Maximum and Actual ET from Grasses and Grass-Like Plants

Two studies of mountain meadow water use were conducted along the Little Laramie River and in the Upper Green River Basin of Wyoming. Monthly and seasonal data from twelve non-weighing lysimeters are reported for 2 to 4 year periods. Water tables in the lysimeters were maintained at levels similar to the surrounding areas. During the latter portion of the growing season, water supplies often become limited and irrigation is infrequent or completely discontinued. Results show the variation in water use, from a relatively high rate in years when water supplies (thus, river flows) are high to low in years when water supplies are low and water tables are deep. A calibration of the Penman-Monteith model for the estimation of evapotranspiration (ET) is given.