Soil Erosion and Runoff from Planting to Canopy Development as Influenced by Tractor Wheel-Traffic

ABSTRACT A rainulator was used to apply rainfall at known energy to field plots on which a 2-yr history of con-trolled wheel traffic had been established. Standard runoff collection and measuring procedures were modi-fied to separate soil losses and runoff occurring in the wheel tracks from those occurring in the nontracked area. In addition to measuring soil and water losses, various measurements were made on both the matrix soil and the sediment in order to determine basic cause and effect relationships between wheel traffic, soil compac-tion and erosion. Compaction from wheel traffic increased bulk density and decreased total porosity of the tilled layer, both of which reduced infiltration and increased runoff and soil loss. Soil moisture content at the time of tillage was low enough so that any compensating effects of compaction on aggregate stability, random roughness and matric po-tential were minimized, thus leaving the wheel tracks in a more erodible condition than the nontracked areas.