Abstract
Phosphorus (P) availability in soils limits crop yields in many regions of the world, while excess of
soil P triggers aquatic eutrophication in other regions. Numerous processes drive the global spatial
distribution of P in agricultural soils, but their relative roles remain unclear. Here, we combined
several global datasets describing these drivers with a soil P dynamics model to simulate the
distribution of P in agricultural soils and to assess the contributions of the different drivers at the
global scale. We analyzed both the labile inorganic P (PILAB), a proxy of the pool involved in plant
nutrition and the total soil P (PTOT). We found that the soil biogeochemical background (BIOG) and
farming practices (FARM) were the main drivers of the spatial variability in cropland soil P content
but that their contribution varied between PTOT vs PILAB. Indeed, 97% of the PTOT spatial variability
could be explained by BIOG, while BIOG and FARM explained 41% and 58% of PILAB spatial
variability, respectively. Other drivers such as climate, soil erosion, atmospheric P deposition and
soil buffering capacity made only very small contribution. Our study is a promising approach to
investigate the potential effect of P as a limiting factor for agricultural ecosystems and for global
food production. Additionally, we quantified the anthropogenic perturbation of P cycle and
demonstrated how the different drivers are combined to explain the global distribution of
agricultural soil P.
