A balanced supply of nitrogen, phosphorous and potassium (N.P.K) is essential to improve crop productivity in any agricultural system. It is estimated that nearly 3.9 x 1015 tonnes of nitrogen is present in the atmosphere in its elementary form. None of the living organisms except a few bacteria are capable of using this nitrogen directly as a nutrient source. Rhizobium, Azospirillum and Azotobacter are the most important nitrogen-fixing bacteria and the preparations containing them are commonly known as bio-fertilizers. Some bacteria like Bacillus megaterium var phosphaticum are commercially used for solubilizing phosphorous in soil. They are known as PSM (phosphate solubilizing microorganisms). Another bio fertilizer, which is becoming popular nowadays, is mycorrhizae. They are used for field establishment of nursery stock, improvement of phosphorous nutrition of plants and biological control of certain soil borne pathogens. Our bio fertilizer preparations are Rhizobium, Azospirillum, Azotobacter, Phosphobacteria, V.A.Mycorrhiza and Bio-potash.