Nitrogen Management for Maximum Efficiency and Minimum Pollution

This chapter discusses twofold: to consider the impacts of nitrogen (N) in the environment, and to examine various management systems for conservation of N in agro-ecosystems. A number of potentially adverse impacts of N on health and the environment can be identified. Nitrite is absorbed into the blood where it oxidizes the Fe of hemoglobin to the ferric state, forming methemoglobin which cannot function in oxygen transport. The long-term evolution of N use in agriculture likely will involve increased reliance on biological N fixation and better management of wastes. Lowered rates of irrigation is one management practice that would seem desirable from at least two standpoints; less total N leached and less denitrification from the drier soil. In general, adverse impacts of N occur when N inputs greatly exceed amounts which can be efficiently used by crops. Loss of N through leaching or denitrification before this period can result in environmental pollution and reduced yields.