耕作措施及雨强对南方红壤坡耕地侵蚀的影响

选择典型南方红壤区平均坡度为10°的坡耕地小区进行天然降雨观测,对横坡耕作、顺坡耕作、顺坡耕作+植物篱、稻草覆盖4种耕作措施在侵蚀过程中的径流泥沙和养分流失特征进行研究。结果表明,监测期间,径流深和泥沙流失量基本随雨强的增大而增加。随着耕作措施由顺坡耕作向顺坡耕作+植物篱、横坡耕作、稻草覆盖的转换,减流效益、减氮效益和减磷效益依次增大。稻草覆盖措施减流效益最佳,为91.77%;横坡耕作措施减沙效益最佳,为98.91%;稻草覆盖、横坡耕作和植物篱3种措施在防治高强度降雨引发的土壤侵蚀和养分流失具有较高的效益。耕作措施对泥沙粒径分布有影响。与顺坡耕作、横坡耕作相比,植物篱和稻草覆盖措施能够更有效地拦截径流中的粗颗粒。该研究可为南方红壤丘陵区坡耕地选择合适的耕作措施和防治农业非点源污染提供依据。

Effects of Cultivation Measures and Rainfall Intensities on the Slope Erosion in Red Soil Sloping Cropland

The natural rainfall was observed in the runoff plots with 10° slope in red soil region. Five treatments:bare land as control (CK), down slope tillage (DT), hedgerows with down slope tillage (DT+HG), contour ridge tillage (CT) and straw mulch (SM) were designed. The effects of cultivation measures and rainfall intensities on runoff depth, sediment yield and nutrient losses were evaluated. The results showed that the runoff depth and sediment loss were increased with the increasing rainfall intensities during the rainfall events. With the cultivation measures changed from DT to DT+HG, CT and SM, the effectiveness of the cultivation measures on reducing runoff, nitrogen and phosphorus was increased respectively. The average annual runoff reduction (91.77%) of SM was the highest. But the sediment reduction (98.91%) of DT was the highest. The SM, CT and DT+CT measures were effective in preventing soil erosion and nutrient loss caused by the heavy rainfall. Cultivation measures influenced the sediment size distribution. The DT+HG and SM treatments were more effective on trapping coarser particles compared with DT and CT treatments. This study was helpful for selecting the suitable cultivation measures and provided data support for the protection and regulation of soil and water losses and non-point pollution in sloping cropland.