Question

What are 'biofertilizers'? Explain them with suitable examples.

Answer 1

A biofertilizer is a substance which contains living microorganisms. When they are applied to seeds, plant surfaces or soil they colonize the rhizosphere or the interior of the plant. They then promote growth by increasing the supply or availability of primary nutrients to the host plant.

Rhizobium is a soil bacterium which is found in symbiotic relation with leguminous plants. It produces root nodules and fixes atmospheric nitrogen into an organic form which is used by the plants as nutrients.

Hence Rhizobium is used as a biofertilizer.

Cyanobacteria are free-living or symbiotic soil bacteria. They fix atmospheric nitrogen in term of nitrates and nitrites by a biological process like Rhizobium

that increases crop yield.