Spatial Variability Of Soil Properties And Soil Carbon, Nitrogen Storage Of Small Watershed In Southern Ningxia

Due to pieces topography, successive low hilly and long-term serious soil erosion, the vastLoess plateau have not contented tract. It is the most typically ecological fragile region of theChina and all over the world. It is also one of economic backwardness area in Chinese socialdevelopment. Take the comprehensive treatment watershed-Shanghuang as an example, the notreatment watershed-Sidigou as a reference. Geostatistics combined with GS+and ArcGIS9.3that were use for analysis the spatial variability and spatial distribution of soil moisture, soil bulkdensity, soil organic carbon content, soil total nitrogen content, soil carbon density, soil nitrogendensity. And the effect of soil land uses, slope position on soil properties, soil carbon, nitrogenstorage. With small watershed soil properties, dynamics, quantization process and soil carbon,nitrogen storage analysis and comparation, provide the basis for vegetation restoration, ecologicalevaluation and management, rational utilization of land resources. The conclusions werefollowed:（1） According to the variation coefficient classification, the optimal theory model thatfitting by geostatistics software GS+and distribution figure that used spatial interpolationmethod—Kriging, the result as followed, Soil moisture content: western area> eastern area>middle area; Soil bulk density were increased from west to east, the low vaule mainly concentrateupon natural grassland and shrub land; Soil organic carbon content: eastern area> middle area>western area; Soil total nitrogen content increased from east to west. Soil organic carbon density:eastern area> middle area> western area; In eastern area, soil nitrogen density were more higherthan western area.Regional soil moisture content, soil bulk density, soil carbon, nitrogen content and soilcarbon, nitrogen density were belong to medium intensity variation. The spatial variability wasless obvious which is caused by regional selt-relative factors. The system has a weak spatialvariability that except effect by natural factors, such as soil parent materials, topography, land usetypes, it also influenced by human interference factors which were the dominant factors.（2） Soil properties in different slope positions displayed different. The vaules of soilmoisture content on Mao top were higher than Mao slope, the lowest one was valley. Soil organiccarbon and total nitrogen: valley> Mao top> Mao slope. Except soil bulk density, the differentamong Mao top, Mao slope and valley in other soil properties displayed obviously. As soil depth increasing, the contents of other properties were gradually decreasing. The difference of soilproperties amone different slope postions were caused by regional hydrothemal configuration andvegetational distribution.（3） Soil properties in different land use types displayed different. Soil moisture content:terrace land> natural grassland> farmland> abandoned land> shrub land> artificial grassland>orchard; The difference of soil bulk density in different land use type showed unconspicuous, soilbulk density of abandoned land, shrub land and natural grassland were lower than other land usetypes; Soil organic carbon content: nautal grassland> orchard> shrub land> abandoned land>terrace land> artificial grassland> farmland; Soil total nitrogen content: natural grassland> shrubland> abandoned land> terrace land> orchard land> artificial grassland> farm land.In different land use types, the soil organic carbon and total nitrogen content of naturalgrassland were highest, and the lowest land use type was farm land. Compared with farmland, soilbulk density in vegetation restoration conditions, such as natural grassland, abandoned land andshrub land were lower. The result showed that the Grain for Green measures can effective enhancesoil organic carbon, nitrogen and improve soil quality.（5） Due to the differents of land use types area and soil carbon, nitrogen density, thedifference of soil carbon, nitrogen stroge between comprehensive treatment watershed and nontreatment watershed were obviously. In comprehensive watershed--Shanghuang, the main landuse types are shrub land（22052.81t、6525.12t） and natural grassland （14573.14t、3634.42t） which occupied70.43%of the total area. And the soil carbon, nitrogen stroge account for78.7%and75.84of the total storage. In non-treatment watershed—Sidigou, the main land usetype is farmland which area account for52.85%of the total. And the soil carbon, nitrogen strogeoccupied44.29%and53.03%, respectively. The result illustrated that soil carbon, nitrogenstorage would improve effectively in vegetation restoration conditions.