According to the 2022 Census of Agriculture, nearly 754,000 acres of cover crops were planted in Wisconsin. As more farmers turn to using cover crops to improve their soils, they are learning the same species also protect against weeds.

Cereal rye, which produces 4,000 to 5,000 pounds of biomass per acre, “can provide tremendous weed control in a crop,” says Rodrigo Werle, a state expert on cover crops for weed control. The University of Wisconsin Extension associate professor and weed specialist says, “Cereal rye for soybeans has become the No. 1 cover crop in Wisconsin for weed control.”

There are some caveats though, Werle notes. “It’s not as good in a dry year like 2023,” he says. “Heavier soils take longer to accumulate biomass.” He’s also found that cereal rye does not work as well in corn as in soybeans. His research focuses mainly on a corn-soybean rotation. Adding wheat to the rotation brings in the possibility of working with radishes or other cover crop species.

“There are several factors to consider,” Werle says. “It’s a little different than recommending herbicides. Growers are going to have a little extra work to do on the farm. They need to be strategic.”

Werle says he sees a lot of cases of cover crop failure while driving around the state, while at the same time also seeing a lot of fields with rye plantings.

“Rye establishes itself,” he says. “All you need to do is get it there in time. It will survive winter and grow in spring.” To build enough biomass to suppress weeds, Werle advises planting cereal rye as early as possible in the fall and allowing it to grow as late as possible in the spring to achieve the 4,000 to 5,000 pounds of biomass per acre for good weed control.

At the same time, he says, “you need to produce enough biomass but not too much — it’s a fine balance.” He says a preemergence residual herbicide sometimes has a “tremendous amount of interception.”

Cost-sharing for cover crops

Werle says government programs are available for cost-sharing on cereal rye. “Some pay a significant amount of money,” he says. “They should be checked out.”

Research by UW-Madison graduate student Guilherme Chudzik, working with Werle, has shown that cereal rye biomass of at least 3,500 pounds per acre reduced giant ragweed in soybeans by at least 50%.

In other research, reported by wiscweeds.info, a website for information on controlling weeds, cereal rye was the least sensitive species to the most effective herbicides for waterhemp control in soybeans, followed by radishes. Red clover and annual ryegrass were the most sensitive species to the most effective herbicides for waterhemp control.

Werle adds that while observing cropland around the state, he sees that farmers are concerned about soil health and water quality.

“Wisconsin farmers definitely are at the forefront for adapting sustainable practices,” he says.

Still, Erin Silva, a UW-Madison professor of organic and sustainable agriculture, has been quoted as hoping for more, especially among cash croppers who may fear that cover crops could negatively impact their money crops. She cites enough evidence to the contrary for more farmers to make the move, particularly with common cover crops like cereal rye.

SEEDING COVERS: Cade Christensen from CAL Drone Applications LLC fills a drone with cover crop seed.

Sheboygan County farm committed to covers

“If rye is the cover crop, it’s certainly going to hold down weeds,” says Sheboygan County, Wis., farmer Brody Stapel. Stapel and his brother Jory and dad, Rudy, farm 1,000 acres at Cedar Grove and Howards Grove.

While Stapel says weed control is not the primary reason they use rye as a cover crop, he says it is one of the reasons they use it in rotations. Plus, they think enough of it to also raise the crop commercially for seed sales.

The family rotates corn, soybeans and wheat, and uses both rye and triticale as cover crops. They also raise annual grasses for livestock feed. Stapel points out that they have had success with rye as a cover crop following silage corn and wheat.

Cover crops became part of the family’s rotation beginning in 2017 on land devoted to wheat. By 2019, they had converted every acre to cover crops.

Stapel acknowledges that it was a struggle last fall to plant rye on grain corn acreage. “We used a drone to spread rye seed. We did it in October,” he says.