Using Prairie Filter Strips to Protect Wisconsin Water

WASHINGTON COUNTY, Wis. – Prairies of the past could be a modern conservation tool for Wisconsin farmers. 

Native prairie plants can act as a sponge and slow soil runoff from rain. Research from Iowa State University shows planting dense, diverse and deep-rooted prairie strips next to corn and soybean fields has environmental benefits.  

Sand County Foundation is working with six farmers to demonstrate how prairie strips work on Wisconsin farms of varying soil types, typographies and management styles. 

Filtrating rain, soil sediment and nutrients across a narrow strip of prairie keeps soil on the field and out of waterways. Or as farmer Ross Bishop puts it, “The goal is to stop chocolate milk from leaving the farm.” 

For Bishop, one of two project participants from Washington County, ‘chocolate milk’ is rainwater that washes off his rolling fields located just a half hour’s drive from downtown Milwaukee. The Milwaukee Metropolitan Sewerage District is supportive of preventing sediment and phosphorus in farm runoff from reaching the Milwaukee River and Lake Michigan, in lieu of water treatment plant updates.  

Bishop belongs to a voluntary group of farmers working to improve soil health and water quality in the Cedar Creek watershed. Several similar farmer-led groups have formed in Wisconsin with state funding to prevent and reduce runoff from fields. 

As a long-time advocate of no-till farming practices, Bishop does not plow farmland in order to reduce erosion and improve soil health. He’s also an advocate of technology that precisely determines which portions of a field are prone to erosion and the least productive. 

In some cases, the sites best suited to filter runoff are also the least profitable for growing crops. It’s that trade off that Sand County Foundation hopes will convince other farmers to plant prairie filter strips.   

“The prairie strip concept is designed to integrate the prairie into the farm system in a manner that meets the farm’s operational and environmental goals,” said Greg Olson, Sand County Foundation’s Field Projects Director. 

Iowa State University’s research shows phosphorus and sediment loss can be reduced by 90 percent when just 10 percent of unproductive cropland is converted to stiff-stemmed, deep-rooted grasses and forbs.

In addition to improving water quality, prairie filter strips can work double duty by providing food and habitat for insect pollinators, monarch caterpillars, and other wildlife. This dual benefit is why the Southeast Wisconsin Chapter of Pheasants Forever has provided assistance for prairie plantings at the Washington County farms of Bishop, and Dan Stoffel. 

With technical assistance from Sand County Foundation staff, Stoffel has planted four prairie strips. At 25 feet in width the strips were designed with modern farm machinery in mind. 

“Our goal is to fit this perennial conservation practice conveniently within annual row crop operations,” said Craig Ficenec, Sand County Foundation Program Director. 

“It’ll be interesting to see how it turns out,” said Stoffel, who began his career as a biochemist before farming with his brothers Lee and Tim. 

Stoffel located his prairie strips on a hillside in the Town of Kewaskum, separating a hilltop hay field from soybeans below. He learned there’s an art to mixing prairie seeds. Some contain more pollinator-friendly varieties, and all must reflect the region’s hardiness zone. Adding oats provides fast ground cover to compete against weeds. 

Prairies take time to get established, but over time the native plants crowd out weeds and reseed themselves. It requires mowing in the first couple of years to control weeds, and an occasional controlled burn thereafter. Stoffel said mowing the strips doesn’t take long. His biggest initial concern was the threat of attracting invasive weeds. However, he’s found it easy to walk through the strips and pull any offending weeds by hand. 

Stoffel’s ancestors began farming in Wisconsin in the 1880s. He credits his father with being an agricultural innovator, as an early adopter of no-till practices and having one of Wisconsin’s first dairy milking parlors. With prairie strips, he may find himself on the cusp of a conservation breakthrough. 

Sand County Foundation’s prairie filter strip project is supported by the North Central Region Sustainable Agriculture Research & Education (SARE) program, University of Wisconsin’s Center for Integrated Agricultural Systems, and Valley Stewardship Network. For more, visit: https://sandcountyfoundation.o...

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Sand County Foundation is the nation’s leading voice for private conservation. Based in Madison, the non-profit organization is dedicated to working with private landowners to advance the use of ethical and scientifically sound land management practices that benefit the environment. www.sandcountyfoundation.org