Conserving and Optimizing Limited Water for Crop Production

Abstract

Proper soil and crop management systems are critical for sustainable production in semi-arid environments, and there are principles that apply to both dryland (non-irrigated) and limited-irrigation systems. In the non-irrigated environment, crop residue from no-till systems permits more diverse crop rotations with less frequent fallow, which leads to increased precipitation-use efficiency. Soil improvements from no-till systems include decreased soil erosion, increased soil organic matter, improved soil structure, and increased infiltration rate. These soil improvements create a positive feedback loop by making more water available to the crop, increasing yields, and returning more crop residues to the soil. In the Great Plains of the United States, we have found that annualized grain production from no-till systems with less frequent fallow can be increased by 75% with an increase in economic return from 13% to 36% compared with the traditional wheat-fallow cropping system. There is also a need to increase water productivity for irrigated crop production because of competition for water by municipal and industrial users, drought, and declining groundwater supplies. The adoption of cropping systems that use less water and insure economic sustainability must be developed. We have found that limited-irrigation practices that time irrigations with critical growth stages can reduce water use of corn by 50% while reducing yields by only 30%. Alfalfa was found to have great potential for limited irrigation because of its natural drought tolerance and perennial growth habit. Many of the principles of water-conservation practices identified in the United States are adaptable to India's conditions. Soil and crop management systems that use less water and that are sustainable and economically viable in India's limited water environment must be developed.