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Corn+Soybean Digest

Cover Crop Starter | Great Resources Offer Help with Valuable Practice


A list of cover crop benefits came easily for more than 50 farmers at the Iowa Crop Advantage workshop:  erosion control, weed control, improved soil organic matter, nutrient retention, better water infiltration and reduced nitrogen losses.

But these farmers came to drill down into the details: Which species to plant? Drilling or aerial seeding? The best time to plant?

Getting into cover crops can be complicated, admits Sarah Carlson, research and policy director for Practical Farmers of Iowa (PFI). Even your location can change both the answers and where to go to find them.

“For example, Dave Robison’s blog ( is a terrific source if you’re in Indiana or Ohio, but you have to be careful how you use the information if you’re north of Interstate 80 in Iowa,” she says. “The weather makes a difference in what works best.”

For growers just getting started, Carlson suggests several information sources and an easy “starter recipe:”

“In a corn-soybean farming system, especially north of I-80, you need to over-seed by plane or Highboy. That should be when soybean leaves are yellowing or corn is at black layer stage, probably around Sept. 1.

“That’s a good time to fly on winter wheat or winter rye. They can sit on the soil surface for a while until it rains and you will still get a good stand. Winter rye is built for this (northern) climate. It’s really hardy, grows at cold temperatures and if it’s actively growing, it can be easily killed in the spring using an herbicide,” she explains.

“You have to watch, however, because rye can get away from you. If you’re going into corn, you have to kill the rye two weeks before planting. This and other best management practices can reduce the risk of yield loss from winter rye.”

Growers who’ve never used a cover crop before may want to try oats before corn instead, she suggests. 

The basic recipe is different for anyone raising short-season soybeans, seed corn, seed soybeans or corn silage. 

“With a shorter crop you can drill winter small grains instead of aerial seeding. This improves soil to seed contact, and drilling before Oct. 1 will ensure a good, hardy stand,” Carlson explains.

To locate state-specific guidance, she urges growers to check out the Midwest Cover Crops Council (MCCC) website ( locate the best state sources in Illinois, Indiana, Iowa, Michigan, Minnesota, North Dakota, Ohio and Wisconsin.

MCCC also offers practical reference books through its website – Managing Cover Crops Profitably and The Midwest Cover Crops Field Guild, newly published this winter.

“For getting specific questions answered, your state Extension can often help, but one of the best things you can do is get on Dave Robison’s e-mail list or follow his blogs,” Carlson recommends. “That’s where your questions can be answered by experienced farmers, Extension and NRCS agents across the Corn Belt.” 

Finally, there are varying levels of support available for farmers interested in conducting on-farm cover crop trials, Carlson says.

“In some states it may only be providing guidance, but in Iowa the PFI has conducted on-farm studies since 1987, and we have funding to help with the costs. 

“Demonstration is what we’re about,” Carlson says, offering to field growers’ questions at 515-232-5661.

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