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ARS Home » Southeast Area » Florence, South Carolina » Coastal Plain Soil, Water and Plant Conservation Research » Research » Publications at this Location » Publication #284968

Title: Greenhouse gas emissions and denitrification within depressional wetlands of the southeastern US coastal plain in an agricultural landscape

item Miller, Jarrod
item Ducey, Thomas
item Brigman Jr, Percy
item OGG, CHARLIE - Natural Resources Conservation Service (NRCS, USDA)
item Hunt, Patrick

Submitted to: Wetlands
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/2016
Publication Date: 1/31/2017
Citation: Miller, J.O., Ducey, T.F., Brigman Jr, P.W., Ogg, C.O., Hunt, P.G. 2017. Greenhouse gas emissions and denitrification within depressional wetlands of the southeastern US coastal plain in an agricultural landscape. Wetlands. 37(1):33-43.

Interpretive Summary: Carolina Bays are wetlands that reside alongside of land used for agriculture and can therefore receive nutrient runoff. Three of these wetlands in South Carolina were tested for nitrogen cycling and gas emissions over a 2-year period. Temperature was observed to control carbon dioxide and nitrous oxide emissions from the bays. The addition of nitrogen to soils as you went further into the Bays had a greater effect on enzyme activity than at the edge. Both fungal and Gram-bacteria were also greater at the field/wetland interface. Overall, manure appears to have little impact on gas emissions within adjacent Carolina Bays.

Technical Abstract: Carolina Bays are depressional wetlands on the Coastal Plain of the southeastern USA. These wetlands are often adjacent to agricultural land and may be the recipients of nutrient runoff. Because of their saturated conditions, nutrient cycling may be important for water quality. Three small bays in South Carolina were selected for denitrification and greenhouse gas analysis. A transect of four points was sampled within each Carolina Bay in May, July, September, and November over a two-year period. Gas emissions were measured in-situ using a photoacoustic gas analyzer, and soil samples were brought back to the lab for denitrification enzyme activity and microbial analysis. Emissions of nitrous oxide averaged 1.8 milligrams of nitrous oxide/square meter/day, with a median of 0.47. Many measurement events of nitrous oxide were below detection and did not vary within the bays. The highest nitrous oxide flux was observed in the adjacent agricultural field that received poultry manure applications. The carbon dioxide emissions from Carolina Bays averaged 15.8 grams/square meter/day and were largely controlled by temperature. Denitrification enzyme activity had a larger response to nitrate additions further into the bays. Gram+ bacteria were also greater deeper into the bays, while Gram- and fungal populations were greater at the field/wetland interface. Manure application had some minor affects on denitrification within the bays, but did not appear to increase gas emissions over the period measured.