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Corn+Soybean Digest

New field strips save nutrients

Diverse prairie grass species strategically located within row crops deliver conservation benefits far beyond the 10 to 20 of a field they occupy according to seven years of research
<p>Diverse prairie grass species strategically located within row crops deliver conservation benefits far beyond the 10% to 20% of a field they occupy, according to seven years of research.</p>
Conservation prairie strips improve surface runoff water quality, but not tile drainage.

When it comes to conservation, small prairie strips make a big difference in surface runoff. And not just any strips: ones designed, contoured and placed according to scientific criteria developed over seven years by Iowa State University (ISU) researchers. Science-based trials of row crops integrated with prairie strips (STRIPS) are 15- to 30-foot-wide strips placed strategically among row crops to anchor sediment and nutrients.

The concept unites conservation and row-crop productivity in the same space. “Strategically locating a little bit of prairie in the right spots harnesses most of the benefits you would get [from] large prairie patches,” says ISU STRIPS Investigator Lisa Schulte Moore (

Conservation benefits from STRIPS are impressive and greatly disproportionate to the 10% of space they occupy in row-crop fields. The following results come from seven years’ results at the Neal Smith National Wildlife Refuge, Prairie City, Iowa:

  • 95% surface sediment retention
  • 90% surface phosphorous (P) retention
  • 84% surface nitrogen (N) retention

The site is not tile drained and has 6% to 10% slopes. If a site had tile drainage, “we would not expect the N-retention numbers to be as high because tile shunts some water beneath prairie strips, with no chance to interact,” says Schulte Moore. “The P- and sediment-retentions numbers would remain high.”


Not waterways or buffer strips

Don’t confuse these prairie strips with traditional buffer or filter strips, which often consist of cool-season grasses. A strip-species mix is more diverse and deeply rooted than buffer strips or grass waterways planted with bromegrass, “a shallow-rooted monoculture,” says Tim Youngquist, STRIPS farmer liaison. He collaborates with farmers to tailor the concept to individual goals and circumstances. The stiff, upright plant stems in prairie strips impede flowing water, sediment and nutrients.

Conservation waterways are often designed to convey water down a slope while anchoring soil. By contrast, prairie strips lie strategically along field contours, perpendicular to slopes, much as terraces are laid out, he adds. “They don’t require earth-moving equipment to install, like terraces.”

There is no one-size-suits-all strip size, number or placement. “Each field is unique; each farmer’s entrepreneurial spirit is different,” Youngquist adds. “We consider equipment width and ‘farmability’ to avoid dramatically changing a field’s existing farming pattern.”


Spraying and mowing

Farmers plant and spray around prairie strips. Because strips are oriented on the contour, they can be similar to farming with grass waterways, says Schulte Moore.

“It’s not significantly different than planting and spraying around fence lines, terraces, or other field buffers,” Youngquist adds.

Gary Van Ryswyk, Mitchellville, Iowa, farms prairie strips at home and on the ISU test plots. Spraying or planting around the strips has not been a problem for him, “because they’re positioned for clear access to every acre I farm,” he says.

The layout of the strips is key. “We implement them to take advantage of existing traffic lanes and grass waterways to be sure farmers have easy strips access,” says Schulte Moore.

Strips need to be mowed the first three years to allow sunlight to penetrate the canopy, which boosts boost young plant establishment and allows the prairie grass species to dominate in the strip. However, “It’s important to note that the strips deliver conservation benefit in their very first year, although they can take up to three years to reach peak conservation effectiveness,” says Schulte Moore.

Per the directive of the STRIPS’ team, Van Ryswyk bales the prairie grass strips after harvest during strips establishment. Others have also used a prescribed burn, which mimics nature’s weed control plan.

After those first three years, no mowing is involved. “Prairie strips aren’t a weed problem for farmers,” says Schulte Moore.


The cost to integrate prairie strips into row crops ranges from $24 to $35 per acre, and a Conservation Resource Program (CRP) contract can possibly offset farmers’ costs, Schulte Moore says.

Iowans surveyed recently were willing to pay for improved conservation efforts such as STRIPs. Read more about the survey.

Ask your Farm Service Agency (FSA) service center for details on how STRIPS may be eligible for funding under CRP or the Environmental Quality Incentives Program.

Not your average conservation strips

Science-based trials of row crops integrated with prairie strips (STRIPS) only occupy 10% of a field, yet provide disproportionately large conservation benefits, trials show:

  • Prairie strips’ stiff-stemmed native prairie plants effectively slow water and sediment flow better than cool-season forage grasses like smooth brome, which can lie flat under pounding rains. (Brome is often used for buffer strips or grass waterways.)
  • The diverse prairie species found in prairie strips provide excellent habitat for pollinators, beneficial insects, game birds and wildlife.

Prairie strips are now located on 100 acres total on 17 farms in Iowa and northern Missouri.   

For more details and farmers’ firsthand observations on farming with STRIPS, see this new video:

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