Simulating peanut yield and irrigation applications with the CSM-CROPGRO-Peanut model

The management of on-farm irrigation systems involves the choice of irrigation method, timing, and the quantity of water applications. In Georgia, farmers' irrigation applications are largely unknown because of no reporting requirement. Recent droughts and a water dispute with the neighboring states - Alabama and Florida- highlighted the need for an accurate estimate of water use by agriculture. An accurate simulation of irrigation water use is needed to help improve yield predictions and contribute to the resolution of the tri-state water dispute. The objective of this study was to evaluate the performance of the CSM-CROPGRO-Peanut model in simulating irrigation applications and its impact on peanut yield in farmers' fields in southwest Georgia. A set of different irrigation thresholds was used to run the CSM-CROPGRO-Peanut model. We then compared the simulated irrigation applications for each of the irrigation thresholds with the amount of water that the farmers actually applied during the 2003 growing season. We found the best agreement between simulated and observed irrigation applications with the 50% irrigation threshold. However, the irrigation applications by farmers could be much higher than with the 50% irrigation threshold during critical stages of crop growth and development when no adequate rainfall occurs. Similarly, peanut yield was simulated well by the model with the 50% irrigation threshold. This study showed that the CSM-CROPGRO-Peanut model can be a useful tool for estimating farmers' irrigation applications and its impact on yield. Potential users of this model could include policy makers, planners, and regulators that deal with water issues.