Subnational variation in sustainable nitrogen management across Indian croplands and its linkage with state-level governance

Abstract

Abstract Sustainable food production requires the reconciliation of agricultural productivity with environmental protection, a challenge especially acute in rapidly intensifying systems. India exemplifies this tension through heavy reliance on synthetic fertilizers and strong regional variation in nitrogen use efficiency. Yet subnational trajectories of nitrogen sustainability and their drivers remain poorly understood. Using five decades of district-scale data, we show that India’s Sustainable Nitrogen Management Index (SNMI), which integrates nitrogen yield and nitrogen use efficiency, improved nationally, declining from 1.02 to 0.84, mainly through productivity gain. However, spatial variation nearly doubled over the same period. The Indo-Gangetic Plains showed relatively stable SNMI trajectories, whereas the central-western plateau experienced a more than three-fold increase in variability. Even neighboring states with similar agroclimatic conditions diverged sharply. Within Western Plateau region, Madhya Pradesh achieved almost threefold higher nitrogen yield while maintaining lower nitrogen surplus than Maharashtra, reflecting differences in crop diversification, irrigation, procurement and input-use patterns. These findings show that governance and management contexts can strongly shape nitrogen sustainability, highlighting the need for region-specific sustainable intensification strategies.