Relation of potential evapotranspiration to environment and kind of plant

The purpose of this investigation was to establish relationships between potential evapotranspiration and several elements of weather, potential evapotranspiration as influenced by the surroundings and irrigation of the surroundings, and potential evapotranspiration of Kentucky bluegrass, sweet corn, and celery. High correlations were found between measured potential evapotranspiration (PE) of bluegrass and open‐pan evaporation, atmometer evaporation, average temperature, solar radiation, and duration of sunshine when data were grouped into between‐rain periods. When the same data were grouped into seven‐day periods, relatively low correlations were obtained. Uniform surroundings, watered daily, were found to reduce measured PE of bluegrass 23.2 pct below bluegrass in non‐uniform surroundings which were not watered. Measured PE exceeded evapotranspiration computed by the Thornthwaite empirical formula by 10 to 70 pct and appeared more closely associated with amount of rainfall than with mean temperature. Water use by sweet corn was found to be 22.2 pct higher than use by bluegrass. Although the surrounding area of celery was watered each day, PE was 11.0 pct greater than that of bluegrass, the surrounding area of which was not watered. When compared with PE of bluegrass which received daily irrigation of surroundings, water use by celery was 36.8 pct greater.