| The studies of soil spatial variation,especially on the research of quantification process has the vital significance not only improve the utilization efficiency of farmland water but also improve the management, especially for the "precision agriculture" in China.As soil is effected by natural factors and human activities, so the soil becomes a change of the space-time continuum, and with high spatial variability.In the 1970s, Burgess introduce geostatistics into soil science field to overcome the shortage of classical statistical theory in the study of spatial variation regularity of soil properties.Geostatistics focused on the analysis of regional spatial structure variables, simulation and spatial interpolation, GIS focus on the space reveal and query.Now they were combined and the development of the trend is very quickly. This paper on the basis of previous studies, application the basic principles and methods of the geostatistics, and use the module of Geostatistical Analysis and Spatial Analysis in the Arcmap of GIS, take XinZheng for example, study the spatial variation of the soil nutrient situation, so as to effectively use research in soil fertilizer science test.With the help of GIS and geostatistics,take XinZheng for example , the result of studying on the spatial variability of 7 soil fertilities,namely soil PH, organic matter,total nitrogen, available phosphorus,available kalium, slowly available kalium, available zinc can be showed.1. The test sample district is the XinZheng city which located in the central henan province,the terrian is high in west and middle,low in east ,north and south.It has high mountail , hillock and plain in XinZheng city.And it also have three types of soil which are cinnamon soil, moisture soil and aeolian sandy soil.Due to the soil tillage years and every field of different soil fertility, resulting in the productive forces, it shows the different soil nutrient contain to the high spatial variability.2. Soil properties varied sharply,with available phosphorus showing the highest CV(75%),and available zinc the lowest(12%),with others the medium values. Soil nutrient like oganic matter, total nitrogen,soil PH, available zinc all fit the ormal distribution,and available phosphorus,available kalium, slowly available kalium also fit the ormal distribution after logarithm change.3. According to the soil nutrient of variance in XinZheng city and choose suitable theory model for optimal parameter estimation.Then analyse isotropy and anisotrppy of soil nutrients,the analyst of isotropy indicated that the soil nutrient variograms model based on the theory of spherecial model and exponential model;The range of 7 soil nutrient is between 57 and 380 meters.The minimum of range is available phosphorus which is only 57.78 meter,and the range of organic matter, slowly available kalium, soil PH and available zinc is 376 meter,which is much bigger. The minimum of nugget-to-soil ratio is slowly available kalium which is only 15.22%,this showed that the change are effected by structural factors which causing the space between auto correlation function. The maximum of nugget-to-soil ratio is available phosphorus which is 85.75%,this showed that human behavior are greatly effected it.The other soil nutrient's nugget-to-soil were between 25% to 75%. The result shows that these properties on the spatial correlation of spatial variation is structural factors (such as soil forming factors) and random factors (fertilization cultivation measures).The analyst of anisotropy indicated that 7 soil nutrient significantly in different directions to the anisotropic structure characteristics,Available phosphorus,available kalium have different nugget value, sill value and range,this is the typical characteristic of zonal anisotropy. Slowly available kalium,organic matter and available zinc not only have the characteristic of zonal anisotropy but also have the characteristic of geometriea nisotropy. The range of 7 soil nutrient is between 57 to 380 meters, and the range of avaible phosphorus is only 57.78 meter which is the minimum.Various nutrients in different directions of space mutation scales are not the same, the soil nutrient in the spatial distribution of the geometry is extremely irregular. The 7 soil nutrient content of space mutation has obvious characteristic, use of the method of kriging interpolation method for spatial analysis of soil nutrient and soil, according to the census and the second in henan province, the cultivated land fertility XinZheng combination classification standards and evaluation of the practical soil nutrient and grading. From the soil classification can be seen, the interpolation of organic matter and total nitrogen in space mutation, southern content than the trend of soil organic matter, total nitrogen in northeast of effective phosphorus content in spatial distribution, the effective available phosphorus content in southeastern north, available kalium gentle effect potassium content is gradually decreased from south to north, soil PH interpolation figure shows the acidic soil is normal, the content of available zinc in the medium level effectively.Kriging interpolation results shows the surface soil nutrient content with high spatial variability, and certain space pattern, the spatial distribution of soil nutrient content, but although there are significant differences in all directions, and from low to high nutrient content distribution regularity of gradient still exists. Through the seven of soil nutrient and spatial interpolation distribution of statistics, more accurate and intuitive understanding of XinZheng city soil nutrient status and the spatial distribution of soil nutrient deficiency.This paper using ArcGIS technology, combination geostatistics theory and method, using kriging interpolation draws seven soil nutrient interpolation of XinZheng city which can generally classification of soil nutrient and understand each space on the spatial distribution situation. This results can adjust agricultural fertilizer and water management measures, and it is significant for reasonable soil testing fertilizer work.
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