EVAPOTRANSPIRATION AND SOIL WATER RELATIONSHIPS FOR SPRING WHEAT AND SOYBEAN

Publisher Website
Google Scholar
Abstract
Nonlinear models were used to statistically analyze the relationship betwen evapotranspiration and soil water content at variable levels of potential evapotranspiration. Using precision weighing lysimeters, daily evapotranspiration for spring wheat (T. aestivum L.) and soybean [G. max (L.) Merrill] was obtained. Soil water content in the root zone was measured by neutron attenuation. For purposes of analysis, the highest volumetric water content within the root zone was used as the indicator of available water to the plant. Similarly, pan evaporation was used as an index of pontential evapotranspiration. Eight models were tested, using pan evaporation, soil water content, or both to predict evapotranspiration. The R2 values obtained were 0.89 for wheat and 0.76 for soybean. The 2 simple variables do a good job of predicting evapotranspiration and describing the relationship of soil water content and potential evapotranspiration to actual plant water use.