Saturated buffers: Improvements and issues

• Published in: Journal of environmental quality Vol. 53; no. 2; pp. 232 - 240
• Main Authors: Eldridge, Emma E., Schoonover, Jon E., Williard, Karl W. J., Sadeghpour, Amir, Gillespie, Jackie C.
• Format: Journal Article
• Language: English
• Published: United States 01.03.2024
• ISSN: 0047-2425; 1537-2537
• DOI: 10.1002/jeq2.20548

Saturated buffers are a newly developed agricultural best management practice used to redirect tile flow away from waterways, thereby mitigating nutrient losses and downstream eutrophication. This study evaluated the potential benefits of a novel saturated buffer design, which included pitchfork‐shaped (PF) dispersion lines and a backflow check valve, that was installed alongside a traditional or standard (ST) buffer on a field in Moultrie County, Illinois, in the spring of 2019. Daily flow measurements and routine water samples were used to monitor the movement of water through both buffers and estimate nutrient loads. During observation days in 2020 and 2021, the PF buffer diverted 35% and 1.9% of incoming tile flow, respectively, while the ST buffer increased effluent rates by 116% and 137% over the same period. Both the PF and ST buffers experienced backflow from 30% to 47% of the monitoring period, well above the often reported 5%. Ultimately, the efficacy of saturated buffers could be improved with minimal, low‐cost additions to their designs. Check valves are a simple supplement to saturated buffer design that can enhance flow diversion and potential nutrient removal. Added dispersion lines provide more opportunity for diversion of tile flow; however, they require more land to be removed from agricultural production and could increase backflow volumes, so the costs and benefits should be weighed. Core Ideas Saturated buffers can increase total discharge and nutrient loads to a waterway as a result of backflow. Additional distribution lines increased dispersion, but they also carried the risk of greater backflow volumes. A one‐way check valve prevented backflow within the pitchfork buffer. The standard buffer design contributed excess effluent via backflow in 2021 and 2022. The pitchfork buffer design decreased effluent discharge in 2020 and 2021. Plain Language Summary Saturated buffers (SBs) can prevent harmful impacts of nutrient losses from artificially drained fields. A typical SB uses one distribution line to divert water into a buffer zone. This study compares a standard SB to a new design, with three distribution lines and a check valve to prevent backflow, installed side‐by‐side on the same field. We found that SBs have potential to increase the water and nutrients that are drained from a field, but the backflow check valve can prevent excess water loss. Furthermore, the added distribution lines diverted more water into the buffer. These findings are important so farmers can maintain crop production while minimizing damages to water resources.