Rising Disparity in Sustainable Nitrogen Management Across Indian Croplands

Sustainable food production requires reconciling agricultural productivity with environmental protection, a challenge that is particularly acute in rapidly intensifying systems. India, the world's most populous country and a global hotspot for nitrogen pollution, illustrates this dilemma through its extensive dependence on synthetic fertilizers and marked variation in nitrogen use efficiency between regions. However, insight in subnational trajectories of nitrogen sustainability and their principal determinants is lacking. Using district-scale data that span the past five decades, we show that the national Sustainable Nitrogen Management Index (SNMI), which integrates nitrogen yield and nitrogen use efficiency, has steadily improved, declining from 1.02 to 0.84. At the same time, spatial disparity almost doubled, with pronounced regional contrasts: the Indo-Gangetic Plains exhibited relatively stable improvements in SNMI, showing only a 14% increase in variability, while the central-west plateau recorded more than a three-fold increase. Furthermore, adjacent (political) states with comparable agroclimatic conditions diverged sharply in their N management; Madhya Pradesh achieved higher nitrogen harvests with approximately 35% lower fertilizer inputs than Maharashtra through diversified cropping, expanded irrigation and procurement incentives. These results highlight that differences in state-level governance and policy interventions can be as influential as agroclimatic conditions in shaping N sustainability. They underscore the need for region-specific and tailored strategies to achieve sustainable intensification while protecting environmental resources.