Regional water quality impacts of intensive row-crop agriculture: A Lake Erie Basin case study

Intensive row-crop agriculture dominates land use in the northwestern Ohio River basins draining into Lake Erie. Detailed, long-term studies of water quality in these rivers reveal high unit-area P loads entering Lake Erie, even though gross erosion rates are relatively low. Concentrations of nitrate-N and currently used herbicides are also high from May through July, both in surface waters and in public water supplies derived therefrom. To reduce P loading to Lake Erie, water quality management agencies are advocating adoption of conservation tillage. Conservation tillage could increase nitrate and herbicide contamination of area waters. This region's detailed baseline nutrient and herbicide data provide an opportunity to evaluate the effects of conservation tillage on a variety of water quality parameters. To separate weather-related from management-related effects, an ecosystem approach is advocated.