<p dir="ltr">Cropland expansion and intensification negatively impact water quality in downstream waterways through increased nutrient loading in the form of agricultural runoff and the loss of natural features that support water storage and nutrient removal. Nowhere is this more evident than the Corn Belt region of the United States where intensive row crop production generates high crop yields but also disproportionately high nutrient export to the Mississippi River. Depressional wetlands were a defining feature of this landscape prior to agricultural land development and are known to retain high levels of nutrients. Thus, protection, restoration, and creation of these wetlands is an increasingly important part of nutrient mitigation strategies in this landscape. Anoxic soils inherent to these wetlands provide the necessary oxidation-reduction (redox) conditions for nitrogen removal via denitrification, but also promote the production of greenhouse gasses including carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). Denitrification is a key water quality function via conversion of nitrate to N₂ that can also yield high fluxes of N₂O when incomplete. The key environmental factors that govern efficiency of this process and relative differences in nitrogen removal efficiency among wetland types are not well constrained. To address this gap, denitrification rates, greenhouse gas benthic production rates, greenhouse gas emission rates, and environmental conditions were measured in a series of wetland mesocosms with distinct plant species (reed canary grass, rice cutgrass, arrowhead, and an unplanted control) during peak biomass and plant senescence. My results revealed a denitrification stimulation effect from nitrate pulsing that differed significantly by plant type and that responses varied by stage of plant growth. Specifically, I found that labile carbon components resulting from root exudates, decomposition of plant residues and soil organic matter also positively influence denitrification. Additionally, I found that benthic production of CH₄ and CO₂ varies by plant type, as does surface flux for CO₂. Aerenchyma tissue was identified as a controlling factor in greenhouse gas emissions in the mesocosms, and a determining factor in the relationship between benthic production and system flux of greenhouse gasses. My work shows the importance of plant selection to improve design and management practices in agricultural wetlands.</p>