Based On The Analysis Of Geomorphic Partition Spatial Variability Of Soil Nutrients And Sampling Design Research

Soil nutrient distribution has obvious spatial differences. Soil sampling design plays a critical role in capturing information about spatial distribution of soil nutrients, directly affects the research of soil nutrient spatial variance. The research of soil nutrient spatial variance is the precondition to the implement of soil management which acts according to circumstance and time, and the foundation to the realize precise agriculture and the sustainable utilization of the soil resources.Using geostatistics and several math methods, this paper simulates the spatial structure of soil nutrient elements of LanTian County in Shannxi Province, and expresses it quantitatively in support of several spatial analysis softwares of GIS and geostatistics softwares. It deeply reviews the laws of soil nutrient spatial variance and systemically studies the soil sampling methods of different study units and different geomorphologic types. Combining the methods of classic statistic analysis and spatial sampling optimizes the sampling method, and is of great importance in theory to the research of soil nutrient spatial variance. The main results are as follows:1. The geostatistics method based on GIS can fairly represent the rule of soil nutrient spatial variance. The regional research that considers the terrain conditions can better reflect the spatial variance structural and distribution pattern of soil nutrients. The four types of soil nutrients all show previous spatial correlation. The correlation is moderate and is stable in the whole area. The soil nutrient variables in the study area all show semi-variation structures. The regional research that considers the terrain conditions indicates that the semi-variation structure is unstable which reflected in the result that the areas of different geomorphologic types have different semi-variation fitting models.2.The distribution of four types of nutrient elements has obvious directive effect. The distribution of organic matter and available N (alkaline hydrolyzing nitrogen) is obvious structural in north-south and east-west direction and the variation in east-west direction is bigger than that in north-south direction. Agricultural production and management measures make the difference. The spatial variability of organic matter, available N, available P was mainly caused by random factor, and local hydrothermal condition has more significant influence. The spatial variability of available K is more related to human activities. The extents of spatial variability of the four nutrient elements are different. The variation of available N caused by structural factor is highest. Organic matter and available K varies less and available P the lowest.3. This article studied the most appropriate sampling methods under different geomorphologic study areas and different research purposes, and verifies the feasibility of the methods. The result shows that the SS Sampling method is suited to the soil attribute variables research based on administrative districts. The SSSampling method not only reflects the sampling information under different level study units flexibly and efficiently, but also can better inflect the regional variance characteristics of soil nutrient elements. It is a effective sampling method which is suited to the sampling under different regional unites.4. To the study areas which have complicated terrain, space hierarchical sampling method is a better choice. The stratified result has great influence on the precise of sampling result. On the base of proper stratifying index and detailed hierarchical files, the sampling result has high precise and is representative. To the mountain area, the sampling method of classical samples which collaborate environment factor only needs less samples to get more precise spatial predict result, which has high economic significance.