Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 1, 1999
Publication Date: N/A
Technical Abstract: The Food and Agriculture Organization (FAO) publication 56 contains calculations for estimating crop water use using grass reference evapotranspiration (ET) and a dual crop coefficient that includes soil water evaporation. We compared measured ET (ETm) of irrigated grain sorghum [Sorghum bicolor (L.) Moench] in 1997 and 1998 with that predicted using the FAO model (ETFAO). The sorghum was grown in lysimeters containing clay loam, silt loam, and sandy loam cores placed on platform scales. In both years, ETFAO and ETm differed only by a maximum of seven percent for crops in the three soils and were often within one percent, depending on the specification of components controlling soil water evaporation. Based on this study, the FAO model is an excellent tool for predicting ET of irrigated grain sorghum.