Aqueous And Gaseous Nitrogen Losses Induced By Fertilizer Application

Anthropogenic input of reactive nitrogen to ecosystems has led to significant environmental consequences [Galloway et al., 2003; Aber et al., 1998]. Use of nitrogen fertilizers in agriculture has a direct impact on water (NO3) and atmospheric pollution (N2O, NO, NH3) [Vitousek et al., 1997]. Groundwater NO3 concentrations exceed drinking water standards in many areas [Byrnes, 1990; Scanlon et al.,2007], resulting in potential human health effects (i.e., methemoglobulinemia [Hill, 1996]). Elevated NO3 concentrations in leachate and surface water can also lead to eutrophication of lakes and estuaries [Lowrance et al., 1997]. Agricultural land also has been identified as the major anthropogenic source of nitrous oxide (N2O) [Mosier, 1998; Intergovernmental Panel on Climate Change (IPCC), 2007] and an important source of nitric oxide (NO) [Yienger and Levy, 1995] entering the atmosphere. Because the formation of these N species in soils is primarily through volatilization, nitrification, and denitrification [Bremner, 1997; McKenney and Drury, 1997; Firestone and Davidson, 1989], theirrelease rates can drastically increase with elevated inputs of nitrogen from fertilization. Nitrous oxide (N2O) is an important greenhouse gas and is also involved in the destruction ofstratospheric ozone [IPCC, 2001]. Nitric oxide (NO) emissions contribute to the formation of tropospheric ozone and acid deposition [McTaggart et al., 2002]. NH3 emissions affect the environment in the form of wet and dry depositionof NH4 + salts, causing acidification of poorly buffered soils and eutrophication [van der Weerden and Jarvis, 1997]. Such concerns have stimulated extensive studies in recent years to identify potential mitigation options for reducing N leaching and emission from agroecosystems [Skiba et al., 1997]