Evapotranspiration Crop Coefficients for a Hot and Arid Climate`` PDF

Keywords

crop, grass, alfalfa

Abstract

The evapotranspiration of crops is often determined from the reference evapotranspiration, ET (of alfalfa or grass) by using suitable crop coefficients. This technique can easily be adopted for computerized irrigation scheduling. To obtain crop coefficients under hot and arid conditions , some of the crops were grown in lysimeters and their ET was obtained . The ET measurements for a uniform and well watered stand of alfalfa, grown in lysimeters, were also made and the reference ET for 20 cm tall alfalfa was obtained from the record. For most of the crops, the ET and hence the crop coefficients fall into phases in accordance with the growth stage , namely: initial, flowering and fruiting stages. The crop coefficients were found to change considerably from one stage to another, in some cases. Hence a single value of a crop coefficient is usually not suitable for the entire crop season. Values of the ET crop coefficients are given for some crops , for better estimates of ET under hot and arid climates in general and Saudi Arabia in particular.