*2.5.1.2 Phosphorus solubilization*

The phosphorus BFs contain phosphorus solubilizing microorganism (PSM) which solubilize solid phosphorus salts and mobilize them to roots for absorption. Phosphotika and Azotobacter are the main bacterial PSMs which have no crop specificity for symbiotic relations. Pseudomonas, Bacillus, Rhizobium, Enterobacter, Penicillium, and Aspergillus are main PSM genre. Bacillus, Rhizobium, and Pseudomonas are potassium solubilizing microbes. Combinations of bacteria and fungi are also used.

Cyanobacteria or Blue Green Algae (BGA) which are free-living nitrogen fixing bacteria have symbiotic relation with Azolla (aquatic fern) floating as green mat over water. These nitrogen fixers are also used in BF formulations for rice paddy crops and other similar crop plants.
