COS 216-6 - Ecosystem services and disservices from edge-of-field solutions to agricultural tile drainage pollution

Abstract: Edge-of-field management practices designed to reduce nutrient pollution in waterways may support or alter critical habitat and ecosystem services in and around agricultural systems. Information on both target and non-target effects is needed to support management decisions as large-scale pollution reduction strategies are implemented. We identified and reviewed the ecosystem services and disservices provided by several edge-of-field best management practices (BMPs) designed to intercept and treat tile drainage nutrients and engaged with US Corn Belt stakeholders involved with agriculture and nutrient reduction strategies to identify barriers and research needs associated with implementation of these BMPs. The BMPs identified in this analysis were (1) controlled drainage, also known as water table management; (2) drainage water recycling; (3) denitrifying bioreactors; (4) saturated buffers; and (5) constructed or restored wetlands designed for water quality improvement, herein referred to as water-quality wetlands. We examined 119 studies and found the five BMPs were all effective for removing nitrate with varying degrees of other potential benefits and disservices (e.g., greenhouse gas production). Drainage water recycling and water quality wetlands have the potential to provide the most co-benefits as they can intercept both surface and drainage flows while also potentially providing habitat and recreation opportunities. However: the disservices and benefits associated with the various BMPs have not been adequately evaluated; surface flow dynamics are understudied across all reviewed management practices; a complete accounting of phosphorus species and flow pathways for all management practices is needed; field evaluations of the habitat benefit of all management practices is needed; and greenhouse gas dynamics are understudied across all management practices. While all management practices we reviewed are expected to reduce nitrate loads, addressing these knowledge gaps regarding non-target effects and co-benefits will help better inform management decisions for diverse stakeholders across the US Corn Belt as large-scale nutrient reduction strategies are implemented.