Divergent nitrogen transition pathways during global agricultural development
Reactive nitrogen (N) inputs underpin global food production, but increasing protein provision while limiting agricultural N pressure remains a major sustainability challenge. Here, we analyzed changes in N use, cropland N surplus and protein supply across 130 countries from 1992 to 2022 to assess whether recurrent N-transition patterns emerge during agricultural and economic development. Countries followed divergent trajectories rather than converging toward a common N transition. Absolute decoupling, with increasing protein supply and declining cropland N surplus, occurred in 35.4% of countries, while others showed relative improvements or increasing N pressure. Cropland N surplus rose more steeply as agricultural N inputs intensified. Long-term trajectories revealed contrasting forms of N-system reorganization, from persistently lower-pressure systems to intensifying systems. Absolute decoupling occurred across diverse economic contexts and was not systematically associated with development level. Higher-development countries that decoupled generally reduced N surplus from higher starting levels but still ended with higher surpluses. Thus, increasing protein provision while reducing N surplus is achievable, but improvement does not necessarily imply convergence toward low N pressure.