By: Greg LaBarge and Glen Arnold
As corn silage harvest starts, livestock producers and commercial manure applicators will follow with fall manure applications. Manure should be incorporated with a toolbar at application or soon after application with tillage to keep nutrients in place. Incorporation works well to preserve P and K for future crops, but nitrogen (N) is different. N is initially retained in the soil but will leach through tile or volatilize into the air unless we capture it in a growing crop. Cover crops fit well in the role of N retention. Ohio edge-of-field research monitoring agricultural practice impacts shows a reduction of tile nitrate losses of 84% with cover crops. Plus, there is an added benefit of preventing soil erosion.
Cereal rye, wheat, and oats are common cover crops after manure application. However, farmers also use radishes, clover, annual ryegrass, Sudan grass, or almost any species they are comfortable growing. Some species can provide harvestable forage back to the farm.
- Cereal rye is frequently planted. Because rye over-winters, research has shown it can capture and hold 25 to 50 pounds of nitrogen per acre in the organic form as roots and plant tissue. It germinates at lower temperatures than oats and may be planted later in the fall. However, less nitrogen will be retained due to less biomass accumulation.
- Another excellent cover crop for recycling nitrogen is wheat. Like cereal rye, can wheat germinates at lower soil temperatures, overwinters, and is an easy cover crop to control the following spring. It will also capture large amounts of the available nitrogen from livestock manure.
- Oats are sometimes used as a fall cover crop but need to be planted soon after silage harvest. Drilling oats improves germination and growth. Oats will not overwinter.
Cover crops can help livestock farmers recapture nutrients and conserve soil by reducing erosion. All livestock producers should consider Best Management Practices when applying manure. The goal should be to combine nutrient recovery and protect the environment. For more information on cover crops, consult https://www.midwestcovercrops.org/.