I recently had a conversation and live Q&A session about cover crops with my Iowa State University (ISU) colleague, Matthew Helmers, that was broadcast live to some 250 farmers and recorded as a part of the Beyond the Basics: Advanced Cover Crop Series webinars produced by Iowa Learning Farms (ILF). Over the past several years, he and I have had many opportunities to speak with farmers about cover crops at events and on their farms. In these conversations it has been clear that while interest in cover crops continues to grow, many are still looking for more details and specific guidance that can jump-start success on their farm.
In the broadcast webinar we covered a lot of ground and answered many questions from the audience, but in this article, I will highlight the part of our discussion focused on cover crop adoption and advice to farmers on achieving cover crop success.
In Iowa, cover crop acres top 1 million — representing 5-10% of corn and soybean acreage, and the situation across other Midwestern states is reportedly similar. To maximize the collective benefits of cover crops that include water quality improvement goals, erosion prevention and soil health improvement, we need to be looking at 40-50% coverage.
Planning for Success
Introducing cover crops is a big change to the cropping system as a whole, but the changes can create a more resilient production system. Getting started requires an examination of and often modifications to tillage activity, fertilizer timing and application methods, and herbicide programs.
The nuts and bolts of a successful start with cover crops include:
- Adopt no-till.
- Review herbicide programs to ensure there are no residuals that will prevent germination in the fall.
- Establish a seeding program that meets goals for each farm or field.
- Seeding can be done by plane, UAV, drilling or broadcast
- Consider live seeds per acre rather than pounds per acre
- Select a seed mix that aligns with cash crop and land management goals
- Manage timing to ensure fall establishment
- Plan termination timing in relation to cash crop planting requirements.
- Planting soybeans into “green” cover crops
- Herbicide termination 10-14 days before planting corn
A good resource to guide for a specific set of conditions and goals is the Whole Farm Conservation Best Practices Manual from Iowa Learning Farms.
Goal-driven Species Selections
While cereal rye is probably the most widely used cover crop, it is not a one-size-fits-all choice. Species selections should be customized to address land and soil conditions as well as operational goals.
For erosion control, we want to use small grains with root systems that hold the soil in place. To maximize the benefits ahead of corn, a mixture that includes oats as well as clover or brassicas such as radish, mustard and rapeseed may be the right approach. For hard and clay soils or areas compacted by equipment, the typical long tap roots of brassicas will be more effective in pushing through the compaction layers than the fibrous root systems of grasses.
Other options include crimson clover or hairy vetch, mixed with oats or a winter triticale or winter wheat that can over-winter but not have the same vigorous growth in the spring as cereal rye (which can affect corn crop productivity).
When Do We See Results?
While some benefits of cover crops such as reductions in erosion and nitrate leaching can be seen immediately, more complex systemic benefits can take longer to become evident. Many farmers report changes to soil health and water infiltration after 2 to 5 years of persistent cover crop use. However, from a scientific perspective it can take as long as 5 to 10 years to document the small changes to organic matter, infiltration rates and other factors before we can really start to detect changes from a soil health perspective.
Resources to Get Started
There are numerous cost share programs that can help to offset cover crop seeding expenses. Check with your local NRCS Service Center on availability and qualifications. University extension programs in every Midwestern state are also great resources for advice and information about cover crop approaches.
If you want to dig deeper into our wide-ranging conversation about cover crops, please visit the ILF webinar archives.
The next edition of Beyond the Basics: Advanced Cover Crop live webinars will be:
April 15, 2026, at noon CDT – Live Webinar with ISU weed scientist Wesley Everman
Click here to register for these cost free ILF webinars.
