The main sources of biofertilizers are

The main sources of biofertilisers are bacteria, fungi and cyanobacteria. In paddy fields, cyanobacteria serve as an important bio-fertiliser. Many members of the genus Glomus form mycorrhiza. The fungal symbiont in these associations absorbs phosphorus from soil and passes it to the plant. Some bacteria can fix atmospheric nitrogen while free-living in the soil (examples Azospirillum and Azotobacter), thus enriching the nitrogen content of the soil.