Submitted to: American Society of Agri Engineers Special Meetings and Conferences Papers
Publication Type: Proceedings
Publication Acceptance Date: 3/9/1998
Publication Date: N/A
Technical Abstract: Throughout the Midwest over 30 percent of the cropland has subsurface drainage. This practice is necessary to remove excess water from the poorly drained soils and allow for crop production. However, the environmental implications of this practice have not been documented except in limited studies. This study was undertaken on the Walnut Creek watershed to evaluate the impact of subsurface drainage on stream and ground water quality and the role of water use by the crop as part of the water balance in drained agricultural areas. Monitoring of subsurface drainage has been done since 1991 and shows a pattern of spring peaks in discharge after the soil thaws and continuing into the summer until the crops begin to extract more soil water than is supplied by precipitation. Mobile chemicals, e.g., nitrate-nitrogen and pesticides, follow the pattern of drainage in their movement through the soil profile. Removal of nitrate-nitrogen from the soil profile varied among years depending upon the summer precipitation pattern. Reducing the movement of agricultural chemicals through subsurface drainage requires modifying the availability of chemicals in the soil profile.