Sulphur is a vital element for plants next to nitrogen (N), phosphorus (P), and potassium (K). It is an important constituent of proteins, enzymes, vitamins, lipids, carbohydrates, and other biomolecules. Sulphur is required for growth and development of plants especially in the crop production. Sulphur undergoes a number of biological alterations in nature carried out exclusively by microbes through sulphur cycle. Oxidation of sulphur is the most important step of S cycle which improves soil fertility. It results in the production of sulphate, which can be easily used by the plants, while the acidity produced by oxidation step helps to solubilize plant nutrients and thus improves soil health. Sulphur deficiencies in soils of tropical and subtropical regions have been recognized for many years and have been reported from over 70 countries, including India.
Use of sulphur oxidising bacteria has been reported to enhance mustard growth, which is an important protein supplement in animal feed. SOBs promote mustard growth via increase in the height, weight, no. of siliquae, 100 seed weight, oil content, leaves protein content, leaves chlorophyll content, viable rhizospheric bacterial count. Hence, the mustard inoculated with SOB has a higher quality. Use of such SOB inoculated mustard as a protein supplement in animal feed can have a favourable outcome in terms of animal growth and production.