Spatial Variability of Topsoil Organic Matter and Total Nitrogen in Linfen Basin,Shanxi and Its Influencing Factors

[Objective] The objective of this study was to provide a firm scientific foundation for the evaluation of soil fertility and nutrient management by exploring the spatial characteristics of soil organic matter(SOM) and total nitrogen(TN),and the influencing factors.[Method] A total 1,186 topsoil(0-20cm) samples in arable land were taken across Hongdong County in Linfen basin in Shanxi Province.Topsoil SOM and TN were determined.The classic and geostatistical methods were used to analyze the data.The spatial variability of SOM and TN was investigated via their semi-variance models generated by GS+.The semi-variance model and GIS input was then used in a second software package: ArcGIS 9.2,to render SOM and TN classification maps for Hongdong County.[Results] The average SOM and TN content were high;16.05 and 0.82 g kg-1 respectively.The coefficients of variation for SOM and TN were 46.10% and 32.47% respectively.Analyses of the semi-variance models indicated that the range: the distances over which the variables were spatially-related,were 20.9 km for SOM and 21.5 km for TN.[Conclusion] The SOM and TN contents were generally high in central Hongdong whilst they were low in the northwest and southeast of the county and caused mainly by topography,soil type,soil texture and the impact of fertilization practices.