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Ecosystem services in Iowa agricultural catchments: Hypotheses for scenarios with water quality wetlands and improved tile drainage
Citation:
Mitchell, M., Shawn Dayson Shifflett, T. Newcomer-Johnson, A. Hodaj, W. Crumpton, J. Christensen, B. Dyson, Timothy J. Canfield, S. Richmond, M. Helmers, D. Lemke, M. Lechtenberg, Chris Taylor, AND Kenneth J. Forshay. Ecosystem services in Iowa agricultural catchments: Hypotheses for scenarios with water quality wetlands and improved tile drainage. JOURNAL OF SOIL AND WATER CONSERVATION. Soil and Water Conservation Society, 77(4):426-440, (2022). https://doi.org/10.2489/jswc.2022.00127
Impact/Purpose:
Iowa is responsible for a large portion of crops grown in the U.S., but the state is also responsible for contributing nutrients to the Gulf Coast. Nutrients entering the Gulf Coast can contribute to low oxygen conditions in the water column that can harm aquatic organisms. A group of Iowa stakeholders representing agricultural producers, land managers, and researchers met seven times in late 2018 and early 2019 and was asked to describe research needs that could support management practices and decisions that will improve water quality leaving the state while providing other benefits. The stakeholder group identified the importance and relevance of a small watershed analysis of a collection of environmental benefits associated with wetlands installed to intercept and treat water leaving the agricultural watershed, in combination with improvements in the agricultural drainage system. In this article we discuss the stakeholder engagement process, report our findings from a literature review of water quality wetlands and agricultural drainage improvements, report our hypotheses for scenarios where water quality wetlands are combined with agriculture drainage system improvements, and identify areas that require more research. This manuscript will be of interest to land managers and landowners looking to optimize crop production, reduce nutrient pollution, minimize greenhouse gas emissions, and provide habitat and recreational opportunities. Additionally, the manuscript highlights a collaboration between EPA’s ORD and Office of Water, EPA Region 7, the Iowa Department of Agriculture, Iowa Farm Bureau, Agribusiness Association of Iowa, Iowa State University, Iowa Department of Agriculture and Land Stewardship, and the Iowa Department of Natural Resources.
Description:
Nutrient loads from agricultural runoff in the upper Midwest continue to contribute to Gulf Coast hypoxia and harmful algal blooms due to insufficient retention of nitrogen and phosphorous associated with row crop agriculture and highly productive soils. In the coming decades, much of the drainage infrastructure in this region will be rebuilt to modern design standards. At the same time, the region is developing and implementing strategies to reduce nutrient export. A group of Iowa stakeholders representing agricultural producers, land managers, and researchers met seven times in late 2018 and early 2019 and was asked to describe ecosystem service information needs that could support nutrient best management practice decisions in Iowa. The stakeholder group identified the importance and relevance of a catchment-scale (i.e., small watershed) analysis of a set of priority ecosystem services associated with targeted water quality wetlands (wetlands installed strategically to intercept agricultural drainage channels to receive runoff and tile drainage) and agricultural tile drainage improvements. These potential modifications were codified into four scenarios for literature analysis and hypothesis development including: (1) a baseline, no change scenario representing the most prevalent current landscape with underperforming tile drainage infrastructure and degraded wetland functions; (2) upgrade of tile drainage infrastructure without a water quality wetland; (3) installation of a water quality wetland at the drainage district catchment scale but with no drainage improvements; and (4) a combination of adding a water quality wetland and tile drainage infrastructure upgrades at the catchment scale. Synthesizing published field-scale and modeling results across a collection of relevant studies suggests that the combined scenario of improved drainage paired with a water quality wetland may result in increased crop yields, habitat, pollination, and educational and cultural services as well as decreased global warming potential relative to the baseline scenario. Nitrate export will likely decrease in the combined scenario, depending on net agricultural export and wetland effectiveness. To better substantiate these findings, more catchment-scale research in the region is required, particularly in the areas of water quality, wetland carbon sequestration, wetland habitat quality, and educational and cultural services. Additionally, research is needed to address the effect of upgrading drainage infrastructure on ecosystem services, as most reported ecosystem service effects have been for new drainage installations. Fully integrated assessments, particularly at the catchment scale, will be key to understanding how land management approaches like adding water quality wetlands and improved drainage affect both agricultural production and ecosystem services.
URLs/Downloads:
DOI: Ecosystem services in Iowa agricultural catchments: Hypotheses for scenarios with water quality wetlands and improved tile drainage