(a) Farmers prefer biofertilisers to chemical fertilizers because.
(i) They help to get high yield of crops by making the soil rich with nutrients and useful microorganisms necessary for the growth of the plants.
(ii) Chemical fertilizers make the environment polluted by releasing harmful chemicals and show biological magnification.
(iii) Biofertilisers destroy only those harmful components from the soil that cause diseases in the plants.
(iv) Biofertilisers are environment friendly and protect the environment against pollutants.
(b) Fungi are known to form symbiotic association with plants called Mycorrhiza. Many members of the genus Glomus forms mycorrhiza. The fungal symbiont in this association absorbs phosphorus from soil. Arbuscular mycorrhizal fungi play a vital role as a phosphatic biofertilizer.
Cyanobacteria are autotrophic microbes widely distributed in aquatic and terrestrial environments many of which can fix atmospheric nitrogen, e.g., . Anabaena, Nostoc, Oscillatoria, etc.
