PHOSPHATE-SOLUBILIZING BACTERIA AND FUNGI IN VARIOUS CULTIVATED AND VIRGIN ALBERTA SOILS

Abstract

Seventeen sites throughout southern Alberta were sampled in the spring of 1981. Total and NaHCO 3-extractable phosphorus and soil texture were determined for each soil sampled. Phosphate-solubilizing and total bacterial and fungal populations were determined by serial dilution and plate counting. Available P constituted an average of 1% of the total P present in the soils. Phosphate-solubilizing bacteria and fungi made up 0.5 and 0.1%, respectively, of the total bacterial and fungal populations. A highly significant correlation was found between the numbers of total and phosphate-solubilizing fungi and the levels of total P in the soil. As a group, the fungi were superior to bacteria in solubilizing both freshly precipitated calcium phosphate and Idaho rock phosphate. Fungi also retained this ability over many subculturing transfers. A high percentage of the bacterial isolates lost their solubilizing ability when subcultured. A significant correlation was found between an organism’s ability to solubilize freshly precipitated calcium phosphate in agar plates and Idaho rock phosphate in solution culture. Key words: Fungi imperfecti, Penicillium sp., phosphate-solubilizing microorganisms