Effects of the amount of stubble mulch and overland flow on erosion of a cracking clay soil under simulated rain

Abstract

A field study by using simulated rain and run-on water was carried out to determine the effects of different amounts of wheat stubble mulch (ranging from 0.1 to 3 t ha-1) and increasing discharge on erosion. Rain-flow erosion decreased with increasing amounts of stubble. Concentrations of bed-load sediment carried by rain-flow decreased with increasing plot discharge. As discharges increased, overland flow probably became too deep for drop impact to effectively disturb the soil surface and entrain sediment. Only plots carrying 0.1 t ha-1 stubble showed definite scour by overland flow. However, sediment concentrations produced by scour were well below those measured in rill flow on bare soil at this site, showing that even very small rates of stubble mulch can, in some situations, significantly reduce erosion. Discharges at which rilling develops fully must be much larger than those at which scour by overland flow is initiated. Future work will need to consider discharges much larger than those used in this study.