Investigation of the spatial variability of nitrogen and phosphorus in purple soils in Jiangjing City, Sichuan, China
江津市紫色土中N、P养分元素区域空间变异性研究

In this paper, the spatial distribution pattern of the total nitrogen, available nitrogen, available phosphorus and total phosphorus in surface purple soil (0-20 cm) with a city region were analyzed by applying geostatistics combined with GIS. The spatial distribution pattern of the four soil nutrient parameters were quantitatively described with semivariogram and the soil nutrient content distribution pattern was constructed by using Ordinary Kriging and lognormal Kriging optimal interpolation. The results indicated that total nitrogen, available nitrogen showed a normal distribution, the others with a lognormal distribution; the analyst of semivariogram indicated that the total nitrogen showed the pure nugget effect with the nugget of 0.2, others were correlated in a given spatial range (50 m) with mild spatial relativity, the nugget-to-sill ratio was from 25% to 75%. Preliminary analysis was made for the spatial variability of the soil nutrients by using the group map of the soil nutrients with Ordinary Kriging. These results could be useful for further application in precision fertilization and for evaluation of non point polluting of agricultural lands.