Brimstone, of three different particle size gradings, was compared with finely powdered gypsum in a three year study, on a white clover pasture. Dry matter yield and sulphur recovery were highest ,from gypsum in the first harvest, but brimstone sulphur gave better residual effects. Fineness of grinding influenced the initial availability of brimstone sulphur. The possibility of using particle size gradings to obtain a degree of controlled availability in sulphur fertilizer is discussed in relation to graziers' present and possible future demands. In mixtures of elemental sulphur with soluble sulphate, fertilizers, for example sulphur-fortified superphosphate, a limited amount of delayed release from the elemental sulphur could spread the response over a longer period.