Making Prairie Practical: Expanding Flexibility in Planting Methods for Retired Marginal Lands and Edge-of-field Nutrient Reduction Practices
- Laura Jackson
- Justin Meissen
Issue
Conversion of marginal land to permanent perennial cover is a highly effective nutrient reduction practice, but it only makes economic sense when the land is marginally productive or is enrolled in strategic, edge-of-field conservation practices such as prairie strips. Despite these benefits, farmers may be deterred by rigid implementation requirements. In previous INRC-funded work we demonstrated that some widely recommended practices for site preparation and seeding lack clear data to support them.
Objective
Our overall goal is to expand the suite of cost-effective methods, increasing farmer flexibility and facilitating participation in the Conservation Reserve Program. There are three objectives:
1) compare combinations of alternative planting times, planting implements, and recommended seeding rates;
2) compare alternative cropping history and associated site preparation, which currently constrains farmers to plant into soybean stubble; and
3) address farmer questions about the long-term benefits of adopting native plantings, a large up-front investment that is purported to accrue benefits over time.
Approach
The approach for Objective 1 is to establish a planting flexibility experiment on marginal crop ground testing two levels of planting time, seeding equipment and seeding rate in a fully factorial design. We will measure multiple aspects of vegetation function (erosion resistance, pollinator resources and biodiversity) and cost-effectiveness (cost per 1000 plants).
For Objective 2 we will compare the results of dormant broadcast seeding in corn stubble and soybean stubble, in a side-by-side demonstration.
For Objective 3 we will re-sample 1-2 trials originally supported by INRC after 7-8 years to assess the provision of long-term ecological benefits. These trials were conducted on marginal ground, in the context of CRP plantings. Results will inform recommendations for installing perennial vegetation on marginal land, expanding options for a proven nutrient reduction practice.
Project Update
December 2025
During the reporting period, we conducted a follow-up vegetation survey on one of our earlier INRC projects (broadcast vs. drill seeding experiment in Black Hawk County) and began preliminary data analysis. We repeated the field sampling protocol used in 2019-2020 this August, and began repeating the data analysis procedures used in Meissen 2020.
Preliminary results indicate that small-seeded species remained more abundant over the long term (7+ years) in broadcast seeded sites compared to drill seeded sites. As expected though, both seeding methods produced successful stands (dense, biodiverse stands of native species).
In September, we collected data and ran preliminary data analyses on seedling establishment in a new demonstration area at UNI’s Irvine Prairie addressing dormant broadcast seeding into corn vs. soybean residue. The area dormant broadcast into soybean stubble produced seedling densities that were similar to other areas seeded into soybean stubble at Irvine prairie (36 seedlings/m2), which is a density similar to other studies (Meissen et al 2020, Glidden et al. 2023). In the areas dormant broadcast into corn stubble, we found 68.8 seedlings/m2, a 92% increase compared to the soybean residue areas. A difference this large was unexpected, though encouraging. This finding mirrors anecdotal data from those who use this technique (eg. Iowa DNR, prairie restoration contractors) who consider it a preferred method.
Further analysis will investigate any species-specific patterns that drive the difference in seedling establishment between seedbed types. We designed and partially implemented the new planting flexibility experiment at Irvine Prairie. Throughout Aug-Oct, we designed and laid out the new field experiment on marginal lands in the farmed area of Irvine Prairie. We were able to establish the experiment described in the initial proposal using 48, 5x20m plots arranged in two blocks. On November 14th, we seeded the early-dormant seeding treatments. We will complete implementation in March 2026 when we seed the late-dormant treatments.