Effect of Slope on Water Balance Under Center‐Pivot Irrigation

The effects of slope on soil water storage and other water balance components under center‐pivot irrigation were studied in Gage County, Nebraska. Soil water, surface runoff, precipitation, and irrigation were measured for soils of low infiltration on slopes of 2, 4, and 8% under corn ( Zea mays L.). Evapotranspiration was calculated. Soil water content (0‐ to 137‐cm depth) during the growing season was higher in soils on 8% slopes than in soils on slopes of 2 and 4%. Runoff from all slopes was not associated with sprinkler irrigation in the crop production system studied. As slope increased, surface runoff caused by rain increased, and internal drainage beyond the 137‐cm depth decreased at approximately the same rate. The overall water depletion during the growing season was not significantly affected by slope.