Paper presented at the 11th North American Agroforesty Conference, which was held May 31-June 3, 2009 in Columbia, Missouri.In Gold, M.A. and M.M. Hall, eds. Agroforestry Comes of Age: Putting Science into Practice. Proceedings, 11th North American Agroforestry Conference, Columbia, Mo., May 31-June 3, 2009.Denitrification is recognized as the major mechanism for reducing nitrate in riparian buffers and thus diminishing non-point source pollution (NPS) of surface water bodies subject to high nitrogen loads. However, increasing denitrification rates in riparian buffers may be trading the problem of NPS pollution of surface waters for atmospheric deterioration and increased global warming potential because denitrification produces nitrous oxide (N2O), a greenhouse gas also involved in stratospheric ozone depletion. It is therefore important to quantify the emissions of N2O from different kinds of vegetated riparian buffer systems, and identify ways to minimize emissions while simultaneously maximizing denitrification. We measured N2O emissions from soils; nitrate (NO3--N) and dissolved N2O in groundwater; and soil properties in riparian forest buffers, warm-season and cool-season grass filters, and a crop field located in the Bear Creek watershed in central Iowa. Results suggest that N2O emissions from soils in all riparian buffers were significantly less than in the crop field, but no differences among types of riparian buffers were observed. Nitrate in outflow groundwater of riparian buffers was significantly lower than in inflow groundwater of riparian buffers. However, dissolved N2O in inflow and outflow groundwater of riparian buffers were not significantly different from one another. These results are useful in developing management protocols for riparian forest and other perennial vegetation practices for NPS pollution attenuation and additional multiple benefits.Thomas M. Isenhart (1), Dong-Gill Kim (2), and Richard C. Schultz (1) ; 1. Natural Resource Ecology and Management, Iowa State University, Ames, IA, 50011. 2. Department of Civil and Environmental Engineering, University College Cork, Cork, Ireland.Includes bibliographical references
