Recent research from Iowa State University in collaboration with the Soil Health Institute reveals that prairie strips can significantly improve soil health in a surprisingly short timeframe. Prairie strips, which are strips of herbaceous, perennial plants measuring between 30 and 100 feet, are integrated into crop fields to mimic the benefits of Iowa’s native prairies, while minimizing disruption to crop production.
The findings, published in the Journal of Soil and Water Conservation, indicate that these prairie strips can enhance various soil health indicators within just 10 to 12 years. Specifically, the study demonstrated improvements in eight out of twelve soil health measures, including remarkable increases in soil aggregate stability, microbial biomass, soil organic matter, and water-holding capacity.
Key Findings on Soil Health Improvement
The research highlights significant advancements in several critical areas of soil health. For instance, soil aggregate stability—a measure of soil’s resilience against erosion—increased by as much as 80%. Additionally, microbial biomass, which is crucial for nutrient cycling and carbon sequestration, saw a rise of up to 54%. Furthermore, the living and dead carbon content in soils, referred to as soil organic matter, increased by up to 23%, while maximum water-holding capacity improved by 7%.
According to Marshall McDaniel, an associate professor of agronomy at Iowa State and lead coordinator of the study, the extent of these changes was unexpected. “It has been thought that it would take much longer to see some of these levels of change, especially in soil organic matter and maximum water-holding capacity,” he stated.
The study employed a “paired chronoscope” approach, comparing 15 paired control and treatment sites with prairie strips ranging from two to thirteen years old. These sites represented four of Iowa’s seven major landforms, with a majority located on private farmland. Soil health was assessed in the top six inches of soil, with a more detailed evaluation conducted at the oldest prairie strip located at the Neal Smith National Wildlife Refuge near Prairie City.
Broader Benefits and Future Research Directions
Further research led by Cole Dutter, the lead author of the study, examined broader implications of soil health under prairie strips. The findings revealed significant changes in microbial communities extending deep into adjacent cropland soils. Elevated enzyme levels related to nutrient cycling were observed, suggesting increased nutrient availability for crops and enhanced carbon storage capabilities.
Additionally, the effects of prairie strips on soil moisture and plant-available nutrients reached more than three feet (up to one meter) beyond the strips, all while having minimal impacts on crop yields. This demonstrates the quick benefits prairie strips can offer, even though they occupy only a small fraction of a field.
Some farmers have expressed interest in rotating their prairie strips every ten years to maximize soil health benefits across their fields. Lisa Schulte Moore, director of ISU’s Bioeconomy Institute and a collaborator on the study, noted that ongoing research is exploring this idea. “Cole has initiated some interesting research looking at this idea,” she said, adding that initial findings indicate long-term boosts to soil health and crop yields from rotating strips.
As Dutter prepares to transition to a faculty position at California State University, Stanislaus, he aims to continue his involvement in prairie strips research. He emphasized that these strips provide a relatively quick method to enhance soil health at the surface level, with potential benefits for deeper carbon storage yet to be fully understood.
The researchers also highlighted that the assessment methods for aggregate stability and water-holding capacity used in this study are straightforward and accessible. “These DIY tests are great tools that landowners can use to assess soil health on their own fields after implementing management changes like prairie strips,” McDaniel stated. For example, aggregate stability can be measured using a smartphone app, while the maximum water-holding capacity can be assessed using simple household items.
Funding for this research 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. The findings underscore the significant potential of prairie strips in enhancing soil health, providing a promising avenue for sustainable agricultural practices.
