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Journal of Environmental Science and Management 12(1):25-41 (June 2009)
ISSN 0119-1144
Assessment of Ecosystem Services of Lowland Rice Agroecosystems in
Echague, Isabela, Philippines
Januel P. Floresca, Antonio J. Alcantara, Corazon B. Lamug, Corazon L. Rapera,
and Candida B. Adalla
ABSTRACT
Ecosystem services are the benefits people obtain from ecosystems. In lowland rice
agroecosystems, these include regulating services on groundwater recharge, nutrient cycling and
biological control of insect pests and grain yield provisioning service. These ecosystem services were
estimated and analyzed in NIA irrigated and pump irrigated lowland rice farms during wet season
2005 and dry season 2006 in two barangays of Echague, Isabela.
Groundwater recharge, which was estimated based on saturated hydraulic conductivity and
growing period with standing irrigation water in the paddy, was 2,421.7 m3 ha-1 cropping-1. Soil
nutrient cycling, which was estimated using the rice straw yield and its nutrient content,
consisted of 16.9 kg N ha-2, 12.0 kg P2O5 ha-2 and 55.8 kg K2O ha-1 cropping-1. Biological control of
insect pests by spiders expressed in terms of predator-prey ratio was 9:61 and 7:24 in the wet
season 2005 and dry season 2006, respectively. Rice grain yield was 3,530.7 kg-1 ha-1 cropping1.
The assessment was done using transdisciplinary research methods. Methodologies in
agronomy, soil hydrology and insect ecology were used to estimate the amounts of ecosystem
services and environmental psychology was used to explain why farmers used different farm
management practices based on their knowledge, attitudes, perceptions and resources
constraints. Farm management practices affected the amounts of ecosystem services.
Key words: ecosystem services, lowland rice agroecosystems, transdisciplinary research
INTRODUCTION
Ecosystem services are the benefits people
obtain from ecosystem functions (Contanza et al.
1997; Cork et al. 2001; Cork 2001; UN 2003).
These include provisioning services such as food,
fuel, and fiber; regulating services such as
climate regulation and flood control, nutrient
cycling and biological control of insect pests.
Changes in these services affect human
well-being in many ways (UN 2003). Among the
direct drivers of change are the external inputs
such as irrigation, fertilizers and pesticides.
A ubiquitous feature of the Philippine landscapes,
rice fields cover 12% of the country’s total land
area. Much is known about the economic impact
of rice fields and its effects on the social and cultural
systems. However, very little research has been
done on how rice farms have affected the ecological
dynamics of the tropical ecosystems. Considering
that majority of the Philippine population depend
highly on rice for their nutrition and on rice farming
for livelihood, the need to understand the larger
ecological implications of allocating scarce lands to
rice production is now urgent. A good understanding
of how rice fields, as ecosystems, contribute to the
wider range of ecosystem services is needed (ARF
2000).
The ecosystem services of lowland rice
agroecosystem need to be assessed to enhance
productivity, food safety, and environmental
protection. The assessment of the ecosystem
services should be in the context of change in
sources and levels of inputs, outputs and
environmental burdens brought about by variations
in season and cultural practices.
This study sought to answer the following
Assessment of Ecosystem Services of Lowland Rice Agroecosystems
in Echague, Isabela, Philippines
26
questions: 1) How can the ecosystem services on
groundwater recharge, soil nutrient cycling,
biological control of insect pests and crop yield
of lowland rice agroecosystem be measured? 2)
Are the magnitudes of ecosystem services of
lowland rice agroecosystems affected by the kind
and level of inputs brought about by variations in
farming practices and cropping seasons?
by the farmer according to his knowledge,
perceptions, attitudes and resources constraints to
implement the farming activities on irrigation,
land preparation, seedling establishment,
fertilization, pest management, harvesting,
marketing and by-product utilization.
The farm inputs are obtained either from
natural sources (creeks or rivers for irrigation
water, organic materials from rice straws or
weeds, and biological control agents like spiders)
or from man-made sources (inorganic or organic
fertilizers, and pesticides). Rice farmers may opt
to mainly use man-made inputs rather than natural
inputs with some trade-offs on input levels,
which would change the output levels (dry grain
yield and rice straws) and other ecosystem
services.
The conceptual framework on the assessment
of ecosystem services of lowland rice
agroecosystem is presented in Figure 1. The
lowland rice agroecosystem is described in terms
of its structure and functions. The structure refers
to the arrangement by which the components
(biophysical and socioeconomic components) are
interacting in space and time while function
refers to how the various components interact to
pr oduce ecosystem ser vices like gr ain
production, recharge of groundwater, as well as
nutrient cycling and biological control of insect
pests.
Ecosystem services of lowland rice
agroecosystem are outputs produced from the
farming activities provided with farm inputs.
Outcomes of these outputs vary because of varied
kinds and levels of inputs applied for each farm
activity and varied biophysical characteristics.
The kinds and levels of inputs depends on the
farm management practices/technologies opted
Lowland Rice Agroecosystem
Biophysical Conditions
Socioeconomic Conditions
•
•
•
•
•
•
•
•
Climate
Topography
Soil & Water Resources
Flora & Fauna
Income/Capital, Land Tenure
Technology, Market
Perceptions
Attitudes/Preferences
Kinds & Levels of Inputs
Assessment
(InputOutput
Analysis)
•
•
•
•
•
•
•
Land preparation
Method of planting
Irrigation
Fertilizer application
Pest management
Harvesting
By-product utilization
Ecosystem Services
Regulating/Supporting
Services (Non-marketed)
•
•
•
Groundwater recharge
Soil nutrient cycling
Biological pest control
Grain Yield
Provisioning Service
(Sale; Household
consumption; Seeds;
Payment of labor)
Figure 1. Conceptual Framework on the assessment of ecosystem services of lowland rice ecosystems.
Journal of Environmental Science and Management Vol. 12. No. 1 (June 2009)
The provisioning service on grain yield is the
amount of palay harvested from the rice plant.
Regulating services which include groundwater
recharge, soil nutrient cycling and biological control
of insect pests are those residual products resulting
from the ecological processes (water and nutrient
cycle, predation) during the rice growing period.
Groundwater recharge is the output derived
from the percolation/infiltration of irrigation water
applied in the rice fields. It is dependent on the
porosity of the soil that regulates its flow rate
through the soil. Groundwater recharge volume
builds as standing water remains in the fields
during the cropping period.
Nutrient cycling is the reuse of mineralized
nutrients in the rice plant dead biomass (rice
straw) for the next rice cropping. The more rice
straws are recycled, the higher the nutrient
cycling. This depends on the farmer’s preference
or decision to manage the rice straw whether to
use it for compost, or just leave them in the field
to be plowed under, pile or burn. Plowing under
rice straw left in the field undergoes anaerobic
decomposition that emits large amounts of methane
that contribute to global warming.
Biological control of insect pests is the natural
regulation of insect pest population through
predation of spiders that consume insect pests,
which result in the prevention of crop damage.
Due to slow effect of biological control to control
pests, farmers use insecticides with varied toxicity
levels. The more toxic insecticides kill more
predators.
The quantified magnitudes of ecosystem
services would be used as the basis for valuation
of the economic benefits derived from these
ecosystem services. The total economic value of
ecosystem services will be used as basis for
decisions and policies to protect lowland rice
lands from conversion to other non-agricultural
uses.
The general objective of this paper was to
elucidate the assessment of grain yield, groundwater
recharge, soil nutrient cycling and biological
control of insect pests as ecosystem services of
lowland rice agroecosystems with different sources
27
sources of irrigation and cropping seasons.
Specifically, the paper explained the following
methodologies:
1. Estimation of the magnitude of each of
the four ecosystem services;
2. Analysis of the effects of the different
farm management practices (e.g. irrigation,
method of planting, fertilizer application,
pest control) and biophysical conditions
(e.g. soil type, cropping seasons) on the
ecosystem services;
3. Analysis of the farmers’ behaviors (shown
from their existing farm management
practices) and attitudes toward each
ecosystem service; and
4. Discussion of the significance and
implications of the magnitudes of the four
ecosystem services.
MATERIALS AND METHODS
Selection of the Study Sites, Sample Farms
and Farmer Respondents
The study sites were selected based on the
source of irrigation, landscape position of the
farms and training of farmers on IPM for lowland
rice production. The lowland rice farms in
Barangay Sta. Monica represented the NIA
irrigated farms in the floodplain while those in
Barangay San Manuel represented the pump
irrigated farms on rolling areas.
A total of 12 sample farms were randomly
selected in each study site using simple random
sampling without replacement. The farmers of
these sample farms were the respondents for
personal interview on socio-demographic and
economic information, rice cultural practices,
crop yield and profitability of rice farming and
perceptions of and attitudes toward the ecosystem
services.
The names of the farmer respondents were
identified from the masterlist provided by
agricultural technicians (ATs) of the Department of
Agriculture (DA), Echague, Isabela. Personal
interviews were conducted using a pre-tested
survey questionnaire.
28
Assessment of Ecosystem Services of Lowland Rice Agroecosystems
in Echague, Isabela, Philippines
Assessment of Ecosystem Services of Sample Farms
The assessment of four ecosystem services of
the sample farms focused on the estimation of
grain yield, groundwater recharge, soil nutrient
cycling and biological control of insect pest of
rice. The quantification was basically done using
input-output analysis. The kinds and levels of
inputs were determined from farmers interview
on method of land preparation and growing period
of direct seeded or transplanted lowland rice,
frequency and time of irrigation, kinds of fertilizers
used (inorganic, organic or foliar) amount applied,
method (basal or topdress) and time of application,
kinds and amount of pesticides used (insecticides,
herbicides and molluscicides), frequency/time of
application, price of pesticides. Rice grain and
straw yield were determined.
Estimation of groundwater recharge. The
recharge of groundwater is the infiltration
(percolation) of surface water from soil top to the
Vadose water zone and farther to the aquifer in the
rice field during the rice-growing season. The
estimation of the amount of recharged water was
based on three factors: effective area of rice field, soil
infiltration rate, and number of irrigation days when
fields had standing water (Matsuno et al. 2002).
The estimated groundwater recharge of a farm
is the product of saturated hydraulic conductivity
(mm d-1) and total number of days the rice fields
were saturated with water. The equation to estimate
groundwater recharge is as follows:
GWR = 10 KT x DWS
where:
GWR = volume of groundwater recharge (m3 ha-1)
KT = saturated hydraulic conductivity (mm day-1)
DWS = days of water saturation of rice fields
Measurement of saturated hydraulic
conductivity (KT). Since the soils in the rice
fields were saturated, soil infiltration (or percolation)
was estimated using Darcy’s saturated hydraulic
conductivity (KT) - falling head method.
2.3 x a x L
H1
KT (cm s-1 at ToC) = -------------------- x log10 --Axt
H2
a
H1
= 0.598 x --- x log10 --------t
(H-H1)
where:
a = cross-sectional area of stand pipe (cm2)
L = length of soil sample (cm)
A = cross-sectional area of soil sample (cm2)
H1 = height from water level of bath to initial
water level in stand pipe
H2= height from water level of bath to final
water level in stand pipe = H – H1
Three sample points in each sample farm
were established with three eight-inch dm x 30
cm deep permeameters made of GI sheet. The
permeameters were inserted into the paddy soil
up to the hard pan and its reading gauge (1 cm
diameter hose) was filled with water up to 50 cm
level. Readings on the downward logarithmic
trend of water were recorded every hr for eight
hrs measurement.
Estimation of Soil Nutrient Cycling. Soil
sampling was done once before plowing for each
cropping season. Two sets of composite soil samples
(approximately 1 kg) were collected from the
paddy fields of each sample farm– one set for
wet season (WS) 2005 and one set for dry season
(DS) 2006. The samples were air dried and analyzed
for total N and available P, K and Zn at the DA
Soils Laboratory, Ilagan, Isabela. The gap between
the farmers’ actual fertilizer application and
recommended levels were determined.
Soil nutrient cycling was estimated in terms
of the potentially recyclable soil nutrients (N, P,
K) provided by rice straw biomass for the next
cropping season. The recent data of Obcemea et
al., (2005) on nutrient contents of rice straw
(0.48% N, 0.34% P2O5 and 1.58% K2O) were
used. The estimated amount of rice straws was
based on a grain-straw ratio of 1:1 wherein the
dry grain yield (kg ha-1) was approximately
equivalent to the biomass (kg ha-1) of rice straws
produced.
Rice straws left in the fields and piled after
threshing were also estimated using samples
collected from a one sq. m. area in each farm.
The samples were sun dried, weighed and
calculated on a per hectare basis. These rice
straws left in fields could undergo anaerobic
decomposition in paddy soils, which would emit
larger amounts of greenhouse gases such as methane
Journal of Environmental Science and Management Vol. 12. No. 1 (June 2009)
(CH4) and ammonia (NH3) that contribute to global
warming. If the rice straws are burned, CO2 and
smog will also be emitted.
Estimation of Biological Control of Rice
Insect Pests. Biological control of rice insect
pests was estimated in terms of the predator-prey
ratio which is the ratio of sample population of
generalist predators specifically spiders to sample
population of insect pests (including worms and
flying insects) which were collected using sweep
net. The sweep net was used for sampling insects
such as leafhoppers, worms, rice bugs and spiders.
The efficiency of the method depends on the
stage of the crop, the speed of sweeping, the angle
of the net and the type of insect being sampled.
Sampling is best done in the early morning or late
afternoon when insects and spiders are usually most
active. Collection of spider and insect pest
samples for each farm was done at 50-70 days
after sowing (DAS) during the booting to heading
stages.
Estimation of Grain Yield. Using the data
obtained from personal interviews with farmer
respondents, grain yield was estimated in terms
of the dry grain equivalent of the total harvest
(threshed yield) without deducting the amount of
palay utilized for various purposes such as sold
either fresh (newly threshed) or dried grain,
payments in-kind for irrigation service fee (ISF)
to NIA, harvester share, thresher share as well as
palay stored for household consumption and
seeds for the next cropping. The equivalent dry
grain yield was based on observed shrinkage of
about 19.4% of newly threshed yield according
to one of the farmer respondents.
Statistical Analyses
The biophysical characteristics of the rice
landscapes were described using means and
ranges. The socio-demographic/economic
characteristics of the farmer respondents and
their behaviors as shown in their existing farming
practices were described using frequency analysis.
Also, using a five-point Likert scale of
agreements or disagreements, the farmers’
attitudes toward each ecosystem service were
analyzed using frequency analysis.
29
Comparison of means using t Test (paired for
even data and two sample equal variance for
uneven data) was used to compare the estimated
ecosystem services among farms with different
sources of irrigation, cropping seasons and
methods of seedling establishment.
Analysis of variance was used to determine
differences in predator-prey ratios among three
types of insecticides (green, blue and yellowcoded).
RESULTS AND DISCUSSION
Biophysical Characteristics of the Study Sites
Location and Accessibility. Barangay Sta.
Monica is located three km southwest of
Barangay Ipil, Echague, Isabela, the major palay
trading center located at Maharlika Highway. On
the other hand, Barangay San Manuel is located
10 km southwest of Barangay Ipil. Both study
sites (Barangays Sta. Monica and San Manuel)
are accessible to all types of vehicles through a
gravel barangay road.
Topography. The landscape of Barangay Sta.
Monica is generally flat with patches of slightly
rolling areas in the western part. Its elevation
ranges from 70 to about 100 m above sea level
(masl). The 12 sample farms were situated within
70 – 75 masl (Figure 2). On the other hand, the
landscape of Barangay San Manuel is rolling
with elevations ranging from 70 to about 100
masl. The 12 sample farms are situated within 70
– 80 masl (Figure 3).
Climate. The climatic conditions in the two
study sites are similar. They belong to Type III
which is characterized by no pronounced wet and
dry season, relatively wet from May to October,
dry for the rest of the year.
Water Resources. Based on rainfall pattern
in Echague, Isabela obtained from the Philippine
Astronomic, Geophysical, and Astronomical
Services Administration (PAGASA) Agromet
Station at Isabela State University, the amounts
of water available for irrigation in the wet and
dry seasons were 191.9 and 111.0 mm mo-1,
respectively.
30
Assessment of Ecosystem Services of Lowland Rice Agroecosystems
in Echague, Isabela, Philippines
Figure 2. Topographic and land use map of Barangay Sta. Monica showing the 12 NIA irrigated sample
farms in the 322 ha rice landscape.
Figure 3. Topographic and land use map of Barangay San Manuel showing the 12 pump irrigated
sample farms in the 250 ha rice landscape.
Journal of Environmental Science and Management Vol. 12. No. 1 (June 2009)
The surface water resources of Barangay Sta.
Monica are the NIA - Magat River Integrated
Irrigation System (MRIIS) gravity earth canals
and creeks (draining to the Ganano River). However,
farmers depend primarily on the NIA irrigation
canal as the source of irrigation water for their
year-round (two croppings) rice production. On
the other hand, the surface water resources of
Barangay San Manuel are the impounded creeks
(locally called “tanggal”) draining to the
Dumatata River. Farmers depend primarily on
centrifugal pumps for irrigation of rice fields in
their year-round (two croppings) rice production.
Farmers’ Existing Farming Practices
Irrigation. Irrigation by flooding was done
two days before plowing the paddy fields. The
rice farms in Barangay Sta. Monica were served
with the NIA irrigation canals while in Barangay
San Manuel, farmers used centrifugal pumps to
draw irrigation water from nearby impounded
creeks (“tanggal”).
Land Preparation. Land preparation in both
sites was similar. Most of the rice paddies were
prepared using hand tractor and draft animals.
Rice Variety Used. Most rice farmers used
one inbred rice variety per cropping that was
either purchased from traders or DA, or exchanged
with other farmers. Late maturing hybrid rice
varieties such as Mestizo 1 (M1) were used for
wet cropping season while early maturing
varieties such as M3 were used for dry season
cropping.
Method of Planting. Planting was done either
by direct seeding or transplanting. In Barangay
Sta. Monica, most farmers (58.3%) practiced
direct seeding while in Barangay San Manuel,
about 92% practiced transplanting.
Fertilizer Application. All farmers were
applying fertilizer without conducting soil analysis.
Most farmers did not burn rice straws, but only
left them in the fields after harvest and after
threshing, piled the rice straws in one paddy.
Foliar fertilizers were used by mixing with
insecticides and sprayed at late vegetative to
flowering stages.
31
Pest Control. The most common rice insect
pests observed by the farmers were green leaf
hopper (GLH), armyworm, cutworm and rice
bug. Most farmers claimed that rice bug was the
most damaging and thus mandatory spraying of
insecticide was done once or twice during the
milking stage. Golden kuhol damaged the crop
during the seedling stages.
Harvest and Postharvest. Harvesting in all
the sample farms was done manually using
scythe. Threshing in all the sample farms was
done using mechanical thresher. Hauling was
done through cart (“patuki”) pulled by carabao.
In the absence of mechanical dryers, sun drying
of grain was the common practice of farmers. In
both barangays, the farmers’ produce was usually
sold to the trade center in Barangay Ipil,
Echague, Isabela.
Reduction of Inputs. The farmers employed
certain techniques to conserve/minimize irrigation,
fertilizer and pesticide inputs and/or reduce
losses. They were able to save half to two bags
inorganic fertilizer (urea) by using organic fertilizers.
The use of organic fertilizer also resulted to
reduction in water application. A farmer also
observed lessening of top dress of paddy where
rice straws had been piled in the previous planting.
More farmers applied their knowledge on IPM by
monitoring first their fields (e.g., see if there were
more flying insects) before applying pesticides.
Farmers Attitudes toward Ecosystem Services
Attitudes toward Groundwater Recharge.
Most of the farmers (92%) in the NIA irrigated
farms agreed that groundwater recharge is an
important source of irrigation water, 75% agreed
that irrigation water in the rice fields infiltrates
into the soil and recharges groundwater, and 83%
agreed on the need for the protection of the
watershed/subcatchment to sustain the availability of
groundwater. About 83% of the farmers in the pump
irrigated farms strongly agreed that groundwater
recharge is an important source of irrigation
water, 75% strongly agreed that irrigation water in
the rice fields penetrates the soil and recharges
groundwater, and 83% strongly agreed on the need
for the protection of the watershed/subcatchment
to sustain the availability of groundwater.
32
Assessment of Ecosystem Services of Lowland Rice Agroecosystems
in Echague, Isabela, Philippines
Attitudes toward Soil Nutrient Cycling. In
the NIA irrigated farms, 58% of the farmers
agreed and 42% strongly agreed that rice straws
left in the fields contain nutrients usable by rice
plants for the next cropping, and that decomposed
rice straws would improve soil fertility and would
reduce application of commercial inorganic fertilizers.
On the other hand, in the pump irrigated farms,
83% agreed and 17% strongly agreed that rice
straws left in the fields contain nutrients usable
by rice plants for the next cropping, and that
decomposed rice straws would improve soil
fertility and would reduce application of
commercial inorganic fertilizers.
Attitudes toward Biological Control of Insect
Pests. Most farmers in both study sites agreed
that there are a number of beneficial arthropods
(insects, spiders) present in rice fields that feed
on insect pests; beneficial insects/predators/
spiders are killed when spraying pesticides; more
spiders are killed when more frequent spraying
are done or more toxic pesticides are applied; and
pesticides have harmful effects on human health.
Attitudes toward Grain Yield. Based on
the five-point Likert Scale, most farmers agreed
(83.3%) and some strongly agreed (16.7%) that
their rice yield provides sufficient food and
income for their household’s basic needs, even
extra incomes for education, appliances and
purchase of farm equipment as well as providing
them inputs or payments for inputs (e.g.
irrigation service fee and farm labor).
Assessment of Groundwater Recharge
Water management practices in the study
sites. In Barangay San Manuel, centrifugal
pumps were used to lift water from the impounded
water (“tanggal”) along creeks to the farm and
applied every three days with 5 cm of flood water
in the paddy while in Barangay Sta. Monica, NIA
gravity irrigation system provided continuous
flooding of 5-15 cm d-1 (2-6 inches) depth. For
the direct seeded rice crop, the rice fields were
irrigated for 106 and 96 days during the WS 2005
and DS 2006, respectively. On the other hand, for
the transplanted rice crop, the fields were irrigated
for 94 and 86 days during the WS 2005 and DS
2006, respectively.
Bhuiyan et al. (1995) reported that less water
was used during land preparation for wet seeded
rice (WSR) because of shorter time to complete
land preparation activities compared with
transplanted-rice farms. In WSR, seeds required
only 24–36 hrs of soaking and incubation to be
ready for sowing in the field.
In the transplanted-rice scheme, seedlings
were nurtured in the seedbed for about one
month and farmers would not prepare the land
unless the seedlings were ready for transplanting.
In other countries such as China, where land
preparation was already very short, seedlings
were raised in well-confined places such that
farmers can irrigate just the seedbeds without
having to spread irrigation all over the field
(Guerra et al. 1998).
Saturated hydraulic conductivity and
groundwater recharge. The mean saturated
hydraulic conductivity of the soils in the NIA
irrigated farms was 2.4 mm d-1 while in the pump
irrigated farms was 2.8 mm d-1 as shown in Table
1. There were no significant differences in
saturated hydraulic conductivities among farm
types because the study sites belong to the same
soil type which is Cauayan clay loam.
Table 1. Saturated hydraulic conductivity of soils
of the sample farms in the study sites,
CY 2006.
Site
NIA Irrigated Farms
Pump Irrigated Farms
Hydraulic conductivity
(mm d-1)
2.4
2.8
Comparison of Means
NIA vs pump irrigated farm is not significant (ns)
In the NIA irrigated farms, the mean
estimated groundwater recharge for direct seeded
rice was 2,669.3 m3 ha -1 cropping-1 while the
estimate for transplanted rice crop was 1,854.0
m3 ha-1 cropping-1. In the pump irrigated farms,
the mean estimated groundwater recharges were
2,626.0 and 2,503.6 m3 ha-1 cropping-1 for direct
seeded and transplanted crops, respectively
(Table 2).
The estimated groundwater recharges
significantly differed among direct seeded and
transplanted rice crops in the NIA irrigated farms
33
Journal of Environmental Science and Management Vol. 12. No. 1 (June 2009)
but not in the pump irrigated farms where most
farms (11 out of 12 farms) where transplanted.
The direct seeded rice crop required a longer
growing period with standing irrigation water in
the paddy than the transplanted rice crop. The
estimated groundwater recharges in the wet season
crop were significantly higher than those in the
dry season crop in both sites (Table 2). During
the wet season when farmers used late maturing
varieties, the growing period was longer. Early
maturing varieties were used in the dry season.
The total irrigation requirement of rice
(evapotranspiration + seepage and percolation
losses) is 1,750 mm cropping-1 or 17.5 mm d-1
(for 100 days crop growth period) (Bouman,
2001). Percolation of irrigation water into the
groundwater of lowland irrigated landscape
contributes to groundwater recharge. This could
be used for irrigation when this is pumped out
from the area. It could contribute about 13.7% of
irrigation water in NIA irrigated farms and about
16% in pump irrigated farms if groundwater
would be used.
Farmers’ behavior and attitudes toward
groundwater recharge. The existence of small
water impoundments (“tanggal”) along creeks
and even from non-impounded creeks enabled
the farmers in the pump irrigated farms to use
surface water instead of groundwater with shallow
tube well (STW) pumps to irrigate their rice
fields. They used transplanting method instead of
direct seeding to reduce fuel consumption for
pumping irrigation water. On the other hand,
there was no indication on the need for pumping
groundwater by farmers in the NIA irrigated
farms despite late arrival of irrigation water in
the main canal considering their location being in
the downstream of the Magat Dam in Ramon,
Isabela which is about 35 km away. Most of the
farmers practiced direct seeding because of
sufficient and continuous supply of irrigation
water from the main canal.
In spite of their recognition of the importance
of groundwater for irrigation, farmers in both
study sites did not have activities (either as
individual or as organized group) to protect the
groundwater through the protection of the
subcatchment’s natural vegetation or watershed
as the major source of groundwater recharge.
Assessment of Soil Nutrient Cycling
Fertilizers applied in the sample farms. Actual
application of inorganic fertilizers by farmer
respondents did not match with the fertilizer
recommendations based on the soil chemical
analysis. There was an apparent excessive use of
urea (46-0-0) and complete fertilizer (14-14-14)
which farmers applied as topdress. All farmers
were not able to apply the recommended 10 kg
ZnSO4 ha-1 before planting.
In the NIA irrigated farms, the levels of N
applied was only significantly higher than the
recommended levels in WS 2005 for inbred rice
plants, while for hybrid rice plants, the levels of
N applied did not differ significantly with
recommended levels in both cropping seasons
(Table 3). On the other hand, in the pump
irrigated farms, the levels of N applied for inbred
rice plants did not significantly differ with
recommended levels among cropping seasons
while for hybrid rice plants, the levels of N
applied in both cropping seasons were significantly
lower than the recommended levels.
Only the actual levels of P application for
Table 2. Groundwater recharge (m-3) in the study sites, WS 2005 and DS 2006.
Method of
Planting
NIA Irrigated Farms
Pump Irrigated Farms
Mean
Direct seeded
WS 2005
2,801.4 (7)
DS 2006
2,537.1 (7)
WS 2005
2,756 (1)
DS 2006
2,496 (1)
2,663.9
Transplanted
1,936.4 (5)
1,854.0 (5)
2,614.9 (11)
2,392.4(11)
2,300.6
Comparison of Means
Direct Seeded vs Transplanted
NIA Irrigated Farms (WS + DS)
significant at 5%
Assessment of Ecosystem Services of Lowland Rice Agroecosystems
in Echague, Isabela, Philippines
34
hybrid and inbred rice plants were significantly
different during DS 2006 in the NIA irrigated
farms (Table 3).
Rice straws left in the fields after harvest
were plowed under and mixed with saturated soil
during land preparation for the succeeding crop
with short fallow period. However, large amounts
of rice straws underwent anaerobic decomposition
in paddy soils that emit greenhouse gases
(GHGs) like methane (CH4) and nitrous oxide
(N2O). These GHGs contribute to global warming.
Estimated rice straw production. The
estimated rice straw yield for the inbred rice was
higher in WS 2005 than in DS 2006 in both study
sites (Table 4). Similar pattern was observed for
hybrid rice in the pump irrigated farms. The
amount of rice straw left in the field was
significantly lower than the straw yield with
inbred rice in WS 2005. Overall, about 81% of
the rice straw was left in the field. The rest was
piled in a paddy where mechanical threshing was
performed.
The estimated rice straw plowed under in the
NIA irrigated farms was 3,208.33 and 2,750.00
kg ha-1 for WS 2005 and DS 2006, respectively,
while the estimated rice straw biomass plowed
under in the pump irrigated farms were 3,083.33
and 2,500.00 kg ha -1 for WS 2005 and DS 2006,
Table 3. Comparison between the recommended and actual fertilizers levels (kg ha-1) for inbred and
hybrid rice plants in the two study sites, WS 2005 and DS 2006.
Fertilizer Use
Recommended
Actual
Recommended
Actual
NIA Irrigated Farms
Pump Irrigated Farms
WS 2005
DS 2006
WS 2005
DS 2006
N
P205 K20
N
P205 K20
N
P205 K2O
N
P205 K20
Inbred rice plants
59.1 25.5 34.1
78
22
31.5
60
30
15
75
25
30
84.5 27.5 24.9
86.6 26
23
70.1
28.6
12.7
76.9
37
18
Hybrid rice plants
120
30
30
100
23.3
15
120
30
30
105
54
24
70.6
52.6
24.5
67.1
42.6
19
Comparison of Means
NIA Irrigated Farms (WS 2005)
N
significant
Recommended vs Actual fertilizer level for hybrid
Pump Irrigated (WS 2005)
N
significant
Pump Irrigated (DS 2006)
N
significant
Actual fertilizer levels for Inbred vs Hybrid
Pump Irrigated ( DS 2006)
P
0.003
significant
Table 4. Rice straws yield and left in the fields after harvest by plant type, WS 2005 and DS 2006.
Parameter
Straw yield
(kg ha-1)
Straw left in
the field (%)
NIA Irrigated Farms
Inbred
WS 2005
DS
2006
4,125.2
3,396.9
(11)
(10)
78
85
Comparison of Means
Pump Irrigated Farms
Hybrid
Wet
Dry
2005
2006
2,739.0
(2)
73
P
2 samples;
equal variances
Rice Straw Produced vs Rice Straw Left after Harvest
NIA Irrigated , Inbred (WS 2005)
0.009
significant
Inbred
Wet
Dry 2006
2005
3,178.8
2,809.5
(6)
(4)
84
80
Hybrid
Wet
Dry
2005
2006
3,986. 3,436.9
0 (6)
(8)
88
79
35
Journal of Environmental Science and Management Vol. 12. No. 1 (June 2009)
ha-1 K2O for WS 2005 and 12.0 kg ha-1 N, 8.5 kg
ha-1 P2O5, 39.5 kg ha-1 K2O for DS 2006 (Table 5).
respectively (Table 4).
Rice straws produced after threshing were
usually piled in one paddy (for all the sample
farms) to decompose for the next season crop.
The estimated amounts of rice straw piled after
threshing in the NIA irrigated farms were 22 and
21 % of the straw yield for WS 2005 and DS
2006, respectively while in the pump irrigated
farms, these were 14 and 21 of the straw yield for
WS 2005 and DS 2006, respectively (Table 4).
Soil nutrients from rice straws piled after
threshing. The amount of rice straws piled in
one paddy after threshing was higher in the wet
than in the dry season. However, its full utilization
depends on farmers’ preference either to compost
or use these for other purposes (e.g., mushroom
production).
If the piled rice straws were burned, large
amounts of nutrients (80% of N, 25% of P and
21%of K) would be lost and large amounts of
smog air pollutant and CO2 would be emitted to
the atmosphere that could eventually contribute
to global warming (Mandal et al. 2004).
Soil nutrients in rice straws produced.
Obcemea et al. (2005) reported that the nutrient
content of rice straw was 0.48%N, 0.34%P2O5
and 1.58%K 2O. Based on these values, the
estimated amounts of nutrients in the rice straws
in the NIA irrigated farms were 19.7 kg ha -1 N,
14 kg ha-1 P2O5, 64.9 kg ha-1 K2O for WS 2005
and 15.8 kg ha-1 N, 11.2 kg ha-1 P2O5, 51.9 kg ha-1
K2O for DS 2006 (Tables 5). On the other hand,
in the pump irrigated farms, these were 17.2 kg
ha-1 N, 12.2 kg ha-1 P2O5, 56.6 kg ha-1 K2O for
WS 2005 and 15.1 kg ha-1 N, 10.7 kg ha-1 P2O5,
49.7 kg ha-1 K2O for DS 2006 (Tables 5).
Farmers’ behaviors and attitudes toward
soil nutrient cycling. All farmer respondents did
not scatter in the rice field composted rice straws,
which were piled after threshing from the previous
crop, because they perceived it to be laborious and
time-consuming. Although farmers did not burn the
rice straws, which may have resulted to large amounts
of nutrients loss and carbon dioxide and smog
emission that could contribute to global warming,
benefits from rice straw utilization were not
maximized. Farmers appreciated the fertilizer potential
of rice straw but did nothing to fully utilize it.
Soil nutrients from rice straws plowedunder. The nutrients (N-P2O5-K2O) from rice
straws plowed under in the NIA irrigated farms
were 15.4 kg ha-1 N, 10.9 kg ha-1 P2O5, 50.7 kg
ha-1 K2O for WS 2005 and 13.2 kg ha-1 N, 9.4 kg
ha-1 P2O5, 43.5 kg ha-1 K2O for DS 2006. On the
other hand, in the pump irrigated farms, these
were 14.8 kg ha -1 N, 10.5 kg ha -1 P2O5, 48.7 kg
Assessment of Biological Control of Insect Pests
Insect pests and spiders population and
Table 5. Nutrient content of the rice straw yield, rice straw left standing in the field and of the harvested
rice straw with threshed panicles. WS 2005 and DS 2006.
Site
Total Rice Straw
Yield
N
P2O5
NIA Irrigated Farms
Pump Irrigated Farm
Site- mean (2 SITES)
19.7
17.2
18.5
14.0
12.2
13.1
NIA irrigated Farms
Pump Irrigated Farms
Site-Mean
MEAN (2 SEASONS)
15.8
15.1
14.4
16.9
11.2
10.7
10.9
12.0
Rice straw Left in the
field
Harvested Rice Straw
with Threshed Panicle
Nutrient Content (kg ha-1) **
K2 0
N
P2O5
K2 0
N
WS 2005
64.9
15.4
10.9
50.7
4.3
56.6
14.8
10.5
48.7
2.4
60.8
15.1
10.7
49.7
3.4
DS 2006
51.9
13.2
9.4
43.5
2.6
49.7
12.0
8.5
39.5
3.1
50.8
12.6
8.9
41.5
2.8
55.8
13.9
9.8
45.6
3.1
P2O5
K2 0
3.1
1.7
2.4
14.3
7.9
11.1
1.8
2.2
2.0
2.2
8.7
10.2
9.3
10.2
Assessment of Ecosystem Services of Lowland Rice Agroecosystems
in Echague, Isabela, Philippines
36
predator-prey ratios. The dominant insect pests
collected in 100 m2 sample areas using sweep net
at booting to heading stages (50-70 DAS) were
green leaf hopper (GLH), cutworm and armyworm,
which were the prey, while the dominant predator
species of spiders were Lycosa and Tetragnata.
The mean predator-prey ratios in the NIA irrigated
farms were 10:92 and 6:23 for WS 2005 and DS
2006, respectively while in the pump irrigated
farms, these were 9:31 and 7:26 for WS 2005 and
DS 2006, respectively (Table 6). The predatorprey ratio did not significantly differ among plant
types (hybrid vs. inbred) and study sites but
significantly higher during WS 2005 than in DS
2006 for inbred rice plants in the NIA irrigated
farms. This was due to remarkably high population
of insects in WS 2005 than in DS 2006 (Table
7). The relatively high temperature and humidity
during the wet season offered a more favorable
condition for insect pests.
Table 6. Predator-prey ratio in NIA and pump
irrigated farms, WS 2005 and DS
2006.
NIA Irrigated Farms
Direct Seeding (n = 7)
Transplanting (n = 5)
Mean
Pump Irrigated Farms
Direct Seeding (n = 1)
Transplanting (n = 11)
Mean
Mean (2 Sites)
WS 2005
Predator:
Pest Ratio
7:91
14:92
10:92
DS 2006
Predator:
Prey Ratio
5:29
7:14
6:23
20:6
8:33
9:31
9:61
10:13
2:27
7:27
7:26
Comparison of Means
WS 2005 vs DS 2006
NIA Irrigated (Inbred)
significant at 5% level
All the predator-prey ratios exceeded the
ability of a Lycosa to consume 45 brown plant
hoppers d-1 as cited by Settle et al. (1996) or a
predator-prey ratio of 1:45. However, there is no
information on consumption rate of spiders for
GLH and cutworms/armyworms. Meanwhile,
considering that spiders are generalist predators,
such values could be adopted.
Toxicity and costs of pesticides used.
Farmer respondents used 32 different brands of
pesticides which are approved by the Fertilizer
and Pesticide Authority (FPA). These pesticides
belong to different toxic categories (color codes)
ranging from green (least toxic), blue
(moderately toxic) and yellow (highly toxic)
pesticides. Red (extremely toxic) pesticides,
which are banned, were not used.
Most of the farmer respondents in pump
irrigated farms used green-coded insecticides,
molluscicides and herbicides (Table 7). However,
in NIA irrigated farms, most of the farmer
respondents (58.3%) used 1 liter of Direk, a
moderately toxic herbicide which was applied at
2-4 days after planting/sowing (DAP/DAS) and
its price was P760 l-1. About 25% of farmer
respondents used 1 liter of Nurelle, which is a
yellow-coded (highly toxic) insecticide at 15
DAT and this costs P795 l-1. Cymbush and
Smash, a green-coded insecticide, were used at
60-65 DAT. Green-coded pesticides were the
cheapest. The blue- and yellow-coded pesticides
were more expensive than the green-coded ones.
Predator-prey ratio by toxic categories of
insecticides. Predator-prey ratios using combined
samples from before and after spraying and
grouped according to toxic categories (color
codes) of insecticides with practically the same
volume (l ha-1) applied are presented in Table 8.
Although apparently, the absolute values of
predator-prey ratios were higher in green-coded
insecticides than in blue- and yellow-coded
insecticides for both the study sites and cropping
seasons, there were no significant differences in
their magnitudes.
Farmers’ behaviors and attitudes toward
biological control of insect pests. High and
increasing cost of pesticides constrained farmers
to apply pesticides based on product dosage
recommendations. Farmers’ knowledge from
IPM training enabled them to reduce application
by observing first the fields before they spray.
However, farmers’ limited knowledge on toxic
categories (color codes) of pesticides trapped
them to use highly toxic pesticides. Spraying of
highly toxic yellow-coded insecticides killed
more predators that naturally regulate insect pest
population of rice.
Their existing practice of reducing their
37
Journal of Environmental Science and Management Vol. 12. No. 1 (June 2009)
Table 7. Brand names, toxic categories (color codes), quantity and costs of pesticide applied by farmers in
the study sites, CY 2005.
Brand Name
NIA Irrigated farms
Herbicide
Direk
Forward
Rogue
2-4D
Machete
Nominee
Grassedge
Insecticide
Chix
Cymbush
Magnum 5EC
Smash
Nurelle
Vindex
Amihan
None
Molluscide
Aquadin
Baylucide
Control
Maso
Net
Surekill
Color
Code*
Frequency Distribution
Count
%
QTY
Unit
Unit-Price
Blue
Blue
Blue
Green
Green
Green
Yellow
7
1
1
2
1
3
1
58.3
8.3
8.3
16.7
8.3
25.0
8.3
1.07
1
1
0.42
1
0.58
1
liter
bot
liter
liter
liter
liter
liter
1473
560
Blue
Green
Green
Green
Yellow
Yellow
Green
3
3
2
3
3
1
1
1
25.0
25.0
16.7
25.0
25.0
8.3
8.3
8.3
0.5
0.25
0.5
1
1
1
1
liter
bot
liter
liter
liter
liter
liter
690
650
450
450
795
350
350
Green
Green
Green
Green
Green
Green
1
4
1
1
1
5
8.3
33.3
8.3
8.3
8.3
41.7
1
2
1
10
4
1
box
liters
liter
sachets
packs
box
850
980
800
80
85
800
6
1
3
2
50.0
8.3
0.79
0.4
0.67
3
liters
liter
quart
packs
338
1300
527
88
1
1
8
2
1
3
8.3
8.3
66.7
16.7
8.3
25.0
1
2
0.66
1
0.33
0.67
quart
liter
liter
bag
liter
liter
420
620
458
520
900
433
6
1
1
1
1
50.0
8.3
8.3
8.3
8.3
0.58
1
0.5
4
2
liter
kilo
pack
sachets
kilos
843
320
250
95
920
Pump Irrigated Farms
Herbicides
Machete
Green
Nominee
Green
Sofit
Green
Sonic
Green
Insecticides
Cyclone
Green
Decis R
Green
Magnum 5EC
Green
Furadan
Yellow
Karate
Yellow
Vindex
Yellow
Molluscides
Baylucide
Green
Metabait
Green
Snail Kill
Green
Sure Kill
Green
Trap
Green
Green = Toxic category 4 (Least toxic)
Blue = Toxic category 3 (Moderately toxic)
Yellow = Toxic category 2 (Highly toxic)
699
350
800
400
Assessment of Ecosystem Services of Lowland Rice Agroecosystems
in Echague, Isabela, Philippines
38
insecticide application would address conservation
of spiders as biological control agents, however,
their lack of information regarding toxic categories
(color codes) of pesticides would have a threat to
biological control of rice insect pests ecosystem
service and pose human health risk.
Assessment of Grain Yield
Dry grain yield. The dry grain yields in the
NIA irrigated farms were 4,110.3 kg ha-1 for WS
2005 and 3,287.3 kg ha-1 for DS 2006 while in
the pump irrigated farms, these were 3,582.4 kg
ha-1 for WS 2005 and 3,142.8 kg ha-1 for DS 2006
(Table 9). There were no significant differences in
the dry grain yield among plant types (hybrid vs.
inbred), methods of planting (direct seeded vs.
transplanted) and study sites (Tables 9 and 10).
Direct seeding of inbred plants was mor e
preferred in wet season than in dry season.
fertilizers in order to attain their maximum yield
potentials. However, farmers applied significantly
lower amounts of actual fertilizers applied
particularly for N as compared to the recommended
levels for hybrid rice (Table 3). Farmers managed
hybrid rice plants in the same way as inbred rice
plants wherein they applied practically the same
levels of fertilizers both for inbred and hybrid
rice as there was no significant difference in
fertilizer usage for these crops.
Farmers’ behaviors and attitudes toward
grain yield. In terms of increasing grain yield,
most of the farmers in both barangays disagreed
and some strongly disagreed (mostly those who
attended trainings on IPM and organic farming)
on the continual application of inorganic fertilizers
and pesticides. With this attitude, farmers
resorted to the use of hybrid rice that has high
yield potential to apply their knowledge from the
training on hybrid rice production.
Hybrid rice plants require higher amounts of
Table 8. Predator-prey ratio and kind and amount of insecticide applied (l ha-1). WS 2005 and DS 2006.
Kind of
Insecticide
NIA Irrigated Farms
WS 2005
DS 2006
Predator:
Amount
Predator: Amount
Prey Ratio of Insec- Prey
of Insecticide
Ratio
ticide
Applied
Applied
( l ha-1)
( l ha-1)
Pump Irrigated Farms
WS 2005
DS 2006
Predator: Amount
Predator: Amount
Prey
of Insec- Prey
of InsectiRatio
ticide
Ratio
cide
Applied
Applied
( l ha-1)
( l ha-1)
Green*
Blue*
Yellow*
0.27 (8)**
0.153 (3)
0.165 (4)
0.59 (11)
0.44 (4)
*
0.8
0.7
0.8
0.50 (8)
0.50 (3)
0.27 (4)
0.5
0.5
0.5
0.8
0.6
0.41 (11)
0.35 (11)
0.5
0.5
** number of farms
Green = Toxic category 4 (Least toxic)
Blue = Toxic category 3 (Moderately toxic)
Yellow = Toxic category 2 (Highly toxic)
Table 9. Grain yield (kg ha-1) with different planting methods in NIA and pump irrigated farms, WS 2005
and DS 2006.
Site/ Method of Planting
NIA Irrigated Farms
Direct Seeded (n = 7)
Transplanted (n = 5)
Sub-mean
Pump Irrigated Farms
Direct Seeded (n = 1)
Transplanted (n = 11)
Sub-mean
Mean (2 Sites)
WS 2005
DS 2006
Mean
3,890.7
4,417.8
4,110.3
3,101.0
3,548.1
3,287.3
3,495.8
3,982.9
3,698.8
2,416.8
3,688.4
3,582.4
3,846.4
2,416.8
3,208.8
3,142.8
3,215.0
2,416.8
3,448.6
3,362.6
3,530.7
Journal of Environmental Science and Management Vol. 12. No. 1 (June 2009)
39
Table 10. Grain yields (kg ha-1) of different plant types with two methods of planting in the NIA and
pump irrigated farms, WS 2005 and DS 2006.
Plant Type
Direct seeded
Transplanted
Transplanted
Inbred
Inbred
Hybrid
NIA Irrigated Farms
WS 2005
DS 2006
3,890.7
3,101.0
4,535.4
4,087.4
2,739.0
In spite of the use of high yielding hybrid
rice variety by farmers who attended training on
hybrid rice production, there was still a problem
of low yield, i.e. the hybrid yield potentials were
not attained. Farmers who planted hybrid variety
provided inadequate fertilizers to their crops.
This was due to high and even increasing price of
fertilizers. Moreover, farmers either applied
excessive or inadequate amounts of appropriate
kinds of fertilizers because they did not have basis
on the right kinds and amounts of fertilizer to be
applied that could have been determined through
soil analysis.
CONCLUSIONS AND RECOMMENDATIONS
The theoretical contribution of the study to
the body of knowledge in ecosystem services of
lowland rice agroecosystem are elucidated based
on the following results: a) Direct seeding results
in higher groundwater recharge than transplanting;
b) Plowing under of rice straw provides more
potentially recyclable soil nutrients than the harvest
straw with threshed panicle; c) Application of
more toxic or yellow-coded insecticides (such as
Chlorpyrifos) reduces predator-prey ratio more
than the less toxic insecticides like the green-coded
ones; and d) Use of hybrid rice variety does not
guarantee substantial increase in grain yield if
recommended levels of fertilizer application is
not followed. These results consistently elucidate
a theory that farm management practices and
technologies resorted to by farmers according to
their knowledge, perceptions, and attitudes
within their resources (financial, information,
market) either increase or reduce ecosystem
services.
In terms of the methodological contribution,
the study produced a highly quantitative ecosystem
services assessment of lowland rice agroecosystem
using integrated biophysical and socio-economic
Pump Irrigated Farms
WS 2005
DS 2006
3,331.2
2,809.5
3,986.0
3,436.9
research methods from various disciplines. For
the quantitative estimation and analysis of
groundwater recharge and soil nutrient cycling,
soil science and agricultural engineering
(irrigation and hydrology) are needed.
Methodologies on insect ecology and agronomy
are used to estimate and analyze biological control
of rice insect pests and grain yield provisioning
service. Environmental psychology is needed to
analyze farmers’ actual behaviors expressed in
terms of farm management practices in relation
to their knowledge (e.g. training on IPM),
perceptions of problems and constraints and
attitudes toward ecosystems services. As rational
beings, farmers manage their farm within their
capital and resource and time constraints without
considering environmental consequences and
degrading ecosystem services. Analysis of these
socio-economic factors and available resources in
the farm is needed in identifying strategies
(including incentives and regulations) to promote
ecosystem service enhancing practices and
discourage ecosystem service degrading practices.
The cumulative effects of ecosystem services like
soil nutrient build-up and biological control of
insect pests could be monitored continuously.
The practical contribution of the study is in
terms of the quantified magnitudes of ecosystem
services of lowland rice agroecosystem that
would be used to promote farm management
practices that enhance these ecosystem services
while reducing environmental burdens such as
the following: a) The use of hybrid rice following
the recommended levels and methods of fertilizer
application will increase grain yield to attain the
yield potentials and rice straw production which
would enhance soil nutrient cycling; b) Proper
management and maximum utilization of rice
straws as compost would contribute to reduction
of GHG (methane and N2O) emission that has
high global warming potential; c) With dependable
40
Assessment of Ecosystem Services of Lowland Rice Agroecosystems
in Echague, Isabela, Philippines
supply of irrigation water, direct seeding and the
use of late maturing varieties for wet season
would contribute to increased groundwater
recharge; and d) The use of green-coded
insecticides which are safe to human health
would enhance effectiveness of spiders as
biological control of insect pests and would further
lead to reduction in the cost of pesticides inputs.
Results of the present study strongly suggest
that the following issues and topics be studied
further: a) Comparative analysis of impacts on
global warming of rice straw burning and anaerobic
decomposition of rice straw by plowing under; b)
Estimation of the seepage of irrigation water
from the paddy in higher slopes which is re-used
as irrigation water at lower slopes; and c)
Landscape ecological management of watersheds
and subcatchments as sources of irrigation.
The recommendations and implications are
as follows: a) The quantified amounts of ecosystem
services could be readily valued using appropriate
valuation techniques (e.g., market value for grain
yield and replacement costs for non-marketed
ecosystem services such as groundwater recharge,
soil nutrient cycling and biological control of rice
insect pests); and b) Information on the farm
management practices and technologies that
enhance ecosystem services should be shared
with the farmers and the public.
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ABOUT THE AUTHORS
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Januel P. Floresca, PhD. in Environmental
Science with cognate field in Agricultural
Economics and University Research Associate I,
Isabela State University, Echague, 3309 Isabela
Philippines.
Antonio J. Alcantara, PhD., Professor and
former Dean, School of Environmental Science and
Management (SESAM), UPLB.
Corazon B. Lamug PhD. †, Professor and
former Dean, College of Arts and Sciences
(CAS), UPLB.
Corazo n L. Rapera, PhD., Pr ofessor,
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Candida B. Adalla, Ph.D., Professor and
former Dean, College of Agriculture (CA),
UPLB.
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ACKNOWLEDGEMENT
This article is part of the doctoral dissertation
of Dr. Januel P. Floresca titled “Assessment and
valuation of ecosystem services of lowland rice
† Deceased.