Sulphur, an essential component for both plants and animals, is found in both organic and inorganic forms in soils, 75–90% of the total is made up of organic forms such sulphate esters and carbon-bonded sulphur. Sulphur-containing minerals, plant and elemental residue, and external contributions such air deposition are the most common sources of sulphur in soils. Plants with a sulphur shortage have poor nitrogen metabolism, which leads to protein biosynthesis, chlorosis, low oil percentage, and, ultimately, reduced yield. The conversion of organic sulphur in organic materials to inorganic form is mostly due to microbiological activities. Organic sulphur is mineralized to sulphate and taken up by plants in well-aerated soil. Inorganic sulphur is immobilized to organic form and absorbed into microbial tissue at the same time. The speed at which these processes occurObviously, the activity of microorganisms is influenced by soil reaction, temperature, moisture, crop residue addition, and a variety of other elements. Several enzymes in soil, such as arylsulphatase, play an important part in the sulphur mineralization process, albeit little information on the breakdown pathway is available at this time. In addition to this, inorganic sulphur in soil is subjected to a variety of oxidation and reduction processes that are controlled by microorganisms. A group of bacteria in a proper environment oxidises various reduced inorganic sulphur compounds and uses the energy produced. The sulphur cycle and its modification by diverse organisms were discussed in this chapter.