Soil Nutrient Status and Spatial Distribution Characteristics of Farmland in Beijing East-South Suburb

With the principle of uniform distribution,increasing the sampling density at crtical area,and considering plantation types,fifty-eight farmland surface soil samples were collected from Zhangziying town in daxing District to investigate soil fertility status and nutrient spatial distribution characteristics via chemical analysis and SPSS correlation analysis.The results showed that the average values of soil organic matter,total N,available P,available K contents,and pH value were 14.5g/kg,1.13g/kg,82.1mg/kg,129.1mg/kg and 8.16,respectively.To evaluate the soil fertility according to national soil nutrient classification method,soil total N and organic matter contents were at the medium level and lower middle level.For soil organic matter content,87.9%soil samples fell in the scope of gradeⅢ-Ⅴ.Totally,soil available P content was at higher levels,which was mainly at the gradeⅠ-Ⅲfor 87.9% samples.But the variation coefficient of available P was 113.73% which showed that available P spatially varied greatly.Soil available K content was at the middle level.The results of correlation analysis showed that,five kinds of soil nutrient contents were correlated significantly.Comparing soil nutrient content of different type of farmland,the content of organic matter,total N,and available P were in following order greenhouse vegetableopen field vegetablecrop fieldorchard.While the content of available K was performed by greenhouse vegetableorchardopen field vegetablecrop field.With Ordinary Kriging method in the geo-statistic module of ArcGIS,the spatial distribution characteristics showed that soil nutrient was higher in the north and the central area than the south area of the town;especially the central region exhibited the highest levels.