Temporal And Spatial Variations Of Soil Properties In The Gravel Mulched Field Of The Central Arid Zone In Ningxia

The gravel mulched field is a special tillage style in arid and semi arid area in northwest in China. The gravel mulched industry have become pillar industry of the Central Arid Zone in Ningxia and pressure sand melon become geography product, and its area has reached 1 million mu in the year of 2007. It is necessary to research temporal and spatial variations of soil properties in different sampling scale to know the quality of soil resources. And it help to understand the evolution of the temporal and spatial variation characteristics of soil fertility and make the fallow measures and provide a comprehensive basis for the central Ningxia sandy land agricultural drought for the healthy and sustainable development of sandy land agricultural.The paper mainly use the geo-statistical method. And to analyze the physical properties, chemical properties and the attribute value of biological properties and the pressure value of soil physical properties in the field scale and Xiangshan by the software of SPSS、GS+、Suffer、Arc GIS. The results as follows:(1) To analyze the soil physical properties, chemical properties and enzyme activities of soft sand gravel mulched field of 1 a.3 a,5 a,7 a,10 a and in different depth adjacent control field of 0-10cm, 10-20cm,20-30cm, and get the effects result of gravel mulch on soil properties:soil mechanical composition increase with the pressure sand years, and show significant changes to the coarsening. Coarse sand content decreased with soil depth gradually. Compared with the control group, the bulk density of soil in the pressure increases, the capillary porosity and total porosity decreased, capillary moisture capacity and saturated water content decreased. The soil water content of pressure sandy is higher than the control group obviously. And it explains pressure sand could decrease the evaporation of soil water effectively and improve the water use efficiency.The content of salt in the soil pressure are lower than the control group, it explain pressure has the function to reduce soil salinization. Nitrogen, Phosphorus, potassium and other fertility status of pressure soil decreased with the year of pressure, and the content of 1 a is the highest in all years, but the soil nutrient of 3a dropped more obvious than la. The difference between the length of fertility level shows significantly. Four kinds of soil enzyme activity increased with the increase of the overall and showed a trend of decrease on the whole. Soil organic matter, total nitrogen, available phosphorus and clay content on soil enzyme activity was relatively strong. Therefore, it should focus on the maintain and improvement of soil fertility in the process of farming. Fertilizer should take the organic fertilizer and slow-release fertilizer as the main fertilizer, and dressing should use leaf fertilizer. In addition, we should adjust the cropping system, make reasonable allocation of fallow and production to keep excellent characteristics of the gravel mulched field and avoid the phenomenon of soil barren(2) Taking the 10×10m field scale of Hong Juanzi Village, Xingren County, Ningxia Hui Autonomous as example, and research the spatial variability of soil physical properties in different depth on the gravel mulched field. The main result as follows:In different sampling depth, the soil bulk density, total porosity and capillary porosity show weak variation and the saturated water content shows medium variation. Soil saturated hydraulic conductivity in depth of 0-10 cm shows medium variation and belongs to pure nugget effect are effected by random factors. Soil saturated hydraulic conductivity in depth of 10-20 cm shows strong variation and are effected by structural factors. Bulk density shows pure nugget effect in the two sampling depth and are effected by random factors. The average values of various physical properties of soil in the depth of 10-20 cm are bigger than 0-10 cm. There is negative correlation between saturated hydraulic conductivity and bulk density, but optimistic correlation between saturated hydraulic conductivity and saturated water content, total porosity and capillary porosity. The spatial interpolation of physical property shows difference on values, but similarly on the degree of density and trend of changes. We should strengthen the protection measures to the south farming, and improve the physical properties of soil and the efficiency of land use in the future. The spatial distribution map could provide data support and theoretical guidance for the research of field management and the implementation of precision agriculture.(3) To analyze spatial variability of soil physical properties of Xiangshan of 0-20cm,20-40cm of Xiangshan area in Ningxia, the results as follows:the soil bulk density belongs to weak variation, and the total porosity, saturated water content, capillary porosity and saturated hydraulic conductivity belong to medium variation. The average value of soil physical properties in 20-40 cm is bigger than 0—20 cm. The spatial correlation of physical property in the depth of 0-20cm is relatively strong, but the spatial correlation of saturated hydraulic conductivity, saturated water content and capillary porosity relatively weak in the depth of 20-40cm. The soil bulk density and total porosity has the medium spatial correlation. The spatial interpolation of physical property shows difference on values, but similarly on the degree of density and trend of changes. The physical property in the northwest is better than the southeast in the area of Xiangshan. To achieve the purpose of stable, excellent production, it should strengthen the tillage management system, and reduce the effect of human factors and improve the utilization rate of the gravel mulched field.