Design and Management of On-Farm Wetlands for Water Quality and Climate Regulation

View the project final report

Commodities

Practices

• Natural Resources/Environment: wetlands

Wetland creation and restoration are an important part of nutrient management strategies in watersheds with intensive row-crop agriculture, because these systems are effective sinks for nitrogen, phosphorus and carbon sequestration. Many of the same environmental conditions that support the capacity of wetlands to capture nutrients also stimulate the release of methane (CH₄) and nitrous oxide (N₂O), which are potent greenhouse gases (GHGs) that drive climate change. Climate change is driving increased frequency and severity of intense rainfall events, including an increasing level of rain on snow and rain on snow. This threatens to increase the delivery of nutrients to downstream wetlands, creating a positive feedback. Thus, identifying wetland strategies that minimize releases of GHGs while maintaining water quality benefits. This project, “Design and Management of On-Farm Wetlands for Water Quality and Climate Regulation,” will address this demand through research and outreach efforts. 

Two main factors of wetland design and management are vegetation and hydrology. Variability in nutrient retention, carbon sequestration, and GHG release have been linked to vegetation and water table management. Yet, there is considerable uncertainty about the mechanisms that drive these differences. Further, data on individual plant species, which could be used by managers to optimize plantings, are not available. This research addressed the uncertainties related to how wetland plant species influence microbial functions using twelve experimental mesocosms planted with one of three wetland species and a novel integration of biogeochemical methods. The effects of plant species were assessed using CH₄, CO₂, and N₂O flux estimates and nutrient retention in the experimental mesocosms. The mechanisms that explain differences across treatments were identified by measuring soil and plant characteristics and rates of denitrification, methanogenesis, and N₂O production. Multivariate analyses will be used to identify characteristics that explain the response of wetland functions to differences in plant species. A major outcome of this research will be the development of actionable guidelines for plant selection of wetlands that effectively treat agricultural drainage and runoff while reducing GHG emissions. The achievement of research and outreach outcomes will support progress toward reaching nutrient reduction goals while limiting contributions to climate change. 

The primary learning outcome is to increase the actionable knowledge of how wetland plant species can be leveraged to maximize water quality and climate regulation benefits, which can inform the restoration efforts of land managers and wetland practitioners. These wetland practitioners may be employed by state and local government, NRCS, environmental consulting firms, and non-profit agencies that invest in wetland restoration, such as Ducks Unlimited and The Nature Conservancy. NRCS engineers and other wetland practitioners are the primary interface between county agencies, farmers, and non-profits who might be proponents of wetland adoption. A secondary learning outcome is to increase the knowledge and awareness of K-12 students of the role of wetlands in sustainable agriculture. 

If the learning outcomes are effectively met, we anticipate the following actions: wetland practitioners will incorporate this guidance into future wetland designs to make planned wetlands more sustainable, farmers will adapt management of existing wetlands (e.g. planting or removing certain plant species) based on management guidance to make wetlands more sustainable, and more K-12 students will consider pursuing careers in sustainable agriculture and environmental science. Although these action outcomes are anticipated, tracking these changes in behavior is beyond the proposed scope of the project.