Evaluation of global research on agricultural nitrogen pollution between 1990 and 2023: Challenges for more efficacy and equity

Excessive and inefficient nitrogen (N) use in agriculture poses pervasive environmental threats for Water quality, Air quality, Greenhouse gas emissions, Ecosystems and biodiversity, and Soil (WAGES). However, it is unclear whether the global distribution of research corresponds to the severity of these threats. Here we provide a global assessment linking research outputs across WAGES with cropland N surplus, a proxy for the severity of N threats. We show that N surplus correlates well with the number of publications addressing WAGES threats, although marked regional disparities exist. Higher income countries distribute research more evenly across threats associated with high fertiliser inputs, while lower income countries prioritise soil research, particularly soil fertility. Publications from lower income countries account for only 8 % of the total and focus largely on food security rather than on N pollution. Since these countries are responsible for half of global N losses, they represent important “low hanging fruits” where targeted research can simultaneously improve food security and reduce N pollution. Our study highlights the need to strengthen research capacity, support locally led priorities, and better align research investments with the severity of N threats to advance toward more equitable and effective N management.