The phosphorus legacy offers opportunities for agro ecological transition (France 1850-2075)
Management of the non-renewable resource phosphorus (P) is critical to agricultural sustainability. The global P cycle is currently disturbed beyond planetary boundaries, mostly due to large excess P use in the agriculture of industrialized countries, while P is lacking in the Global South. The trajectories of P management and their effects on future sustainable agriculture were investigated for the case of France from 1850 to 2015 based on empirical data and simulations of two coupled biogeochemical models. Here we show that while French cropland soils have accumulated significant amounts of P, mainly sourced from former colonies or protectorates, P reserves in grassland soils have been depleted. Scenario calculations indicate that current P reserves may on average allow for another 60 years of agricultural production without mineral P application. In the light of a possible upcoming P scarcity, this time frame offers an opportunity for a transition towards regionally closed P loops and enhanced sustainability, allowing for fairer international distribution of P resources in the future.