In general across the Midwest, conditions are good for planting wheat and cover crops this fall.
“Right now everyone seems to have pretty ideal soil conditions,” said University of Illinois Extension educator Nathan Johanning. “There’s moisture in the soil. It’s not sloppy and wet or nearly as dry as it had been. Cereal cover crops tend to like it better on the drier side.”
As farmers gear up for corn and soybean harvest, many will be following with either wheat or a cover crop to cover the ground through the spring. What, when and how much can vary.
“It depends on what your goal is and when you want to kill it,” said Lowell Gentry, a University of Illinois research scientist. “There are different rates for different purposes.”
Pioneer agronomist Sarah Strutner expects a big push in wheat planting this fall.
“Wheat acres are going to be way up. I believe we’re already sold out of wheat,” she said. “It might be earlier than usual. We’ve been planting earlier maturity soybeans and they’re getting into the fields now to get beans cut.”
Gentry’s research is aimed largely at addressing nitrate loss into the water table, specifically how much above-ground cereal biomass is needed for a measurable reduction in tile nitrate.
“Just about a half-ton is the magic number,” he said. “It’s not a lot of biomass.”
He has been impressed with the efficacy of planting cereal rye, one of the more popular covers planted in the Midwest.
“We tried winter barley in front of corn this year. It’s not quite as aggressive as cereal rye,” he said.
One thing Gentry and other researchers are discovering is that there is an inverse relationship of cereal rye biomass to percent of nitrogen produced.
“If I let it grow three times larger, that small plant had two-thirds of the nitrogen than the one that grew three times more,” he said. “The earlier we kill it, the narrower the carbon-nitrogen ratio is, and that’s a good thing when you’re talking about nitrogen cycling.
“You don’t want microbes out-competing your corn plants for mineralized nitrate. That’s what’s happening: direct competition. It’s too much biomass. With soybeans it doesn’t matter. It doesn’t seem to be bothered that microbes are chewing up that residue and tying up nitrogen. The soybean can get around that little problem.”
Many areas of the Midwest have had sufficient rainfall during the growing season, and farmers are getting into the fields to harvest corn. With soybeans close behind, conditions for putting in wheat and cover crops will be top of mind.
Johanning pointed out that dry conditions are ideal for putting in fall-planted crops.
While soil enhancement is a major goal of planting cover crops, there is some benefit of weed control. Still, Gentry warns against placing too much emphasis on that aspect.
“I’m not sure if that’s the way to go to totally replace a post-emergence herbicide,” he said. “That would be a lot to ask.”