Lysimetric Evaluation of Daily Potential Evapotranspiration Models for Grain Sorghum

Abstract

Evapotranspiration (Et) information is needed for many applications in agricultural and natural resource management, but commonly 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.

Comparison of Crop Evapotranspiration by FAO, BREB and Pristley-Taylor methodsin mustard Crop in Central Bihar Region

“…[ ] The psychrometric constant, γ (kPa °C-1), is the ratio Jamieson, 1982;Steiner et al, 1991;Rana, 1998;German, 1999 Eq. 2 eq.…”

A crop water stress index and time threshold for automatic irrigation scheduling of grain sorghum

“…At midnight, if the cumulative time for the past 24 h was greater than 420 min, then an irrigation was scheduled to be applied using computer control over the automatic blocks of the field the following morning. Because Manual and Automatic irrigations were scheduled on alternate days, the full irrigation level for automatic treatments was based on twice the peak daily crop water use rate of grain sorghum at the location (2 × 10 mm = 20 mm) (Steiner et al, 1991). Irrigations for the automatic control treatments were 80%, 55%, 30% and 0% (designated I 80%A , I 55%A , I 30%A , and I 0%A ) of 20 mm.…”

Estimation of Canopy Resistance and Surface Moisture Availability in a Rice Paddy Field

“…A number of empirical approaches have been proposed to estimate canopy resistance (Weert and Kamerling [7]; Slabbers [8]; Lafleur and Rouse [9]; Allen et al . [10]; Kim and Verma [11]; Saugier and Katerji [12]; Steiner et al [13]; Lafleur and Roulet [14]; Todorovic [15]; Oue [2]; Katerji and Rana [16]; Abtew and Melsse [17]). In this study, the canopy resistance estimated with solar radiation is applied to show the stomatal response to the environment.…”