Using cover crops with fall manure applications

By Glen Arnold 

Corn silage harvest is in process, and this will free up farm fields for manure application. Livestock producers and commercial manure applicators have started the fall manure application season which will continue through soybean and corn harvest next month. To best capture the nutrients in manure, it should be incorporated during application or as soon as possible afterwards. Livestock producers should also consider using cover crops to capture more of the manure's nutrients — especially the nitrogen — and prevent soil erosion.

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The most common cover crops used with livestock manure are cereal rye, wheat, and oats. However, farmers have also used radishes, clover, annual ryegrass, Sudan grass, or almost anything they are comfortable growing. Farmers should work with their soil and water conservation district to be certain that the cover crop mixture meets the requirements to live through the winter months.

Cereal rye is the most commonly planted cool-season grass for capturing excess nitrogen. Because rye overwinters, research has shown it can capture and hold 25 to 50 pounds of nitrogen, in the organic form as roots and plant tissue, per acre. It germinates at lower temperatures than oats so it can be planted later, but less nitrogen will be recycled the later in the fall the rye is seeded.

Another cover crop that is excellent at recycling nitrogen is wheat. Like cereal rye, wheat germinates at low 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 the livestock manure.

Oats are sometimes used as a cover crop in the fall, and need to be planted soon after silage harvest. Drilling oats improves germination and growth before frost. Some farmers in northwest Ohio have had great success surface seeding oats and incorporating with shallow tillage.

Cover crops can help livestock farmers recapture manure nutrients and conserve soil by reducing erosion. Livestock producers should consider Best Management Practices when applying manure. The goal should be to combine nutrient recovery and to protect water quality.