Effects Of Straw Mulching On Soil Erosion Process In Karst Slope Farmland

Tillage measures are important factors affecting soil erosion on slopes.In order to reduce soil erosion,straw mulching is widely used in non-karst regions as a protective cultivation measure.The soil erosion in karst area includes both the common surface loss and its special underground leakage.Therefore,in order to reasonably evaluate the applicability of straw mulching measures on karst slope land,it is necessary to further clarify the impact mechanism of straw mulching measures on savannah slope soil erosion.This study takes the karst slope cultivated land as the research object,and uses the method of artificial rainfall in the field to analyze the impact of different coverage conditions on the soil erosion process of the karst slope farmland.Research indicates:?1?Whether under light rain intensity(45 mm·h^-1)or heavy rain(90 mm·h^-1),straw mulching can effectively reduce runoff.Under moderate rain intensity(45mm·h^-1),compared to no coverage,the total runoff of the lower slope decreased by55.6%and 52.8%,respectively,at a coverage of 20%and 50%.The total runoff at the mid-slope location was reduced by 19.5%and 36.4%,respectively,at a coverage of20%and 50%.?2?The surface runoff processes under different straw coverages showed a trend of steady growth after rapid increase of runoff.Straw cover can effectively reduce the surface runoff intensity at the time of stabilization.Under moderate rain intensity(45mm·h^-1),compared with the non-coverage condition,the surface runoff intensity at the mid-slope position under the conditions of coverage of 80%,20%,and 50%decreased by 17.8%,respectively.46.4%and 67.8%;Compared with the uncovered condition,the surface runoff intensity at the downslope stability under 20%and 50%coverage decreased by 21.4%and 13.3%,respectively.?3?Straw mulching can slow infiltration on the one hand,lagging behind the time of onset of abortion in the soil,on the other hand,it reduces the contact area between raindrops and soil,and easily produces runoff directly on the stalks,reducing surface runoff and runoff time.With the increase of coverage of the local table,the straw cover changes the nature of the runoff time of surface runoff lags behind that of the abortion flow in the soil,and the flow in the soil begins to lag behind the surface runoff time.?4?Compared with the non-coverage conditions,the amount of erosion can be effectively reduced under covered conditions.In the downhill position,under the uncovered conditions,the surface erosion amount was 67 kg·hm^-2,which was 6,8,and 4.8 times higher than the coverage of 20%,50%,and 80%,respectively.In the mid-slope position,under the uncovered conditions,the surface erosion amount was68 kg·hm^-2,which was 6,7.1 and 4.8 times that of the 20%,50%and 80%coverage.In the uphill position,under the uncovered conditions,the surface erosion amount was68 kg·hm^-2,which was 1.8,2.4,and 2 times of that under the coverage of 20%,50%,and 80%,respectively.The results of the study provide a scientific basis for understanding the effect of straw mulching measures on the soil erosion process of karst slope farmland,and provide reasonable basis for the rational deployment of soil and water conservation cover measures in karst slopes.