Rice production in Asia needs to increase to feed a growing population. Though a complete assessment of the level of water scarcity in Asian rice production is still lacking, there are signs that declining quality of water and declining availability of water resources are threatening the sustainability of the irrigated rice-based production system. Drought is one of the main constraints for high yield in rain-fed rice. Exploring ways to produce more rice with less water is essential for food security and sustaining environmental health in Asia. This chapter reviews the International Rice Research Institute (IRRI)’s integrated approach, using genetics, breeding and integrated resource management to increase rice yield and to reduce water demand for rice production. Water-saving irrigation, such as saturated-soil culture and alternate wetting and drying, can drastically cut down the unproductive water outflows and increase water productivity. However, these technologies mostly lead to some yield decline in the current lowland rice varieties. Other new approaches are being researched to increase water productivity without sacrifice in yield. These include the incorporation of the C4 photosynthetic pathway into rice to increase rice yield per unit water transpired, the use of molecular biotechnology to enhance drought-stress tolerance and the development of ‘aerobic rice’, to achieve high and sustainable yields in non-flooded soil. Through the adoption of water-saving irrigation technologies, rice land will shift away from being continuously anaerobic to being partly or even completely aerobic. These shifts will have profound changes in water conservation, soil organic-matter turnover, nutrient dynamics, carbon sequestration, soil productivity, weed ecology and greenhouse-gas emissions. Whereas some of these changes can be perceived as positive, e.g. water conservation and decreased methane emission, some are perceived as negative, e.g. release of nitrous oxide from the soil and decline in soil organic matter. The challenge will be to develop effective integrated natural-resource-management interventions, which allow profitable rice cultivation with increased soil aeration, while maintaining the productivity, environmental services and sustainability of rice-based ecosystems.

/pdf/rice-production-in-water-scarce-environments-hguc0cm6sy.pdf

Rice production in water-scarce environments

Applying a model of the multioutput firm, econometric results are reported for irrigated production in four multistate regions of the American West. Cross-sectional microdata from the Farm and Ranch Irrigation Survey and limited-dependent variable methods are used to estimate crop-choice, supply, land allocation, and water demand functions for field crops. Farm-level water demand is decomposed into the sum of crop-level water demands, and crop-level demands are further separated into an extensive margin (land allocations) and intensive margin (short-run water use). Response to water price (measured as groundwater pumping cost) occurs primarily at the extensive margin.

Multicrop Production Decisions in Western Irrigated Agriculture: The Role of Water Price

https://sites.uclouvain.be/afepa/wp-content/uploads/2015/08/Impact-of-Water-Pricing-in-Spain-Berbel-2000.pdf

The impact of water-pricing policy in Spain: an analysis of three irrigated areas

The issue of groundwater management remains a practical concern in many regions throughout the world, while water managers continue to grapple with the question of how to manage this resource. In this article, we attempt to bring the most advanced and appropriate tools to bear on the issue of resource allocation involving groundwater. Our objective is to demonstrate the state of the art in the literature on ways to think about this complex resource and to deal with the important economic issues emanating from its complexity. We present the conceptual framework within which economists examine the elements interacting in the management of groundwater resources, indicate why the role of the market is limited with respect to the price of this very complex resource, and point to the mechanisms that can pull competitive groundwater price and quality-graded quantity of groundwater in line with their equilibrium levels. In particular, we critically review economic models of groundwater use, examine the potential for groundwater management, discuss the difficulties encountered in the estimation of the relevant control variables of such models, and identify the advantages and limitations of the instruments devised for the efficient use (allocation) of this resource. Finally, we argue that devised regulatory schemes usually ignore the information and knowledge needed for their implementation, and we suggest a core of conditions necessary for successful groundwater management reforms.

Current Issues in the Economics of Groundwater Resource Management

The issue of groundwater management remains a practical concern in many regions throughout the world, while water managers continue to grapple with the question of how to manage this resource. In this article, we attempt to bring the most advanced and appropriate tools to bear on the issue of resource allocation involving groundwater. Our objective is to demonstrate the state of the art in the literature on ways to think about this complex resource and to deal with the important economic issues emanating from its complexity. We present the conceptual framework within which economists examine the elements interacting in the management of groundwater resources, indicate why the role of the market is limited with respect to the price of this very complex resource, and point to the mechanisms that can pull competitive groundwater price and quality-graded quantity of groundwater in line with their equilibrium levels.
In particular, we critically review economic models of groundwater use, examine the potential for groundwater management, discuss the difficulties encountered in the estimation of the relevant control variables of such models, and identify the advantages and limitations of the instruments devised for the efficient use (allocation) of this resource. Finally, we argue that devised regulatory schemes usually ignore the information and knowledge needed for their implementation, and we suggest a core of conditions necessary for successful groundwater management reforms.

/pdf/current-issues-in-the-economics-of-groundwater-resource-ezq1jd3chd.pdf

Current issues in the economics of groundwater resource management

A two-stage simulation/mathematical programming model is presented for determining the optimal intraseasonal allocation of irrigation water under conditions of limited water supply. The model is applied to a series of water shortage scenarios under both surface and center pivot irrigation. Economically efficient irrigation management is shown to involve the coordination of a number of managerial decisions, including irrigation scheduling, crop substitution, the adoption of improved irrigation labor practices, and idling land. The results indicate that significant

An Irrigation Model for Management of Limited Water Supplies

Discussions of surface irrigation have appeared in the literature for many years. Familiar among the early works are the names of Parker (15), 4 Israelsen (9), and Lewis and Milne (12). In the last...

Surface Irrigation Hydraulics – Kinematics

Atwo-stage simulation/mathematical programming model was developed to determine the optimal intraseasonal allocation of irrigation water under conditions of limited water availability. The model was applied to a representative surface irrigated farm in Washington State's Columbia River Basin. Results from applying the model to a series of incifeasingly severe water shortage conditions indicated a large potential for water conservation in the assumed production setting. Farm-level water supply reductions of 40% translated to about 10% decrease in economic returns. Income losses resulting from water shortages were minimized through the conjunctive management of irrigation scheduling, irrigation labor practices, and several other short-run responses to water deficits. The combination of crop water simulation and farm-level economic optimization models was shown to be a compatible merger of techniques for representing the engineering and economic irrigation environment.

Irrigation Optimization Under Limited Water Supply

Optimum sorghum planting dates in western Sudan by simulated water budgets

IRRIGATION schedules for corn grown in Washington's Columbia Basin during 1984 and 1985 in silt loam and sandy loam soils recommended by three commercial irrigation schedulers were analyzed using the SPAW-IRIG model. Alternate irrigation strategies were simulated with SPAW-IRIG and compared to those recommended by the commercial schedulers. Simulated irrigation depths and yields compared well the schedulers results for silt loam fields, but much more water was applied to sandy loam fields than simulations indicated was necessary for full irrigation. As compared to irrigating every three days, deficit irrigations scheduled by a yield reduction index (YRI) showed a potential savings of at least 280 mm of applied water and more than $90/ha increase in net economic returns.

Day L. Bassett

Papers

An Irrigation Model for Management of Limited Water Supplies

Surface Irrigation Hydraulics – Kinematics

Irrigation Optimization Under Limited Water Supply

Optimum sorghum planting dates in western Sudan by simulated water budgets

An Analysis of Irrigation Scheduling Methods for Corn