Abstract:

By the method of geostatistics combined with GIS，spatial variability of soil nutrients and pH value were studied in a farmland covering an area of 2562 hm2,located at Sanqishi Town in Ningbo City,Zhejiang Province.The result showed that semivariograms of soil nutrients were best described by exponential model;the ratios of nugget and sill of available kalium,OM and pH value were lower than twentyfive percent,which showed their strong spatial correlation;while that of available phosphorus and available nitrogen were in the range between 25% and 75%,which showed medium spatial correlation.By using Kriging interpolation and according to the nutrients' criterion of classification,we could master the levels and characteristics of spatial variability of nutrients of soil.In general,the contents of available nitrogen,available phosphorus and OM were rich in the studied area,while that of available kalium were between moderate and low.The value of pH was low and the soil showed acidic.By the principle components analysis combined with Kriging,the general status of the soil nutrients could be appraised.The investigation results could supply scientific foundation and reference for appropriate fertilization,sitespecific management and effectively controlling agricultural nonpoint source pollution for local area and similar areas in the Yangtze River Delta.

Key words: oil nutrients, spatial variability, geostatistics, Kriging