Spatial Variability of Soil Nutrients Based on GIS in Jiangling County of Hubei Province

Geostatistics combined with GIS was applied to analyze the spatial variability of soil nutrients in topsoil(0～20 cm) in Jiangling County of Hubei Province.The statistical results showed that the coefficients of variation of all the observed nutrients belonged to the middle degree.Semi-variance analysis indicated that the semivariograms of available N,available P,and organic matter were best-fitted by exponential model,except for that of available K,which was best-fitted by Gaussion model;The spatial variability of available N,available P and available K were primarily caused by random factor,while that of organic matter was mainly produced by structural factor.The results also indicated that the spatial correlation of the four tested soil nutrients at this large scale was moderately dependent,but spatial scale was different.The ranges of available N,organic matter and available P were same,which were 49.1 km;the ranges of available K was 17.9 km,respectively.The Kriging method and GIS technique were applied to calculate the unobserved points and were used to generate the filled contour map.The richness and deficient status of soil nutrients could be viewed from the map.