A review of ecosystem services from edge-of-field practices in tile-drained agricultural systems in the United States Corn Belt Region

Abstract

Edge-of-field management practices that reduce nutrient pollution from tile drainage while contributing habitat and other ecosystem services are needed to enhance agricultural systems in the US Corn Belt Region. In this review, we identified edge-of-field and catchment scale agricultural conservation practices for intercepting and treating tile drainage. The reviewed conservation practices were (1) controlled drainage, also known as drainage water management (USDA-NRCS Code 554); (2) drainage water recycling (USDA-NRCS Code 447); (3) denitrifying bioreactors (USDA-NRCS Code 605); (4) saturated buffers (USDA-NRCS Code 604); and (5) constructed or restored wetlands designed for water quality improvement (USDA-NRCS Code 656) herein referred to as water quality wetlands. We examined 119 studies that had information on one or more of the following ecosystem services: water retention, water quality improvement (e.g., nitrate, phosphate, sediment, or pesticide retention), wetland habitat (for birds, aquatic organisms, and pollinators), crop yield improvement, and other benefits (e.g., recreation, education, aesthetic appreciation, greenhouse gas retention). We found the five edge-of-field practices were all effective at 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 provide surface water systems for capturing surface flows in addition to tile drainage while also potentially providing habitat and recreation opportunities. However, the following research needs are identified: 1) the disservices and benefits associated with drainage water recycling have not been adequately evaluated; 2) surface flow dynamics are understudied across all reviewed management practices; 3) a complete accounting of phosphorus species and flow pathways for all management practices is needed; 4) field evaluations of the habitat benefit of all management practices are needed; and 5) greenhouse gas dynamics are understudied across all management practices. While all management practices are expected to reduce nitrate loads, addressing these knowledge gaps will help inform holistic management decisions for diverse stakeholders across the US Corn Belt.

Keywords: Agricultural conservation practice; Corn belt; Greenhouse gases; Habitat; Nitrogen; Phosphorus.

Fig. 1.

Controlled drainage design showing two water control structures used to raise the depth of the drainage outlet. Grey-blue color corresponds to groundwater. Numbers correspond to the following: (1) Tile drain outflow; (2) Surface runoff; (3) Flow moving downstream. Image adapted from trans formingdrainage.org.

Fig. 2.

Potential conservation practice benefits based on literature review for several benefit categories. Each radial section corresponds to an approximate 20% improvement, with a maximum improvement shown of 40%. Sections marked with an asterisk (*) indicate uncertainty due to lack of study and or high dependency on practice management or local conditions. ¹Other Benefits and Wetland Habitat sections are qualitative comparisons while all other metrics are quantitative and represent the mean of evaluated studies. Other Benefits were sediment retention, recreation, education, aesthetic appreciation, pesticide retention, and greenhouse gas retention; these other benefits were not explicitly included as sectors of the wheel diagram because of limited information available about these ecosystem services. CD= Controlled drainage; WQW= Water quality wetland; DB = Denitrifying bioreactor; DWR = Drainage water recycling; SB= Saturated buffer.

Fig. 3.

Water quality wetland layout. Grey-blue color corresponds to groundwater. Numbers correspond to the following: (1) Tile drain outflow; (2) Surface runoff; (3) Flow moving downstream.

Fig. 4.

Denitrifying bioreactor layout showing the use of water control structures to divert a portion of tile-drainage into a woodchip bioreactor. Large arrow indicates direction of subsurface flow through the woodchip bioreactor. Grey-blue color corresponds to groundwater. Numbers correspond to the following: (1) Tile drain outflow; (2) Bypass flow when bioreactor is full; (3) Flow moving downstream.

Fig. 5.

Drainage water recycling layout. Grey-blue color corresponds to groundwater. Numbers correspond to the following: (1) Tile drain outflow; (2) Potential surface runoff; (3) Drainage water reuse for irrigation. Image adapted from transformingdrainage.org.

Fig. 6.

Saturated buffer layout. Grey-blue color corresponds to groundwater. Numbers correspond to the following: (1) Tile drain outflow; (2) Drainage water flow through saturated buffer; (3) Flow moving downstream. Image adapted from transformingdrainage.org.