ISU prairie strips study yields options to improve conservation
Prairie strips placed within fields offer a way for row-crop producers to meet environmental goals while still satisfying demands for food, feed and fuel, according to Iowa State University research.
“Results of our study suggest that if you put a small portion of crop land into native vegetation, you could achieve substantial benefits with less total land used than had previously been in the federal Conservation Reserve Program,” said Lisa Schulte Moore, associate professor of natural resource ecology and management. “You just need to be strategic about where you put the native vegetation.”
Schulte Moore and other ISU scientists have been conducting the study, known as STRIPs (Science-based Trials of Rowcrops Integrated with Prairies), at the Neal Smith National Wildlife Refuge in Jasper County since 2005. The project team is working to create six demonstration sites around the state in association with the Iowa Department of Agriculture and Land Stewardship and the USDA-Natural Resources Conservation Service.
In the last several years substantial demand for row crops has drawn hundreds of thousands of acres of environmentally sensitive land in Iowa and beyond from the federal Conservation Reserve Program. The CRP helped farmers plant resource-conserving vegetation to improve water, prevent soil erosion and develop wildlife habitat.
Schulte Moore said the study’s results offer farmers a viable option for land that has come out of the CRP program.
“We’ve seen dramatic environmental improvements with as little as 10 percent of the land in prairie strips placed on the contours of row-cropped watersheds,” she said.
Improvements include a 95 percent reduction in sediment transport, 90 percent reduction in phosphorus and total nitrogen transport and 60 percent reduction of surface water flow from the experimental sites, which are cropped on a corn-soybean rotation using no-till.
Matt Helmers, associate professor of agricultural and biosystems engineering and extension agricultural engineer, says the stiff, upright stems and deep roots of prairie plants are essential. They slow the flow of water and encourage infiltration, keeping soil and nutrients in the farm field where they are needed. With minimal upkeep, diverse prairie communities are able to withstand drought and intense rain.
“Prairie strips would rank among the least expensive in-field management practices, costing approximately $40 per treated acre per year for establishment and management,” said Helmers.
In the study, prairie strips are placed perpendicular to the flow of water with spacing and configuration designed to fit farming and machinery needs. There is the potential that the strips can be moved as sediment is deposited on the upslope edge or machinery needs change, making them a flexible and attractive alternative to terraces for certain slopes and soil types.
Native prairie plantings also provide better wildlife habitat than non-native grasses, which are typically used for grassed waterways and terraces on farmland.
“Prairie strips could expand in-field habitat and assist grassland songbird populations currently in steep decline, support pollinators including native bees and play a role in integrated pest management by providing habitat for beneficial insects,” said Mary Harris, adjunct assistant professor of entomology and natural resource ecology and management.
“The STRIPs project shows we can find cost-effective solutions that achieve substantial environmental benefits, while ensuring good crop production,” said Schulte Moore. “The study shows we can strike a balance by blurring traditional lines between agriculture and conservation.”
Schulte Moore says the project has spurred interest from IDALS, the Iowa Department of Natural Resources, the National Park Service and farmers.
Funding for the STRIPs project over the past eight years has been provided by Iowa State’s College of Agriculture and Life Sciences and Leopold Center for Sustainable Agriculture, the National Science Foundation, the U.S. Forest Service, the USDA Agriculture and Food Research Initiative and IDALS.