Elemental sulphur is oxidized into sulfuric acid by soil bacteria.
With alkaline water, soil pH will increase over time and stabilize around 8.2, if calcium is the predominant cation in the soil. In these soils lowering pH is necessary to increase the availability of calcium and micronutrients, particularly iron and manganese. Elemental S has a high potential to burn plant tissue and can lower soil pH too much if used improperly or at too high an application rate. Sulfur is oxidized by soil bacteria, thereby forming sulfuric acid which is the substance that lowers soil pH. Each 10 pounds of elemental S generates enough acidity to neutralize 30 pounds of lime. Warm temperatures and good moisture and aeration are required for S oxidizing bacteria to function.