Lysimetric Evaluation of Daily Potential Evapotranspiration Models for Grain Sorghum
1991
Steiner, J. L. | Howell, T. A. | Schneider, A. D.
Evapotranspiration (Eₜ) information is needed for many applications tions in agricultural and natural resource management, but corn - monly used prediction equations have not been adequately tested far the dry, high radiation, windy conditions of the Southern Great Plains. In order to test such equations, two precise weighing lysimeters at Bushland, TX, were used to measure daily Eₜ from wellwatered, irrigated grain sorghum [Sorghum bicolor L.) Moench] in 1987 and 1988. Forms of the Penman, Penman-Monteith, Jensen-Haise, and Priestley-Taylor models were evaluated for prediction of potential evapotranspiration (Eₜₚ). The Penman-Monteith model provided the best predictions of Eₜₚ and predicted well across the entire range of measured Eₜ. Forms of the Penman model with empirically fit wind functions overpredicted Eₜₚ by 20 to 409/0, and aftempts to fit a linear wind function to our data were not satisfactory The Jensen-Hake model, requiring only daily mean temperature and solar radiation data, overpredicted by 30%, but performed consistently across the range of Eₜ measured. Modification of the Priestley-Taylor model with vapor pressure deficit or temperature advection terms is recommended. Without such modification, the model overpredicts at low Eₜ rates and underpredicts at high Eₜ rates.
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