Winter Cereal Rye
Rye (Secale cereale) is the most common and reliable cover crop in the upper Midwest because it is one of the few cover crops that can successfully establish when planted late in the growing season, it is winter hardy throughout the region, and accumulates meaningful amounts of biomass before spring planting of the subsequent crop. Winter rye is the hardiest of cereal crops and can be seeded later in the fall than other cover crops and still provide considerable dry matter. It also has an extensive soil-holding root system that can lead to significant reduction of nitrate leaching. It is widely adaptive, growing best in cool, temperate zones, but having the ability to perform in infertile, sandy or acidic soil, and poorly prepared land. Rye can establish in very cool temperatures and will germinate as low as 1°C and vegetative growth only requires 3°C. With vegetative growth still active at near freezing temperatures, winter rye has a longer time to establish after germination, which is an important factor in North Dakota. With longer time for biomass growth, rye can be a good weed suppressor in the spring.
Winter rye as a cover crop is proven to have the ability to be integrated into existing corn (Zea mays L.)-soybean production systems, feasibly implemented over large areas, and have been highlighted as a cost-effective strategy for improving environmental stewardship. Rye is the best cool-season cereal cover for absorbing unused soil NO3-N. It has a fast growing fibrous root system, which helps scavenge for residual NO3-N throughout the soil profile. Where rye has been overseeded into soybeans in August, leaching losses from September to May has been shown to be less than 5.6 kg of nitrogen (N) per ha-1. Rye has also shown increases in the concentrations of exchangeable potassium (K) near the soil surface by bring it up form lower in the soil profile.