Cover Crop Seeding Techniques: Overseeding

Here at Iowa Learning Farms, we’ve been hard at work these past few weeks getting cover crops seeded at our demonstration sites across the state. As cover crops continue to grow in popularity, there are a lot of questions to consider when first getting started. One of the most common questions we get asked at field days, workshops, and county fairs is “How do you plant the cover crop?”

There are a variety of cover crop seeding techniques out there, including overseeding, broadcast seeding, aerial seeding, drilling, and more. Over the next few days, we’ll highlight several of these techniques in individual blog posts.

Up first is the overseeding technique – seeding the winter cover crop into a standing grain crop. Here in Iowa, one of the biggest challenges is that our window of time for fall cover crop growth is limited, particularly if the cover crop is seeded post-harvest. Overseeding extends that window of time, allowing for earlier seeding, germination, and growth (provided there is adequate precipitation and/or soil moisture to get started).

The high clearance interseeder is prepped and ready to plant cover crops at the Iowa State University Northern Research and Demonstration Farm near Kanawha on August 27, 2015.

During the last week of August, we overseeded several of our cover crop demonstration sites in north central Iowa with a high clearance seeder. This work was done in partnership with Hagie Manufacturing of Clarion utilizing their Cover Crop Interseeder, which was developed in 2013, allowing their high clearance sprayer to be converted to a seeder.

With the seeder kit, there are individual drop tubes that attach and, as the name implies, drop the seeds directly in the interrows as you drive through the standing crop (yes, we seeded into standing corn!). The cover crop seed is loaded into a seed hopper, and then you’re ready to go! Read more about these and other high clearance seeders in the Iowa Farmer Today article titled Manufacturers work to meet cover crop needs.

The view from up top: looking out across the field with the cab and the seed hopper (loaded with cereal rye) in the immediate foreground.

Overseeding of winter cover crops into standing corn just outside Clarion on August 27, 2015; the cover crop seed travels down through the drop tubes, pictured here, and is dropped below the canopy of the standing corn.

The boom on the high clearance seeder can be adjusted to different heights. Our demonstration plots were seeded at two different heights for comparison – one set of plots was broadcast seeded below the canopy, while other plots were seeded above the canopy. Later in the fall, a third seeding technique will be implemented – post-harvest drilling.

These trials are part of a USDA-NRCS Conservation Innovation Grant titled “Evaluating Planting Techniques for the Successful Establishment of Cover Crop Mixtures and Single Species in Iowa.”

Visit ILF’s Cover Crop Resources page to learn more about our ongoing cover crop demonstration projects and the many cover crop informational resources we have available. And stay tuned for additional cover crop seeding techniques to come!

–Ann Staudt