The spring seeding of cover crops in Quebec began five or six years ago and Dan Towery had grave concerns. How does it make sense to consider adding annual ryegrass between rows of knee-high corn in June?

But after repeated trips to Quebec to witness the successes – including a bump in corn production – Dan is more than cautiously optimistic. He’s now pushing forward with vigor various trials with spring “interseeding” of cover crops in the northern Corn Belt.

Last year was the first limited trial and it was successful, both in terms of the cover crop surviving but also in terms of corn production. Perhaps the biggest benefit of a spring cover crop seeding: by doing the planting in the spring, it eases farmers’ fall schedule, pressed as they are with corn harvest and weather suitable for establishing a cover crop planted so late in the year. Pictured below is an older harrow that was retrofitted (removed some teeth and adding a Gandy linear seeder on top) that was funded by the Oregon Ryegrass Commission, a pioneer in cover crop research trials and education in the past 20 years.

Last year, in different control plots, the bump in corn production over adjacent fields was 6 bu/ac using annual ryegrass, and 15 bu/ac using hairy vetch. “We’re not sure why the hairy vetch was so much more beneficial to the corn production,” he said, “but my hunch is that hairy vetch being a nitrogen fixer, there’s something going on with the mycorrhizal (fungal) hyphae in conjunction with the corn roots.” We’ll be looking at learning more that connection this year.”

This year, Towery is overseeing the expansion of the test plots “in the northern one-third of the Corn Belt.” Towery said he’s curious how far south the practice will be tolerated. “The more heat, the more dryness, the less likely we’ll see a successful spring cover crop program.”