A resource-based phosphorus footprint for urban diets

Large amounts of phosphorus resources, such as mineral fertilizers and manure, are mobilized globally to produce the food consumed in cities. Accounting for the use of these resources can allow cities to plan for interventions that reduce related pressures in their hinterlands, conserve resources, and lead to more circular food systems. In this study we calculate a resource-based phosphorus footprint for the food consumption in Brussels Capital Region and use it to compare different strategies towards increased circularity: waste reuse, waste reduction, dietary changes and shifts to locally produced food. The P footprint of an average inhabitant in Brussels is 7.7 kgP cap yr −1 , 10 times higher than the physical P consumption of 0.7 kgP cap yr −1 . About 60% of the total P inputs into food production are through manure, and the rest through mineral fertilizers; almost 80% of the inputs occur outside Belgium. Most of these inputs are related to the cultivation of feed for livestock, which is why a shift to vegetarian and vegan diets can reduce the footprint down to 4.8 kgP cap yr −1 and 0.9 kgP cap yr −1 . To the contrary, consuming only food produced in Belgium would increase the footprint to 12 kgP cap yr −1 , mostly as a result of the high manure use in the north of the country. A reduction in the P footprint signifies an absolute reduce in total resource use that can alleviate pressures in the hinterland and promote a city’s transition towards circularity.