The use of phosphate-solubilizing bacteria can be a low-cost alternative to agroforestry systems in the Amazônia, where prices, transport, and producers' low buying capacity make the use of soluble fertilizers difficult. On soils without a cultivation past, phosphates are combined mainly to Al, while on previously limed and cultivated soils, these phosphates are combined with Ca, limiting their use by plants. There is little information on phosphate-solubilizing bacteria (BSF) in the Amazon; thus, further studies are needed. The first step should be to study the ecology of these bacteria to identify where, and how frequently they occur. Samples of plant roots were collected in the states of Acre, Amazonas and Rondônia, and placed in Petri plates in a specific medium to identify their presence. This study used 28 species of plants of several families and two types of multiple vegetation (pasture and secondary forest). The presence of these bacteria was very low (0-10%), suggesting that, under those conditions, they do not contribute to improve plant nutrition with P.
microbial ecology; phosphorus; acidity; fruit species; legume; grass