Growers who use cover crops are increasingly turning to a tool that can flatten out their actively growing fields, usually in a single pass.

Known as a “roller/crimper,” the technology can help reduce and sometimes eliminate the need for herbicides and is ideal for organic farmers and growers interested in reducing herbicide use.

Cover crops can improve soil quality; and in organic operations, they play a major role in keeping weeds in check.

Crimpers boost those benefits. They have been used for years in South America and are beginning to catch on in the United States, says Ted Kornecki, an agricultural engineer at the Agricultural Research Service’s National Soil Dynamics Laboratory in Auburn, Ala.

He has conducted a study evaluating several crimpers to give guidance to growers and has patented three crimper designs.

There are several types of crimpers. Most involve some type of rolling, paddle-wheel-like cylinder that attaches to a tractor and barrels over a field, tamping down and crimping the cover crop into a smooth mat to kill it.

About 3 weeks later, a planter, running parallel to the roller’s path, can plant seeds directly into the ground without significantly disturbing the biomass mat. The technology has shown promise in early trials and demonstrations.

“It definitely works,” says Frank Randle, who helped evaluate a crimper similar to one designed by Kornecki as part of a 4-year demonstration project on his farm near Auburn. Randle used cereal rye and crimson clover as cover crops before planting organic watermelon, squash, okra, and tomatoes. The clover was difficult to kill with the crimper, but the device terminated the rye effectively.

After the 4th year, Randle did have to till the plots to control some perennial weeds, but the crimper could be used again continuously for years after that.

“Yields actually increased a bit over time with the rye because we were adding carbon to the soil, and these are sandy soils that really need some help,” Randle said.

The project was a cooperative effort between ARS and USDA’s Natural Resources Conservation Service (NRCS). Funding was provided by an NRCS Conservation Innovation Grant.

‘Termination’ rates are key

Cereal rye is a fairly common choice of cover crop among growers, Kornecki says. Rye is typically planted in the fall, killed in the spring, and left to decompose before a cash crop, such as corn, is seeded through it.

The effectiveness of crimping a cover crop largely depends on its ‘termination rate’, or the percentage of it that dies after crimping. Studies show that termination rates of about 90 percent are optimal to ensure that enough residue remains on the soil surface to form a dry, brittle mat that will be easy to penetrate with seeding equipment.