Abstract:

The organic carbon contents, C/N ratios and organic carbon density of four typical cropland soil types (black soil, cinnamon soil, paddy soil and latosol) were studied. The result indicated that the SOC (organic carbon content) decreases with soil depth. While the SOC of cinnamon soil is the lowest, the carbon sequestration potential is large. The C/N ratios of black soil and latosol were higher than cinnamon and paddy soil. All the C/N values of the topsoil of farmlands are lower than those of the second national soil survey in China. As a consequence, it may influence the nitrogen cycling and the ecological environment. There is obvious difference in organic carbon content and organic carbon density among these soils under different land use.

Key words: soil organic carbon, organic carbon density, soil profile, C/N ratio