Nitrogen Use Efficiency in Crop Production in India: Trends, Issues, and Challenges

Nitrogen use efficiency (NUE) in crop production, the proportion of applied nitrogen (N) removed by the harvested yield of crops, dictates food security, loss of N to the environment, and efforts to curb climate change due to N2O emissions. Monitoring and maintaining high NUE assumes great importance in India because it is the second-largest consumer of fertilizer N in the world. Based on N input and N output data from 1961 to 2018 available at the Soil Nutrient Budget domain of the FAOSTAT database for different countries, trends in NUE, N output in harvested yield, and surplus N in India were compared with those in North America and the global average. The proportion of fertilizer N in the total N input for crop production in India is increasing since the advent of the Green Revolution in the mid-1960s, but NUE has declined from 48 to 35% in 2018; NUE in North America was 58% in 1961 and 53% in 2018. Substantially less maximum yield under saturating N input regimes, as well as N-based yield gap in India as compared to in North America or the world, suggest that there is a limited scope of achieving substantial yield gains in India by applying more fertilizer N. Although the maximum yield under saturating N input regimes based on the period 2010 to 2018 has increased than when based on 1961 to 2009, farmers in India need to greatly improve crop and fertilizer N management in terms of adopting technological innovations and avoiding N application more than the need of the crops to achieve NUE closer to that observed in North America. Adoption of site-specific N management strategies hold great potential but adoption of technologically advanced N options such as controlled release N fertilizers, and nitrification and urease inhibitors will depend upon benefit: cost ratio of their use in India.