Research by scientists at Iowa State University, in collaboration with the Soil Health Institute, has revealed that prairie strips can enhance soil health more quickly than previously anticipated. These strips, consisting of 30-100 ft of herbaceous, perennial plants integrated into agricultural fields, aim to mimic the ecological benefits of Iowa’s native prairies while minimally impacting crop yields.
Previous studies established that incorporating prairie strips, covering approximately 10% of a field, can significantly boost biodiversity, enhance pollinator habitats, reduce erosion, and improve water quality. However, the effects of these strips on soil health had not been thoroughly investigated—until now.
Research findings published in the Journal of Soil and Water Conservation indicate that prairie strips can improve several key soil health indicators within a span of just 10 to 12 years. The study demonstrated significant advancements in eight out of twelve soil health metrics and notable increases in additional areas. Among the most impressive results were:
– **Soil aggregate stability**: Increased by up to 80%, indicating enhanced resilience to erosion.
– **Microbial biomass**: Increased up to 54%, reflecting growth in the microscopic organisms crucial for nutrient cycling and carbon capture.
– **Soil organic matter**: Increased by 23%, essential for maintaining healthy soil ecosystems.
– **Maximum water-holding capacity**: Improved by up to 7%, showcasing the soil’s enhanced ability to retain moisture.
Marshall McDaniel, an associate professor of agronomy at Iowa State University, expressed his enthusiasm regarding the speed of these changes. “It was an exciting surprise to see the degree of these changes over just a decade or so,” he noted. He emphasized that previous assumptions suggested these improvements would take longer, particularly in terms of soil organic matter and water retention.
The study employed a “paired chronoscope” method, which utilized 15 paired control and treatment sites featuring prairie strips aged between 2 and 13 years. These sites represented four of Iowa’s seven major landforms, with most located on private farmland. Researchers measured six aspects of soil health in the top six inches, while a more in-depth assessment took place at the oldest prairie strip (12 years old) located at the Neal Smith National Wildlife Refuge near Prairie City, led by Elizabeth Riecke from the Soil Health Institute.
Further findings from this research, led by Cole Dutter, who completed his doctorate in sustainable agriculture and soil science, revealed significant changes in microbial communities extending from the prairie strips into adjacent cropland. These shifts included increased enzyme levels related to nutrient and carbon cycling, which could enhance nutrient availability for crops and improve carbon storage. Notably, the impact of prairie strips on soil moisture and plant-available nutrients extended more than 3 feet (up to 1 meter) from the strips, with minimal effects on crop yields.
The research underscores the rapid benefits derived from implementing prairie strips. Dutter noted that some farmers are considering rotating their prairie strips after 10 years to further distribute the advantages across their fields. Lisa Schulte Moore, director of ISU’s Bioeconomy Institute, who contributed to the study and developed the STRIPS conservation practice, stated, “Cole has initiated some interesting research looking at this idea. It is showing some long-term boosts to soil health and crop yields from rotating strips within fields.”
As Dutter prepares to transition to a faculty position at California State University, Stanislaus, he intends to continue his involvement in prairie strips research. He emphasized the potential for prairie strips to enhance soil health in the upper soil profile and hinted at further research needed to explore carbon storage at greater depths.
The researchers also highlighted that the methods for measuring aggregate stability and water-holding capacity are accessible and inexpensive, enabling landowners to assess soil health independently. McDaniel mentioned that the Slakes app, maintained by the Soil Health Institute, can be easily used to measure a soil’s resistance to erosive forces. Additionally, the maximum water-holding capacity can be gauged using simple tools like a funnel and coffee filter.
Funding for this significant research primarily came 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 provide critical insights into the benefits of prairie strips and their role in promoting sustainable agricultural practices across Iowa and beyond.
