不同耕作措施下金沙江下游紫色土区坡耕地产流产沙特征

Runoff and Sediment Yield of Sloping Farmland in Purple Soil Area of the Lower Jinsha River under Different Tillage Measures

金沙江下游紫色土区坡耕地水土流失严重,研究不同耕作措施对紫色土坡耕地土壤侵蚀的影响,对紫色土区水土流失防治具有重要意义。本研究以凉山州会东县紫色土区坡耕地为研究对象,采用野外径流小区法,基于21次自然降雨事件下的降雨和径流输沙数据,研究不同耕作措施对紫色土坡耕地产流产沙特征的影响。结果表明:(1)与顺坡垄作相比,平作、横坡垄作、顺坡垄作+秸秆和横坡垄作+秸秆的径流深分别减少12.24%、18.32%、36.42%和49.75%,土壤流失量分别减少57.34%、40.79%、69.89%和88.30%;(2)5种耕作措施下径流深和土壤流失量均随降雨等级增加呈增加趋势,顺坡垄作径流深为对应横坡垄作+秸秆小区的1.79~3.41倍,且倍数随降雨等级的增大而减小。横坡垄作土壤流失量在中雨和大雨条件下均显著低于顺坡垄作(P<0.05),而在暴雨条件下二者无显著差异;(3)5种耕作措施下的径流深和土壤流失量与降雨量(Pm)、最大30min雨强(I30)和降雨侵蚀力(EI30)均呈显著正相关,其中径流深与Pm相关系数最大,为0.89~0.93,土壤流失量与I30相关系数最大,为0.91~0.95;(4)5种耕作措施的径流深与土壤流失量之间均呈幂函数关系,决定系数均大于0.82。综上,横坡垄作结合秸秆覆盖能有效抑制水土流失,研究结果可为紫色土坡地水土流失防治及水土保持效益评价提供理论依据。

Soil erosion is one of the major problems in the purple soil area of the lower Jinsha River, and soil conservation tillage measures have high efficiency in preventing soil erosion. To quantitatively classify the effects of tillage measures on runoff and sediment yield, a study was conducted by runoff plots position observation method in Huidong County, Liangshan Yi Autonomous Prefecture, China. Compared with slope ridge tillage, the runoff depths of plat tillage, contour ridge tillage, slope ridge tillage+mulching and contour ridge tillage+mulching decreased by 12.24%, 18.32%, 36.42%, and 49.75%, and the sediment yield decreased by 57.34%, 40.79%, 69.89%, and 88.30%, respectively. The runoff depth and sediment yield gradually increased along with rainfall levels. Under drizzle, moderate rain, heavy rain and rainstorm, the runoff depth of slope ridge tillage was 3.41, 2.38, 2.04 and 1.79 times higher than that of the contour ridge tillage, respectively. The sediment yield of contour ridge tillage was significantly lower than that of slope ridge tillage under moderate rain and heavy rain, whereas there was no significant difference between contour ridge tillage and slope ridge tillage under rainstorm. Pearson correlation analysis showed significant positive correlation in rainfall amount(Pm), maximum rainfall intensity in 30 min(I30) and rainfall erosivity(EI30) with runoff depth and sediment yield under five tillage measures. The correlation coefficients between runoff depth and Pm, sediment yield and I30 varied from 0.89 to 0.93 and 0.91 to 0.95, respectively. Sediment yield was positively related to runoff depth by a power function, and the coefficients of determination were greater than 0.82. In conclusion, contour ridge tillage combined with straw mulching effectively controlled soil erosion induced by water. These results could provide a theoretical basis for the prevention and control of soil erosion and the evaluation of soil and water conservation benefits in the purple soil region.