Stripping Conservation to its Bare Essentials


Prairie Grass in Winter
Planting just 10 to 20 percent of a crop field with patches of prairie can reduce erosion by 95 percent and runoff by 90 percent.

Gary Van Ryswyk's concern for how his farming methods impact the landscape is obvious. A practitioner of a no-till system that avoids disturbing a field's surface as much as possible, he is particularly focused on keeping soil in place.

"None of us who farm want the soil to move—we care," Van Ryswyk told me one summer afternoon while standing in a central Iowa soybean field he no-tills. "I was one of these guys who didn't think we were losing that much soil. I was shocked at how much was being lost."

He was referring to a waist-high pile of eroded real estate next to a collection flume at the bottom of the field. It was a reminder that even a cutting edge conservation system can't always prevent land from slipping away.

On the other hand, the researchers Van Ryswyk works with have been somewhat surprised at the lack of eroded soil being collected by a flume just a few hundred feet away. The soybeans above that particular collector are also being grown under no-till and the field slope is the same. But growing in strategic spots on the second field plot are patches of native prairie.

Van Ryswk is raising crops on the Neal Smith National Wildlife Refuge and the prairie plantings are part of a study coordinated by Iowa State University's Leopold Center for Sustainable Agriculture. Called STRIPs (Science-based Trials of Rowcrops Integrated with Prairie), the study has produced impressive results: planting just 10 to 20 percent of a crop field to native prairie “strips” (some of the plantings look more like ragged slices of pie) consistently cuts erosion by an astounding 95 percent. The plantings, which have been in place since 2007, can reduce phosphorus and nitrogen runoff by as much as 90 percent.

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