| Eighty-four sampling plots of 5 m×5 m were collected from a field in Er-shi-li-pu Village of Xining City,Qinghai Province,China.Soil organic matter,available N,available P,and available K were measured,and the patterns of spatial variations of soil nutrients were analyzed.The results indicated that the spatial variability of organic matter,available N,and available K was not obvious while the spatial variability of available P was obvious.The spatial variability of organic matter,available N,and available K was mainly caused by structural factors and that of available P was primarily caused by random factors.The semi-variogram of organic matter was well described by exponential model while that of available N,available P,and available K was described by spherical model.In order to analyze the soil nutrients accurately in fields of chestnut soil,the appropriate sampling density was between 1 to 11 m. |