Spatial distribution of soil nutrients in the south-north hills in Lanzhou and the affecting factors

The spatial distribution of soil organic matter, total nitrogen, total phosphorus of the South-north Hills in Lanzhou has been studied and the effects of vegetation types and environment factors such as aspect, altitude, gradient on spatial distribution of soil nutrients have been analyzed. The results showed a spatial variability of soil organic matter; total nitrogen was significant and spatial coefficient of variation is respectively 55.946%, 49.597%. However, the spatial variability of total phosphorus was not significant and the spatial coefficient of variation was 8.935%. Vegetation types affected the soil organic matter and total nitrogen contents and the effects on soil organic matter were significant. Environment factors affected soil nutrient contents, as well. Soil on south-facing slopes contained significantly less organic matter, total nitrogen and total phosphorus compared with north-facing slopes. Differences in organic matter and total nitrogen contents were significant. A significant correlation was found between the altitude and the contents of organic matter, total nitrogen and total phosphorus; that is to say, as altitude is higher, the contents of soil nutrients distinctly increased. The correlation with gradient and soil nutrients was of a negative, but not significant, correlation.