Spatial and temporal patterns of soil fertility quality and analysis of related factors in urban-rural transition zone of Beijing

The objectives of this study were (i) to assess soil fertility quality changes in time and space using grey relational analysis (GRA) and geographic information systems (GIS) in the urban-rural transition zone of Beijing and (ii) to explore the variation features of soil fertility under different land use types and soil management practices. The distribution map of soil fertility quality showed that soil fertility quality was best in the north, south, southeast and middle part of the district in 1980. The first-grade quality (I) was mainly in the southeast and the third-grade quality (III) was mainly in the north, south, northwest, east and middle part of the district. The area of first-grade quality (I) and the third-grade quality (III) increased from 79.17 to 120.10 km(2) and from 111.59 to 184.53 km(2) from 1980 to 2007, respectively, while the area of second-grade quality (II) decreased from 81.64 to 70.68% of the total land area from 1980 to 2007. The main factors influencing the spatial distribution of soil fertility quality were land use and soil management practices. The increasing trend of soil fertility quality might be attributed to the widespread practices of straw returning and organic manure applications.