Mineral nitrogen fertilizers: environmental impact of production and use

The industrialized agro-ecosystem is formed by technological and environmental subsystems, interacting strictly among one another to guarantee high quantitative and qualitative productivity requested by the market. Efficient management, at the moment, requires a large use of fossil fuels that often severely affect the environmental subsystem. Therfore, the agro-ecosystem produces a high environmental impact, both at the local and global scale. Mineral nitrogen fertilization represents one of the main agricultural practices with a high emission of pollutants in the atmosphere, soil and water. This practice is necessary to guarantee high crop yields in spite of soil nitrogen depletion, which is linked to the progressive degradation of the soil organic matter. The environmental loading of nitrogen mineral fertilizers is due to the activities of the technological subsystem (production, transport, application), to the alteration of some soil microbial processes and to the excess supply not absorbed by the cultivated crops. The present chapter will review the environmental impact of nitrogen fertilization by analyzing the effects caused by the interactions of the technological and environmental subsystems. The environmental loads associated with the technological subsystem will be described by means of Life Cycle Assessment (LCA) approach. The Life Cycle Assessment is a method which is able to quantify the environmental aspects and potential impacts associated with a product, process, or activity throughout its entire cycle of life: from extraction of raw materials, through production, use and maintenance, to decommissioning at the end of life. The procedure is in accordance with the ISO 14040 and ILCD Handbook. Moreover, the main environmental effects of the nitrogen fertilizers application on soil environmental subsystems will be described. In detail, the state of art of the effect of nitrogen application on soil microbial activities, responsible for the production of atmospheric pollutants (carbon dioxide, methane, nitrogen compounds) and nitrogen dispersion in water bodies, will be presented. Mitigation strategies for both sub-systems suitable for reducing the environmental impact in the use of nitrogen fertilizers will be also reported. © 2014 Nova Science Publishers, Inc.