Groundwater contamination is an ever-increasing concern on a national level as well as locally. Increasing amounts of nitrate-nitrogen (NO3-N) being delivered by rivers, including the Mississippi, have resulted in an oxygen-depleted area or hypoxic zone in the Gulf of Mexico. (Turner and Rabalais, 1994b). This nutrient loading has caused nitrogen-limited phytoplankton to bloom. Decom-position of these blooms depletes oxygen levels forming seasonal hypoxic conditions (Rabalais et al., 1996). Nitrogen (N) loading studies analyzing the sources and losses of N to the Mississippi River basin show the Midwest corn and soybean producing area to be the largest total contributor of N (Burkart and James, 1999). Therefore the land-use practices and management at the local level can influence NO3-N contributions to distant river basins. The concern for water quality protection and the association of groundwater contamination with widespread use of N fertilizers for crop production, make the development of practices that reduce NO3-N contamination a high priority.