Two greenhouse growth trials were performed to assess inoculation with phosphorus (P)-solubilizing microorganisms (PSM) in combination with alternative sources of phosphate in pearl millet (Pennisetum glaucum) cultivation: One using sandy soil and the other using clayey soil. The treatments comprised five P sources, with or without inoculation with PSM B119 (Bacillus megaterium) and B2084 (Bacillus subtilis) strains. Amendment of alternative sources (granulated, branned organomineral, and Bayovar rock) of P along with PSM inoculation produced more plant dry mass on sandy soil, which was not observed on clayey soil. Phosphorus use efficiency (PUE) did not differ between inoculated and non-inoculated treatments, and it was higher with the alternative P sources, compared to triple superphosphate (TSP) treatments. Available P content in the soil was higher with TSP, in sandy soil, and with PSM inoculation. Overall, acid and alkaline phosphatases and ?-glucosidase activity was higher in clayey soil, compared to sandy soil, which contains little organic matter; it was also higher with alternative P sources, compared to TSP, and in inoculation treatments, showing the potential of using PSM inoculation and alternative P sources to achieve higher sustainability and productivity in agriculture.