Assets of legumes to face the stakes of food security and climate change.

This paper highlights the challenges facing agri-food systems, including ensuring sufficient and healthy food in a context of population growth and environmental constraints. Agriculture is both impacted by climate change and contributes to greenhouse gas emissions. Water and air pollution from fertilizers, as well as biodiversity loss due to intensive farming practices, are also of concern. The article explores the concept of planetary boundaries, particularly those related to agricultural and food systems, such as climate change, biodiversity, and nutrient cycles. It emphasizes the need to reconcile environmental goals with social equity, considering diets and their environmental impact. The analysis of the reactive nitrogen cycle, i.e. proteins and nitrogen, led to the discussion of scenarios to reduce nitrogen releases and return within planetary boundaries. Legumes are considered as a key element for more sustainable agricultural systems. They contribute to symbiotic nitrogen fixation, thus reducing dependence on synthetic nitrogen fertilizers and associated GHG emissions. Improving biomass production, nitrogen use efficiency, and reducing losses and waste are identified as levers for action. The article also highlights the importance of modifying agricultural production systems and diets to ensure food security while respecting planetary boundaries. In order to achieve that, it is necessary to use all biotechnical and organisational innovations but also to adapt political and regulatory framework in order to significantly change the dominant agrifood regimes.