The Study On The Soil And Water Conservation Benefit Of Different Vegetation Patterns In Rainy Area Of West China

Through one year of field observation in the runoff plots, we studied the amount of precipitation, soil erosion, nutrient loss, atmospheric wet deposition and soil physicochemical property in different plantation patterns(Eucalyptus grandis plantation with ground cover, E. Grandis plantation without ground cover, Cryptomeria fortunei plantation with ground cover, C. fortunei plantation without ground cover, Agricultural land and waste grassland) in Rainy zone of west China.The results showed as follows:l.Soil erosion mostly happened from June to October when the rainfall was higher. The amount of rainfall and soil erosion showed:August>July>September>June>October. The surface runoff of agricultural land was the highest, and the soil erosion modulus was less than both plantations without ground cover (C. fortunei plantation and E. grandis plantation)., but more than grassland and both plantations with ground cover. The surface runoff and soil erosion modulus of grassland was the slightest. The surface runoff and soil erosion modulus of C. fortunei plantation without ground cover was120%and270%higher than C. fortunei plantation with ground cover respectively. The surface runoff and soil erosion modulus of E. Grandis plantation without ground cover was200%and5420%higher than Eucalyptus fortunei plantation with ground cover respectively. The surface runoff and soil erosion modulus of E. Grandis plantation without ground cover was62.4%and1930%of Cryptomeria fortunei plantation with ground cover respectively. It indicated that the ground cover played an important roll in reducing soil erosion.2.The runoff nutrient loss (total soluble N, NO3--N, NH4+-N, soluble P, soluble K+, total soluble C, soluble C) in grassland was the smallest compared to other plantations. The runoff nutrient loss in agricultural land is the biggest except soluble K+. The runoff nutrient loss of E. grandis plantation with ground cover was smaller than without ground cover. The runoff nutrient loss of C. fortunei plantation with ground cover was bigger than Eucalyptus except total C. The runoff nutrient loss of C. fortunei plantation without ground cover was bigger than E. grandis.The amount of sediment nutrient loss (TN, TP, TK, organic, soluble N, available P, NN, fast available K) was related to sediment loss, which in grassland was the smallest and in E. grandis plantation without ground cover was the biggest. The nutrient loss in Agricultural land was smaller than fortunei plantation without ground cover, except TP loss was the biggest and TK was bigger than C. fortunei plantation. The nutrient loss in C. fortunei plantation with ground cover was bigger than E. grandis. The nutrient loss in C. fortunei plantation without ground cover was smaller than E. grandis.3.The wet deposition in July and August was the biggest, when the soluble S and soluble TN was the maximum. The wet deposition in waste grassland was bigger than nutrient loss. C. fortunei plantation and E. grandis plantation with ground cover did better in keeping wet deposition nutrient.4.The effects of ground cover on changing volume weight of soil and porosity happened mainly in0-10cm soil layer. As the depth grew, the effects got smaller. The condition of volume weight of soil and porosity in plantation with ground cover was better than without ground cover. The condition of volume weight of soil and porosity in grassland was worse than C. fortunei plantation. Soil venting quality in C. fortunei plantation witht ground cover is bigger than without ground cover. The Soil venting quality in agricultural land was the worst. The soil moisture content in different layers showed:0～10cm<20～40cm<10～20cm. The soil moisture content in different plantation patterns showed:agricultural land>C fortunei plantation with ground coverage> grassland>C. fortunei plantation without ground coverage>E. grandis plantation with ground coverage>E. grandis plantation without ground coverage. The maximum water-holding capacity and capillary water holding capacity in fortunei plantation with ground cover was better than fortunei plantation without ground cover, and of which the C. fortunei plantation is better than corresponding E. grandis plantation. The field capacity in C. fortunei plantation without ground cover was bigger than with ground cover, which was oppsite to the field capacity in C. fortunei plantation without ground cover was bigger than without ground cover, which was oppsite to E. grandis plantation. The soil permeability showed:grasslandsE. grandis plantation with ground cover>agricultural land>C. fortunei plantation without ground cover>E. grandis plantation without ground cover>C.fortunei plantation with ground cover.5.The nutrient(organic, TN, soluble N, NO3-N, TP, available P, K+) in C. fortunei plantation with ground cover was more than without ground cover, but the available S was oppsite. The amount of TN, soluble N, NH4-N, available P and K+in E. grandis plantation with ground cover was bigger than without ground cover, except Organic, TP, available S and NO3-N. The ground cover increased the soil acidity in C. fortunei plantation and decreased soil acidity in E. grandis plantation. The siol acidity of topsoil in forest plantation with ground cover was bigger than subsoil, which was the oppsite in forest plantation without ground cover. C. fortunei plantation had the biggest soil acidity.6.The amount of microbial biomass C in forest plantation with ground cover is bigger than without ground cover. In top soil between0-20cm, ground cover had a bigger effect on microbial biomass C in C. Fortunei plantation than E. grandis plantation. The amount of microbial biomass C and N was the biggest in grassland.All above suggested that all the plantations can reduce the surface runoff, it’s good to reduce soil erosion and improving soil physical and chemical properties through keeping a good ground cover. The C. fortunei plantation had a better effection to improve the physical and chemical properties of soil compared with E. grandis plantation. Keeping a good ground cover were not only beneficial to increase the plantation soil and water conservation function, but also improve the soil physical and chemical properties, enhance the nutrient supply of soil for the plantations, and helpful to maintain the sustainable development of plantation.