NCR207 Multi-State Research Committee:

Drainage Design and Management Practices to Improve Water Quality 

Background, Issues and Justification

Excess nitrate (NO₃) in drinking water can be toxic to humans¹, requiring costly treatment of water for human consumption. Excess N in estuaries and coastal waters enhances algal growth² and is implicated in the formation of a hypoxic zone in the Gulf of Mexico³. The principal sources of nitrogen to the Mississippi river are the agricultural basins within the Midwest corn-belt^{4, 5}. Major source of NO₃ in surface waters within these basins is artificial subsurface drainage^{6, 7}. While much of this loss of N is commonly attributed to overuse of commercial N fertilizer, studies by Keeney and DeLuca⁸ and Willrich⁹ illustrate that considerable N loss was occurring before the wide spread use of inorganic fertilizers and that N leaching loss is more of a result of crop production per se (drainage, tillage, etc.) than of irresponsible fertilizer use. Within the twelve state North Central Region, there are >41,000,000 acres of drained cropland under production (Appendix 1), with up to 50% of all land under production being drained in some states¹⁰. These lands are some of the most productive in the world, but only if adequate drainage is provided.

In addition to the role subsurface drainage plays in transporting nitrate to surface waters, there is continuing concern for its role in transporting pesticides to streams and lakes. Subsurface drainage may also play a central role in a number of emerging issues. These include the transport of pathogens and pharmaceuticals to surface waters as a result of manure application to drained land exhibiting preferential flow behavior. Drainage may also play a significant role in the transport of phosphorus to surface waters and often exceeds levels suitable for fishable, drinkable, and swimmable rivers and lakes. There is growing evidence that subsurface drainage waters can also exceed the P concentration levels recommended by EPA for surface waters.

In a recent review by Dinnes et al.¹¹, several approaches were proposed for reducing the impact of drained agricultural lands on surface water quality. These included the use of alternative crop rotations and cover crops, improvements in the timing and rate of fertilizer application, and redesign and management of drainage systems to reduce the contribution of nitrate mass to surface waters. Currently, researchers across the North Central Region are investigating these and other approaches for reducing nutrient and other contaminant losses from drained croplands. While this research has shown promising results, there is little coordination or interaction amongst the different state researchers. Thus, there is little exchange of new ideas amongst researchers and as a result little synergy that such exchange could produce in developing new approaches to improve water quality. Lack of coordinated evaluation of alternative management practices and drainage designs across the Region hinders attempts to identify effective practices for reducing contamination of surface waters within the different states. A coordinated research program, focused on the unique characteristics of subsurface drained lands, would be of considerable benefit to farmers, the drainage industry, and the various state departments of agriculture and natural resources who will be charged with identifying and implementing management and infrastructure changes to reduce surface water contamination. This coordinated research effort will also be of benefit to the Agricultural Drainage Management Task Force within the ARS-NRCS-CSREES Partnership Management Team and the USDA-NRCS who are charged with evaluating the efficacy of alternative drainage designs and management approaches as nutrient control practices.

Literature Cited:

1. Heathwaite, A.L., T.P. Burt, and S.T. Trudgill. 1993. Overview - the nitrate issue. p. 3-21. In T.P. Burt, et al. (ed.) Nitrate: Processes, patterns and management. John Wiley and Sons, New York.
2. Ocean Studies Board and Water Science and Technology Board, Commission on Geosciences, Environment, and Resources, National Research Council. 2000. Clean coastal waters: Understanding and reducing the effects of nutrient pollution. National Academy Press, Washington, DC.
3. Rabalais, N.N, W.J. Wiseman, R.E. Turner, B.K. Sen Gupta, and Q. Dortch. 1996. Nutrient changes in the Mississippi River and system responses on the adjacent continental shelf. Estuaries 19:386-407.
4. David, M.B., and L.E. Gentry. 2000. Anthropogenic inputs of nitrogen and phosphorus and riverine export for Illinois USA. J. Environ. Qual. 29:494-508.
5. Goolsby, D. A., W. A. Battaglin, B.T. Aulenbach, and R.P. Hooper. 2001. Nitrogen input to the Gulf of Mexico. J. Environ. Qual. 329-336.
6. David, M.B., L.E. Gentry, D.A. Kovacic, and K.M. Smith. 1997. Nitrogen balance in and export from an agricultural watershed. J. Environ. Qual. 26:1038-1048.
7. Goolsby, E.A., W.A. Battaglin, G.B. Lawrence, R.S. Artz, B. T. Aulenbach, R. P. Hooper, D. R. Keeney, and F. J. Stensland. 1999. Flux and sources of nutrients in the Mississippi-Atchafalaya river basin: Topic 3 Report for the Integrated Assessment of Hypoxia in the Gulf of Mexico. NOAA Coastal Ocean Program Decision Analysis Series No. 17. NOAA Coastal Ocean Program, Silver Spring, MD. 130 pp.
8. Keeney, D.R., and T.H. DeLuca. 1993. Des Moines river nitrate in relation to watershed agricultural practices: 1945 versus 1980s. J. Environ. Qual. 22:267-272.
9. Willrich, T.L. 1969. Properties of tile drainage water. Completion report, project A-013-IA, Iowa State Water Resour. Res. Inst., Iowa State Univ., Ames, IA. 39 p.
10. USDA, 1987. Farm drainage in the United States: history, status, and prospects. Misc. Pub. No 1255. Washington, D.C.
11. Dinnes, D.L., D.L. Karlen, D.B. Jaynes, T.C. Kaspar, J.L. Hatfield, T.S. Colvin, and C.A. Cambardella. 2002. Nitrogen management strategies to reduce nitrate leaching in tile-drained Midwestern soils. Agron. J. 94:153-171.