SIMULATING CORN YIELD RESPONSE TO IRRIGATION TIMINGS - VALIDATION OF THE EPIC MODEL

Models simulating crop growth offer an opportunity to fill important data gaps from experimental plots. Examples include incorporation of many weather conditions as well as alternative management strategies. The simulated data must be reliable, however. This study examined the application of the EPIC growth model to simulate corn (Zea mays L.) yield on the Southern High Plains when water stress was imposed on various dates in the growing season. The EPIC model produced simulated yield distributions with means not significantly (P = 0.05) different from those of the actual data in 2 of the 3 yr considered, and standard deviations of simulated yields similar to those of the actual yields for all 3 yr. Linear regressions of simulated yields on actual yields resulted in slope coefficients not significantly (P = 0.05) different from 1.0 for 2 of the 3 yr. Simulated yields explained 83, 86, and 72% of the variance in actual yields for the 3 yr of measured data. The EPIC model appears useful for further studies of irrigation scheduling for corn.