[en] Wallonia presents a high diversity of soils and the fate of P in the soil-plant systems can highly vary from one region to another. The fate of phosphorus depends upon its forms in the solid constituents of soils, which is seldom characterized. For example, total P determines the soil reserve of P but also the potential P content which can be lost to surface water by erosion but analysis of this parameter is time consuming and rarely performed. This study aims (i) to define functional groups of soils for a differentiate P management, (ii) to estimate total soil P by regression equations based on soil parameters, and (iii) to estimate the quality of these predictions. The study consists in a characterization of 12 parent materials in Wallonia, collected across different land uses. A classification of soils was defined by clustering analysis and 5 groups were defined according to P contents and forms. Using this information in regression improved the quality of predictions. The coefficients of determination vary from 0.83 to 0.99, in comparison to a coefficient of 0.77 for the global regression. Then, pedotransfer functions were validated with an independent external dataset of 55 soils. Estimation of the quality of the prediction of P content (mean error, standard deviation of prediction and root mean square error) was made with global and local regression models. In conclusion, using a soil classification allowed to improve P content assessment by specific regressions and to propose differentiated P management for each group of soils.