Mineralization of phosphorous by phosphate solubilising bacteria isolated from a vertisol

The current experiment unravels P solubilisation potential of soil under long term fertilizer application. Soil samples collected from a 20 years old long term experimental field. Treatments included fallow (no fertilizer, no crop), control (no fertilizer, with crop), 100% N, 100% NP, 100% NPK, and 100% NPK+FYM. P solubilisation potential of soils determined using Ca3(PO4)2 as inorganic insoluble P source. Abundance of total bacteria, phosphate solubilising bacteria (PSB) estimated along with the efficient PSB isolated to evaluate P solubilisation potential using Ca3(PO4)2, rock phosphate and sodium phytate as P sources. P solubilisation rate was highest in 100% NP and lowest in fallow. Abundance of total eubacteria and phosphate solubilizing bacteria (PSB) was high in 100% NP and low in fallow. The 16S rRNA sequences of the isolates were homologues to Paraburkholderia sp. The efficient PSB isolate solubilised Ca3(PO4)2, rock phosphate as well as sodium phytate. Acid phosphatise activity was highest in Ca3(PO4)2 and lowest in sodium phytate. Study concludes that P solubilisation in vertisol under long term fertilizer application is regulated by nutrients, particularly P fractions and abundance of PSB. The PSB solubilise different P sources by reducing pH of medium as well as through acid phosphatase attributes.