Simulating the effects of spatially variable irrigation on corn yields, costs, and revenue in Iowa

In this study, the CERES-Maize crop model was used in conjunction with Apollo, a shell program, to evaluate potential improved yield in a central Iowa cornfield on a spatially and temporally variable basis. Five years of historical yield and weather data were used to calibrate the model over 100 spatially variable grid cells for non-irrigated conditions in the 20.25 ha field. This calibrated model then used 28 years of historical weather data to simulate three irrigation scenarios: no irrigation, scheduled uniform irrigation, and precision irrigation. Irrigation improved yield by at least 500 kg ha(-1) in half of the years simulated. Precision irrigation showed slightly lower yields than scheduled uniform irrigation. Assuming use of a center pivot system, irrigation showed economic returns in only one of the 28 years included in the study. High capital costs were the leading restrictor of economic feasibility. (c) 2007 Elsevier B.V. All rights reserved.