Nutrient recycling potential of excreta for global crop and grassland production

Nutrient recycling from wastes to agriculture can contribute to food production by closing yield gaps, yet the global amount of poorly utilized nitrogen (N), phosphorus (P) and potassium (K) in excreta at a subnational scale has been insufficiently explored. The global amounts found in human excreta and poorly utilized livestock excreta represent 16% (±7%), 8% (±9%) and 14% (±6%) of crop and grassland N, P and K needs, respectively. National recycling of nutrients in poorly utilized excreta could reduce global net imports of mineral fertilizers by 41% N, 3% P and 36% K. In countries where nutrient supply through locally available livestock excreta and mineral fertilizers do not meet nutrient requirements by crops and grasslands, the recycling of poorly utilized excreta could reduce this difference by, on average, 20% N, 11% P and 13% K, therefore contributing to the move towards a circular economy between food consumption and agriculture. Human and livestock excreta are rich sources of important agricultural nutrients, but are currently poorly utilized. Recycling these resources can help close the gap where mineral fertilizers are insufficient.