Saturated buffers: Proven practice with new surprises
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EmailSaturated buffers have long been promoted as a way to reduce nitrate loss from tile-drained farmland, but just how effective are they?
A saturated buffer is a conservation drainage practice that targets nitrate in tile drainage discharge. A new Michigan State University study used a paired-field approach to compare a saturated buffer to a free drainage control field. This method allowed researchers to isolate the effects of subsurface buffer flow and controlled drainage, something previous studies couldn’t do.
The findings revealed more than just nitrate reduction. They offered new insights and a few surprises about how the system works.
How does a saturated buffer system work?
It combines three processes (see Figure 1 in “Unveiling the True Potential of Saturated Buffers”):
- Controlled drainage – manages how much water leaves the field.
- Subsurface buffer flow – treats the water as it moves through the soil.
- Buffer strip – helps treat surface runoff.
Key findings from the new research include:
- How much we’ve underestimated saturated buffer performance in the past.
- Controlled drainage plays a dominant role in nitrate removal.
- The importance of weir management and how a 1-foot adjustment can double nitrate removal.
- Details of a design that can cause backflow and how to prevent it.
Read more in “Unveiling the True Potential of Saturated Buffers,” a new bulletin from Michigan State University Extension.
