[1] Biofertilizers add nutrients through the natural processes of nitrogen fixation, solubilizing phosphorus, and stimulating plant growth through the synthesis of growth-promoting substances.
Blue-green algae belonging to the cyanobacteria genera Nostoc, Anabaena, Tolypothrix, and Aulosira fix atmospheric nitrogen and are used as inoculants for paddy crops grown in both upland and lowland conditions.
[citation needed] In tropical countries, the bottom mud from dried-up ponds which contain abundant blue-green algae is regularly used as biofertilizer in fields.
[citation needed] Plant-Growth Promoting Microorganisms: Mycorrhizal fungi such as: Seaweed and blue green algae: Cyanobacteria: Biofertilizers work through multiple mechanisms.
[7][11] Another mechanism proposed is the AAC-deaminase production of Bacillus species, which prevents excessive increases in the synthesis of ethylene under various stress conditions.
[20] Besides promoting growth by multiple mechanisms, biofertilizers produces substances suppressing phytopathogens, guarding plants from abiotic and biotic stresses and detoxification of belowground pollutants.
It has also been shown that to produce a larger quantity of crops, biofertilizers with the ability of nitrogen fixation and phosphorus solubilizing would lead to the greatest possible effect.