Use of gram-positive phosphate solubilizing bacterium Bacillus aryabhattai in warm-water fishpond to reduce the application of phosphorus chemical fertilizer

The aim of this study was to investigate the possibility of replacing Triple superphosphate chemical fertilizer with biofertilizers as an environmentally friendly approach. The effect of separate and combined triple superphosphate and biofertilizer application under microcosm (Erlenmeyer contains sediment) was evaluated. Gram-positive Phosphate solubilizing bacteria Bacillus aryabhattai strain SB.P3 was used in two levels of inoculation and non-inoculation, and phosphate fertilizer in 4 levels of 0, 30, 70 and 100%. In this experiment, soluble phosphorus, pH and density of solvent bacteria were measured at different times (on days zero (before inoculation), 2, 5, 10, 15 and 20 days after inoculation). The results showed that the bacterial density during the experiment in all groups, in first had an increasing trend, then decreased, and again slightly increased. Treatment 6 (70% fertilizer + bacteria) had the highest bacterial density, which in some time periods was significantly different from other treatments. The amount of water soluble phosphate in all groups at first had an increasing trend, then decreased and then increased again. At different time intervals, no significant difference was observed in the mean of dissolved phosphorus in the treatments with the control. Changes in pH of the treatments indicate a sinusoidal trend in different intervals. Although the bacteria grew well under microcosm and showed good stability in the environment, the results showed that chemical fertilizers and phosphate solubilizing bacteria didn't have a significant effect on fluctuations in soluble phosphorus.