Hybrid seed corn
Seed corn producers have successfully used a double-cropped system in seed corn production with forage cover crops. Hybrid seed corn production is input intensive, including surplus irrigation and fertility.
Seed corn production practices lend themselves to cover crops that provide cover and serve as nitrogen scavengers. Grazing forage cover crops after seed corn production is a common, but underutilized practice.
Typical planting dates occur from early- through late-August during male row destruction. The most common species used are oats, turnip, and radish.
Research on beef gain potential from grazing forage cover crops after seed corn production is unavailable. Similarly, there is no data on grazing effects of succeeding crop production.
The ability to produce a forage cover crop following winter wheat offers increased flexibility because the length of the growing season following wheat harvest is longer following harvest of many of the other crops. This increases the ease of forage cover crop establishment and potential success rate.
There is often adequate residual soil moisture immediately following harvest. In Nebraska, nearly all wheat has been harvested by mid- to late-July and certainly before August 1. The potential exists for either a late-summer planted summer annual or an early-planted winter annual.
Termination the following spring prior to corn planting can be either through winter kill for spring species or herbicide application the following spring for winter species. From a cover crop standpoint, wheat is the only crop where warm-season cover crops can be planted with any reasonable chance of success for producing cover before winter.
Corn and sorghum silage
Silage production systems are unique in that this system removes nearly all of the crop biomass during harvest. It is important that a cover crop be established to reduce erosion potential, especially on sandy soil types.
Planting dates from late August to late September increase the probability of using fall-planted cover crops as forage. It may be desirable to plant a combination of spring and winter species if spring forage is desired.
Corn and grain sorghum
It is not as critical to establish a cover crop following corn and sorghum grain harvest as either corn or sorghum silage or soybean due to the amount of residue that remains following harvest.
In Nebraska corn grain systems, in-season establishment of cover crops in actively growing corn has been used with variable rates of success. There seems to be a greater success rate as this practice moves into northern Nebraska, the Dakotas and Minnesota and into eastern parts of the Corn Belt.
Grain crops other than soybean offer easier opportunities for forage cover crop production. Soybean harvest is usually completed by mid- through late-October in most areas. This does not allow enough time for any species to accumulate appreciable growth prior to the first killing frost.
Planting should occur after October 1 but before December 1. This limits forage cover crop choice following soybean to the winter small grain forage species, such as cereal rye, triticale, wheat, or barley.
To increase the likelihood of grazing forage cover crops following soybean, it may be necessary to select an earlier maturity group soybean. The trade-off is reduced grain yield versus the potential for increased forage production.