Prairie Strips Show Rapid Soil Health Improvement in Iowa

Research from Iowa State University has revealed that prairie strips can significantly enhance soil health in a surprisingly short time frame. Conducted in collaboration with the Soil Health Institute, this study indicates that these strips—comprised of 30 to 100 feet of herbaceous, perennial plants interspersed within agricultural fields—can restore vital ecological functions while minimally impacting crop production.

Published in the Journal of Soil and Water Conservation, the findings demonstrate that prairie strips can improve various soil health indicators within just 10 to 12 years. Previous research has highlighted the benefits of these strips in promoting biodiversity and reducing erosion but had not thoroughly examined their effects on soil health until now.

Key Findings on Soil Health Improvement

The study focused on twelve different soil health indicators and found that prairie strips enhanced eight of them significantly. Notably, the research identified improvements in:

• Soil aggregate stability by as much as 80%, indicating enhanced resistance to erosion.
• Microbial biomass increased by up to 54%, reflecting a boost in the population of microscopic organisms crucial for nutrient cycling and carbon sequestration.
• Soil organic matter increased by up to 23%, essential for maintaining soil health.
• Maximum water-holding capacity improved by up to 7%, demonstrating better retention of moisture.

Marshall McDaniel, an associate professor of agronomy at Iowa State and the study’s coordinator, expressed his surprise at the rapidity of these changes. “It was an exciting surprise to see the degree of these changes over just a decade or so,” he said. “It has been thought that it would take much longer to see some of these levels of change.”

While some measures continued to improve throughout the study period, others plateaued. For instance, both microbial biomass and soil organic matter showed an increase early on but leveled off towards the end of the research. The study utilized a “paired chronoscope” approach, examining fifteen paired control and treatment sites across four of Iowa’s seven major landforms. This design included prairie strips aged between 2 and 13 years and conventional cropland managed in a corn-soybean rotation.

Broader Implications and Future Research

Additional insights emerged from the research, particularly concerning changes in microbial communities. Cole Dutter, who completed his doctorate during this project, noted that microbial changes extended well into adjacent cropland soils. This shift included elevated enzyme levels that could enhance nutrient availability to crops and improve carbon storage.

Moreover, the study revealed that the influence of prairie strips on soil moisture and nutrients can extend more than 3 feet (approximately 1 meter) beyond the strips themselves, all while maintaining minimal impact on crop yields. According to Lisa Schulte Moore, director of ISU’s Bioeconomy Institute, some farmers have shown interest in rotating their prairie strips every 10 years to distribute benefits across their fields.

Dutter, who will soon transition to a faculty position at California State University, Stanislaus, intends to continue researching prairie strips. He believes these strips offer a quick method for enhancing soil health in the upper soil profile and emphasizes the potential for broader applications. “We think there is a lot of potential to expand these benefits throughout fields and even improve yields,” he stated.

The study is notable not only for its findings but also for its approach to soil health assessment. The techniques used for measuring aggregate stability and water-holding capacity are accessible and inexpensive, allowing landowners to evaluate soil health independently. McDaniel pointed out that aggregate stability can be measured using a smartphone app called Slakes, while maximum water-holding capacity can be assessed with simple tools like a funnel and coffee filter.

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. As this area of study continues to evolve, researchers anticipate uncovering more about the long-term benefits of prairie strips on soil health and agricultural productivity.