Deficit Irrigation Strategies for the Western U.S.

Abstract

HighlightsDeficit irrigation may maximize net income when irrigation water supplies are limited or expensive.Water production functions are used with economic parameters to maximize net income with deficit irrigation.Net income may be insensitive to the amount of deficit irrigation if production costs are appropriate for anticipated yield.Deficit irrigation increases risk.Abstract. Competition for, regulation of, and depletion of water supplies in the western U.S. has resulted in reduced water available for irrigating crops. When the water supply is expensive or inadequate to meet full crop water requirements, deficit irrigation (DI) may maximize net income (NI) by reducing use of expensive water or irrigating more land with limited irrigation supplies. Managed DI entails rational planning and strategic water allocation to maximize NI when water supplies are constrained. Biophysical and economic relationships were used to develop NI models for DI and determine water allocation strategies that maximize NI under three types of water supply constraints. The analyses determined that potential benefits of DI are greatest when water is expensive, irrigation efficiency is low, the water supply is flexible, and rainfed production is not economically viable. When production costs are appropriate for anticipated yields, NI is less sensitive to DI planning decisions. Deficit irrigation will become more important as irrigation water supplies continue to decline in the future. Net income analysis can assist growers in making rational DI decisions. Keywords: Deficit irrigation, Economic analysis, Irrigation management, Net income, Optimization, Water productivity.