Effect of different phosphorus sources applied with phosphate solubilizing bacteria on bio-geochemical properties and phosphorus release pattern in vertisol

Various phosphorus (P) fertilizers are used for crop production in different types of soil. But there is a knowledge gap in choosing the right source and form of  P fertilizers to enhance the applied fertilizer use efficiency. An experiment was taken to identify the best phosphorus source and its effectiveness as a source of P in vertisol to unravel this problem of selecting suitable P fertilizer. With this background, an incubation experiment was conducted under laboratory condition to determine the phosphorus release pattern of different P sources [Single Super Phosphate (SSP), Rock Phosphate (RP), Diammonium Phosphate (DAP), Nano phosphate (Nano P), Phosphocompost (PC)] applied with phosphate solubilizing bacteria (PSB) and their influence on biogeochemical properties in vertisol.  Experimental results emphasized that P release from different sources was influenced by soil pH, electrical conductivity (EC), cation exchange capacity (CEC), soil organic carbon (SOC), and microbial population. Applied P sources significantly(p=0.05) influenced the CEC, SOC, and microbial population except for soil pH and Ec. The maximum release in available P was obtained at 30 and 60 days after incubation with SSP +PSB  (35.8 and 40.1 mg kg-1) and Nano P + PSB (33.9 and 38.6 mg kg-1) applied treatments, respectively.Whereas at 90 days after incubation Nano P + PSB (42.3 mg kg-1) and Phosphocompost + PSB (40.4 mg kg-1) treatments recorded the maximum P availability and minimum P (15.2, 13.9 and 11.8 mg kg -1) release was noticed in the control treatment throughout the period of incubation. It was evident that SSP or Nano P along with PSB application might be the best P source for Vertisol.