Effects of Land Use on the Contents of Soil Active Organic Carbon

The contents of soil active organic carbon(dissolved organic carbon,DOC;microbial biomass carbon,MBC) of different soil samples were investigated at five different land use sites in hilly area of purple soil,Sichuan Basin,and the relationships between DOC,MBC,TOC(total organic carbon) were analyzed.The results showed that the contents of DOC and MBC under fiver land used patterns were obviously different and DOC generally followed the series vegetableorchardpaddyforestarable,the content of MBC was paddyorchardvegetableforestarable,the significant difference was derived from the distinctness of organic matter input,farming system and soil management types.DOC constituted 0.58%,0.28%,0.19%,0.57% and 0.28% of TOC under vegetable,arable,forest,orchard and paddy.MBC constituted 3.57%,3.09%,2.38%,2.67% and 3.42% of TOC under vegetable,arable,forest,orchard and paddy,respectively.Soil active organic carbon could be used as an index of soil fertility because of its close correlation with soil physiochemical properties.The contents of DOC and MBC have correlation to different degree with soil organic carbon at five different land use sites.