Agricultural trade impacts global phosphorus use and partial productivity.

The spatio-temporal distribution, flow and end use of phosphorus (P) embedded in traded agricultural products are poorly understood. Here we use global trade matrices to analyse the partial factor productivity of P (output per unit of P input) for crop and livestock products in 200 countries and their cumulative contributions to the export or import of agricultural products over 1961-2019. In these six decades, the trade of agricultural P products has increased global partial factor productivity for crop and livestock production and has theoretically saved 67 Tg P in fertilizers and 1.6 Tg P in feed. However, trade is now at risk of contributing to wasteful use of P resources globally due to a decline in trade optimality, as agricultural products are increasingly exported from low to high partial factor productivity countries and due to P embedded in imported agricultural products mainly lost to the environment without recycling. Integrated crop-livestock production systems and P-recycling technologies can help.