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Drewnoski: Planting date makes a difference in cover crop quality, yield

by Wyoming Livestock Roundup

There is a lot to consider when planting a cover crop for grazing. Timely planting, as well as selection of the right species can impact yield and quality, according to University of Nebraska Beef Systems Specialist Mary Drewnoski.

“When we talk about cover crops, what we are really talking about is trying to put forage production into a system with an already proven cash crop,” Drewnoski told producers during the Nebraska Grazing Conference in Kearney, Neb.

“It is a little different than a traditional annual forage system. What that means is we have a window of opportunity if we are looking at fall forage production. It is graded in our growing degree system,” she explained.


“Planting date is extremely important when we are thinking about fall forage production,” Drewnoski stated.

Referring to some previous research, she showed producers the difference in size of a Purple Top turnip and a seed radish planted Aug. 25 versus Sept. 8. While the earlier planted radishes and turnips were of significant size, the later planted ones had leaves, but barely any radish or turnip growth.

“The heat units make a lot of difference,” she explained. “There was a quarter of a heat unit decrease during those two weeks.”


A common question from producers is what to plant as a cover crop. Drewnoski recommended first looking at when they want to plant the crop.

“If the producer can get it in before Aug. 10, warm season grasses, like sorghum Sudan or pearl millet, will provide the most yield,” she said.

However, if producers are worried about prussic acid or don’t plan to graze until later in the season, cool season grasses like oats or brassicas may be a better option.

“Oats and brassicas will maintain a high quality, while still producing a significant yield,” she explained. “If producers are planting after Aug. 10, they may want to consider a winter sensitive, cool-season species like oats, possibly spring Triticale or brassicas, like rape, kale, turnips or collards,” she said.

After Sept. 10, which Drewnoski considers to be the final date for fall forage production, producers should plant something they can utilize in the spring.

“I would consider winter hearty rye or Triticale based on the potential date for grazing and the potential termination date,” she said. “If producers are looking for the earliest possible spring forage, rye or cereal rye is pretty hard to beat. But, it will get rank if it is grazed later into the season.”

“If they can’t keep pressure on it, producers will lose more quality with cereal rye than Triticale,” she noted.

Cereal rye may also be the best choice if a producer plans to graze May 1, and winter Triticale for grazing in June or later.


Planting as early as possible to maximize fall growth is important.

“If producers are trying to work this into a cropping system, they will probably be harvesting at the same time they need to be planting this cover crop,” she explained.

Producers may want to consider hiring it out just because that extra two weeks of growth could pay for itself.

“If they are thinking about forage production, they need to get it planted as early as possible,” she said.

If producers have access to irrigation, she strongly encourages them to put a little water on to get the plants to germinate.

“These plants are really not growing till they are germinated,” she said. “The dryland situation is tougher, because we can’t manage the moisture. We can’t control rain.”

Gayle Smith is a correspondent for the Wyoming Livestock Roundup. Send comments on this article to

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