Biofertilizers and their importance in soil fertility

5. Rhizobium is a genus of Gram
negative soil bacteria that fix
nitrogen. Rhizobium species form
an endosymbiotic nitrogen-fixing association with
roots of (primarily) legumes and other flowering
plants.
It is a biofertilizer that contains non-symbiotic Azotobacter
bacteria which has the ability to fix atmospheric Nitrogen.
Azotobacter is used for increasing the number & length of
roots and shoots. Helps to increase the crop yield.
Azospirillum, a symbiotic nitrogen-fixing bacterium seen
in non leguminous plants, it has the ability to colonize the
plant roots and fixing atmospheric Nitrogen.

6. Phosphate solubilizing microbes (PSMs) are a group of
beneficial microorganisms capable of hydrolyzing organic and
inorganic insoluble phosphorus compounds to soluble P form
that can easily be assimilated by plants.
Azolla is a small water fern that grows on the surface of water
bodies or on moist soil. Due to the presence of the nitrogen-
fixing cyanobacterium Anabaena azollae, it fixes molecular
nitrogen. This fern is used as biofertilizer for rice.
Cyanobacteria are used in agricultural crop improvement
because of their adicity to fix atmospheric nitrogen and make
it available to the plants. This improves the yield of the crops
and also reduces the cost of application of nitrogen fertilizers.
The main benefits of vesicular-arbuscular mycorrhizal (VAM)
involve the increased uptake of nutrients especially
phosphorus and transport them to the host plant. They
belong to the class zygomycetes and are responsible for
improving the growth of host plant species.