模拟玉米茎秆流对土壤侵蚀的影响

Effect of Simulated Corn Stem Flow on Soil Erosion

玉米茎秆流是降雨过程中经玉米冠层截留后沿茎秆流向根部的水量,是种植坡地地表径流的重要组成部分,对植物根部的土壤侵蚀过程具有重要影响。采用人工模拟降雨方法,研究了成熟期玉米茎秆流对坡地土壤侵蚀的影响。试验土槽长为0.40 m、宽为0.23 m、深为0.14 m;采用直径为2 cm的PVC管模拟成熟期玉米茎秆,高度为1.2 m;模拟茎秆流量为5,10,15 g/s,用相同降雨条件下无茎秆流坡地作为对照措施;降雨强度为60,90,120 mm/h,降雨历时108 min,坡度为10°。结果表明:(1)与对照措施相比,茎秆流具有加快坡地地表产流的作用;(2)模拟茎秆流条件下地表产流量和产沙量均高于对照,相较无茎秆流坡地,3个降雨强度下各茎秆流量的产流贡献率为14.90%~43.10%,产沙贡献率为12.47%~26.75%;(3)茎秆流在茎秆周围地表形成细小股流,促使坡地土壤侵蚀过程由面蚀向细沟侵蚀转变,从而增加了坡地土壤侵蚀量。因此,在坡地水土流失计算与评价中应考虑茎秆流的土壤侵蚀作用。

Corn stem flow is the amount of water flowing along the stalk to the root after intercepted by the corn canopy during rainfall.It is an important component of surface runoff on the slope and has an important effect on the soil erosion process at the root of the plant.In this paper,artificial rainfall simulation method was used to study the effect of corn stem flow on soil erosion in sloping field.The test soil trough was 0.40 m long,0.23 m wide,and 0.14 m deep.A PVC pipe with a diameter of 2 cm was used to simulate the corn stalk at the maturity stage and the height was 1.2 m.The simulated stem flow was 5,10 and 15 g/s,with the same rainfall under the conditions,the stalk-free sloping land was used as a control measure.The rainfall intensity was 60,90,120 mm/h,the rainfall lasted 108 minutes,and the slope was 10°.The results showed that:(1)Compared with the control measures,the stem flow has the effect of accelerating sloping surface runoff.(2)The surface runoff and sediment yield under simulated stem flow were higher than the control,compared with no stem flow slope,under three rainfall intensities,the contribution rate of runoff from the three stems was 14.90%~43.10%,and the contribution rate of sand production was between 12.47%and 26.75%.(3)The stem flow formed a small surface around the stem,and the currents caused the soil erosion process to change from surface erosion to gully erosion,thereby increased the slope soil erosion amout.Therefore,the soil erosion of stem flow should be considered in the calculation and evaluation of soil erosion on slope farmland.