| Soil erosion is one of the main factors affecting the productivity of sloping farmland in purple soil areas.In this study,we observed the runoff and sediment yield in the runoff plots which located in the Suining Soil and Water Conservation Experimental Station for 33 years.Analyzed the law of runoff and sediment yield by using the double cumulative curves(DMCs),and compared the composition of particles at different depths and different positions.The results showed that:(1)Annual average runoff increased from 5° to 15°,but decreased from 15° to 25°.The sediment yield increased with the increase of slope.(2)Compared with planting Silphium Perfoliatum,the annual runoff depth and sediment yield of planting wheat-and-corn increased by increased by 39.84%,and the annual sediment yield increased by 232.63%.Compared with transversal slope cultivation,the runoff depth and sediment yield of ridge planting decreased by 34.18% and 49.38% respectively.(3)With the increase of slope,the impact of tillage measures and crops on runoff will be gradually reduced,while the impact on sediment yield was not obvious.(4)The contribution range of rainfall to runoff and sediment yield change were 142.39%~36.02% and-86.64%~44.69%,respectively.The contribution rate of tillage measures on runoff and sediment yield were 63.98%~242.39% and 186.64%~55.31%,respectively.(5)Long-term tillage and rainfall caused the runoff plots to form the upper left erosion and the lower right accumulation,and the greater the slope,the more obvious of this trend.With the increase of slope,the balance line of scouring and silting will tend to be parallel with the upper and lower edges of the runoff plot and closer to the bottom of the slope.The particle composition of the soil layer within 0~40cm depth of the experimental plot is not much different,but the plot is different from the top of the slope.There was also no significant difference in the content of particles of the same particle size at the runoff plots. |
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