Halving nitrogen waste in the European Union food systems requires both dietary shifts and farm level actions

The pivotal role of nitrogen to achieve environmental sustainable development goals and transform our food system is recognized in an ambitious nitrogen waste reduction target in the Farm to Fork Strategy of the European Commission. But is this a realistic objective and if so, what are the pathways that lead to success? To answer these questions, we first established, as a baseline, an updated food system nitrogen budget for the EU for the year 2015. The EU used 20 Tg of virgin (new) N to deliver 2.5 Tg N in food and 1.2 Tg N in fibres to consumers, yielding a food-system nitrogen use efficiency (NUE) of 18%. We then built a simple model to combine intervention options that (a) increase farm level nitrogen use efficiencies, (b) reduce food waste increase recycling of waste and improve waste treatment, or (c) achieve a dietary shift towards healthier dietary patterns. The largest potential to increase N efficiency of the current agro-food system was found to lie in the livestock sector. From 144 possible combinations of intervention options analysed, we found that 12 combinations of interventions would reduce nitrogen losses by about 50%, 11 involving diet change. We further carried out an assessment of the societal appreciation of combinations of interventions considering private and public costs of the intervention measures, public benefit through effects on health and increased biodiversity of ecosystems, and public costs for overcoming socio-cultural barriers. Results show that a combination of moderate intervention options achieve halving of N losses at lowest societal costs. We conclude that systemic approaches are paramount to achieve deep nitrogen reduction targets and diet change appears to be an essential condition for success.