Poster 208 – Click on poster below to view presentation from author.
Co-Authors: Sara McMillan, Jacob Hosen
Creating and restoring wetlands on farms can reduce nutrient export from row-crop agriculture. While agricultural wetlands can improve water quality, wetlands may also be a source of potent greenhouse gases (GHGs), such as nitrous oxide and methane, that contribute to climate change. We posit that certain types of wetland plants based on residue composition will maximize complete denitrification, while reducing the release of potent GHGs. Wetland plant residue influences the composition and long-term fate of soil organic matter (SOM), thereby regulating lability of SOM and microbial processes that influence water quality and GHG emissions. Our proposed model is a wetland in central Indiana with emergent plant communities and a shallow impoundment that drains surrounding farmland. To test our hypothesis, we are 1) measuring denitrification, sulfate reduction, and GHG production rates across wetland soils underlying different plant communities, 2) conducting experiments to test the effect of plant residue at multiple stages of decomposition in microcosm experiments, and 3) characterizing the composition of added plant residue, the nature of SOM, and other soil properties. Preliminary results demonstrate that the type of wetland plant residue significantly affects methanogenesis and denitrification rates. Additionally, total and incomplete denitrification rates vary significantly across soils underlying different plant communities. By focusing on identifying vegetation-related controls of water quality improvements and GHG production, we have the potential to guide wetland creation and restoration design to maximize the benefits of embedding wetlands in agricultural landscapes.
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