Three levels (0, 400 or 800 mg S kg(-1)) of elemental sulfur (S degrees) or gypsum (CaSO4 center dot 2H(2)O) were applied to soil samples. The soil samples were incubated and analyzed weekly during an 8-week period to determine changes in soil pH, EC value, SO4-S and available Mn contents. Regardless of sources, sulfur application continuously decreased the soil pH and increased the electrical conductivity of soil during the eight week experimental period. The lowest pH value (pH 7.04) was observed with 800 mg S kg(-1) elemental sulfur application, and the highest EC value (1330.33 mu S cm(-1)) was obtained with 800 mg S kg(-1) gypsum application. The tested soil SO4-S content variations depended on the incubation time, sulfur sources and application levels. SO4-S content of soil showed a linear increase throughout the 8 week incubation as S degrees was applied. The highest SO4-S value of 53.34 mg kg(-1) about 20 folds higher than that of control was observed with 800 mg S kg(-1) elemental sulfur application. Incubation time, sulfur sources and the application levels had significant effect on the available Mn contents.