Agricultural drainage effects on water quality in Southeastern U.S.

A review of literature and summary of research results are presented on the effects of drainage on water quality in North Carolina, South Carolina, Georgia, and Florida. Principal findings from the predominate coarse-textured soils of the Atlantic Coastal Plain include increased nitrate-nitrogen losses associated with improved subsurface drainage. Benefits of drainage include potential reductions in organic nitrogen (N) and phosphorus (P) losses from these mineral soils. Results of drainage investigations on organic soils in the Everglades Agricultural Area of Florida indicate that phosphorus is the primary limiting factor for eutrophication problems in Lake Okeechobee. P losses can be potentially reduced by using slow versus fast drainage, retaining drainage water from vegetable and sugarcane fields (on sugarcane or fallow areas), and minimizing water-table fluctuations. Some of these potential practices and their resultant effects need additional verification for application to other areas and conditions.