U.S. Department of Agriculture (USDA) scientists are giving guidance to farmers on using a tool designed to maximize the advantages of planting cover crops. The technology, known as a “roller/crimper,” can reduce and sometimes eliminate the need for herbicides.
Cover crops can improve soil quality, and in organic operations, they play a major role in keeping weeds in check. Crimpers have been used for years in South America and are catching on in the United States, according to Ted Kornecki, an agricultural engineer with the Agricultural Research Service (ARS) National Soil Dynamics Laboratory in Auburn, Ala.
ARS is the USDA’s principal intramural scientific research agency, and this research supports the USDA priority of promoting international food security.
Kornecki and his colleagues assessed the effects of three experimental rolling and crimping systems—including two they designed—on soil moisture, yield, and other factors in a northern Alabama sweet corn field. They planted cereal rye as a cover crop for three successive Octobers, crimped it each year during the following April with three different roller/crimpers, and planted sweet corn three weeks after that. They passed the crimpers over the rye at two different speeds to assess the effects of different speeds.
Using cereal rye as a cover crop helps the soil retain moisture, reduces erosion, promotes the formation of soil organic matter and provides a physical barrier to control weeds. The effectiveness of using rye with a crimper largely depends on the rye’s “termination rate,” or the percentage of it that dies off when it is crimped. Studies show termination rates of about 90 percent are optimal to ensure sufficient stalks and plant material remain on the soil to form a dry mat that can be penetrated with seeding equipment.
The results, published in 2012 in HortScience, showed that the roller types and operating speeds did not affect soil moisture, and that the rollers produced higher yields than the control treatment at both speeds. The rollers were not as effective at killing the rye as the chemical glyphosate applied as a control, but that was because the researchers planted the corn on the recommended dates, and that meant having to roll the rye earlier than when termination rates would have been optimal.
Based on their findings, the researchers recommend that growers in Alabama plant the rye by late September, instead of mid-October, so that it can be rolled two weeks earlier in the spring. They also recommend making multiple passes with the roller to increase termination rates.