Evaluating daily evapotranspiration estimation methods: A comparison of potential evapotranspiration equations and irrigation scheduling models with weighing lysimeter measurement

Four popular methods of calculating a potential evapotranspiration (ET) rate were evaluated. The calculated rates were compared to measured ET of alfalfa from a large weighing lysimeter. The affect of climatic data collected from two differently exposed weather stations at the same geographical location was also evaluated. The comparison incorporated various methods of calculating the vapor pressure deficit term in the "combination" potential ET equations.;Crop ET from two irrigation scheduling programs and the CERES-Maize crop model were compared to actual ET rates of maize from a large weighing lysimeter.;The FAO modified Penman equation performed well at estimating daily potential ET. The CERES-Maize model estimated daily crop ET of corn well, while the irrigation scheduling programs had limitations in their method of predicting the crop physiological maturity which affected the estimated crop ET rate late in the growing season.