Organic Carbon Change and Distribution of Soil Aggregates Under Different Land Uses

Organic carbon change and distribution of soil aggregates were analyzed under different land uses such as arable,garden plots,woodland,and abandonment land by field investigation and indoor analysis.Results indicated that by the percentage,the size groups of soil aggregates were in the order of 5,2～5,0.5～1,1～2,0.25,and 0.25～0.5 mm and by the organic carbon content,the size groups were in the order of 5,2～5,1～2,and 0.5～1 mm in the 0.5 mm size groups.In the 0.5 mm size groups,the organic carbon change was relatively complicated.The organic carbon content in arable land,woodland,and abandonment land was the highest in 0.25 mm fraction of soil aggregates.The organic carbon content in the garden plot was the highest in 0.25～0.5 mm fraction of soil aggregates.The difference was the largest in 5 mm fractions of soil aggregates among the four land uses and the difference decreased with the increasing aggregate size.Under different land uses,the proportion of the organic carbon and total organic carbon for the 0.25 and 0.25～0.5 mm soil aggregates was lower than that for 2～5,5,and 0.5～1 mm soil aggregates.