Soil-Landform Relationships And Their Modeling Within Single Mapping Unit

The formation of soil is influenced by national and man-made factors together. The properties of soil have large space variance because the formation factors are difference in different space. Terrain is one of five soil formation factors, and it can influence the moisture-temperature conditions and distribution of soil formation substance to influence the properties of soil distinctly. So the relation between soil properties and space is very significant. The most knowledge of the relation between soil and terrain is from the investigation of the plot and line in a large scale. Researching the distribution regulation of soil with terrain depends on the judgement of abstract modeling about the relation of terrain and physiognormy , and the models come from some soil scientists experience. There is few abstract researches in the fix quantity of the space variance between soil and terrain, especially in the small field. But it is very convenient for researching the fix quantity between soil and terrain with the development of space analysis and statistical technology in recent years. In this paper we applied correlation analysis and match modelinges which are from Geostatisticas to research the relation of soil properties and terrain in the region about 7500m in the west of Shaoxing county where the soil come from argillaceous rock, and visual the space variance of the soil properties by application of GIS. We get five results by application of these technology at last.(1)The properties of soil genesis and fertility have large changes in map unit and the variance is continuous in space. The genesis properties about soil depth, slope deposit depth, clay content, silt content, sand content , iron-manganese concretion depth and the fertility properties about organic matter, total N, CEC, total Fe, total Mn, total Cu, total Zn correlate with elevation or slope significantly. It means there are some flaws to determine the properties of map unit by depending on the properties of some classic soil profiles because they are difficult to show the change of soil properties in map unit.(2)Semivariance analysis show the parameter of C₀ / C + C₀ about all the soil properties arevery small . This means the space variances of the soil properties are influenced by structural variance significantly. Because the area of the research region is very small(7500m²), the influence of climate and parent materials is very small ,we can conclude that the space variance is mostly influenced by terrain.(3) Most of the space variance about the soil genesis and fertility properties can be explained by the change of elevation and slope in map unit. And logarithm model can express the relation between soil depth ,clay content and terrain very well. The curve model can express well the relation between silt content, sand content, slope deposit depth, iron-manganese concretion depth ,all the soil fertility properties and terrain. So we can forecast the space variance of the soil propertities by depending on elevation and slope in map unit.(4)We determined the soil quantity by application of continuous modeling, scatter modeling and concept modeling to determine the subjection and applying principal component analysis to determine coefficient. The result shows that the soil quantity has large variance in map unit. And the soil quantity descends when the elevation ascends. We seperate the field to erode and deposit regions by the distribution of terrain and slope deposit, and statistics analysis shows there has much difference between the two regions. So we think the difference of soil properties in map unit are result from the difference of elevation and slope in terrain which always result in the moving of soil fertilities and water.