Annual Ryegrass is sometimes confused with Cereal Rye. They are very distinct from one another. Cereal Rye (Secale cereale) is a grain, related closer to wheat than to a grass.
Annual ryegrass (Lolium multiflorum) has traditionally been used for lawns and as a forage crop for livestock. In the past decade, however, annual ryegrass has also become popular as a cover crop, used in No-Till farm operations over the winter, grown in between cash crops like corn and soybeans.
There are many different varieties of annual ryegrass, some more suitable for use as a cover crop than others. Ongoing variety research and field trials will eventually lead to optimal seed mixes for various geographic locations and soil types.
Oregon's Willamette Valley produces more than 90% of the annual ryegrass seed grown in the USA and is the primary source of quality annual ryegrass seed being used for cover crops in the Mid-West.