Farmers who harvest corn silage will often drill cereal rye at 2-2.5 bushel per acre 1 inch deep (no more than 2 inches deep) , apply manure, and then harvest 3-5 wet tons (1.5 to 2.5 tons dry matter) of spring forage before planting corn or soybeans. Manure or extra nitrogen (50-75 pounds actual N) is critical for good forage growth in the fall and spring and to prevent the corn from turning yellow (N deficiency) next spring. Cereal rye will absorb 3-3.5%N and 0.2% of its total biomass as N and P respectively.
Oats drilled immediately after corn silage at 2 bushel per acre is another option if forage is desired this fall possibly resulting in 1-3 tons (.5-1.5 tons dry matter) with adequate moisture by Mid-December. Oats harvested in Early December should be wet baled to preserve forage quality. If the farmer does not want forage, 0.5 to 1 bu/A oats, cereal rye or barley makes a great cover crop going to soybeans. Other options include a mixture of crimson clover (8 pounds) and radish (2 pounds) which can either be broadcast or drilled (0.25-0.5 inches deep) or winter peas (20 pounds seeded 1 inch deep) and radish (1-2 pounds seeded 0.25-0 .5 inches deep) in alternating rows.
In general, farmers should avoid planting grass cover crops before corn due to a high carbon to nitrogen ratio unless they are willing to apply a large amount of N fertilizer or have manure to help decompose the cover crop biomass. Farmers need to remember that soil microbes feed first and organic residues generally need more nitrogen to decompose, so next year’s corn crop is either second or third in line for soil nitrogen. To avoid yellow corn or N deficiency in the spring, apply 50 to 75 pounds of actual nitrogen in your starter. Soil microbial populations double with every 10˚ F increase in soil temperature, so coming out of a cold winter with cold soil temperatures, the soil microbes are not recycling as many soil nutrients until the soil warms up.