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Killing A Cover Crop

Cover crops restore nutrients in the soil, prevent erosion, and choke out weeds. But there comes a point where you have to kill the cover crop. All plants want to reproduce, and if the cover crop is allowed to seed it can build up a seed bank in the soil that could haunt you for years to come.

Jerry Hall is the president of Grassland Oregon. He says the time to kill a cover crop is in the spring. If it dies due to winterkill, you’re good to go. Otherwise, Hall says there are three main methods of termination.

"You’ve got conventional tillage which you’re actually working them into the ground like a green manure crop," he says. "You have herbicides, a non-selective herbicide works well. Or you can go in there and use what they call a ‘roller-crimper’ that rolls and cuts off and crimps the plant so it terminates it that way."

Deciding which method to use is determined by your access to equipment. Hall says if you’re a conventional tillage person, you’re already going to till the soil. No-till farmers have the option of an herbicide or the roller-crimper.

Once the plants are dead turn them under the soil. Some cover crops are considered “bio-fumigants” and continue offering benefits.

"Go in there, you’ll want to chop them up into small pieces and then till them in and incorporate them in the soil. As those plant tissues decay, they actually fumigate the ground and get rid of harmful insects and nematodes, as well as some of them are designed to help control weed seeds," says Hall.

Depending on the cover crop species and method of killing it, you may need to leave some time before planting something else in that location.

Learn more about terminating cover crops