Saturated buffers: Improvements and issues

Area of Science:

• Agricultural best management practices
• Water quality improvement
• Nutrient management

Background:

• Saturated buffers are a new practice to reduce nutrient runoff from agricultural tile drainage.
• Eutrophication from nutrient losses remains a significant environmental concern.

Purpose of the Study:

• To evaluate a novel saturated buffer design with pitchfork-shaped (PF) dispersion lines and a backflow check valve.
• To compare the performance of the novel PF buffer against a standard (ST) saturated buffer.

Main Methods:

• Installation of PF and ST saturated buffers in Moultrie County, Illinois.
• Daily monitoring of water flow and collection of water samples to estimate nutrient loads.
• Analysis of diversion rates and backflow occurrences over two observation periods.

Main Results:

• The PF buffer diverted 35% and 1.9% of tile flow in 2020 and 2021, respectively.
• The ST buffer increased effluent rates by 116% and 137% in 2020 and 2021.
• Both buffer types experienced significant backflow (30-47%) exceeding typical levels.

Conclusions:

• Saturated buffer efficacy can be improved with low-cost design additions.
• Check valves enhance flow diversion and nutrient removal potential.
• Dispersion lines increase diversion but require land and may increase backflow; cost-benefit analysis is needed.