Courtesy USDA/ Matthew Ryan
In a field of rolled cereal rye, ecologist Steven Mirsky evaluates ground coverage of the rye mulch and weed emergence through it.
USDA scientists are helping farmers adopt an environmentally friendly practice that’s catching on nationwide: rolling rye when using it as a cover crop.
Cereal rye is increasingly being used as a cover crop because it prevents erosion, helps the soil retain nutrients, and reduces the need to till the soil, according to Steven Mirsky, an ecologist in the Agricultural Research Service’s Sustainable Agricultural Systems Laboratory in Beltsville, Md. This research supports the USDA priorities of responding to climate change and promoting international food security.
When used as a cover crop, rye is planted in the fall, killed in the spring, and left to decompose in the same fields where soybeans and other cash crops are later planted. But instead of mowing their rye, many farmers are now flattening it by attaching a rolling, paddlewheel-like cylinder with metal slats to a tractor and barreling over the rye, tamping and crimping it into a mat.
Rolling rye with a roller-crimper uses less energy than mowing, is faster and only needs to be done once per season. Unlike mowing, it also leaves rye residue intact in the field, forming a thick mat that can provide better weed suppression, Mirsky says.
Mirsky planted two common types of rye, Aroostook and Wheeler, in test plots in Pennsylvania at six 10-day intervals in two successive autumns. He used a 1½-ton steel roller-crimper, constructed by colleagues at Pennsylvania State University, to flatten the rye at 10-day intervals each spring. He then visually rated the rye’s regrowth on a scale of 0 to 100, six weeks after each plot was flattened.
The results, published in Agronomy Journal, show that the best time to roll the rye is when it reaches 50 to 75 percent of its flowering state, because that’s when rolling consistently kills the rye. The researchers also are working to develop a web-based tool that growers around the country can use for guidance, possibly by typing in ZIP codes or other information that identifies their locations.