RELATIONSHIP OF SOIL AND PLANT CHARACTERISTICS TO EROSION AND RUNOFF ON PASTURE AND RANGE

Most soil loss equations for pasture and rangeland have been developed using data from studies conducted on cropland. This study was conducted to further determine relationships of soil and vegetation factors to soil loss and water runoff from reclaimed pastures and rangeland. Simulated rainfall was applied, using a sprinkler-head grid system at a rate of 46 mm h-1 (1.8 inches/hour), to 4.0 m x 22.1 m (13 x 72 feet) plots on reclaimed mined and native Cabba and Sen soils. Treatments included reclaimed heavily, moderately, and lightly grazed pastures; reclaimed burn; reclaimed ungrazed; native grazed; native burn; and native ungrazed runoff plots. Percent bare ground was the most important factor explaining soil loss. As ground cover increased, soil sediment in the runoff decreased because of less soil detachment. Total vegetative dry matter was the most important factor explaining runoff. Vegetation and ground cover were related highly to soil loss and runoff factors, whereas soil bulk density, soil water, root weight, soil aggregation, and soil particle size generally were not. Vegetation and ground cover factors and soil bulk density and root weight were related to runoff. Vegetation and surface soil factors were of major importance in explaining soil erosion on rangeland compared to subsoil factors generally associated with soil erodibility on cropland. These findings deserve consideration as equations are developed for predicting soil loss and runoff from pastures and rangeland.