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Water
Management Issues
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Water
availability (along with high-yielding varieties and fertilizers)
has led to the rapid expansion of rice-wheat cultivation in
South Asia. However, concern has been expressed about the long-term
sustainability of the rice-wheat system as there are indications
of yield stagnation or a tendency to decrease with time over
parts of the Indo-Gangetic plains. The expansion of irrigation
by exploitation of ground and surface water has resulted in
environmental problems such as declining groundwater tables,
salinity and water logging etc. Growing competing demands for
water require that productivity of water-use in rice-wheat rotation
is improved so that food output is not adversely affected. Recommendations
are needed on how to grow more food with less water at minimal
economic and environmental costs. This would require research
at the farm, irrigation system and policy levels so as to incorporate
hydrological, economic and environmental linkages of water use.
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Research
Issues in Water Resources Management
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The
water resources issues are analyzed in an integrated way at
all the three levels i.e. farm, irrigation system and macro
policy. This is so because there are hydrological linkages between
what is done at the farm level and what was is at the irrigation
system level. For example, a crop variety requiring less water
input per unit of land may save water costs for the farmer but
will save water at the system level only if it reduces consumptive
use of water (by changing the crops or their timings or their
locations). Further, solution to the drainage problem at the
farm level may require actions at the irrigation and drainage
system or sub-system level (e.g. horizontal drainage or groundwater
pumping). Thus, we consider it is important not only to carry
out research for improving productivity of water use in the
field but also to quantify the consequences of farm level actions
at the system level and vice-versa.
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Other
prominent issues are the linkages between farmer’s profitability
and policy changes such as regulations on groundwater use, water
and energy prices and input and output prices. For example,
raising electricity prices for groundwater pumping will make
it more expensive to irrigate rice and the farmer will either
reduce water applied to rice crop or switch to another crop
(depending on what happens to crop yields and output prices).
These actions by the farmer will reduce rice output but will
also arrest the declining water tables in the region. This would
require an analysis of the trade-off between food output and
declining water tables (an environmental concern).
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Water
quality and land degradation issues are included as part of
the research program in Consortium. For example, heavy dosages
of fertilizers and pesticides increase non-point pollution of
water bodies which has implications for water quality (both
surface water and groundwater) for drinking and livestock and
for irrigation. Further, water pollution from industrial toxic
wastes and domestic sewage reduces the availability of water
of acceptable quality for irrigation. Hence, research studies
are planned to explicitly consider the water quantity and quality
impacts of regulation, pollution charges and water prices for
industrial and household users.
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The
research issues are classified into different levels e.g., strategic,
adaptive, policy etc. Strategic research will include those
activities where new knowledge will be developed through new
experiments or through modification of ongoing field research.
Adaptive research will aim at selecting appropriate methods
or technologies (out of available ones) for conditions in a
particular region or farm. Most of the strategic and adaptive
research will be carried out at the farm level by NARS in collaboration
with other agencies and IARCs. Policy research will be carried
out both at national and regional levels.
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Farm
Level
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Research
at the farm level takes into account the interactions among
all the factors of production: seed, soil, water and farm practices.
The specific areas of farm level research include the following:
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Puddling
(i.e. the flooding of paddy fields) entails a significant
consumption of water, and accompanying water losses. There
is a need to examine carefully the costs and benefits of
puddling, and to seek ways to (a) reduce water losses during
puddling, and (b) minimize percolation losses during crop
growth while creating optimal root growth environments for
rice under different types of soils.
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Crop
growth and water use models are needed to identify areas
of intervention for improving water use efficiency in different
water supply situations. For instance, in the regional water
balance model, the contribution of bunded rice production
to in-situ rainwater conservation, groundwater recharge
and run-off control should be evaluated.
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There
is a need to investigate alternate tillage operations (including
zero and minimum tillage) for better root growth to achieve
improved water and nutrient use efficiency and crop productivity
through minimum energy expenditure.
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Water
management strategies are intimately related to nutrient
losses and therefore crop yields. Recommendations are needed
on water management practices that reduce water and nutrient
losses, based on an understanding of the interaction of
tillage and nutrients with respect to water management practices.
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Research
on water-use efficiency requires accurate measurement of
water applications from the source to the field. Presently
national research centers appear to lack the required level
of equipment and skills needed for such accurate measurement.
Appropriate training will need to be provided to field researchers
covering the use of flow/measuring and soil-moisture-measuring
devices and techniques, data analysis and data interpretation.
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In
many areas rice-wheat cultivation is practiced using traditional
and wasteful water application methods and schedules. There
is a need to identify practical water application methods
and schedules for rice and post-rice crops that are appropriate
for the specific water supply situations in given areas
(e.g. areas with heavy soils, poor drainage).
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In
addition to the input factors noted above, other on-farm
development activities, including field leveling and rectangulation,
field layout and design, the alignment of the conveyance
system and strategies for reducing water losses, may have
considerable impact on water consumption and/or productivity.
There is a need to assess (and, where necessary, make recommendations
for improving) existing technologies, and develop criteria
for identifying the most critical on-farm variables.
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For
instance, farmers may be encouraged to use less water if
they can overcome their habit of extending the use of flooding
as a method of land preparation and early cultivation of
rice to the follow-on dry season wheat crop. Again, dry
rice planting may increase sustainability in water short
areas if farm families, accustomed for centuries to wet
rice farming can be persuaded to try something new.
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There
is a need to evaluate options to mitigate, and where possible
control, salinity impacts in selected areas, for example,
by the introduction of salt tolerate varieties.
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Research
is required to investigate the effects of alternative planting
techniques, including direct seeding of rice, surface seeding
of wheat and minimum tillage of what after rice, on water
use and crop performance.
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Policy
and System-Level
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Issues
at stake are (a) investment requirements for further surface
and groundwater development, and (b) explore issues of (a) the
use of groundwater and (b) the use of pesticides, agro-chemicals
and effluents discharge. Further, system level analyses and
policy research would include the impact of changes such as:
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a
clear definition of water rights
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water
pricing and electricity and diesel pricing
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input
and output prices
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incentives
for salinity mitigation.
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land
consolidation
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rainwater
harvesting
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water
storage structures
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tank
irrigation
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simple
and inexpensive water control and measuring field structures
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low
cost lining materials.
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The
reason Yaqui Valley farmers most often give for adopting bed
planting is that the system reduces production costs—by an estimated
30% in the Valley. Bed planting achieves cost savings by:
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- reducing
the amount of N applied;
- reducing
nitrogen loss;
- lowering
the number of tillage operations;
- lowering
seeding rates;
- reducing
lodging;
- facilitating
mechanical and manual weeding; and
- reducing
the need for herbicide applications.
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Other
components are (a) investigate the need for investment and technical
support required for private sector groundwater development
including manual pumps, cavity wells, low-lift pumps, use of
renewable energy, etc. (b) evaluate alternatives to large scale
irrigation schemes and (c) evaluate the impact of water control
structures on water delivery and agricultural performance (d)
an evaluation of the long term impact of appropriate new water
harvesting structures and techniques (e) present an analysis
of the use of agro-chemicals and nutrients, and their concentration
in drainage effluents in areas with known use of fertilizers
and agro-chemicals.
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Goal
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The
overall goal of all the activities of Water Management research
is to formulate practical, user-friendly intervention strategies
for rice-wheat farmers that increase (a) resource use efficiency,
(b) productivity and (c) sustainability. Specifically, this
outlines:
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Research
activities that will be undertaken at the national level
by each of the NARS in collaboration with other NARS, government
departments concerned with water issues and national and
international research institutes and IARCs. These research
activities will include strategic and adaptive research
at the farm level and at the irrigation system level and
policy and institutional issues which affect farmers’ profitability
and /or influence quantity and quality of water available
for agriculture.
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Activities
at the regional level which will be of common interest to
NARS and IARCs and will result in generic conclusions from
comparative analyses. The objective of these activities
will be to maximize the synergy benefits of working together
using a common framework and methodologies.
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Development
of appropriate research studies is hampered by the lack of accurate
information on the water requirements of rice-wheat in various
agro-climatic areas on the one hand, and water availability
and use by rice-wheat farmers on the other.
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