Knowing the differences between annual ryegrass and cereal rye will allow farmers to choose the best applications for each crop, which will improve profitability.
But many growers and seed dealers confuse these crops because they share the word “rye” in their names, according to a news release from the Oregon Ryegrass Commission.
Annual ryegrass is a cool-season grass, while cereal rye is a grain that has growth characteristics much like wheat. Annual ryegrass seed costs slightly less than cereal rye, is much smaller and weighs 26 pounds per bushel. The seed of cereal rye is much larger and weighs 56 pounds per bushel.
Like many cover crops, annual ryegrass builds soil, reduces runoff and erosion, sequesters nitrogen, improves water infiltration and increases organic matter. Annual ryegrass is easy to establish in the fall with adequate moisture. For best results, it needs to grow for 45 to 60 days before freezing temperatures arrive. Annual ryegrass is more susceptible to winterkill, which can be caused by a lack of snow cover combined with very low wind chill and multiple freeze-thaw events.
Annual ryegrass residue breaks down more quickly than that of cereal rye. In trials in the Midwest, about 70 to 80 pounds of nitrogen per acre were available to the following row crop, after annual ryegrass was burned down. These results depended on field history.
Many farmers look for a cover crop capable of breaking through layers of soil compaction. Annual ryegrass performs much better than cereal rye, especially below 24 inches. The roots of row crops will follow the annual ryegrass roots deeper for nutrients and moisture that otherwise would not be available.
“In a dry year on a fraigpan soil, I’ve seen a 50 bushel-per-acre-boost in corn yield, where one part of the field is no-till and the other has had 6 years of annual ryegrass as a cover crop,” Dan Towery, a crop advisor with Ag Conservation Solutions, in W. Lafayette, Ind., says.
Mike Plumer, a University of Illinois Extension agronomist and cover crops specialist, says he would never recommend cereal rye to solve soil compaction.
Cereal rye is one of the most common cover crops.
“You can plant it later than many other cover crops and don’t have to worry about winter kill,” Towery says.
Cereal rye will survive all right in low rainfall, but it doesn’t do well in excessive moisture. It also grows fine in low soil fertility and sandy soil. Annual ryegrass does just fine in a wet climate. While it prefers fertile soil, annual ryegrass does well on poor, rocky soils and will do better than cereal rye in denser clay soils, according to the Sustainable Agriculture Network.
More biomass is a plus for cereal rye during the fall, winter and early spring because it provides good weed control. Annual ryegrass also is effective with weed control.
Cereal rye can dry out topsoil during a dry spring if it is not killed with a timely application of herbicide. On the other hand, cereal rye can get away from growers in a wet spring and can grow more than 6 feet high. That mat of residue can keep soils from drying out and warming up in a timely fashion. Heavy residue from cover crops can interfere with planting, according to a Purdue University study.
Annual ryegrass is generally burned down when it reaches 8 to 16 inches high. With far less biomass than cereal rye, annual ryegrass offers growers more flexibility because it doesn’t consume as much soil moisture. However, annual ryegrass is more of a challenge than cereal rye to burn down during cool weather when glyphosate doesn’t translocate as well.
While annual ryegrass and cereal rye both sequester nitrogen, cereal rye has more vegetation above ground in the spring, especially if it’s allowed to grow. That growth can tie up nitrogen, so it’s best to eliminate cereal rye while it’s less than 16 inches tall.
Whatever cover crop growers choose, Towery recommends starting on a small scale.