Wet soil microcosms were established to determine effects of organic matter and nitrate additions on microbial respiration and redox potentials. Organic matter (1%) and nitrate (100 ppm and 200 ppm) treatments were applied in factorial combination. Soil pH, redox potential, and CO2 emissions were measured. Data were analyzed by ANOVA for repeated measures and separately by sampling day. Addition of organic matter significantly (P<0.05) and consistently increased CO2 emissions and decreased redox potentials. On Day 42 nitrate significantly (P<0.05) increased redox values. This study indicates a tendency for organic matter to decrease soil redox potential both in absolute terms and relative to the suboxic-anoxic boundary. Our findings portend that additions of organic matter may quickly and markedly decrease soil redox potentials and increase CO2 emissions in wetlands, whereas additions of nitrate may have complex and sporadic effects on redox potentials.
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D. Gardiner and S. James, "Wet Soil Redox Chemistry as Affected by Organic Matter and Nitrate," American Journal of Climate Change, Vol. 1 No. 4, 2012, pp. 205-209. doi: 10.4236/ajcc.2012.14017.
 G. Sposito, “The Chemistry of Soils,” Oxford University Press, New York, 1989.
 L. G. M. Baas Becking, L. R. Kaplan and D. Moore, “Limits of the Natural Environment in Terms of pH and Oxidation-Reduction Potentials,” Journal of Geology, Vol. 68, No. 3, 1960, pp. 224-284.
 M. E. Essington, “Soil and Water Chemistry: An Integrative Approach,” CRC Press, Boca Raton, 2004.
 S. L. Whitmire and S. K. Hamilton, “Rapid Removal of Nitrate and Sulfate in Freshwater Wetland Sediments,” Journal of Environmental Quality, Vol. 34, No. 6, 2005, pp. 2062-2071.
 T. Mansfeldt, “Redox Potential of Bulk Soil and Soil Solution Concentration of Nitrate, Manganese, Iron, and Sulfate in Two Gleysols,” Journal of Plant Nutrition and Soil Science, Vol. 167, No. 1, 2004, pp. 7-16.
 N. P. Hume, M. S. Fleming and A. J. Horne, “Denitrification Potential and Carbon Quality of Four Aquatic Plants and Wetland Microcosms,” Soil Science Society of America Journal, Vol. 66, No. 5, 2002, pp. 1706-1712.
 J. R. White and K. R. Reddy, “Influence of Selected Inorganic Electron Acceptors on Organic Nitrogen Mineralization in Everglade Soils,” Soil Science Society of America Journal, Vol. 65, No. 3, 2001, pp. 941-948.
 F. E. Matheson, N. L. Nguyen, A. B. Cooper, T. P. Burt and D. C. Bull, “Fate of 15N-Nitrate in Unplanted, Planted and Harvested Riparian Wetland Soil Microcosms,” Ecological Engineering, Vol. 19, No. 4, 2002, pp. 249-264.
 T. E. Davidsson and M. St?hl, “The Influence of Organic Carbon on Nitrogen Transformations in Five Wetland Soils,” Soil Science Society of America Journal, Vol. 64, No. 3, 2000, pp. 1129-1136.
 M. R. Burchell II, R. W. Skaggs, C. R. Lee, S. Broome, G. M. Chescheir and J. Osborne, “Substrate Organic Matter to Improve Nitrate Removal in Surface-Flow Constructed Wetlands,” Journal of Environmental Quality, Vol. 36, No. 1, 2007, pp. 194-207.
 X. Zhang, S. E. Feagley, J. W. Day, W. H. Conner, I. D. Hesse, J. M. Rybczyk and W. H. Hudnall, “A Water Chemistry Assessment of Wastewater Remediation in a Natural Swamp,” Journal of Environmental Quality, Vol. 29, No. 6, 2000, pp. 1960-1968.
 National Research Council, “Compensating for Wetland Losses under the Clean Water Act,” National Academy Press, Washington, 2001.
 Wetland Training Institute, “Field Guide for Wetland Delineation, 1987 Corps of Engineers Manual,” Wetland Training Institute, Glenwood, 2002.
 R. D. DeLaune, I. Devai, C. Crozier and C. W. Lindau, “The Influence of Soil Redox Conditions on Atrazine Degradation in Wetlands,” Agriculture Ecosystems and Environment, Vol. 66, No. 1, 1997, pp. 41-46.
 United States Department of Agriculture-Soil Conservation Service, “Soil Survey of San Patricio and Aransas Counties, Texas,” US Government Printing Office, Washington, 1979.
 W. H. Patrick, R. P. Gambrel and S. P. Faulkner, “Redox Measurements of Soil,” In: D. L. Sparks, et al., Eds., Methods of Soil Analysis, Soil Science Society of America, Madison Wisconsin, 1996, pp. 1155-1273.
 United States Department of Agriculture, “Soil Quality Test Kit Guide,” US Government Printing Office, Washington, 1998.
 Analytical Software, “Statistix 8 Users Manual,” Analytical Software, Tallahassee, 2003.
 L. J. Puckett and T. K. Cowdery, “Transport and Fate of Nitrate in a Glacial Outwash Aquifer in Relation to Ground Water Age, Land Use Practices, and Redox Processes,” Journal of Environmental Quality, Vol. 31, No. 3, 2002, pp. 782-796.
 M. Healy and A. M. Cawley, “Nutrient Processing Capacity of a Constructed Wetland in Western Ireland,” Journal of Environmental Quality, Vol. 31, No. 5, 2002, pp. 1739-1747.
 P. J. Bohlen and S. M. Gathumbi, “Nitrogen Cycling in Seasonal Wetlands in Subtropical Cattle Pastures,” Soil Science Society of America Journal, Vol. 71, No. 3, 2007, pp. 1058-1065.
 L. J. Lund, A. J. Horne and A. E. Williams, “Estimating Denitrification in a Large Constructed Wetland Using Stable Nitrogen Isotope Ratios,” Ecological Engineering, Vol. 14, No. 1-2, 2000, pp. 67-76.