Mobilization of Rock Phosphate Phosphorus through Bacterial Inoculants to Enhance Growth and Yield of Wetland Rice

Pot and field studies were undertaken to assess the substitutability of triple superphosphate (TSP) by a phosphorus (P) fertilizer mixture (PFM) comprising TSP, rock phosphate (RP), and P-solubilizing bacterial inoculants for wetland rice. Six single and two dual inoculants were formulated with Enterobactor gegovie and five Bacillus species and tested in pot and field experiments. Soil-available P and tissue P contents were analyzed, and yield data were recorded. In the pot experiment, the dual inoculant containing E. gegovie + B. mycoides and the single inoculant B. subtilis increased yields by 32% and 25%, respectively, over the TSP control. Under field conditions, E. gegovie + B. subtilis, and E. gegovie + B. pumilus increased grain yield by 22-27% over the TSP control (574 g m-2). Results revealed that 50% of TSP could be substituted with RP along with seed inoculants formulated with E. gegovie, B. pumilus, and B. subtilis under tested conditions.