Effect of Potential Evapotranspiration Estimates on Crop Model Simulations

ABSTRACT TWO potential evapotranspiration (PET) equations were used in sorghum, wheat, and corn crop models. The models had been developed using one of these equations (Priestley-Taylor). Using the Penman in lieu of the Priestley-Taylor PET equation had a significant effect upon water-related model outputs (e.g., evapotranspiration and soil water) and yields based upon 30 years of simulations at three locations in Texas and one in Kansas. Because the Penman equation considers advected energy it may result in more accurate PET estimates and, consequently, water balance simulations. Based on Priestley-Taylor model yields, predictions using the Penman model were 42, 71, and 41% less for sorghum, wheat, on.