Cover crops provide a wide variety of benefits, from capturing root-zone N to improving soil tilth. But cover crops that interfere with your cash crop can do more harm than good, which is why terminating them is so important.

The easiest cover crops in the upper Midwest are probably oats, tillage radish and/or Austrian winter peas, which die naturally in winter weather, notes Florian Chirra, Ohio State University Extension educator in Bryan, Ohio. Chirra is one of three Extension agents in the Great Lakes Cover Crop Initiative, an EPA-funded program to demonstrate, evaluate and promote cover crops in the watersheds that feed Lake Michigan, Lake Huron and Lake Erie.

Planted after wheat harvest or into standing soybeans or corn, oats can anchor nutrients left behind near the surface by the previous cash crop. The oats return most of those captured nutrients to the soil as their own foliage, stems and roots break down after winterkill. Oat root systems also help build soil organic matter and improve tilth, Chirra says.

For more dramatic impact on tight soils’ tilth, tillage radish is known for its long, sturdy roots taproots that dig deep in the soil to loosen hardpans and capture N.

Austrian winter peas, clover and other legumes can fix N in the soil. They are often planted in a blend with other cover crops to provide a boost to the cover, or in dense enough stands to add some “free” N to the field. Legumes are often paired with a grass to capture the fixed N and protect it from leaching.