Prairie Strips Enhance Soil Health in Just a Decade

New research from Iowa State University, in collaboration with the Soil Health Institute, reveals that prairie strips can significantly enhance soil health much faster than previously anticipated. These strips, which consist of 30-100 ft sections of herbaceous, perennial plants interspersed within agricultural fields, aim to replicate the ecological benefits of Iowa’s native prairies while minimally impacting crop production.

The study, published in the Journal of Soil and Water Conservation, demonstrates that prairie strips established in approximately 10% of a field can markedly improve various soil health indicators within a span of just 10 to 12 years. Researchers found that these strips improved eight of twelve measured soil health indicators, including a notable increase in soil aggregate stability by up to 80%, microbial biomass by up to 54%, and soil organic matter by up to 23%. Additionally, the maximum water-holding capacity of the soil saw improvements of up to 7%.

Marshall McDaniel, an associate professor of agronomy at Iowa State, expressed his surprise at the rapid changes observed in the soil. “It was an exciting surprise to see the degree of these changes over just a decade or so,” McDaniel stated. He noted that many had believed it would take significantly longer to observe such improvements, particularly concerning soil organic matter and water-holding capacity.

As the research progressed, certain measurements continued to show positive trends. Aggregate stability and water-holding capacity improved consistently throughout the study. However, microbial biomass and soil organic matter reached a plateau as the study approached its conclusion, with microbial biomass even showing a slight decline.

The researchers utilized a “paired chronoscope” method, involving 15 control and treatment sites across four major landforms in Iowa. Each site featured prairie strips ranging from 2 to 13 years old, paired with conventional cropland managed in a corn-soybean rotation. Most of the sites were located on private farmland, demonstrating practical applications for farmers.

The study’s lead author, Cole Dutter, who completed his doctorate in sustainable agriculture and soil science, highlighted broader effects observed in microbial communities. These communities exhibited significant changes that extended far beyond the prairie strips into adjacent cropland soils. The research indicated elevated enzyme levels linked to enhanced nutrient cycling and carbon storage, suggesting potential benefits for crop nutrient availability and carbon retention.

The effects of prairie strips on soil moisture and nutrients were found to extend more than three feet (up to one meter) outward from the strips, with negligible impacts on crop yields. This suggests that prairie strips could be a viable method for improving soil health without compromising agricultural productivity.

Looking ahead, some farmers involved in the study are considering rotating their prairie strips after ten years to maximize the benefits across their fields. Lisa Schulte Moore, director of Iowa State’s Bioeconomy Institute and a collaborator on the project, noted the potential for long-term improvements in soil health and crop yields from rotating strips. Dutter intends to pursue further research in this area as he transitions to a faculty position at California State University, Stanislaus.

“Our related projects show that prairie strips are a relatively quick way to build soil health in the top of the soil profile,” Dutter explained. “We think there is significant potential to expand these benefits throughout fields and even improve yields.”

The researchers emphasized that the techniques used to measure aggregate stability and water-holding capacity are straightforward and accessible to non-scientists. McDaniel mentioned that these DIY tests provide landowners with practical tools to assess soil health after implementing management changes like prairie strips. For instance, aggregate stability can be measured using a smartphone app called Slakes, while water-holding capacity can be assessed with simple materials like a funnel and coffee filter.

Funding for the study was primarily provided by the Foundation for Food and Agriculture Research and the USDA Farm Service Agency, with additional support from the National Science Foundation and USDA Hatch funds. As research continues, the potential of prairie strips to contribute to sustainable agriculture and soil health remains a promising area for further exploration.