Models of Alfalfa Yield and Evapotranspiration

Data of per-cutting yields and annual yields from four cuttings were collected over six consecutive years for alfalfa grown on three lysimeters. Corresponding evapotranspiration was obtained from weekly water balances. Differences in water management created a range of conditions from water for annual yields of 10 ton/acre (22.4 ko m^-²) to 50% yield reductions caused by inadequate soil moisture required to satisfy evapotranspiration demands. Yield and water use efficiency, both annual and per-cutting data, were compared in correlation tests with their corresponding amounts of evapotranspiration. Annual and per-cutting yields were found to be statistically proportional to their evapotranspiration. Annual water use efficiency was not statistically significant with annual evapotranspiration. Although a questionable percentage of the data explained the variance, water use efficiency per cutting and evapotranspiration per cutting had a statistically significant negative correlation.