Human influences on mobility of nitrogen in the environment: Needs for research and management

Nitrogen (N) cycles through air, water and soil and plays an important role in the synthesis of complex N compounds in all forms of life on the planet earth by combining with carbon, hydrogen and oxygen (O). Besides, natural fixation of N by microorganisms, advertent and inadvertent fixation of N by human activities (e.g. landscape transformations, fossil fuel burning and use of N in agricultural fields) are altering the global cycle of N. As a result of human activities, N enters in water bodies (e.g. streams, estuaries and coastal regions) making them hostile for aquatic life and contaminates ground water (used for drinking) through nitrate () leaching which causes a number of health problems to human beings and animals. Hence, reduction in level of in water bodies and ground water is a prerequisite that can be met through sustainable management of natural and modified ecosystems. More specifically, agricultural management practices need to be better designed to synchronize the availability of with that of the crop N demand. These management goals can be achieved by thorough understanding of the origin and fate of N, by using isotopic analysis of N and O in , which can provide the best management options for N in the environment. Overall, an integrated approach would be required to limit N production/use and release to prevent critical environmental limit being exceeded.