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.

Phosphorus (P) deficiency in soil limits crop yields and can be managed by P fertilizers. But mere applying P fertilizers alone may not be effective in justifying its bioavailability. At present global P reserves are declining in an increasing way which urges us to find out alternatives. Thus, the present work was taken to prepare phosphocompost using water hyacinth (Eichhornia crassipes) as feedstock, termite, and normal soil as bulking agents cum decomposers and enriched with single super phosphate. The effect of phosphocompost on rice(var.ADT-43) productivity, P availability and uptake was evaluated by comparing various P fertilizers (single super phosphate, rock phosphate, di-ammonium phosphate, nano phosphate) combined with or without phosphate solubilizing bacteria (PSB). The experiment was laid out in a completely randomized design with seven treatments including absolute control and replicated thrice. Phosphocompost produced with water hyacinth and termite soil microbes come with superior quality and early maturity compared to normal soil. Pot culture study results revealed that rice growth, yield, P availability and uptake were significantly (p<0.05) higher with SSP + PSB, and Nano phosphate +PSB treated plants, followed by Phosphocompost + PSB. The cost of P fertilizer (Rs/ha) related to yield (kg/ha) was found to be significantly low with phosphocompost (Rs.1132/-) than SSP (Rs.1530/-) and Nano P (Rs.2518/-). Further, phosphocompost combined PSB helps in optimizing the P availability in a long run through P solubilization thus sustained the P uptake. The present investigation brings light to the valorization of water hyacinth as compost will be an effective and economically viable alternative for P fertilizers.