Investigation of the Spatial Variability of Soil Nutrients in Saline Soil in Xinjiang

Geostatistics combined with GIS was applied to collect forty-three samples and analyze the spatial variability of soil nutrients(total nitrogen,total phosphorus,total kalium,available nitrogen,available phosphorus and available kalium) in topsoil(0~30cm) from about 2000km2 of typical saline soil of Weigan drainage area in Xinjiang.The results indicated that except for available nitrogen and available phosphorus showing lognormal distribution,the others show normal distribution.The chemical analysis of semivariograms indicated that total nitrogen,total phosphorus and available kalium are best described by exponential model,total kalium,available nitrogen and available phosphorus are best described by spherical model,only organic matter is fitted well using the Gauss model.The results also indicated that the spatial correlation of tested parameters,except total nitrogen and available nitrogen are weekly dependent,the others are moderately dependent,but their spatial heterogeneity degree was different.The ranges of soil nutrients were 14.3km～67.0km.The spatial variability of all soil nutrients are mainly produced by structural factors and random factors.The Kriging method was applied to estimate the unobserved points and then the precise contour maps were obtained.By this way,the spatial variability of soil nutrients can be reflected directly.