Effect of Mulch Rate on Soil Loss by Raindrop Splash

Abstract

Abstract An experiment consisting of 50 rainfall simulator events of 76 mm/hour intensity for 30 minutes was run to examine the effect of oat straw ( Avena barbata Brot.) on splash detachment and transport of soil. Soil available for transport by interrill flow is a function of soil detached by interrill flow, direct splash impact, and secondary splash impact. Soil transported by interrill flow was measured separately from soil transported by rain splash. The small 30 by 30 cm plot minimized overland flow soil detachment because interrill (not rill) flow occurred. Soil transported by interrill flow was measured. Soil transported by splash and by the interrill flow is decreased as straw mulch cover increases from 0 to 96%. The amount of soil moved by rain splash and by interrill flow is linearly correlated with cover level when both processes are considered. At 96% cover, soil loss by splash transport is reduced to < 8% of the bare soil loss, and interrill transport is reduced to 24% of the bare soil loss. The amount of interrill flow of water was not reduced under the experimental conditions which implies that the reduction in sediment loss by interrill flow is the result of reduced detachment by rain splash.