REDIRECTION OF PRECIPITATION BY A CORN CANOPY AND RELATED SOILWATER STATUS1*

Abstract

Redirection of precipitation by a crop canopy significantly affects the distribution of water entering soil. This knowledge can be used to improve crop management practices for protecting ground water. Over a 4-y period, rain and/or irrigation water was collected at 8 equidistant positions between corn (Zea mays L.) rows. Soil water status was measured to a 0.3-m depth in the same relative positions. Wind direction and speed, and crop canopy development influenced the location where throughfall entered the soil surface and resultant soil water content. Stemflow increased to > 60% of incoming precipitation with canopy closure in most years. These large amounts of water entering the soil as stemflow increased percolation in the row and soil water content below the row, the zone of greatest depletion of plant available water. Associated with canopy closure, reduced throughfall reached the soil surface within 0.2 m of the row; hence, a reduced potential for leaching of agrichemicals applied in this area. * Minnesota Agric. Exp. Stn. Scientific J. Series No. 991250097.