The Promise Of Prairie Strips

A new program from Iowa State has the potential to significantly reduce runoff, while improving water quality, wildlife habitat and a farmer’s bottom line.

By Linda Askey

Pressured by downstream property owners and their own desire to conserve their soil and keep their water drinkable, many farmers are looking for conservation programs that are both affordable and effective. One such potential solution, under development for about eight years now, is generating considerable buzz.

The program, called STRIPS—an acronym for Science-based Trials of Rowcrops Integrated with Prairie Strips—is being developed at Iowa State University and involves sowing native prairie plants on carefully selected parcels of farmland. These “strips” of grasses, forbs (non-grass flowering plants) and other plants have been proved to slow, even stop, runoff of soil, as well as phosphorus and nitrogen.

Tim Youngquist, a fifth-generation Iowa farmer and farmer liaison on the STRIPS team, says, “Not a single farmer wants to see the soil wash away, or to see nitrogen and phosphorus in the rivers. No one wants that.”

Yet, he sees considerable room for improvement on many farms. For instance, Youngquist points to STRIPS studies performed via Iowa State University: “We have used big hydrologic flumes to catch the water coming off of a watershed, and it’s just a staggering amount of soil lost. When you see this big white fiberglass box out in the field where we’ve just had a 4-inch rain, and there’s topsoil nearly a foot deep in it—mucky, beautiful, best soil in the world. It’s absolutely washing away.”

Says Iowa State University Associate Professor Dr. Lisa Schulte Moore, one of the STRIPS team leaders, “The big picture is that we are trying to get the most conservation bang for the buck on private lands, recognizing right now that corn and soybeans pay the bills for farmers in the Corn Belt. We are trying to figure out, how do we meet our water quality goals, and how do we maintain our soil?

“How do we do a better job of maintaining our wildlife,” Schulte Moore continues, “including our insects, like monarch butterflies and our pollinators— bees and such—while being attentive to how much land is taken out of crops, which lands we are taking out of crops and what we are transitioning it to?”

Data from STRIPS plots first established in 2007 has provided a sort of ground floor for the initial phase of the study. Results were unprecedented and definitive. Between 2007 and 2012, strategically placed prairie strips covering 10% of a field were able to reduce soil sediment runoff by 95%, phosphorus by 90% and total nitrogen by 84%, when runoff was compared to that from a field of no-till row crops with no remediation. Even in the first season after planting, prairie strips have proved to be effective, although maximum benefit comes with maturity, usually in the third season.

To get that maximum benefit, the STRIPS team has shown 10% of acreage should be planted in prairie strips, which are placed at the foot slope of a field, along waterways, in areas that are wet in spring and in areas that are potentially less productive. Also, prairie strips should be placed mid-field along a contour to slow water runoff as a terrace would, yet without the expense of earthwork.

Tim Smith

Tim Smith

Youngquist explains, “The stiff upright stems [of prairie plants] take so much energy out of the water as it is flowing down the hill, as it boomerangs around between the strips. Some of the sediment drops out in the in-field strips, and by the time it is to the edge of the field, hopefully it is walking and not running. It isn’t going to be cutting the deep trenches.”

Tim Smith, who grows corn and soybeans on his 800-acre family farm, is a newcomer to STRIPS. Yet, in an effort to minimize runoff of nutrients and soil, he has worked for several years with traditional grass filter strips, cover crops and strip tillage. He even gave presentations on what he was doing to other farmers, where in a few instances he shared the podium with a farmer who had implemented STRIPS.

What Smith heard made sense. STRIPS offered the potential to be even more effective than other techniques he’s been using, in part because the program calls for a multi-species planting of deep-rooted—and therefore more effective—native grasses and forbs, which can replace contour buffer strips, riparian buffers and filter strips that are planted in monocultures of grasses such as brome, fescue or rye. So this season, Smith will begin testing the concept on his farm, planting 30 species of prairie plants seeded on 14 acres of areas previously cropped, as well as areas that were formerly monoculture filter strips.

Addressing the cost of a prairie strips program, Schulte Moore says, “If you look at it over 15 years, it is comparable or cheaper than cover crops, and it’s a lot cheaper than terraces. And with terraces you are really only treating the soil erosion and phosphorous piece. You are not addressing the nitrogen piece at all [because it does not bind to soil], and you’re not providing the same wildlife benefits.” With STRIPS, she says, “you get multiple benefits with one practice.”

Indeed, some farmers are hoping to offset the cost of establishment and the loss of cropland by using their prairie strips in other ways. For instance, prairie strips create potential habitat, which brings wildlife. Wildlife, in turn, brings hunters, and hunters bring revenue. Others have mowed the strips for animal bedding, and there’s the possibility of using the biomass as fuel.

Youngquist observes, “The prairie strips are still so new. Maybe some of these things are worth money, but the value chain hasn’t been forged yet. So it is going to be up to the entrepreneurial savvy of some of these farmers who are adopting it now to do their own thing and see how they can profit from them.”

Looking ahead, Schulte Moore says, “We are collaborating with an agricultural decision company called AgSolver. They are providing software to help farmers improve their subfield scale decision-making. They are looking at not only yield and nutrient information, but they are running financial models on top of all this…. If you look at it on the scale of all of Iowa, the initial analysis suggests that there is 10% of Iowa that is in row crop production that hasn’t been profitable even between 2010 and 2013.

“So,” she continues, “let’s farm the best and leave the rest. Wouldn’t it be cool if we put a lot of prairie on the rest?”

“Prairie strips are not a silver bullet; they are not for everybody,” adds Youngquist. “Talking to farmers about taking areas out of production is not always the most comfortable conversation to have. Some people just would not be interested. But if you can couple prairie strips with some contour farming and some cover crops, or just some other practice, it becomes one more tool that farmers can add to their toolbox to help be better stewards of the land.”