Rethinking nitrogen use: need to plan beyond present

Nitrogen, being an integral part of proteins, DNA, RNA, chlorophyll, enzymes, and several other biomolecules, is vital for life on earth. About 50% of global food production is dependent on mineral N fertilizers; hence, it is essential for food security and economic development. Its excessive and inefficient use, however, results in several environmental externalities such as deterioration of air and water quality, soil health, climate change, stratospheric ozone depletion, and loss of biodiversity. Nitrogen pollution is already crossing the planetary boundary, hence it needs immediate attention. However, various environmental damages caused by N losses need to be balanced against the benefits that are associated with N use in agriculture and the role it plays in contributing to food security. It is therefore important to account for the costs and benefits of mitigation policies at local, regional, and global levels. This chapter discusses the N challenge, its impacts on the environment and climate change, its use in South Asia particularly in Pakistan, and the policies aiming at increasing its use efficiencies and reducing environmental impacts of surplus N.