县域土壤养分空间变异特征及合理采样数研究

以地统计学和GIS相结合,以山东费县为例探讨了土壤有机质、全氮、碱解氮、有效磷和速效钾5种养分空间变异特征及县域尺度土壤养分的合理采样数。研究表明,有效磷的变异系数最大,由大到小依次为有效磷>速效钾>有机质>碱解氮>全氮。有机质、全氮、速效钾3种养分呈现中等强度的空间相关性且变程较大,基于土壤养分的空间相关性和克里格插值的独立验证得出费县有机质、全氮和速效钾3种养分合理采样数分别为1 035、842和1 033个,合理采样间距约为1 352、1 500和1 354 m。碱解氮不存在空间相关性,后续采样需要加大采样密度进一步研究其空间结构性。而有效磷呈现很强的空间相关性,但是变程很小,小范围内受人类活动等随机性因素较大,后续采样不能低于目前采样密度。

Study on Spatial Variability of Soil Nutrients and Reasonable Sampling Number at County Scale

Geostatistics combined with GIS was applied to analyze the spatial variability of soil nutrients in Feixian County in Shandong Province at county scale,and reasonable sampling number was also analyzed on this basis.The soil nutrient data in this study included SOM,TN,AN(alkaline hydrolyzing nitrogen),available P and available K.The results showed the coefficient of variation decreased in the order: available P>available K>SOM>AN>TN and available P has the largest coefficient of variations.SOM,TN and AK present moderate spatial dependence and larger range.Based on the spatial correlation of soil nutrients and validation,we concluded that reasonable sampling number of SOM,TN and AK was about 1035,842 and 1033 and sampling interval was about 1352 m,1500 m and 1354 m.AN had no spatial dependence and sampling densities should be increased later for the further study of the spatial structure features of the AN itself.Whereas available P had shorter range and presented strong spatial dependence only in a small range,which was more vulnerable to the influences of extrinsic factors such as human activities.Subsequent sampling densities cannot be lower than the current sampling densities.