A laboratory incubation experiment was conducted for periods (0, 3, 7, 15, 30, 45 and 60 days) to investigate the effect of organic wastes (poultry manure (PM), farmyard manure (FYM), and sheep manure (SM)) with and without phosphorus solubilizing bacteria (PSB) on soil pH, EC, available P, and CO₂ evolution as well as P release kinetics in a sandy calcareous soil. The treatments were arranged in a complete randomized design with three replicates. Soil moisture was maintained at field capacity throughout the incubation period. The organic manures (OM) were applied to soil at a level of 20 g kg^-1soil. The efficiency of Bacillus megaterium as a phosphate-solubilizing bacterium (PSB) was evaluated for its ability to convert insoluble P into soluble form in liquid culture. PSB demonstrated decreased pH and increased soluble P in the laboratory tests. The incubated soils' pH decreased with OM addition and increasing the incubation periods especially with PSB inoculation, the soil salinity was higher in the manure-amended soils. The CO₂ emissed as follows: PM > SM > FYM >control. Organic manures addition significantly increased soil available P at all incubation intervals especially with PSB inoculation. The PM + PSB-treated soil showed the highest available P content. The Parabolic diffusion model was the best for estimating P release in the amended soils, with higher release rate in the PSB-inoculated treatments. PM and SM yielded the highest counts of PSB. These findings highlight the dual role of organic amendments with PSB in improving phosphorus availability in sandy calcareous soil which reduces the need for the manufactured chemical phosphate fertilizers and support the sustainable agricultural production.