Role of Nitrogen and Its Agricultural Management in Changing Environment

Nitrogen (N) is the most limiting nutrient element for crop production which controls the primary production of the agricultural system. It is one of the key inputs for the green revolution in India which achieved due to the substantial use of synthetic N-fertilizers. Since then the use of N-fertilizers has increased by many folds. The injudicious use of N has severely affected the N cycle causing N losses from cropland via nitrification, leaching and volatilization pathways. These N losses minimize the nitrogen use efficiency (NUE) by the crops and the factor productivity per unit of N application. Besides this it cause various environmental problems such as groundwater contamination due to nitrate (NO3-) leaching, eutrophication of surface water bodies due to runoff loss of N, air pollution and aerosols formation due to oxides of nitrogen (NO and NO2) and ammonia (NH3), and global warming due to nitrous oxides (N2O) emission. The better understanding of N dynamics and factors affecting its losses from cropland can be used to develop the strategies for enhancing NUE and to mitigate the adverse environmental impacts. Management of N is a challenging task and several methods individually and in combination are generally used to manage it efficiently. The decision support tools, integrated nitrogen management (INM), precision nitrogen management, site-specific nitrogen management (SSNM), etc., could be substantially used to enhance NUE and for sustainable crop production. In the present chapter, all the aspect of the N including, various pathways of N cycle, N losses, environmental impacts, and its judicious management to enhance the NUE and to mitigate the adverse environmental impacts have been well discussed.