Sulphur is one of the essential elements to plants. It is necessary for the formation of Chlorophyll the green, light absorbing pigments in plants. A sulphur deficiency results in yellowing, usually of the whole plant, and small leaves with rolled down edges. Sulphur is also the most economical and effective way of lowering the pH of soil. Sulphur is recommended for acidifying soils with a pH of 8.4 or less.