Effects of land use on the distribution of soil active organic carbon

The contents of soil active organic carbon(light fraction organic carbon,dissolved organic carbon,and microbial biomass carbon) of surface soil samples(0-10 cm,10-20 cm) were investigated at five different land use sites in Jian′ou City,Fujian Province,China.The results showed that the contents of soil light fraction organic carbon,dissolved organic carbon and microbial biomass carbon in 0-10 cm declined respectively by 65.97%,64.60% and 54.78% while woodland conversed into orchard land,and those in 10-20 cm decreased by 57.39%,21.88% and 43.71%,respectively.The microbial quotient had minimal impact on different land use.The contents of soil active organic carbon decreased with increasing of soil depth,except the Citrus aurantium orchard soil.It was concluded that the conversion of woodland into orchard land led to a loss of soil active organic carbon,and active organic carbon was sensitive to the change of land use.