Cover Crop Commentary: Fall Seeding
If you frequent any ag forum, chances are you will see discussion on cover crops with opinions ranging from growers who have had success to growers who have given up on them. Cover crops do have the potential to increase organic matter, provide weed control, reduce compaction and erosion, and produce feed for livestock. However, they also come with some potential downfalls and their own set of challenges. Whether you’re on the cover crop train or not is entirely up to you, but if you’re even just a little bit curious, here are a few things to consider for fall cover crop seeding in Iowa and across the Midwest.
Fall Cover Crop Seeding Methods
One of the first steps to integrating cover crops into an agronomy plan is deciding how to seed in the fall. There are multiple ways to approach cover crop seeding.
Drilling
While drilling guarantees the best seed distribution and seed-to-soil contact, it is also dependent upon the corn and soybean harvest being completed. Depending on how long that takes, drilling might not be able to take place until after the ideal planting date (mid to late October). Less grow time equals less biomass and nitrogen uptake (Licht, 2019).
Broadcasting with Incorporation
Broadcasting with incorporation is the most common seeding method we see our customers using. This method can occur using a single or double pass system. One example would be using an air seeder or applicator like the Valmar 56 Series attached to a piece of equipment. After the seed is broadcasted, it should be incorporated into the soil using vertical tillage or another tillage form. Some growers use a rig that allows them to seed and incorporate (i.e., broadcasting seed while applying dry fertilizer and tilling) in a single pass rather than two. We find that growers in our area prefer broadcasting cover crop seed with dry fertilizer and following with tillage. Broadcasting with incorporation should also take place from mid to late October after the corn or soybean crop has been harvested (Licht, 2019).
Overseeding
Overseeding is done using high-clearance equipment or aerial broadcasting since it takes place when there is standing corn or soybeans in the fall (Licht, 2019). Aerial seeding is one of the more common seeding methods used in the Midwest because it can be done while the corn or soybean crop is still in the ground around late August to early September. Overseeding should take place by September 15. Aerial seeding also allows for more acres to be seeded in less time. However, it tends not to be as evenly distributed and has a greater likelihood of the seed being eaten by rodents or birds. To combat this, it is better to plant a heavier cereal grain and overseed when the soil is not dry (Licht, 2021).
Aerial seeding can also now be done using a drone; however, it is not done this way much in our area yet. Drones can more easily navigate smaller fields, more obstacles or acres near urban areas, all of which make it more difficult to seed using a plane (Swoboda, 2020). Only time will tell how soon this method hits our area. Planes, on the other hand, can be more cost-effective at times, especially for growers with more acres. There are also other factors at play including the cost and availability of either option.
Timing
Timing … it’s everything when it comes to cover crops. When it comes to drilling or broadcasting with incorporation, the timing challenge is waiting for the fall corn and soybean harvest to be completed, which can reduce growing time. On the other hand, for overseeding, cover crops cannot be planted too early because corn and soybeans will shade the seeds and prevent germination, but the earlier cover crops, like rye, can get planted, the better. Plus, the earlier a cover crop is planted, the more biomass it will generate, leading to important benefits.
Since seed-to-soil contact cannot be guaranteed with overseeding, the soil surface and weather conditions also need to be accounted for. When the ground is too dry it can hinder germination. For this reason, it’s ideal to postpone overseeding until rain chances improve if the soil is particularly dry. Cereal rye, a common cover crop in Iowa, is also a good option during drier times because it has a better overwintering survival rate (Licht, 2021).
Cover Crop Funding Opportunities
With conservation at the forefront of federal and private funding, there are multiple cost-share opportunities for growers willing to implement cover crops into their operations (Viner, 2023). Federal programs like EQIP help share the cost of cover crops. Private funding can also come from organizations like Practical Farmers of Iowa, which has a program that is stackable with other programs like EQIP (Bader, 2020).
Make the plan. Adapt the plan. Execute the plan. Adjust the plan.
In addition to developing a plan for how you want to seed your cover crops, it’s important to consider how you will terminate cover crops and when you will terminate. Termination should happen at least 10 to 14 days before planting, especially for corn (Anderson, 2023). If termination does not happen enough in advance, detrimental effects can occur for the field. There are growers who cut termination too close to planting time.
Even though cover crops have been around for many years, we are still learning more about how to best use them. The ever-unpredictable weather does not make that any easier. Nevertheless, without a plan and some practice, you will most likely not see the results you are hoping for. There is no “one size fits all” approach. Fortunately, there are resources out there for getting started with cover crops, and of course, our agronomists are always here to help provide answers on seed and application options.
Sources
Anderson, M. (2023). Cover crop termination review for 2023. Iowa State University Extension and Outreach. https://crops.extension.iastate.edu/blog/meaghan-anderson/cover-crop-termination-review-2023
Bader, Z. (2020). Iowa cover crops: Answers to 8 common questions. Iowa Farm Bureau. https://www.iowafarmbureau.com/Article/Iowa-Cover-Crops-Answers-to-Common-Questions
Licht, M. (2019). A look at cover crop seeding methods. Iowa State University Extension and Outreach. https://crops.extension.iastate.edu/blog/mark-licht/look-cover-crop-seeding-methods
Licht, M. (2021). Considerations when overseeding cover crops. Iowa State University Extension and Outreach. https://crops.extension.iastate.edu/cropnews/2021/07/considerations-when-overseeding-cover-crops
Swoboda, R. (2020). Drones fly on cover crop seed. Farm Progress. https://www.farmprogress.com/technology/drones-fly-on-cover-crop-seed
Viner, A. (2023). Funding charges up conservation efforts. Iowa Farmer Today. https://agupdate.com/iowafarmertoday/news/state-and-regional/funding-charges-up-conservation-efforts/article_fd94a852-110d-11ee-9ee7-afc493fee9d0.html