Class 12 Biology Microbes In Human Welfare Microbes as biofertilizers

Microbes as biofertilizers

Biofertilizers are organisms that enrich the nutrient quality of the soil.

The main sources of biofertilizers are bacteria, fungi and cyanobacteria.

Some microbes used as biofertlizers are-

  • Rhizobium form root nodules in leguminous plants and fix atmospheric nitrogen into organic forms, which is used by the plant as nutrient.
  • Free living bacteria like Azospirilium and Azotobacter fix atmospheric nitrogen, hence increases nitrogen content of the soil.
  • Many members of the genus Glomus form Mycorrhiza, which is the symbiotic association of fungi with roots of the plants.

The fungal symbiont in these associations absorbs phosphorus from soil and passes to the plants.

Plants having symbiotic association show resistance to root-borne pathogens, tolerance to salinity and drought, and an overall increase in plant growth and development.

Fig. Mycorrhiza  

Cyanobacteria are autotrophic microbes which can fix atmospheric nitrogen.                   Example - Anabaena, Nostoc, Oscillatoria

Blue green algae also add organic matter to the soil and increase its fertility


Fig. anabaena  

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