Soil Water Recharge Function as a Tool for Preseason Irrigation

ABSTRACT FIELD plot soil water data collected at Colby, Kansas from 1979 through 1982 were used to develop an empirical model to predict available soil water content after corn planting (0 to 1.5 m depth) from fall soil water content and fall through spring precipitation. Soil water storage and storage efficiency were both found to be negatively linearly related to fall soil water content. The overall 3-yr storage efficiency equation had a high correlation, R2 = 0.87 at significance level P > 0.01. The soil water recharge function is centered around a water storage efficiency equation developed over wide ranges of fall through spring precipitation and fall soil water contents. Decision tools predicting the need for fall preseason irrigation based on estimates of fall soil water and the fall through spring precipitation probabilities are presented. This model's simplicity makes it practical as a criterion for determining the need for fall preseason irrigation for corn on the silt loam soils of western Kansas.