Phosphorus circularity in food systems and its relationship with international trade of food and feed

International trade of food and feed is increasing, which may limit nutrient recycling in food systems, to an unknown extent. We examined phosphorus (P) circularity in food systems of 88 main importing countries and 37 main exporting countries for 2000-2018. We inferred P input circularity (P in recycled residues as share of total P inputs), and P output circularity (P in recycled residues as share of total P in residues). Global mean output circularity was 65%, and slightly higher for exporting countries than importing countries. Global mean input circularity for cropland was 77% in importing countries and 62% in exporting countries, suggesting that residues from imported products contributed to P circularity. Our study provide insights in the prospects and mechanisms for increasing P circularity, which may help policy makers to design targeted interventions that minimize the need for synthetic P fertilizer and lower P losses in food systems.