Spatial Variability And Evaluation Of Soil Nutrients In Central Arid Region In Ningxia

The spatial variability of soil nutrients can provide a wide range of the data to manage the soil nutrient more scientifically, avoid the waste of that unnecessary things, it also can be more precision fertilization in the planting process, and in some degree it is treated as the basic work for the accurate and reasonable implementation of precision agriculture. Variability of soil nutrients happens at different spatial locations is an important side of the many attributes of spatial variability of soil. Analysis tools of the spatial data help mapping in many functions of GIS, the model for the spatial data analysis contributes analyzing the message in Geostatistical, and the combing of these two functions can bring something original abstract theory into image and model to solve practical problems simply and quickly, most of all, this can be more efficient and accurate for explaining the principles vividly and Intuitively. In this study, GIS and Geostatistical were used to analyze the spatial distribution characteristics and spatial variability of soil nutrients at dryland water saving agricultural demonstration region in Wangtuan Ningxia, and explored the status of soil nutrient, evaluated the overall level of soil nutrients, the results showed as followed:(1) Among the soil nutrient content, pH’s coefficient is the smallest, which is showed as 0.04, and the maximum coefficient of variation for available phosphorus is 0.61. The total trend is available phosphorus> total phosphorus> K> nitrogen> TN> total salt> organic matter> pH.(2)The correlation analysis between soil nutrient mainly describe the close links in the extent and the degree of interaction of various indicators, and there is no significant correlation between total nitrogen and organic matter, pH, total phosphorus, nitrogen, available phosphorus. Correlation is not significant between total phosphorus and available phosphorus, K and total phosphorus, and the rest are extremely significant correlation. Among them, the correlation coefficient of the nitrogen and total salt was 0.601, the correlation coefficient of nitrogen and pH is 0.662, it shows a highly significant correlation.(3)Organic matter, pH, total phosphorus, nitrogen, available phosphorus, total nitrogen, total salt, potassium have the spatial correlation in a certain range, which is 74m-2110m.The maximum variable range value of nitrogen and total phosphorus are 2110m,the minimum variable range is 74m, the regular pattern of the variable range value for the rest of soil nutrients is total salt> pH> K> available phosphorus> organic matter.(4)From pH spatial distribution on map, the change of gradient is not great because of the range of small change of pH changes. Soil nitrogen content turns little from east of the study area to the west of the study area, and the content of total nitrogen content exhibited lower central region, higher in the east and west; total phosphorus content of the northern areas is higher than the southern region, scattered in various grades and in the south most; available phosphorus content distribution as its northern areas than in the southern region, the eastern content is higher than the western, there are three scattered small area available phosphorus content shows high content; available potassium content in the north is significantly higher than the south, standards of the huge majority region in the south is lower than national levels, northeast content is extremely rich; only the organic matter content in the study area is relatively uniform, showing spatial variability is lower only in the central and western regions; total salt in the northern part is higher than the south, especially in the northern region, decreasing from east to west, while the content in the middle of the southern region was significantly lower than the surrounding area.(5)There is an analysis between soil mechanical composition (Sand, silt, clay) and content of soil nutrient, showing the distribution of the soil nutrient content of available phosphorus,K.nitrogen,TN, total salt, organic matter have a close contact with the soil mechanical composition.(6)The evaluation result from the spatial distribution soil nutrients showed that the B grade land in the northeast region accounted for 38.4% of the study area, the southwest region is distributed by the C grade land, which amounts to 59.18%, The A grade land only refers to some several dot regions in the northeast corner, which is only 0.02% of the total area.