Changes in Soil Physical, Chemical, and Biological Properties Caused by

Changes in Soil Physical, Chemical, and Biological Properties Caused by Artificial Drainage of Wetlands Wetland soils are extremely varied. They are found from the tropics to the subarctic. They can be seasonal or year-round, freshwater or saltwater, organic or mineral. The one thing that all of them have in common is that for at least part of the year they are saturated with water. This saturation has a significant impact on the soil's physics, chemistry, and biota. However, over the past century more than half of all the wetlands in the United States has been drained for agriculture and other uses such as construction. When the soils are drained the physics, chemistry, and biota are drastically changed. This paper is an attempt to describe the changes in artificially drained soils and to consider a few of the consequences of these changes. The physical properties of saturated soils vary somewhat from wetland to wetland but are characterized by certain processes. One is the interaction of the soil with the watertable. Three patterns of possible groundwater flow have been considered: water could flow into the saturated areas from the surrounding area (discharge), making the saturated area the focal point; water could flow through swamps because of local relief (flow-through); or water could flow from the saturated zone into surrounding areas (recharge) possibly due to differential water use by plant communities or pumping (Crownover et al, p. 1199). There can also be vertical exchange of water between the groundwater and saturated soil. For example, capillary effects pull water upward into the soil from the water table. Besides the vertical and horizontal flow of water, the area of the soil taken up by water is important.... ...ater flow patterns through a cypress swamp-pine flatwood landscape: Soil Science Society of America Journal, 59, p. 1199-1206. Fausey, N.R., Brown, L.C., Belcher, H.W. and Kanwar, R.S., 1995, Drainage and water quality in the Great Lakes and cornbelt states: Journal of Irrigation Drainage Engineering, 121, p.283-288. Leventhal, E., 1990, Alternative uses of wetlands other than conventional farming in Iowa, Kansas, Missouri, and Nebraska: EPA/171/R-92/006, 145 p. McBride, M. B., 1994, Environmental Chemistry of Soils: New York, Oxford University Press, 406 p. Mitsch, W.J. and Gosselink, J.G., Wetlands: New York, Van Nostrand Reinhold Company, 537 p. Schipper, L.A., Harfoot, C.G., McFarlane, P.N., and Cooper, A.B., Anaerobic decomposition and denitrification during plant decomposition in an organic soil: Journal of Environmental Quality, 23, p. 923-928.