Pointing to 3 years of studies, researchers don't believe establishing perennial prairies adjacent to cropland would increase weed pressure. (Leopold Center photo)
Perennial prairie strips can help improve ecosystem health on Midwest farms without compromising the benefits of agriculture, according to a multi-year project led by researchers at Iowa State University.
The project began in 2007 with funding from the Leopold Center for Sustainable Agriculture’s Ecology Initiative.
Historically, prairies dominated Iowa’s landscape, creating the rich soils needed for productive agriculture. Now less than 0.1 percent of Iowa’s prairies remain.
The Leopold Center believes that by restoring deep-reaching perennial roots to row-cropped fields, farmers and landowners can reduce erosion and nutrient loss, keep waterways free of agricultural runoff and improve biodiversity.
“We can strategically place perennial vegetation to provide disproportionate conservation benefits,” says Matt Liebman, team member and agronomy professor at Iowa State University. “A small change gives a large effect.”
In July 2007 researchers established a variety of treatments on 14 watersheds at the Neal Smith National Wildlife Refuge. Treatments ranged from conventional agriculture to reconstructed prairie to mixed systems with strategically placed perennial strips covering 10 or 20 percent of the watershed. Flumes at the toe of each watershed collect runoff for sampling.
Recent wet years gave researchers opportunities to see prairie strips at work during high-rainfall events. They found the long, upright stems of prairie plantings helped resist water movement and trap sediment.
In watersheds with 10-20 percent prairie strips in no-till cropland, sediment loss was reduced by more than 90 percent. Nitrate and phosphorus movement also decreased.
They also noticed an enormous increase in plant, bird and insect species in each experimental watershed. In 2010, watersheds with prairie buffers contained an average of 61 plant species, compared to just 19 in cropland.
The researchers feel increased biodiversity provides useful services to farmers as native birds and insects help control pests, pollinators visit both prairie and crop flowers.
"Current crop prices dissuade many farmers from taking land out of production," the researchers say, and stakeholders agreed that financial incentives and technical support are required. One possibility is that farmers can use modern agricultural technologies for “precision conservation,” identifying less productive areas of their farms to target for prairie strips.
Stakeholders also noted the need for one-on-one interactions with farmers, perhaps in the form of demonstration projects around the Midwest. For example, research and demonstration data can reassure farmers that weeds will not increase in cropland adjacent to prairie strips.
For more information, visit the STRIPs website at www.nrem.iastate.edu/research/STRIPs. View a slideshow of the stakeholder meeting at the Leopold Center Web site, or listen to a podcast at the Land Stewardship Project website.