Nitrogen budget of Indian agriculture: trends, determinants and challenges

The discord between the nitrogen (N) fertilizer use and the actual N requirement in Indian agriculture is of enormous concern. When N is overused, it emerges as a threat to the environment, and crop yields are affected when it is underused. Nutrient budgeting is a useful tool in assessing the inflows and outflows of nutrients to the agricultural system and formulating future strategies. We constructed a nitrogen budget for Indian agriculture for 1961–2017. The N input to Indian croplands increased from 4.87 million tons (Mt) to 24.08 Mt during this period. Among the different components of N use in 2017, the contribution of fertilizer is the highest (70%), followed by biological N fixation (16%), manure (9%), and atmospheric deposition (4%). The analysis portrayed Indian agriculture’s transformation from the N deficit value of − 0.61 Mt in 1961 to a surplus-value of 1.21 Mt as of 2017. The crop N use efficiency during the period decreased from 72 to 55%. Since the policies and socio-economic factors are the commonly studied drivers of N fertilizer use, crop production factors have not received due attention. We dissect the contribution of these factors to N fertilizer use. The fertilizer application rate (FAR) is the most important among the major crop production factors that drive N fertilizer use. Our findings propose that the surplus N in Indian agriculture, hastened by higher FAR, may pose serious sustainability issues if not addressed.