Research On Effect Of The Slope Planting Grass To Soil Erosion Process In Purple Soil Region

Ninghua City,located in the area of "the source of three rivers",suffers the most serious soil erosion in Fujian Province.It is one of typical representatives of purple soil erosion region in South China,and its history of soil erosion has been more than a century.In this paper,select the purple soil in Nanjing West,using the method of artificial simulation rainfall,systematically analysis the simulated rainfall conditions in purple soil slope runoff and sediment variation.Following conclusions can be reaced:(1)Three rainfall intensities of slope runoff and sediment yield in order of size are as follows:1.5>1.0>0.5mm/min;cumulative size of runoff and sediment yield is 1.5>1.0>0.5mm/min.(2)The runoff and sediment yield were decreased with the increase of coverage,and the effect of vegetation on reducing sediment loss are significant.When the vegetation coverage is more than 50%,it can play a very good effect of reducing the runoff and sediment.(3)The infiltration rate increases with the increase of the degree of coverage.The larger the vegetation coverage,the smaller the fluctuation of the infiltration rate of rainfall duration.With the increase of soil moisture content in each soil layer,the soil moisture content was also increased.In the late stage of vegetation growth,the roots are mainly concentrated in the 10-15cm soil,leading to 10-15cm soil moisture increased significantly.(4)On the bare slope,erosion and sediment particle size>0.25mm levels of erosion in basically the same and few.erosion sediment particle size<0.25mm proportion in 68%-72%,is the amount of other levels of size 10 times.When there is vegetation cover,the amount of eroded sediment is obviously reduced,and the erosion amount of the sediment particles in the particle size of<0.25mm is reduced by more than 80%,which has a good effect on preventing the loss of soil nutrients.