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Quantifying Corn Yield and Water Use Efficiency under Growth Stage–Based Deficit Irrigation Conditions

Quan X. Fang, L. Ma, David C. Nielsen, Thomas J. Trout, Lajpat R. Ahuja
Practical Applications of Agricultural System Models to Optimize the Use of Limited Water 2014 pp. 1-24
Root Zone Water Quality Model, Zea mays, climatic factors, corn, crop coefficient, deficit irrigation, evapotranspiration, grain yield, guidelines, irrigation rates, irrigation water, meteorological data, soil water, vegetative growth, water requirement, water use efficiency, Colorado
An agricultural system model can help optimize limited irrigation for higher grain yield and water use efficiency (WUE) across varied climatic conditions. In this study, the Root Zone Water Quality Model (RZWQM2) was first calibrated to simulate soil water, ET, and corn (Zea mays L.) yield under a range, 40 to 100% of crop ET under well-watered conditions (i.e., ETc, calculated by the reference ET and crop coefficient), of irrigation treatments from 2008 to 2011 in Colorado. The model was then used to explore grain yield responses to irrigation levels of 40, 60, 80, and 100% ETc (the Shuttleworth–Wallace ET, ETsw, was used as a surrogate for ETc in the model) under 300, 400, and 500 mm of total irrigation water and to provide guidelines to manage limited irrigation using weather data from 1992 to 2013. With 500 mm of irrigation water, high grain yield and WUE were obtained from the 100% ETsw for the vegetative stage and 80 to 100% ETsw for the reproductive stage. With 400 mm of irrigation water, high grain yield and WUE were simulated at 80 to 100% ETsw irrigation targets between the vegetative and reproductive stages. With 300 mm of irrigation water, however, meeting 100% ETsw at the reproductive and 60% ETsw at the vegetative stage achieved the highest grain yield and WUE. Simulations showed that meeting the crop water requirement during the reproductive stage is more important than during the vegetative stage to achieve high grain yield and WUE under water-limited conditions.
USDA Agricultural Research Service (ARS) Corn, Greeley, Colorado