Cover Crops and Manure Following Wheat

Authors: Glen Arnold, CCA, Sarah Noggle, Kyle Verhoff

Following wheat harvest is a great window to get field work started and apply manure to farm fields. We can do a few things to best capture and utilize the nutrients from our manure, such as incorporating during application or as soon as possible after. Another great tool to capture the nutrients is to utilize cover crops. Many of our cover crops have the added benefits of aiding in weed control and possible usage as a forage.

Both solid and liquid manure contains ammonium nitrogen that cover crops can utilize for growth.  This ammonia nitrogen is often lost when manure is applied to warm soils in August and September as soil bacteria converts the nitrogen to a more leachable form. If cover crops can uptake the nitrogen, then less nitrogen is lost to the environment.

Some of the most common cover crops used with 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. A good resource for the cover crop decision process is the Midwest Cover Crops Council selection tool.

• 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 may be planted later, but less nitrogen will be recycled the later in the fall the rye is seeded.

• Following harvest, you are likely to have some volunteer wheat, but planting it as a cover crop is an excellent way to recycle and capture nutrients. Like cereal rye, wheat germinates at low soil temperatures, overwinters, and is an easy cover crop to control the following spring.
• Oats are sometimes used as a cover crop in the fall and need to be planted soon after wheat or silage harvest. Drilling oats improves germination and growth before frost.

Cover crops can be planted before or after manure is spread. In the case where cover crop seeds are broadcasted, shallow incorporation assists with seed-soil contact while keeping the seeds near the soil surface. Additionally, be sure that solid manure is spread thin enough that cover crops can germinate through if the manure is not incorporated.

Cover crops can help farmers recapture manure nutrients and conserve soil by reducing erosion. Producers should consider Best Management Practices when applying manure. If you are participating in an H2Ohio program, be sure to work with your Soil and Water Conservation District to ensure your practices meet any necessary requirements. The goal should be to combine nutrient recovery and to protect water quality.