Coarse or ground sulphur used for correcting sulphur deficiency or for increasing soil acidity is called agricultural sulphur or agri-sulphur. It has a sulphur content of about 90 % . It is oxidized to sulphate ion by soil micro-organisms when applied to the soil. The effectiveness of agricultural sulphur depends on its particle size, the rate, method and time of application, soil characteristics and the environment. Under some soil conditions, sulphur oxidizes slowly, and hence sulphur incorporation should be done 4 to 5 months prior to planting. Biological oxidation of sulphur in well-aerated wet soils is generally rapid.
Blending sulphur with solid N, P and K materials produces a variety of sulphur-based fertilizers. The sulphur component in sulphur-based fertilizers is also called flowers of sulphur or brimstone.