Water Management

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.

Research Issues in Water Resources Management
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.

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).

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.

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.

Farm Level
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:

• 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.
• 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.
• 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.
• 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.
• 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.
• 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).
• 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.
  • 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.
• 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.
• 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.

Policy and System-Level
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:

• a clear definition of water rights
• water pricing and electricity and diesel pricing
• input and output prices
• incentives for salinity mitigation.
• land consolidation
• rainwater harvesting
• water storage structures
• tank irrigation
• simple and inexpensive water control and measuring field structures
• low cost lining materials.

• 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.

Goal
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:

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.

• 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.
• 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.

RWC Publications covering Water Management aspects