Sloping Distribution of Labile Organic Carbon in Eroded Brown Soils in Northwest of Liaoning Province, China

摘要

Soil total organic carbon (TOC), light fraction organic carbon (LFOC), hot-water extractable carbon (HWC), cold-water extractable carbon (CWC) and microbial biomass carbon (MBC) of brown soil in different eroded sites located in a water and soil conservation monitoring station in northwest of Liaoning province were determined to investigate the content and form of soil organic carbon. The results showed that TOC-C contents in upper-slope, middle-slope and lower-slope soils were 3.10, 6.56 and 7.15 g·kg-1, respectively; HWC-C contents were 123, 209 and 252 mg·kg-1, respectively. Obvious vertical migration of LFOC, HWC, CWC and MBC was caused by the processes of slope water-flow wash, transportation and accumulation. Soil MBC content of lower-slope was 10.1 and 5.34 times greater than that upper-slope and middle-slope, respectively. There was very significant positive correlation between CWC, HWC and TOC (R2=1, R2=0.999, respectively), and good correlation was also observed between HWC, CWC and MBC. The average content of HWC was 1.89 times larger than that of CWC. Small microbial quotient (MBC/TOC) indicated the severe soil erosion and low bioavailability of TOC in northwest of Liaoning province. The content and form of soil organic carbon redistributed in different eroded sites, and the environmental effect of soil erosion could be influenced by controlling the soil degradation rate.