In this work, the amount of phosphorus fertilizer that will be necessary to produce food in 2050 is estimated. It is considered that an important part of the added phosphorus (P) is adsorbed or precipitated in the soil and is not available to plants. The P’s legacy is also considered by the model. Various scenarios show the importance of good management that considers the particularity of the soils, the recovery of P from different systems and improving the efficiency of its use.