ABSTRACT The plant cannot absorb phosphorus nutrient in the bound form but must be converted into an available form. Soil microbes have a role in the soil properties such as solubilized phosphor bound by acid secretion, and mineralization of organic phosphate components by converting into inorganic forms. Several types of microorganisms were identified. They can help the plants to provide the nutrients. Soil pH has a role in the availability of inorganic phosphorus. The aim of this study was to determine the effect of the addition of Bacillus aryabhattai to the population of phosphate solubilizing bacteria and soil pH. The research was conducted in the screen house and Integrated Laboratory of Indonesian Agricultural Environment Research Institute (IAERI) from December 2016 to March 2017. The experimental design was Completely Randomized Design with 4 treatment. The treatment involved Control (D1), Bacillus Aryabhattai (D2), Liquid Organic Fertilizer (D3), and Trichoderma (D4). The Pikovskaya medium was used to analyze the phosphate solubilizing bacteria. The results show that Bacillus Aryabhattai has a great influence on the increasing population of phosphate solubilizing bacteria. The population of phosphate solubilizing bacteria in the Bacillus Aryabhattai treatment was 3,1 x 107 cfu/ml, while in the control was 4,1 x 106 cfu/ml. There was found the similarities in trends between the number of phosphate solubilizing bacteria populations and soil pH. Bacillus Aryabhattai has a great potency to increase the plant nutrients especially phosphorus.