Effect of grazing on runoff from two small watersheds in southwestern Wisconsin

Storm runoff from two small open pasture watersheds was measured for 11 years: during the first 7 years both were grazed, and during the last 4 years only one was grazed. Their runoff behavior was similar when both were grazed, but by the third year after cessation of grazing, runoff from the ungrazed watershed had dropped sharply. The ungrazed/grazed ratio for mean total flow had dropped from 1.17 to 0.10 and for mean peak flow from 0.82 to 0.03. After 3 years without grazing a heavy mat of bluegrass blanketed the ground, and soil bulk density was significantly lower.