Mention any three examples of biofertilizer.

Explanation

The main sources of biofertilizers are bacteria, fungi and cyanobacteria.
(i) Rhizobium is a symbiotic nitrogen fixing bacteria. It can fix atmospheric nitrogen into organic forms. They are present in the root nodules of leguminous plants.
(ii) Mycorrhiza is a symbiotic association between a fungus and the roots of the plants. The fungus absorbs the phosphorous from the soil and transfer to the plant.
(iii) Oscillatoria is a cyanobacterium free living, prokaryotic organism. It can fix atmospheric nitrogen into useful forms and is used as biofertilizer.