Annual ryegrass is one of the best choices for a fall planted cover crop because of its versatility, ease of establishment, amazing root system, and incredible nutrient scavenging abilities. It is an excellent soil builder, great at erosion control and weed suppression. The massive root system can add 5000 - 9000 lbs of organic material per acre, growing down to 54 inches, providing channels for air, water, and following crop root systems. Farmers have reported corn root zones down to nearly 5 feet following ryegrass.
Annual ryegrass has extremely fast emergence and establishes quickly on a variety of soil types. It works well alone or in mixes. In severe winter conditions, annual ryegrass can winter kill, but roots have usually grown down 24-32 inches, sequestering leftover nutrients and providing a good start for the following crop. Incorporation will work to kill ryegrass if it is completely covered. If using glyphosate, apply a full rate when the days are warm, averaging over 50°F and the grass is growing vigorously.
Drill at 15-25 lbs/A, 1/4 to 1/2 inch deep or fly on into standing corn at the higher rate. You can also broadcast onto bare soil and roll with a cultipacker. Seed 40 days before killing frost date to help protect from winter kill. Annual ryegrass rates in mixes can be cut to 8-15 lbs.