Phosphorus fractions in Andisol and Ultisol inoculated withBacillus thuringiensisand phosphorus uptake by wheat

Only a small portion of soil phosphorus (P) is available to plants on a short-term basis, and therefore, P taken up by crops in one growing season is small compared to total P (Pt) content of the soil. A group of soil microorganisms capable of transforming insoluble P into soluble and plant accessible forms. The objective of this study was to evaluate the changes in soil P-pools and P uptake by wheat crops as influenced by inoculation withBacillus thuringiensisin two soils (Andisol and Ultisol), the experiment was conducted in pots under greenhouse conditions using a completely randomized design. Wheat plants were inoculated and re-inoculated at 20 and 46 days after sowing, respectively, withB. thuringiensis; and, plant sampling were performed after 46, 66 and 87 and soil at 87 days based on the Zadoks growth scale, and the soil was submitted by Hedley's P fractions. The inoculation withB. thuringiensisaffected significantly some P organic P (P-o) and inorganic P (P-i) fractions in both soils (Andisol and Ultisol), improved P uptake by wheat crop in (Ultisol) and decreased significantly in (Andisol). The positive effect was more consistent in Ultisol than in Andisol, this strain can be solubilized P fraction extracted with conc. HCl-P(o)and HCl 1 mol.