Impact of land use type on soil active organic carbon and its distribution in karst mountain

Soil active organic carbon and its distribution in the soils (0～50cm) under different land use type are studied in Zhong Liang knoll, Chongqing. The results reveal that: 1)the contents of the soil organic carbon (SOC) under different land use types are bamboo land ＞vegetable land ＞grassland＞woodland ＞garden ＞abandoned farmland, and the contents of SOC in the layer between 20 to 50cm deep is more than that between 0 to 20cm; 2) the average contents of soil dissolved organic carbon(DOC) are woodland >bamboo land >abandoned farmland ＞grassland ＞garden ＞vegetable land; 3) the percentage of soil dissolved organic carbon to the total soil organic carbon increased with depth; 4) the easily oxidized organic carbon(EOC) content and its distribution on the profile is consistent with the changes of soil organic carbon content. Correlation analysis shows that the correlation between easily oxidized organic carbon and soil organic carbon gets very significant level (R=0.852,P＜0.0001), proving that the EOC is susceptible to the change of SOC.