Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/16/2007
Publication Date: 7/3/2007
Citation: DeJonge, K.C., Kaleita, A.L., Thorp, K.R. 2007. Simulating the effects of spatial variable irrigation on corn yields, costs, and revenue in Iowa. Agricultural Water Management. 92:99-109. Interpretive Summary: Water stress is a key cause of spatial and temporal yield variability in the rain-fed agricultural systems of the Midwestern United States. In this study, the CERES-Maize model was implemented within a decision support system for precision agriculture to assess the potential of uniform and precision irrigations to improve corn yield for a field in central Iowa. Simulation results demonstrated that both irrigation strategies significantly improved corn yield over the long-term in comparison to no irrigation. However, an economic analysis demonstrated that irrigation was not economical for the Iowa site, mainly because of the high capital costs associated with purchasing and maintaining a center pivot irrigation system. The results of this study are important for researchers in the area of precision agriculture and crop systems management in that it has demonstrated the use of an agricultural systems model to evaluate the potential of an alternative management practice in the Midwestern United States. Producers may also benefit from this research, since it demonstrates that irrigation is not economically feasible in central Iowa under the given economic assumptions.
Technical Abstract: 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.