How do biofertilisers enrich the fertility of the soil?

How does biofertilizers enrich the fertility of soil?

How does humus increase the fertility of the soil ?

Does crop rotation increase the fertility of the soil ?

Does soil erosion affect the fertility of soil? How?

Biofertilisers are prganisms that enrich the nutrient quality of the soil. Which of the following can be used as biofertilisers ?

A : Azotodesmic lichens are biofertilisers enriching nitrogen contents in soil. R : This ability is due to the presence of heterocystous blue-green algae as phycobiont component.