A Preliminary Study on the Effects of Land Use on the Contents of Soil Active Organic Carbon

The contents of soil active organic carbon(dissolved organic carbon,microbial biomass carbon) 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 and TOC 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 as vegetable orchard paddy forestarable,the content of MBC followed the order of paddy orchard vegetable forestarable,the significant difference was derived from the distinction of organic matter input,farming system and soil management types.The percentages of DOC in TOC were separately 0.58% for vegetable field,0.28% for arable field,0.19% for forest,0.57% for orchard and 0.28% for paddy.And the percentages of MBC in TOC were respectively 3.57% for vegetable field,3.09% for arable field,2.38% for forest,2.67% for orchard and 3.42% for paddy.Soil active organic carbon can be used as an index of soil fertility because of its close correlation with soil physic-chemical properties.The contents of DOC and MBC had significant correlation to different degree with soil organic carbon at five different land use sites.