Application of PSM on Ultisol did not gave significant effects to increased available-P in soil (Table 2). It is expected to be due to the application of the PSM only once at the beginning of the planting which cause activity of PSM was not optimum in the end of vegetative phase. The content of Ultisol available-P in the end of vegetative phase due to treatment in this research ranged from 0.61 mg kg-1 to 1.79 mg kg-1. While the content of available-P in sterile soil in a greenhouse experiment have ranged from 1.42 mg kg-1 to 3, 10 mg kg-1
The results showed that mix inoculant of PSB and PSF gave better influence than just PSB or PSF. Treatment of mix inoculant of PSB and PSF increased soil available-P up to 9.09% compared to controls, while treatment of the PSB and PSF independently only able to improve soil available-P up to 11,81% and 23.81% respectively. This is expected to be the synergism between PSB and PSF in transformating of insoluble P which is immobile into available-P which is relatively mobile. Phosphate solublizing microorganims solublized P to be available-P with it's ability to secrete organic acids that can break complex P compounds in the soil (Whitelaw, 2000). Quantity and Quality of organic acids depends on the type of microorganisms itself. Therefore the synergism of PSB and PSF in dissolving P in the soil is closely related to the respective capabilities in producing organic acids.