秸秆覆盖对喀斯特不同类型坡耕地降雨产流的影响

Effects of Straw Cover on Rainfall Runoff in Different Types of Karst Slope Farmland

喀斯特地区土层不连续且常有岩石出露,坡耕地类型多样。为研究秸秆覆盖对不同类型喀斯特坡耕地降雨产流特征的影响,通过野外人工模拟降雨试验,研究裸坡地(BS)、岩石出露型(RE)和砾石覆盖型(RF)3种典型坡耕地类型在4个秸秆覆盖度(0、20%、50%、80%)下的地表径流和壤中流产流特征。研究结果表明:①3种类型喀斯特坡耕地中,RE的平均地表径流系数显著高于其他类型,分别为BS和RF的1.8和7.8倍,而RF的平均壤中流径流系数显著低于其他类型,分别较BS和RE减少了83.7%和78.9%;②秸秆覆盖在BS和RE减少地表径流的效果优于RF,其中20%覆盖度在BS的减流效果最好,较无覆盖减少了26.2%,50%覆盖度在RE的减流效果最好,较无覆盖减少了44.5%;③秸秆覆盖对壤中流的影响较为复杂。秸秆覆盖在RF均会增加壤中流量,在BS均会减少壤中流量,但对RE壤中流的影响无明显规律。研究结果可为喀斯特坡耕地水土保持措施的合理布设提供参考。

The karst is characterized by discontinuous soils and common rocky exposures,with a variety of types of farmland.In order to study the effect of straw mulching on the characteristics of rainfall runoff in different types of karst slope farmland,the characteristics of surface runoff and subsurface runoff in three typical slope farmland types of bare slope land(BS),rock exposure type(RE)and rock fragment type(RF)under four straw mulching degrees(0,20%,50%,80%)were studied through field artificial simulated rainfall test.The results showed that:①In the three types of karst slope farmland,the average surface runoff of RE was significantly higher than that of other types,which was 1.8 and 7.8 times of that of BS and RF,respectively.At the same time,the average subsurface flow coefficient of RF was significantly lower than that of other types,which was 83.7%and 78.9%lower than that of BS and RE,respectively.②The flow reduction effect of straw mulching in BS and RE was better than that of RF.The flow reduction effect of 20%coverage in BS was the best,which was 26.2%lower than that of no coverage.The flow reduction effect of 50%coverage in RE was the best,which was 44.5%lower than that of no coverage.③The effect of straw mulch on the subsurface runoff was more complex.Straw mulching increased subsurface runoff in RF,but straw mulching decreased subsurface runoff in BS,and there was no obvious rule for straw mulching on the effect of subsurface flow in RE.The results can provide a reference for the reasonable arrangement of soil and water conservation measures in karst slope farmland.