Recent research from Iowa State University in collaboration with the Soil Health Institute reveals that prairie strips can enhance soil health measures more quickly than previously anticipated. These strips, which consist of 30 to 100-foot sections of herbaceous, perennial plants interspersed within crop fields, aim to restore some ecological benefits associated with Iowa’s native prairies while minimally impacting crop production.
Prior studies established that prairie strips covering approximately 10% of a field could significantly increase biodiversity and habitat for pollinators, reduce soil erosion, and improve water quality. However, their effects on soil health had not been thoroughly investigated until now. Findings published in the Journal of Soil and Water Conservation indicate that prairie strips can improve various soil health indicators within just 10 to 12 years.
Significant Improvements in Soil Health Indicators
The study found that prairie strips positively affected eight out of twelve soil health indicators, showing marked improvements in several key areas. Notable enhancements included:
- Soil aggregate stability: Improved by up to 80%, indicating a stronger ability of the soil to resist erosion.
- Microbial biomass: Increased by up to 54%, highlighting the growth of microscopic organisms that are vital for nutrient cycling and carbon sequestration.
- Soil organic matter: Enhanced by up to 23%, crucial for maintaining healthy soil.
- Maximum water-holding capacity: Increased by up to 7%, demonstrating the soil’s improved ability to retain moisture.
Marshall McDaniel, an associate professor of agronomy at Iowa State and the study’s coordinator, expressed surprise at the extent of these changes over a relatively short period. “It has been thought that it would take much longer to see some of these levels of change, especially in soil organic matter and water-holding capacity,” he noted.
While some indicators plateaued over time, others, like soil aggregate stability and maximum water-holding capacity, continued to improve throughout the study period. The research employed a “paired chronoscope” approach, utilizing fifteen paired control and treatment sites consisting of prairie strips aged between 2 and 13 years, spread across four of Iowa’s seven major landforms. Most of these sites were on private farmland, providing a practical context for the study.
Broader Implications for Agriculture
Additional findings from the research, led by doctoral candidate Cole Dutter, suggest that prairie strips not only enhance soil health but also influence adjacent cropland. Changes in microbial communities extended far into adjacent soils, leading to increased nutrient cycling and carbon storage potential. The positive effects on soil moisture and plant-available nutrients extended more than 3 feet (up to 1 meter) from the strips, with negligible impacts on crop yields.
These insights point to the rapid benefits of implementing prairie strips, even though they occupy only a small fraction of a field. “Some farmers we have worked with are interested in rotating their prairie strips after ten years to spread the benefits across their fields,” said Lisa Schulte Moore, director of ISU’s Bioeconomy Institute and a collaborator on the study.
Dutter, who is transitioning to a faculty position at California State University, Stanislaus, plans to continue researching prairie strips. “Our related projects show that prairie strips are a relatively quick way to build soil health in the top of the soil profile. We believe there is significant potential to expand these benefits throughout fields and even improve yields,” he stated.
The researchers highlighted that the methods used to measure aggregate stability and water-holding capacity are straightforward and inexpensive, making them accessible to non-scientists. McDaniel noted, “These DIY tests are excellent tools that landowners can use to assess soil health on their own fields after implementing management changes like prairie strips.” He mentioned that aggregate stability can be measured using a smartphone app called Slakes, while maximum water-holding capacity can be assessed with basic equipment like a funnel and coffee filter.
Funding for this significant research came primarily from 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. The findings not only underscore the impact of prairie strips on soil health but also pave the way for sustainable agricultural practices that can benefit both farmers and the environment.
