Final report for GNC21-336
Prairie strips are a conservation practice in Midwest agriculture in which 10% of a rowcrop field is converted to strips of native prairie. Prairie strip implementation controls erosion, reduces pests, improves water quality, and creates wildlife corridors. Preliminary data has also suggested that prairie strips can remove harmful insecticides from farm soils, but the generality and mechanisms of insecticide removal have not been described. Despite their known conservation benefits, adoption of prairie strips remains low across much of the Eastern Corn Belt, suggesting the need to better identify and communicate the benefits of prairie strips in collaboration with agriculture stakeholders. We conducted a paired research and outreach project centered on the ecological and economic benefits of prairie strips on southwest Michigan farms.
In this paired research and outreach project, we 1) conducted a field experiment to identify the mechanism of soil insecticide removal in prairie strips and 2) hosted a farm field day to foster shared learning among agricultural stakeholders on prairie strip implementation and soil health benefits. Our research project included a field study to investigate the removal of insecticides by prairie strips, followed by a laboratory study to determine whether prairie strip soil microbes are degrading neonicotinoids. We found that converting 10% of a rowcrop field reduces soil insecticides at the field scale, and that this reduction was explained by biochemical processes in the surface soil (0-10 cm) of the prairie strips rather than deep soil leaching or plant uptake. We also hosted a field day event at the site of a successful prairie strip implementation in southwest Michigan, where local scientists, farmers, and conservation managers gathered to learn about prairie strip soil health benefits. The field day included presentations by two local prairie strip farmers, a Natural Resources Conservation Service (NRCS) technician, and scientists, a soil pit that showed the impact of prairie strips on the agricultural soil profile, and a wagon tour for participants to see several successful prairie establishments under a variety of management regimes.
Results of our research project were presented at the farm field day and at scientific meetings, and will later be published in a scientific journal centered on agricultural soil conservation. We prepared a 1-page informational flyer for field day participants that describes the Michigan Prairie Strips (MiSTRIPS) outreach program, as well as an informational packet describing the seed mix and management regime associated with each of the prairies on the field day wagon tour.
This project achieved three objectives: 1) we increased the academic community’s understanding of how prairie strips remediate neonicotinoid insecticides, 2) we increased farmers’ and land managers' awareness of prairie strips in southwest Michigan, and 3) we increased farmers’ and land managers' access to a local network of resources for prairie strip adoption. The project also achieved two action objectives: 1) we provided farmers and land managers with resources about prairie strip conservation benefits including pollinator conservation, and 2) we connected farmers and land managers with local contacts who can assist with prairie strip enrollment and implementation.
Stage 1: Field study to assess neonicotinoid movement
To determine the mechanism by which prairie strips remove neonicotinoids at the field scale, we collected samples from a long-term experiment at a farm in Story County, Iowa. This project builds on an existing collaboration with researchers from Iowa State University’s Science-Based Trials of Rowcrops Integrated with Prairie Strips (STRIPS) team.
Samples were collected from one field with 90% rowcrop cover and 10% prairie cover (prairie strip) and one field with 100% rowcrop cover (control). Each field will be sown with corn seeds coated with a commercial neonicotinoid, clothianidin. We collected surface soil cores (0-10cm), deep soil cores (90-100 cm), plants, surface water, and groundwater samples at upslope and downslope locations in each field at two time points in 2021 to capture the spatial and temporal transport of clothianidin (2 treatments x 4 sample types x 6 sampling points x 2 time points , n=96). All samples were analyzed for clothianidin concentration using coupled liquid chromatography-mass spectrometry (LC/MS- MS).
Stage 2: Lab study to assess microbial degradation
To isolate the effect of the soil microbial community on neonicotinoid removal, we prepared microcosms of liquid nutrient broth media amended with a field-representative concentration of clothianidin (0.5 ppm), and inoculated media with prairie and rowcrop soil microbial communities (2 treatments x 10 replicates, n=20). We prepared inocula by extracting supernatant from centrifuged slurries of field-collected prairie strip soil and rowcrop soil in nutrient rich media. We collected samples from each microcosm on six days: day 0 (day of inoculation), day 2, day 5, day 10, day 20 and day 40. Each sample was submitted to the Iowa State University Veterinary Diagnostic Lab for soil clothianidin analysis via LC/MS-MS.
Stage 3: Data analysis and hypotheses
We first analyzed data from Stage 1 - clothianidin concentrations in plant, surface soil (0-10cm), deep soil (90-100 cm), and groundwater in one field with 90% corn and 10% prairie strips and one field with 100% corn and no prairie strips - to understand how prairie strips impact neonicotinoid translocation within the landscape and ultimate removal from the field. We measured plant, soil and water clothianidin as a function of prairie strip treatment, slope position, and sampling date.
We then analyzed data from Stage 2 - clothianidin concentrations in experimental microcosms - to determine whether microbial degradation is driving neonicotinoid removal. We measured microcosm clothianidin as a function of prairie strip treatment and of an interaction between prairie strip treatment * day of experiment.
Our field study showed that converting 10% of a rowcrop field reduces soil clothianidin at the field scale. This reduction was explained by biochemical processes in the surface soil (0-10cm) of the prairie strips rather than deep soil leaching, groundwater leaching, or plant uptake. Our lab study showed that clothianidin removal in prairie strips is likely not driven by microbial degradation, but the project is ongoing, and future work will clarify these results.
In our field study, we measured clothianidin in multiple landscape “compartments” to understand how planting 10% prairie strips impacts clothianidin translocation and ultimate removal from the field. We measured clothianidin in plants, groundwater and soil from one field with 90% corn and 10% prairie strips and one field with 100% corn and no prairie strips. Prairie strips did not affect clothianidin in groundwater, corn and prairie plant tissue, or deep soil (90-100cm); however, prairie strips did reduce surface soil (0-10cm) clothianidin in both monoculture corn and prairie areas. These results suggest that clothianidin removal in fields treated with 10% prairie strips is driven by a biochemical mechanism in the 10% prairie strip field surface soil rather than increased physical translocation of clothianidin into the soil profile, groundwater, or plant tissue.
In our lab study, we tested whether surface soil microbial degradation was the mechanism for clothianidin removal in fields with 10% prairie strips. We measured clothianidin over 40 days in liquid microcosms spiked with 0.5ppm clothianidin and inoculated with three microbial treatments: corn soil microbes, prairie strip soil microbes, and no microbes (control). We found no evidence that prairie strip soil microbes degrade clothianidin at a faster rate than corn soil microbes, but these results were complicated by experimental design issues. In the first iteration of the experiment, microcosms were exposed to sunlight wherein all microcosms exhibited photodegradation of clothianidin at a similar rate across treatments, as well as cross contamination wherein all control microcosms were contaminated by microbes from surrounding microcosms. In the second iteration of the experiment, microcosms exhibited high variance and, in some cases, increasing clothianidin over time, potentially due to high turbidity of microcosm biofilms and interference in LC/MS-MS analysis. We have further experimentation planned after the grant period to clarify whether microbial degradation in surface soils is a mechanism of neonicotinoid removal in fields with 10% prairie strips.
Educational & Outreach Activities
We organized a farm field day centered on prairie strips and soil health in August 2022. The event took place at the Edward Lowe Foundation and included presentations by farmers, land managers, and soil scientists on the implementation, management, and soil health benefits associated with on-farm prairie strips.
First, Jarod Reibel, the Conservation Stewardship Land Manager at the Edward Lowe Foundation (ELF), described the prairie strips implemented on the foundation’s property. The prairie strips at the ELF were integrated into cropland 2014-2015 with the goal of improving soil health, and ELF land managers have since planted over 200 acres of prairie habitat with over 100 species of grasses and forbs into agricultural fields. Jarod’s presentation and field tour provided participants with several examples of prairie strips under different management regimes and the benefits they can provide on Michigan farms.
Next, participants heard a presentation from Marc Hasenick of Hasenick Brothers Farm, located in Springport Michigan. Hasenick Brother’s Farm focuses on soil health as the number one priority in farm operations, using no-till and precision ag technologies to balance production and sustainability. Marc has planted prairie strips and prairie areas on his farm for both ecological benefits and economic benefits. Marc shared his perspective on the economic feasibility of implementing prairie strips independently, without enrollment in state and federal conservation programs.
Lucas Hartman, Conservation Technician for the Van Buren Conservation District, followed Marc’s presentation by discussing a different approach to prairie strip implementation - enrollment in the Conservation Reserve Program’s CP-43 prairie strips practice. Lucas described the criteria and process for enrollment, and answered many participants’ questions about eligibility and cost share options.
The workshop continued with a soil pit demonstration to discuss the benefits of prairie strips for soil health and pollinator conservation. The first discussion was led by Kathryn Docherty, Associate Professor at Western Michigan University in the Department of Biological Sciences. She provided an introduction to soil profiles and carbon storage, comparing the physical, chemical and biological features of cropland vs. prairie soil. Tvisha Martin, a graduate student at MSU in Integrative Biology, followed Kathryn by sharing her research on nematodes in prairie strips as indicators of soil health. Finally, Corinn Rutkoski, a graduate student at MSU in Integrative Biology, described her research on the impact of prairie stips on soil microbial communities and their potential to remediate pesticides that harm pollinators. Scientist presenters fielded many questions related to prairie ecology, concerns about deleterious effects of prairie strips on cropland, prairie strip management, and more.
Economic benefits: Our project provided information and resources to farmers in southwest Michigan to empower them to implement prairie strips on their own land. Our farm field day included several examples of prairie strip implementation: independent prairie strip establishment, enrollment in the Conservation Reserve Program CP-43 program, and multiple prairie management techniques. With this information, more farmers can integrate prairie strips on their land for ecological benefits and for economic benefits that offset costs associated with prairie strip implementation, management, and foregone rowcrop yields.
Environmental benefits: A recent analysis of the Eastern Corn Belt found that farmers’ willingness to adopt prairie strips increases with their perception of prairie strip conservation benefits (Luther 2020). By increasing awareness of prairie strips, our project made progress towards secure soil health, water quality, and native wildlife habitat in Michigan.
Social benefits: Our farm field day connected farmers and advisors with a network of local technical experts who can assist with the implementation of prairie strips on southwest Michigan farms. Our project also advanced our understanding of pollinator protection in diversified agricultural landscapes. Food security relies on the presence of healthy pollinator populations in agricultural systems, and prairie strips are one mechanism to support pollinators amid increasingly simplified farm landscapes.
The importance of bidirectional learning between scientists and agriculture collaborators became clear throughout the implementation of this project. There were several points at which we as scientists learned surprising and valuable information from farmers’ on the ground experience with crop and prairie management. With that, we learned that there is not a one-size-fits-all land management recommendation for implementing prairie strips. The farmers and landowners we collaborated with each have unique challenges on their land that demand individualized management regimes. Agriculture advisors and conservation technicians can be an ideal conduit for this bidirectional learning, leveraging both scientific and technical expertise to deliver personalized management recommendations to local farmers.
- Edward Lowe Foundation Prairie Habitat Tour (Conference/Presentation Material)