Water Production Functions for High Plains Crops

Declining water supplies is the critical resource issue for irrigated agriculture in the High Plains and much of the western U.S. Farmers need to maximize production per unit water consumed to remain economically viable and sustain irrigated agriculture. The Agricultural Research Service (ARS) Water Management Research Unit is developing water production functions for High Plains crops that can help farmers make decisions for allocating limited water supplies among crops. The Unit has developed an irrigated research farm to measure total water balance for a 4 crop rotation (wheat, corn, sunflower, dry beans). The goal is to develop water production functions based on consumptive use, relate yields to soil water deficits and plant stress indicators, and improve existing plant growth models to more accurately reflect water stress effects. Results for the first year corn crop show both grain and total biomass yields nearly proportional to water consumptive use with water use efficiencies of 2.4 and 3.9 kg/m³, respectively.