Introduction
Sustainable crop production depends much on good soil health. Soil health maintenance warrants optimum
combination of organic and inorganic components of the soil. Repeated use of chemical fertilizers destroys soil
biota. In nature, there are a number of useful soil micro organisms which can help plants to absorb nutrients. Their
utility can be enhanced with human intervention by selecting efficient organisms, culturing them and adding them to
soils directly or through seeds. The cultured micro organisms packed in some carrier material for easy application
in the field are called bio-fertilizers.
