|Karlen, Douglas - Doug|
Submitted to: Encyclopedia of Environmental Management
Publication Type: Book / Chapter
Publication Acceptance Date: 10/13/2010
Publication Date: N/A
Citation: N/A Interpretive Summary:
Technical Abstract: High nitrate-nitrogen concentrations in water pose problems for human health and the environment. Groundwater is a major source for human water supplies and for contributing to surface water bodies. Leaching of N fertilizers is a major factor for high NO3-N concentrations in groundwater. Current cropping practices to achieve optimum yields in many grain crops cause excess N to build up in the soil profile, which is then available for leaching to groundwater. Oftentimes there can still be a yield response to N fertilizer at rates which exceed the amount of N that the plants will utilize. Thus, the economic optimum nitrogen level (EON) may be at a level that causes concentrations of NO3-N to exceed maximum contaminant levels (MCL). Turf grasses and container horticultural crops are areas that often receive intensive N inputs. Approaches that can be used to reduce the NO3 leaching potential include: reducing overall N fertilizer inputs; applying N in split applications, i.e. timing the N applications to when plants can better utilize the N; using slow-release N fertilizers; using cover crops to capture part of the N buildup in the soil profile before it can leach to groundwater.