Question

Which one is a biofertilizer?

• A. Mycorrhiza
• B. Nitrogen fixing bacteria
• C. Nitrogen fixing cyanobacteria
• D. All the above

Answer 1

The correct option is D All the above

Biofertilisers are the organisms that enrich the nutrient quality of the soil. The main sources of biofertlisers are bacteria, cyanobacteria and mycorrhiza.
1. Nitrogen fixing bacteria - These are the microorganisms present in the soil including Clostridium, Azotobacter etc. or in plant roots, for example Rhizobium. These bacteria are in a symbiotic association with the roots of legumes that change nitrogen gases from the atmosphere into solid nitrogen compounds that plants can use in the soil.
2. Nitrogen fixing cyanobacteria - Cyanobacteria like Nostoc, anabaena, oscillatoria can fix atmospheric nitrogen into the root nodules of plants.
3.Mycorrhiza - a genus of fungi that is in a symbiotic association with plants is called mycorrhiza. Mycorrhiza solubalises phosphorus from the soil and passes it to the plant.
Therefore, all of the above are examples of biofertilizers as they help increase soil fertility.