In Iowa’s corn-and-soybean country, a small patch of prairie can do more than add a remnant of the landscape that came before the plow. Research at Neal Smith National Wildlife Refuge found that strips of native perennial plants woven into farm fields can help hold soil in place, limit nutrient runoff and provide habitat within a working agricultural landscape.
The approach is straightforward: instead of planting every acre in annual crops, farmers leave some land in native grasses and flowering plants. These prairie strips can be placed along field edges or across slopes, where they intercept water moving downhill. The plants’ dense roots and year-round cover help slow runoff and keep soil from washing away.
Testing prairie inside a farm landscape
Researchers with Iowa State University’s Science-based Trials of Rowcrops Integrated with Prairie Strips project, known as STRIPS, tested the idea in experimental watersheds at Neal Smith National Wildlife Refuge. The watersheds were planted in corn and soybeans, with some also containing prairie strips. That setup let researchers compare how the different land arrangements affected water and wildlife.
A 2017 study in the Proceedings of the National Academy of Sciences reported that watersheds with prairie covering about 10 percent of their area had substantially lower losses of sediment and nutrients than watersheds planted entirely in row crops. In the most effective prairie-strip configuration studied, sediment export fell by 95 percent, total phosphorus by 90 percent and total nitrogen by 84 percent.
Those figures describe the study’s experimental watersheds, not a guaranteed result for every farm. Outcomes depend on factors such as field shape, soil, rainfall and where strips are placed. Still, the results show how a relatively small area of perennial vegetation can influence what leaves a field in runoff.
More than a water-quality measure
Prairie strips also change the kinds of habitat available within crop fields. The native vegetation supports flowering plants and shelter that can benefit pollinators and birds. Researchers reported improvements in measures of biodiversity alongside the reductions in sediment and nutrient loss.
That combination matters because farm landscapes are asked to do several things at once: produce food, protect soil and water, and leave room for other species. Prairie strips do not replace large, connected natural areas, and they are not a complete solution to agricultural runoff. They offer a way to add habitat and ecological functions within fields that remain in production.
The design also makes the idea practical to investigate and adapt. A farmer need not convert an entire field to prairie. Strips can occupy a limited portion of a watershed and be positioned where they are most likely to slow water or protect vulnerable ground. The research gives farmers and conservation planners evidence to weigh alongside costs, farm operations and local conditions.
A small footprint with a landscape-scale question
Iowa’s native prairie was once a defining ecosystem, but most of it was converted to agriculture. Rebuilding prairie in narrow bands cannot recreate that original landscape. It can, however, reconnect native plants to places where crops dominate and help demonstrate that conservation and production need not always be treated as opposites.
The STRIPS research continues to inform efforts to use prairie vegetation as part of farm conservation. Its central lesson is modest but useful: where the plants are placed can matter as much as how much land they occupy. A few carefully located bands of prairie can contribute to cleaner water and richer habitat, while the surrounding fields keep growing crops.
