The different fractions of phosphorus available in the short term were studied by the fractionation method. Soil samples (0-20 cm) were taken during 2021 and 2022 campaigns after the harvests in a test set up on the factorial design with four repetitions. The P sources (Calcined Burkina Phosphate enriched with calcium (CBKCa) and Triple Super Phosphate (TSP)) were applied to the main plots, and the subplots had three distances measured between the point of P fertilizer application and the plant crown (d0=0 d5=5 and d10=10 cm). The results showed that the fractions of inorganic P (Pi) (Pi-resin, Pi-NaHCO3, Pi-NaOH, and Pi-HCl) increased over time both for the different P sources and for the different supply distances. Regarding P sources, no significant difference was noted by the ANOVA for all the fractions, except that of P linked to Calcium (Pi-HCl). Whatever the year and the source of the P, the d5 led to a reduction in all the fractions of between 7% in Pi-HCl and 234% in Pi-NaOH, compared to the d0. In addition, d5 obtained a P content in grains and straw significantly higher than those of samples from d0 and d10. These results will help improve agricultural production.

Keywords: Soil acidity; Pi-HCl and Pi-NaOH fractions; Burkina Faso.