Diets influence dependency on synthetic nitrogen fertilizers

Abstract

Europe’s nitrogen (N) crisis demands innovative food systems solutions to improve N cycling. This study modelled the potential of different diets and circular fertilization strategies to enhance food system N use efficiency (NUE), reduce N surplus, and minimize reliance on synthetic N fertilizers. Results show that circularity helps to improve NUE and total N losses but does not consistently improve N surplus per ha. Synthetic N fertilizer could be reduced by 95% if healthy diets were consumed in circular food systems, increasing NUE from the current 0.17 to 0.53. The reduction of synthetic N fertilizer led to increased use of manure and showed considerable trade-offs with land use and greenhouse gas emissions (GHGe). In contrast, circular systems in which vegan diets were consumed showed the lowest land use and GHGe and a relatively high NUE (~ 0.3). This emphasizes the importance of considering trade-offs and synergies between different environmental impacts when redesigning food systems.