Building Cost-Effective Prairie for Multiple Nutrient Reduction Practices
The contour prairie strip reduces surface nutrient runoff for about the same cost as cover crops, and does not carry the uncertainty of replanting every year. Prairie strips reduce concentrations of shallow groundwater nitrates, and prairie root systems fuel the denitrification process. Building prairie in the agricultural landscape also enhances other ecosystem services including soil quality, wildlife habitat and resilience to flooding. Yet conservation agency staff, professional farm managers and other technical service providers may be reluctant to recommend prairie contour strips because of concerns about a successful outcome.
Cost effective methods of prairie establishment are not well known outside the ecological restoration community. The goal of this project is to improve the effectiveness and predictability of prairie contour strips and other prairie applications, thus reducing barriers to implementation. This will be done through applied research, establishment of training/demonstration sites, and training for practitioners.
Both research and demonstration prairie plantings will consider appropriate species and planting methods for saturated buffers, and for marginal lands with either extremely wet or extremely dry soils. Vegetation sampling will be done with the cost per thousand plants established, and species diversity and plant size reported. To address the goal of reducing barriers to the use of prairie for nutrient reduction, a technical report on earlier experiments and demonstrations, plus research summaries on seed mix design, mowing, season of planting, and stand development/troubleshooting will be created. At least four presentations will be made to agricultural audiences; web resources and printed materials for agricultural audiences will be developed; and there will be continued collaboration with the ISU STRIPS project.
The complete final technical report is provided here: Cost-effective seed mix design and first-year management (PDF). Key highlights, include:
- Diverse, moderately priced seed mixes with a balanced seeding rate of grasses to forbs produce nutrient reducing prairies with the most additional conservation benefits at reasonable cost.
- These benefits accrue faster when paired with first-year mowing management.
- Nutrient reducing prairies with multiple other conservation benefits can be successfully applied to dry marginal soils when seed mixes are designed (without increasing cost) to include dry adapted native plants.
Progress continues on research to provide farmers and contractors with science-based recommendations to implement in-field (prairie strip) and edge of field (marginal land) practices. INRC funds support demonstration/pilot studies to screen for the most promising treatments and to replicate field experiments for formal hypothesis testing.
This quarter, researchers collaborated with UNI faculty on a manuscript based on the Nashua experiment. The restoration and research manager worked with UNI Biology faculty and honors students to create an early draft manuscript. Upcoming work will entail revisions and submission of a completed manuscript to the journal Restoration Ecology. We continue to disseminate preliminary conclusions through multiple channels. A new experiment has been planned and partially implemented, building on results of the Nashua study.
First-year data from the Wapsi-Fairbank dry soil study site continues to be analyzed. Key prairie species- native warm and cool season grasses established well in marginal dry soil, along with important summer and fall flowering forbs. Dry adapted forb species established better than their medium to wet soil counterparts, resulting in the presence of more functional groups- the entire spring forb functional group was missing from the non-customized mix. Cost-effectiveness of native perennial vegetation was comparable in productive (Nashua) versus dry marginal (Wapsi-Fairbank) soils, and plants per dollar was similar for many native grass and forb species among mixes. Upcoming work in the final project quarter will include synthesizing results and writing the preliminary technical report.
We conducted a first-year vegetation sampling at the Wapsi-Fairbank Research Field in September. This new study examines the cost-effectiveness of seed mix customization to match soils in dry marginal lands and assesses associated establishment outcomes. We measured plant density, species richness and plant functional group cover of a seed mix with dry adapted species and a seed mix with mesic soil adapted species. The site was mowed once in July to increase early establishment. Because measures were not compared that would change with plant size, researchers did not measure selected species biomass in this study. Preliminary analysis shows that plant density appears comparable between mixes, though the dry adapted mix produced slightly more forbs. The key difference between the mixes is that species richness in the dry adapted mix was higher than in the mesic mix. Work in upcoming months will consist of formal analysis of vegetation measures and analysis of cost effectiveness.
The technical report synthesizing three years of data from our Nashua experiment was completed and made available on the UNI Tallgrass Prairie website (https://tallgrassprairiecenter.org/sites/default/files/6292_nashuafinalreport_2018.pdf). We also continued collaborating with professor Mark Sherrard to prepare a manuscript based on the results presented in the technical report (with anticipated submission in late 2019).
Throughout the reporting period, the results of the Nashua experiment were disseminated at workshops and conferences with agriculture and conservation audiences. The Research and Restoration Program Manager and the Prairie on Farms Program Manager presented results of the Nashua seed mix experiment on site to multiple high-level USDA staff, including the National Program Manager for the Conservation Reserve Program (FSA and NRCS). The Research and Restoration Program Manager also presented the results of the cost-effective prairie experiment at Nashua to an estimated 50 members of DNR private lands collaborators and employees at the 2018 Annual Iowa DNR Private Lands Meeting in Ames.
Third-year data from the Nashua experiment site was analyzed in October, to assess the overall importance of seed mix and mowing, and compare performance of seed mixes across 10 response variables. Results from the third year were similar to the first two years with respect to the differences between seed mixes. However, most effects of mowing appear to have dissipated in the third year. A new study site in Fayette County was planted.
Vegetation in experimental plots was sampled, with stem density, cover and flower counts for native and non-native species recorded. Biomass samples were processed in drying ovens and information recorded on maximum heights and biomass among seed mix and mowing treatment. Data from the vegetation survey at the Nashua research site was entered and key vegetation measures summarized. Results of this experiment were shared with agricultural audiences at two field days in September. Both field days provided details on best practices related to implementation and management of cost-effective prairie plantings, plus research results from the Nashua experiment.
In collaboration with NRCS and Pheasants Forever, the team finalized the layout and seed mix for a demonstration field where prairie is planted on marginal soils. The project portion to be implemented by the Tallgrass Prairie Center is two acres in size, and located on poor, sandy soils. Each mix will be replicated three times in 0.33-acre strips. Two field days were held in June — one based on the Dysart demonstration sites and one based on the Nashua research site. A research summary was posted on the Tallgrass Prairie Center website that details second year results from the Nashua seed mix experiment.
In collaboration with NRCS, Pheasants Forever and Fayette County Conservation, a study and demonstration farm field was identified for applying prairie to marginal soils. After scouting the site in person, a draft layout of the research/demonstration plots was developed. Close collaboration with the ISU STRIPS team continued on a prairie strips project near Dike, with 6.41 acres seeded at the Roadman Farm site. Further work at this site will include establishment monitoring throughout the summer, and hosting field days on the planted demonstration strips.
Analysis of the second year of data from the Nashua experiment site was completed this quarter, and technical reports generated based on the results. Analyses included the overall importance of seed mix and mowing, and compared performance of seed mixes across 10 response variables, including biomass, flower abundance, native and weed stem abundance, and species richness. To continue planning a future research and demonstration site, researchers worked with NRCS technicians in Fayette County to identify potential locations where prairie could be applied to marginal lands. Throughout the reporting period, results of the Nashua experiment were shared at conferences, meetings and workshops with agriculture and conservation audiences. Close collaboration with the ISU STRIPS team continued by assisting in the implementation of prairie strips near Dike. Five acres were seeded in mid-November. Another six acres will be seeded this spring, with establishment monitored throughout the summer.
Year two data from the Nashua experiment site is being analyzed. Vegetation in experiment plots was sampled, recording stem density, cover and flower counts for native and non-native species. Data from the vegetation survey was summarized for key vegetation measures. Preliminary statistical analysis on the vegetation data was done to test for the significance of mowing and seed mix factors. A literature review was conducted on potential species that are likely to be suitable for use in seed mixes on saturated buffers or wet sites. This information will be used to purchase seed for research/demonstration sites in spring 2017.