Download 4/FS/O/C - India Environment Portal

4/FS/O/C
The Hindu/ Delhi/ 24/ 10/ 07
Carbon sequestration for better dryland productivity
William D. Dar
Dryland farmers need innovative strategies to overcome their difficulties.
The world rejoices over the award of the 2007 Nobel Peace Prize to those who focussed
on climate change, yet even simple agricultural practices can greatly help mitigate this
global challenge. Climate change occurs when there is a build-up of carbon in the
atmosphere. However, if carbon is collected (or sequestered) in the soil and used to
increase productivity, the results are three-fold — a reduction in atmospheric carbon
levels, increased crop yields, and more inc ome for farmers.
Ironic as it may sound, in dryland agriculture the availability of organic carbon in the soil
is the key to increasing productivity. Hence, “look down at the soil to make your
agricultural productivity look up” is the new motto of agricultural scientists, especially
those working with natural resource management and watershed development. This,
however, calls for massive investment by developed and developing countries to support
dryland agricultural research and corresponding support systems.
Although there is much attention and support being given to irrigated agriculture,
drylands occupy 80 per cent of agricultural land and generate 58 per cent of the world’s
staple foods. In fact, most of the food for the poor in the developing countries is produced
in dryland and rainfed areas. More than 95 per cent of the farm land in sub-Saharan
Africa (SSA) is rainfed. In Latin America the figure is almost 90 per cent, in South Asia
about 60 per cent, in East Asia 65 per cent and in the Near East and North Africa 75 per
cent. In India, 66 per cent of the 142 million hectares of arable land is rainfed.
Rainfed areas are also hotspots of poverty, malnutrition, and child mortality. Of the one
billion poor people in the world, India accounts for 25.9 per cent and China 16.7 per cent.
The rest of the Asia-Pacific accounts for 18.3 per cent. Asia is a hub where the poor,
undernourished, and the vulnerable live. This is followed by sub-Saharan Africa, which
accounts for 23.9 per cent.
A close look at the rainfed regions shows a grim picture of water scarcity, fragile
environments, drought, and land degradation caused by low rainwater use efficiency,
high population pressure, poverty, poor infrastructure, and inappropriate policies.
Drought and land degradation are interlinked in a cause-and-effect relationship, which in
turn causes poverty. This unholy nexus among drought, poverty, and land degradation
must be broken if we have to meet the Millennium Development Goal of halving the
number of food-insecure poor by 2015.
Added to this is the threat of climate change. It is anticipated that climate change will
lead to more rainfall variability and increased frequency of extreme events, resulting in
more and longer dry spells due to global warming.
Soil is the key
Innovative strategies are required to help the dryland farmer overcome these difficulties.
As the world’s top research centre for dryland agriculture, the International Crops
Research Institute for the Semi-Arid Tropics (ICRISAT) in Andhra Pradesh is working
on increasing the organic carbon level in the soil through increased sequestration
(accumulation from the environment).
Soil organic carbon is the source of energy to fuel biological activities in the soil, which
in turn control the availability of nutrients for plant growth as well as soil water
availability — a critical yield component in tropical drylands.
Long-term watershed management experiments at the ICRISAT campus at Patancheru
over the last 33 years have consistently demonstrated that drylands can produce 5.1
tonnes of grain per hectare a year, supporting 21 persons as compared to 1.1 tonnes of
grain per hectare a year supporting 4.8 persons in case of farmers’ practice. Moreover,
the system is still gaining at the rate of 78 kg of grain per hectare a year, and the new
equilibrium is yet to be reached.
Along with increased productivity, improved watershed management practices
sequestered 330 kg of carbon per hectare a year up to a depth of 120 cm by intercropping
sorghum and pigeon pea. Increased carbon sequestration not only increased nutrient
supply and turnover capacity of the soil but resulted in substantial changes in the physical
and biological properties of the soil, which increase water holding capacity and the ability
to cope with longer dry spells during crop growth.
Moreover, ICRISAT’s research has shown that legumes in general and pigeon pea in
particular have the ability to sequester more carbon in tropical soils. Through the
adoption of improved water, soil and crop management options, carbon sequestration in
legume-based systems can be improved further. If this is adopted within an integrated
community watershed, the productivity of rainfed agriculture can be doubled, providing
increased incomes to farmers.
Thirst and hunger
Tropical soils are not only thirsty but also hungry, particularly for micronutrients such as
zinc, boron, and secondary nutrients such as sulphur, along with macronutrients such as
nitrogen and phosphorus. ICRISAT’s work has shown that by adopting integrated
nutrient management after testing the soil for deficiencies and combining it with
improved crop varieties and water management, rainwater use efficiency can be increased
by up to 65-70 per cent along with increased productivity and improved livelihoods.
ICRISAT has strengthened its research in partnership with the Indian Council of
Agricultural Research under the National Agriculture Technology Project (NATP)
funded by the World Bank. A study of 58 samples from 28 benchmark spots in the
drylands of India revealed that black soils as well as red soils have the potential to
sequester carbon by adopting suitable cropping with high-yielding varieties and legumes,
along with management practices such as water management and the use of green
manure.
ICRISAT works with a consortium of partners including national agricultural research
systems, State agricultural universities, civil society organisations and farmers’
organisations. Along with accumulating carbon in the soil, our work has led to
convergence, collective action and capacity building to empower dryland communities.
ICRISAT’s watershed development model has been widely accepted in India, China,
Thailand, and Vietnam in Asia. It is also moving to Eastern Africa through South-South
cooperation.
(The writer is Director-General of ICRISATand Chair of the Committee for Science and
Technology of the United Nations Convention to Combat Desertification, the CSTUNCCD).