The Effect Of Soil And Water Conservation And Ecological Effect Of Water And Fertilizer On Soil Under Different Vegetation Restoration Patterns

With the implementation of grain for green project,surface vegetation coverage has been greatly improved; Water loss and soil erosion have been under effectively controlled and the ecological environment have been improved step by step in Weibei plateau. This research regards ranjiagou watershed of qianyang county of Shaanxi province as to study subject,adopting field investigation, fixed-point observation and indoor analysis methods,researching and analyzing the effect of soil and water conservation and ecological effect of water and fertilizer on soil under different vegetation restoration patterns , evaluating functions and effects of different vegetation restoration patterns, this thesis provides a theoretical basis for vegetation restoration of abandoned lands, for the rational allocation and distribution of forest and grass, for ecological environment construction of western regions under taking and for the project of returning farmland to forest and grassland in Loess Plateau. After the research and analysis,the main conclusion were drawn as following:(1) It is evident that the effect of soil and water conservation of enclosure and locust has improved greatly than that which is in farmland. The effect of soil and water conservation of enclosure was better than locust.(2) Through the correlation analysis between biomass of enclosure and the surface runoff ratio and sediment ratio on vegetation restoration pattern (same to locust), we can draw the conclusion that negative correlation between biomass of different vegetation restoration patterns and the surface runoff ratio and sediment ratio. It was showed that improvement of biomass could reduce efficiently the surface runoff and sediment content. Consequently, soil erosion of slope cultivated land was reduced. (3) The soil water content has biggish difference because of different topography, and was different types of vegetation, different restoration time, different vegetation restoration patterns, and different biomass.(4) The soil water's seasonal dynamic change of several different vegetative restoration types and farmland showed the consistent tendency, which presented obviously "V",the soil water content of enclosure was obviously higher than the other's. Different exploitation of soil moisture made the soil average moisture content as well as the soil moisture profile different. Each layered variation coefficients of different vegetative restoration types was different, and vertical change of variation coefficients was also different because of various restoration types.(5) As far as super stratum soil bulk density, the land of converting agriculture land into forest and grass was much significant higher than contrasting farmland, but the substrate soil bulk density was much significant lower than contrasting farmland.(6) The total quantity and each particle fraction of soil aggregate all exceeded the farmlands after returning the grain plots to forestry and grass. Restoration of vegetation causes soil organic matter accumulated rapidly and soil's cementation characteristics and corrosion resistance improved.(7) Most of standard sample land's soil available nutrients in super stratum soil were higher than that in middle or lower part of soil. Among nine standard sample lands, there was much marked difference in the whole nutrient contents in all layers. The soil available nutrients were different in soil profile layers, and were the whole nutrient contents.(8) Among nine standard sample lands, there was much marked difference in content of organic matter in all layers. Soil organic matter contents were all decreased with soil deep increased, which was more obvious for vitex negundovar.heterophylla,arborvitae and enclosure.(9) On the basis of system analysis of soil fertility, using clustering analysis, the author have selected apple, locust, enclosure three kinds of styles as the primary types in converting agriculture land into forest and grass; vitex negundovar.heterophylla and arborvitae two kinds of types as the wash out types; alfalfa has also relatively broad value of popularization.