Abstract: Changes in total sulfur and available sulfur in soils under different land use in the Sanjiang Plain were analyzed to explore characters of the evolution of sulfur content in the soils.Results show that Calamagrostis angustifolia wetland is higher than cropland in content of total sulfur and available sulfur,which indicates cultivation depletes soil S,and soil total sulfur and available sulfur show a decreasing trend with each passing year.After desertion under "Grain for Green" Project for 7 years the contents of total sulfur and available sulfur in the soil increased,but the increase is very limited,which indicates that the soil S pool,once depleted,is hard to restore.Soil sulfur is found to be positively related to soil organic matter,suggesting that decreased soil organic matter due to cultivation might be the main cause of the decrease in S fertility of the soil.So that,increasing soil organic matter is propitious to the maintenance and increase of soil S(fertility).

Key words: Sanjiang Plain, land use, total sulfur, available sulfur