Plant Growth‐Evapotranspiration Relations for Several Crops in the Central Great Plains¹

Abstract

Abstract Lysimeters, which eliminated runoff and percolation below 90 cm, caused about 10 cm of additional water to be available for growth of grain sorghum in 1967. This additional water doubled yields, with an increase in evapotranspiration of only 50%. Evaporation from soil in the lysimeter was only 32% of the evapotranspiration, compared with 50% for the soil surrounding the lysimeter. Evaporation from the soil within a winter wheat crop during the acuively growing period in the spring, was estimated to be 15 and 37% of evapotranspiration for 1966 and 1967 respectively. Evaporation from the soil within the actively growing crop was estimated to be 34 and 20% of the evapotranspiration for oats and millet, respectively. Estimates of the amount of water evaporated from the soil within a crop allowed for estimation of transpiration from measurements of evapotranspiration. This data indicate that production and transpiration are directly related in this dryland area as de Wit (3) suggests.