Biofertilisers are the pool of microorganisms that enriches the nutrient content of soil by enhancing the availability of nutrients to crops. The biofertiliser when applied to seeds, plants, or soil, colonise in the rhizosphere or inside the plant and promotes plant growth. They increase the supply and availability of primary nutrients to the host plant.
Microorganisms that act as biofertilisers are bacteria, cyanobacteria (blue-green algae) and mycorrhizal fungi. Bacteria and cyanobacteria have the property of nitrogen fixation while mycorrhizal fungi preferentially withdraw minerals especially phosphorous for the plant with which they are associated from the soil. The other benefits of mycorrhizal-plant interactions include greater resistance to stresses related to nutrient deficiencies, root rot disease and drought.