The effects of phosphate solubilizing bacterium (<i>Bacillus</i> FS-3) application on phosphorus contents of tomato (<i>Lycopersicon esculentum</i> L.) plant, growing performance and phosphorus forms in soil were evaluated under greenhouse condition. Five different phosphorus fertilizer treatments (normal superphosphate, triple superphosphate, di-ammonium phosphate, phosphoric acid, and rock phosphate) with and without bacterium (<i>Bacillus</i> FS-3) were applied in pots as 344 kg P/ha. Basal

more »

... ertilizers were applied to all the pots as 180 kg N/ha (NH₄NO₃ 33% N), 100 kg K/ha (K₂SO₄ 50% K₂O). The results obtained showed that phosphorus availability from soil increased with phosphate solubilizing bacterium (PSB) application. The amount of plant available form of soil phosphorus fraction (resin-Pi + NaHCO₃-Pi + NaHCO₃-Po + NaOH-Pi + NaOH-Po) increased with PSB application. In all fertilizer types, bacteria application converted approximately 20% of less available phosphorus into labile forms. Statistically significant differences were obtained in shoot and root dry weight of tomato plants treated with PSB application. In all of the fertilizers, plant shoot and root weight and P uptake were greater with PSB applications than without PSB. The highest shoot-root dry weight and P uptake of plant were determined in triple superphosphate (TSP) with PSB application treatment. The data in the present study suggest that the application of PSB (FS-3) may increase the availability of soluble phosphate by dissolving the inorganic forms of phosphate and that bacterial strain tested in this study has a potential to be used as a bio-fertilizer in sustainable and organic agriculture.