest “optimal option” guidelines.
e. Review policy issues, examine existing laws and regulations to combat land
degradation in order to provide appropriate policy support to agricultural and social
scientists, field level workers and farmers themselves to prevent further land
degradation and rejuvenate degraded land wherever possible.
•
Strengthening knowledge and awareness among the government policy making
officials about the problem of land degradation and its impact on agriculture and the
national economy.
Strategies for Arresting Land Degradation In South Asian Countries
241
•
Foster inter-government collaboration on the prevention of land degradation at
SAARC national regional levels.
•
Government and inter-government regular monitoring of the implementation of
policy decisions, identify shortfalls and take necessary measures as and when needed
the fields of
–
Environmentally friendly land use, agricultural enterprises, agribusiness
–
Agricultural production practices beneficial for the land resource base (e.g. IPNS,
ICM, contour cropping, etc.)
–
Housing, settlement and structures
•
Increasing public awareness about the ill effects land degradation through formal
education and media campaigns.
•
Review organizational capacities, modes of operation, HR needs to undertake the
gigantic task of leadership and coordination both at national and SAARC regional
levels.
6. Participating organizations/institutions
•
SAARC Agriculture Centres
•
SAARC NARES institutions and agencies
•
Relevant national government regulatory offices
•
Relevant international institutions and agencies
•
International Agricultural Research Centres in SAARC countries
•
NGOs
7. Approach and Methodology
a. Preparation of country reports: As per existing practice, SAC through its GB
members in the respective countries will identify subject/area related focal
agency/scientists, and they will be mainly responsible for gathering information and
preparing the country status papers.
b. A workshop/expert consultation will be organized to present the country reports and
discuss and review information and suggestions.
c. A compilation containing all aspects of land degradation and corrective measures will
be prepared and distributed to all participants to develop future action plans.
d. The action plans will be submitted to national governments and the SAARC
Secretariate to develop policy formulation and implementation plans for specific land
related issues.
e. SAC will provide leadership and coordination of the activities under the guidance of
the SAC Governing Body.
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Strategies for Arresting Land Degradation In South Asian Countries
8. Outputs
a. SAARC country position papers covering all aspects of land degradation.
b. Compiled study report on ‘Strategies for Arresting Land Degradation in the South
Asian Countries’
c. Priority program/projects development, both national and SAARC regional, and steps
towards their implementations.
d. Short- and long-term impacts of measures against land degradation — ultimately
manifest in prevention of land degradation, reversal of the adverse effects, increased
land productivity without risk of further resource degradation.
References
Blaikie, P. and Brookfield, H. 1987. Land Degradation and Society. Methuen London and New
York.
FAO 1999. Poverty Alleviation and Food Security in Asia: Land Resources. FAO Regional Office
for Asia and the Pacific (RAP), Bangkok. RAP Publication 1999/2.
IUPAC (International Union of Pure and Applied Chemistry) and IRRI (International Rice
Research Institute). 1983. Chemistry and World Food Supplies: Perspectives and
Recommendations. G. Bixler and L.W. Shemilt (eds) Proc. Conf. on Chemistry and World
Food Supplies, Manila, Philippines, 6-10 December, 1982.
K. Kholiquzzaman. 2007. Report in the daily Bengali newspaper “Janakantha”, July 08, 2007,
Bangladesh.
SAARC Statistical Data Book, 2006-2007, Volume 5, 2006/2007. SAARC Agriculture Centre,
Dhaka, Bangladesh.
Z. Karim and Anwar Iqbal (Eds) 2001. Impact of Land Degradation, BARC Soils Pub. No. 42,
Dhaka, Bangladesh.
Strategies for Arresting Land Degradation In South Asian Countries
243
Appendix-B
Recommendations of the Regional Consultation on
Strategies for Arresting Land Degradation
in South Asian Countries
Date: 21-23 June, 2010
Kolkata, West Bengal, India
SAARC Agriculture Centre
BARC Complex, Farmgate, Dhaka-1215
Bangladesh
244
Strategies for Arresting Land Degradation In South Asian Countries
A Regional Consultation on “Strategies for Arresting Land Degradation in South
Asian Countries” was organized by SAARC Agriculture Centre (SAC), Dhaka
Bangladesh in collaboration with National Bureau of Soil Survey and Land Use Planning
(NBSS & LUP), ICAR, West Bengal, India during 21-23 June 2010 at Kolkata. Mr.
Narendra Nath De, Minister In-Charge Agriculture and Consumer Affairs, Govt. of West
Bengal inaugurated the Consultation Meeting. Dr. Anil Kumar Singh, Deputy Director
General (Natural Resource Management), ICAR, New Delhi; Dr. Md. Rafiqul Islam
Mondal, Director, SAC, Dhaka; Mr. AZM Shafiqul Alam, Additional Secretary (PPC),
Ministry of Agriculture, Bangladesh; Dr. Zahurul Karim, Former Secretary and
Executive Chairman, Bangladesh Agricultural Research Council; Dr. Saroj Kumar
Sanyal, Vice Chancellor, Bidhan Chandra Krishi Viswavidyalaya and Dr. Dipak Sarkar,
Director, NBSS & LUP, Nagpur, India were present in the inaugural occasion. A good
number of related senior scientists from SAARC member states attended in the
consultation. Professionals from SAC and NBSS & LUP also attended in the meeting.
The Consultation was completed with five technical sessions followed by plenary
session on 22 June, 2010. Dr. Prithish Nag, Director, National Atlas and Thematic
Mapping Organization, DST, Govt. of India was the Chief Guest on the concluding
session. The third day was kept exclusively for a visit to ICAR Institutes located in and
around Kolkata, West Bengal.
During consultation, representatives of SAARC countries, one each from
Bangladesh, Bhutan, India, Nepal and Sri Lanka and twelve resource persons from ICAR
institutes, ISRO, Government of India and State Agricultural Universities from the host
country participated in the two days deliberations. A total number of nineteen research
papers were presented in the Meeting. Dr. Anil Kumar Singh, DDG (NRM), ICAR,
presented the Key note paper in the Meeting. During consultation meeting, SAC and
NBSS & LUP displayed their products and services
The aim of the consultation meeting is to formulate policy issues, strategies to
undertake joint projects and national programs in order to address the issues of major
concern and collectively find out measures to minimize the impact of land degradation on
the millions of affected people in the SAARC nations, identify needs and scopes of
regional collaboration to take the problem of land degradation.
Extend and trends of land degradation in South Asian countries, processes
responsible for degradation such as erosion, salinization and sodification, acidification,
nutrient mining, imbalanced fertilization, inappropriate land use planning and lack of an
appropriate land use policy in different SAARC countries, were elaborated in the
consultation. The expected influence of climate change on land degradation was also
highlighted.
The influence of various agro-techniques including soil erosion preventive measures,
moisture conservation, correcting water quality, integrated nutrient management,
diversification of agriculture, conservation tillage and gene mining for drought
avoidance, alternate land use planning, inclusion of legumes in crop calendar, legume
based forage production, silvipasture and silviculture based agriculture on degradation
were extensively discussed in the technical sessions.
Strategies for Arresting Land Degradation In South Asian Countries
245
At the end of the group discussion, following recommendations have been emerged.
Researchable issues in South Asia for arresting land degradation
•
Extensive research should be done for developing and framing versatile and robust
database on GIS platform.
•
Focus on developing decision support system (DSS) for integration of land use
technology and planning environment on different scale.
•
Appropriate mapping techniques should be evolved for the delineation of problem
areas including the areas affected with erosion, salinity and sodicity, acidity and
nutrient mining alone or in combination.
•
Research efforts should focus upon studying the temporal and spatial monitoring of
the type and severity of land degradation under different agro-ecological conditions,
using remote sensing and GIS techniques.
•
Delineation and mapping of areas affected with heavy metal pollution should be
taken up at the top of the research agenda; and the impact of heavy metals on human
and livestock after entering into food chain should be investigated.
•
Screening and breeding of crop varieties tolerant to soil acidity, salinity and sodicity,
using conventional and biotechnological methods; evaluation of locally available
alternate mitigation options including several soil ameliorates; amelioration through
phyto- remediation and bioremediations; and water management covering in situ and
ex situ water harvesting techniques should be given top priority.
•
Development of multi-storied agro-forestry (including alley cropping) practices for
sustainable natural resource management.
•
Integrated Farming System models to be developed for sustainable agricultural
production, enhancing livelihood options and building resilience against adverse
impact of climate change.
•
Impact of climate change on land degradation should be monitored, using modern
techniques of remote sensing and GIS.
•
Collaborative research effort among the SAARC member countries may be
considered to address the land degradation problem. SAARC Agriculture Centre may
be taken initiatives to exchange of views, interactions among the scientists and
exchange visits as well as sharing of technologies among SAARC member states are
urgently needed with this regards.
Policy issues for arresting land degradation in South Asia
•
Policy investment should be made in research and development for solving land
degradation problems to ensure food security, poverty alleviation, natural resource
conservation and address climate change issues at the nationally, regionally and
globally. SAC may address issues of concern and collectively identify measures to
reduce impact of land degradation in South Asia.
246
Strategies for Arresting Land Degradation In South Asian Countries
•
All member states and development partners working in the region may revisit their
development agenda in view of intensity of land degradation problems
•
SAARC countries should have their own land use policies pertaining to land
degradation, diversion of agricultural land for non-agriculture uses and these should
be implemented strictly.
•
Policy makers need to be sensitized about the seriousness of the land degradation
problem and the urgency to implement remedial measures.
•
Web based database on land degradation issues including problems and available
mitigation measures should be established. SAC may be developed web based
database for the SAARC member states.
•
Preparedness and capacity building of all stake holders to combat land degradation
should be ensured.
•
Rapid up-scaling of mitigation to technologies of arsenic, selenium, fluoride etc. may
be taken up to reduce public health hazards.
Extension and development issues
•
Inventorization of type and severity of various forms of soil degradation in the
SAARC countries should be made on temporal and spatial basis, using modern tools
and techniques.
•
Development of technology modules for addressing each kind of land degradation
and remedial measures that is easily understandable and adoptable by the
implementing agencies.
•
Action plan/road map for implementation of recommended technologies should be
chalked out following participatory approach on watershed scale.
•
Assessment of impact of technologies at the farmer’s field should be taken up and
appropriate mechanism should be ensured for their up-scaling at state and regional
levels.
•
Sharing of experiences related to utilization of the degraded lands for the productive
purposes by using potential technologies. SAC may be taken up program in this
regard for SAARC countries.
Impact of land degradation on crop productivity
•
Site specific data on impact of different land degradation processes on productivity of
different crops/ land uses/soil based nutrient loss should be collected and documented
and shared amongst all stakeholders for effective refinement in technologies. SAC
can collect data on the topic and share among member states in South Asia.
Strategies for Arresting Land Degradation In South Asian Countries
247
Appendix: C
Program of Regional Consultation on
Strategies for Arresting Land Degradation
in South Asian Countries
During 21-23 June, 2010
Jointly organized by SAARC Agriculture Centre (SAC), Dhaka, Bangladesh &
National Bureau of Soil Survey and Land Use Planning, NBSS & LUP (ICAR), Kolkata,
West Bengal, India
Programme
Day-1: 21 June, 2010 (Monday)
Venue: IndiSmart Hotel, International Tower
Salt Lake, Kolkata
0830
Registration
Inagural Session
0930 1100
Chief Guest
Sh. Naren De
Minister-in-charge, Agriculture, Govt. of West Bengal
Chairperson
Dr. A.K. Singh
Deputy Director General (NRM), ICAR, New Delhi, India
0930
Guests take their seats
0935
Invocation song
0940
Welcome address
Dr. Rafiqul Islam Mondal, Director, SAC, Dhaka
Dr. Dipak Sarkar, Director, NBSS&LUP (ICAR),
Nagpur
0950
Address
Prof. S.K. Sanyal, Vice Chancellor, BCKV
West Bengal, Guest of Honour
1000
Address by the Guest
of Honour :
Mr. AZM Shafiqul Alam, Additional Secretary (PPC),
Ministry of Agriculture, Government of Bangladesh
1010
Remarks by the Chief
Guest
1020
Address by the
President
Dr. A.K. Singh, Deputy Director General (NRM)
ICAR, New Delhi
1030
Vote of thanks
Dr. S.K. Singh, Head, NBSS&LUP(ICAR)
Reg. Centre, Kolkata
1040
Tea Break
248
Strategies for Arresting Land Degradation In South Asian Countries
R&D EFFORTS AND EXPERIENCES ON LAND DEGRADATION IN SOUTH
ASIA
TECHNICAL SESSION I
1115-1350 Chairperson
1115
Prof. S.K. Sanyal, Vice Chancellor,
BCKV, West Bengal
Rapporteurs
Ms. Nasrin Akter, Sr. Programme Officer
(Crops), SAC and
Dr. A.K. Sahoo, NBSS&LUP, Kolkata
Presentation of the Keynote paper
“Strategies for Arresting Land
Degradation in the South Asian
Countries”
Dr. A.K. Singh Deputy Director General
(NRM) ICAR, New Delhi.
Presentation of Country Status
Report
1145
Status Report from Bangladesh
presented
Dr. M. Shahabuddin Khan, Bangladesh
Agriculture Research Institute (BARI)
1200
Status Report from Bhutan presented
Ms. Karma Dema Dorji, Ministry of
Agriculture & Forest, Bhutan
1215
Land degradation status in South East Dr. Dipak Sarkar, Director,
Asian Countries with special reference NBSS&LUP(ICAR), Nagpur
to India
1225
Management of salt affected soils
Director, CSSRI (ICAR), Karnal
/representative.
1235
Status Report from India
Dr. V.N. Sharda, Director,
CSWCR&TI(ICAR), Dehradun
(Title to be obtained)
1245
Issues and strategies for arresting land Director CAZRI Jodhpur/ Representative
degradation in Arid Ecosystem
1330
Open discussion on the papers
presented
1340
Remarks by the Chairperson
1350 –
1445
Lunch
TECHNICAL SESSION II
1500-1520 Chairperson
Professor Dr. Zahurul Karim, Former
Secretary and Executive Chairman,
BARC, Government of Bangladesh
Rapporteurs
Dr. S.K. Pal, Dy. Director (Agri.), SAC
and Dr. K. Das, NBSS&LUP, Kolkata
1520-1645 Presentation of papers
1520
Status Report from Maldives presented Dr. Mohamed Ali, Honourable Minister
Strategies for Arresting Land Degradation In South Asian Countries
249
of State for Fisheries and Agriculture,
Republic of Maldives
1530
Water Policy in India: Issues and
priorities
Dr. B.M. Jha, Chairman, Central Ground
Water Board, Faridabad
1540
Issues on Cropping Strategy in
Degraded Lands – Indian context
Dr. B.S. Mahapatra, Director,
CRIJAF(ICAR), Barrackpore, West
Bengal
1600
Issues and Strategies for Managing
Degraded Soils of Rainfed Agro-Eco
System in India
Dr.B.Venkateshwarlu
Director , CRIDA Hyderabad /
representative
1600 –
1630
Open discussion on the papers
presented
1630
Remarks by the Chairperson
1645 –
1700
Tea
1700 2100
Non-formal Session and Activities
1700 1745
Poster demonstration and free
discussion among participants
1745 1900
Sight seeing tour - if approved
1930 2100
Consultation Dinner
1550
Day-2: June 22, 2010 (Tuesday)
TECHNICAL SESSION III
0900-1200 Chairperson
Rapporteurs
Dr. Rafiqul Islam Mondal
Director, SAC, Dhaka
Dr.Nurul Alam, Sr. Programme
Specialist ( PS&PD), SAC and
Dr. D.C. Nayak, NBSS&LUP, Kolkata
0900 –
1155
Presentation of papers
0900
Status Report from Nepal presented
0920
Land degradation caused due to
Dr. K.S.Dhillon, Retd. Prof., Deptt. of
Selenium content in Soil-Plant-Animal Soil Science, PAU, Ludhiana
System
0940
Application of remote sensing and GIS Dr. P.S. Roy, Dean, & Assoc. Director,
in monitoring and arresting land
(Capacity Building) NRSC, ISRO,
degradation
Dehradun
Dr. Y. G. Khadka
Nepal Agricultural Research Council
250
Strategies for Arresting Land Degradation In South Asian Countries
1000
Status Report from Sri Lanka
presented
Professor Ranjit Mapa
University of Peradeniya
1020
Use of Geo-textiles for arresting Land
Degradation in varied eco-system
Dr K. K. Satpathy, Director,
NIRJAFT(ICAR), Kolkata / Dr. Gautam
Bose, Principal Scientist, NIRJAFT
(ICAR), Kolkata
1020 –
1045
Tea
1045
Land use planning for arresting land
degradation-
Dr. S.K.Singh, Head NBSS&LUP,
Regional Centre Kolkata
1105
Issues and strategies for arresting land
degradation in coastal agro-ecosystem
Dr. B.K.Bandhopadhyay CSSRI
(ICAR), Canning Town West Bengal
1105-1125 Strategies of managing acid soils for
sustainable agriculture in Asian
countries
Dr. D. Jena, Ex-Head Department of Soil
Science and Agricultural Chemistry,
OUAT Bhubaneshwar, Orissa
1125-1145 Soil site nutrient management as a tool Dr. Biswapati Mondal, Prof. of Soil
for preventing soil degradation in
Science, BCKV, Nadia
irrigated agro-ecosystem
1145 1225
Open discussion on the papers
presented
1225-1240 Remarks by the Chairperson
1240 1320
Lunch
TECHNICAL SESSION IV
1320-1340 Arsenic Pollution in South East Asia
with special reference to India and
Bangladesh
1340 1420
Prof. S.K.Sanyal, Vice Chancellor,
BCKV, West Bengal
Thematic Group Work
Facilitator
1340
Introduction to the Group Exercise by
the Facilitator
13401515
Group work (4 parallel groups)
Dr. A.K.Singh, DDG (NRM) / Prof. S.K.
Sanyal, VC, BCKV
Group 1: Research Issues
Co-Facilitator
Dr. Dipak Sarkar, NBSS&LUP
Rapporteur
Dr. Pradip Sen, Jt. Director (Res.), Govt.
of West Bengal
Group 2: Extension and Development
issues
Strategies for Arresting Land Degradation In South Asian Countries
251
Co-Facilitator
Dr. Paritosh Bhattacharya Addl.
Director,
Research,
Dept
of
Agriculture,Govt of West Bengal
Rapporteur
Dr. A.K. Sahoo, Pr. Scientist, NBSS &
LUP
Group 3: Policy Issues
Co-Facilitator
Any Suitable Delegates from other
SAARC
country/Director
CRIDA/
Director CSWCRTI / Jt. Director (Res),
Govt. of West Bengal
Rapporteur
Dr. S.K. Pal, Dy. Director (Agriculture),
SAC, Bangladesh
Group 4: Impact of land
degradation on crop production in
South Asia
1515 –
1535
Co-Facilitator
Dr. M. Shahabuddin Khan, Bangladesh
Agriculture Research Institute
Rapporteur
Ms. Nasrin Akter, Sr. Programme Officer
(Crops), SAC and
Dr. Pradip Sen, Jt.
Director (Res), Govt. of West Bengal
Tea
Technical Session V
1535 –
1615
Presentation and discussion on
group reports
Chairperson
Dr. Pradeep Sen, Jt Director, (Research),
Dept of Agriculture Govt. of West Bengal
Rapporteurs
Dr. S.K.Pal, Dy. Director (Agri.), SAC,
Dr. T.H.Das, Pr. Scientist, NBSS&LUP
(ICAR), Kolkata
1535
Group -1 (10 minutes for presentation
and 10 minutes for discussion)
1545
Group -2 (10 minutes for presentation
and 10 minutes for discussion)
1555
Group -3 (10 minutes for presentation
and 10 minutes for discussion)
1605
Group -4 (10 minutes for presentation
and 10 minutes for discussion)
1615
Remarks by the Chairperson
1615 1630
Drafting of recommendations by the Dr. T.H. Das, Dr. K. Das, NBSS&LUP
Rapporteurs of Session-V, facilitated
and Ms. Nasrin Akter, SAC
252
Strategies for Arresting Land Degradation In South Asian Countries
CONCLUDING SESSION
1630 –
1730
Chairperson
Dr. A.K. Singh, DDG (NRM), ICAR,
New Delhi
Co-Chairperson
Dr. Dipak Sarkar, Director, National
Bureau of Soil Survey and Land Use
Planning, NBSS & LUP, (ICAR), Nagpur
Rapporteurs
Dr. S.K.Singh and Ms. Nasrin Akter,
SAC
1630
Presentation draft Workshop
Recommendations
1640
Remarks
Prof. S.K. Sanyal, Vice-Chancellor,
BCKV
Remarks
Professor Dr. Zahurul Karim, Former
Secretary and Executive Chairman,
BARC, Government of Bangladesh
1650
Remarks
Director of Agriculture, Govt. of West
Bengal / Dr. Pradip Sen, Jt. Director
(Res.), Govt. of West Bengal
1700
Remarks
Chief Guest (to be nominated)
1710
Remarks by the Chairperson
Dr. A.K. Singh, DDG, NRM, New Delhi
1720
Vote of Thanks
Dr. Rafiqul Islam Mondal, Director,
SAC, Dhaka
1720 1740
Refreshment
Day 3: 23 June (Wednesday)
0930-1045 Visit to NBSS&LUP (ICAR),
Regional Centre, Kolkata
1045-1245 Visit to NIRJAFT (ICAR), Kolkata
1245-1500 Visit to CRIJAF (ICAR),
Barrackpore followed by Lunch at
same venue
1500
Back to Hotel
Strategies for Arresting Land Degradation In South Asian Countries
253
Appendix-D
List of Participants of the Regional Consultation on Strategies for Arresting
Land degradation in South Asian Countries
21 -23 June, 2010
IndiSmart Hotel, International Tower
Salt Lake, Kolkata
Sl. No. Name
Designation
Address
1
Sh. Naren De
Minister-in-charge
Ministry of Agriculture and
Consumer Affairs, Government of
West Bengal, India
2
Dr. V.N. Sharda
Director
Central Soil & Water Conservation
Research and Training Institute
218, Kaulagarh Road, Dehradun248195, India
3
Dr. M. Shahabuddin Khan
Ex-Head, Soil
Science Division
Bangladesh Agriculture Research
Institute (BARI)
Joydebpur, Gazipur
4
Ms. Karma Dema Dorji
Programme Director National Soil Services Centre,
Department of Agriculture, Ministry
of Agriculture & Forest,
Thimphu, Bhutan
5
Dr. Ranjit Mapa
Senior Professor
Department of Soil Science
Faculty of Agriculture
University of Peradeniya
Peradeniya-20400
Sri Lanka
6
Dr.Y. G. Khadka, Ph.D.
Chief, Soil Science
Division
Nepal Agricultural Research Council
(NARC), Khumaltar, Lalitpur, Nepal
7
Dr. Md. Rafiqul Islam
Mondal
Director
SAARC Agriculture Centre
BARC Complex, Farmgate,
Dhaka-1215
8
Dr. S. K. Pal
Deputy Director
(Agriculture)
SAARC Agriculture Centre
BARC Complex, Farmgate,
Dhaka-1215
9
Mrs. Nasrin Akter
Senior Programme
Officer (Crops)
SAARC Agriculture Centre, BARC
Complex, Farmgate, Dhaka-1215
10
Dr. Nurul Alam
Senior Programme
SAARC Agriculture Centre, BARC
254
Strategies for Arresting Land Degradation In South Asian Countries
Sl. No. Name
Designation
Specialist (PSPD)
Address
Complex, Farmgate, Dhaka-1215
11
Dr. Biswapati Mandal
Professor
Bidhan Chandra Krishi
Viswavidyalay
Kalyani, dist. Nadia
West Bengal, India
12
Dr. A.M. Puste
Professor
Bidhan Chandra Krishi
Viswavidyalay
Department of Agronomy
P.O. Krishi Viswavidyalaya,
Mohanpur
Nadia, West Bengal, India
13
Prof. Dr. Zahurul Karim
Chairman, CASEED Former Secretary, Government of
Bangladesh & ex-Executive
Chairman, Bangladesh Agricultural
Research Council (BARC)
14
Mr. AZM Shafiqul Alam
Additional Secretary Ministry of Agriculture,
(PPC)
Government of Bangladesh
15
Prof. S.K. Sanyal
Vice Chancellor
BCKV, West Bengal, India
16
Dr. K. Das
Principal Scientist
NBSS & LUP (ICAR), Regional
Centre, Kolkata, India
17
Dr. D. Jena
Ex-Head
Department of Soil Science and
Agricultural Chemistry, OUAT
Bhubaneshwar, Orrisa, India
18
Dr. B.K. Bandhopadhyay
Head
CSSRI (ICAR), Canning Town,
Dist. 24-Parganas, West Bengal,
India
19
Dr. K.K. Satpathy
Director
NIRJAFT (ICAR), Kolkata, West
Bengal, India
20
Dr. P.S Roy
Dean & Assoc.
Director (Capacity
Building)
NRSC, ISRO, Dehradun, India
21
Dr. K.S Dillon
Retd. Profeesor
Department of Soil Science, PAU,
Ludhiana, India
22
Dr. D.C. Nayak
Principal Scientist
NBSS & LUP, Kolkata, India
23
Dr. B. Venkateshwalu
Director
CRIDA, Hyderabad, India
24
Dr. B.S. Mahapatra
Director
CRIJAF (ICAR), Barrackpore, West
Bengal, India
25
Dr. B.M. Jha
Chairman
Central Ground Water Board,
Strategies for Arresting Land Degradation In South Asian Countries
Sl. No. Name
Designation
255
Address
Faridabad, India
26
Dr. S.K. Singh
Principal Scientist & NBSS & LUP (ICAR), Reg. Centre,
Head
Kolkata, West Bengal India
27
Dr. Dipak Sarkar
Director
NBSS & LUP (ICAR), Nagpur,
India
28
Dr. A. K. Singh
Deputy Director
General (NRM)
ICAR, New Dehli, India
29
Dr. Pradip Sen
Jt. Director
(Research)
Govt. of West Bengal, India
30
Dr. T.H. Das
Principal Scientist
NBSS & LUP (ICAR), Regional
Centre, Kolkata, West Bengal, India
31
Dr. A. K. Sahoo
Principal Scientist
NBSS & LUP (ICAR), Regional
Centre, Kolkata, West Bengal, India
32
Dr. Amal Kar
Principal Scientist & Natural Resource and Environment
Head
Division.CAZRI, Jodhpur
33
Dr. Mohammed Osman
Principal Scientist
Central Research Institute for
Dryland Agril.(ICAR),
Santoshnagar, Hyderabad, India
34
Dr. Pradip Dey
Principal Scientist
CSSRI, Karnal, India
35
Dr. Ajoy Kr. Misra
Superintending
Geohydrologist,
Central Ground Water Board,
Kolkata, India
36
Dr. Gautam Bose
Principal Scientist,
NIRJAFT, Kolkata, India
256
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Strategies for Arresting Land Degradation In South Asian Countries
Appendix-E: Consultation Photo Album
257
258
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259
260
Strategies for Arresting Land Degradation In South Asian Countries
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