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New saturated buffer publication available

Article cover photo
Saturated buffers are hidden underground except for a tile drainage control structure. Tim Recker adjusts the stoplogs at the junction of the field tile and the tile within the streambank buffer. (Photo: Joseph L. Murphy/Iowa Soybean Association)

By Carol Brown, ISA environmental communications specialist

The term “saturated buffer” is becoming a buzzword in Iowa’s agriculture arena. Although the concept is simple, it has not been widely adopted — yet.

Streambank buffers — the areas of perennial vegetation in between farm fields and streams — are now being used to reduce nitrates in subsurface tile drains. A saturated buffer consists of a perforated tile installed within the buffer, parallel to the streambank.  A control structure intercepts tile drainage from the field and diverts it into the buffer. The nitrates in the water are removed by denitrification or taken up by the vegetation in the buffer before it enters the stream or other surface water.

“Saturated buffers are an innovative, cost-effective practice for addressing nitrate in drainage water,” said Chris Hay, Iowa Soybean Association (ISA) senior environmental scientist. “If they are sited well, they require very little active management beyond maintaining the buffer itself.”

Hay is one of the authors of a new publication “Questions and answers about saturated buffers for the Midwest” published by the Transforming Drainage project.  The eight-page booklet provides an overview of this edge-of-field conservation practice, providing examples and offering key points to consider, including location siting and projected costs. The expert-reviewed booklet can be downloaded for free through the ISU Extension Store.

Saturated buffers are included in the Iowa Nutrient Reduction Strategy as one of several practices farmers and landowners can use to reduce nitrates entering Iowa waterbodies. The strategy lists recommendations that contribute to the goal of 45 percent load reductions of nitrogen and phosphorus to Iowa waters and downstream.  In the strategy, saturated buffers are estimated to reduce nitrates in subsurface drainage water by an average of 50 percent. Researchers have seen some saturated buffers remove nitrates by as much as 90 percent. The longer the saturated buffer is, the more water it can infiltrate, increasing nitrate removal amounts.

Farmers residing in watersheds involved with Iowa Water Quality Initiative (WQI) projects, can receive financial assistance to install a saturated buffer. They can also obtain assistance through the Environmental Quality Incentives Program (EQIP), but it varies by county. Check with your local Natural Resources Conservation Service (NRCS) office for details on funding and location siting.

The Transforming Drainage project is based at Purdue University and includes several Midwest land grant universities, the United States Department of Agriculture (USDA) and ISA. The project’s website: has more detailed information for drainage management including saturated buffers, controlled drainage and drainage water recycling.

Carol Brown can be reached at

For media inquiries, please contact Katie Johnson, ISA Public Relations Manager at or Aaron Putze, ISA Communications Director at

For permission to republish articles or to request high-res photos contact Aaron Putze at Iowa Soybean Association | 1255 SW Prairie Trail Pkwy | Ankeny | IA | 50023 | US

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