Fall Application of Dairy Manure

Glen Arnold, Manure Management Field Specialist, OSU Extension

Corn silage harvest is the start of serious manure application efforts by dairy farmers and commercial manure applicators across Ohio. We have experienced unusually dry weather in much of Ohio, so fields are suitable for manure application.

The field application of manure, milking parlor water, outdoor lot runoff, and silage leachate is a necessary part of dairy farming. Manure transport and application is a significant expense on dairy farms and can easily approach $150 to $175/cow annually. The rapidly increasing prices of pumps, hoses, and manure application equipment in recent years has forced commercial manure applicators to raise the prices they charge dairy farmers for manure application.

To best capture the fall applied manure nutrients, manure 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 nutrients, especially the nitrogen, and also to prevent soil erosion. Another benefit of cover crops that overwinter is the uptake of nitrogen early in the spring when fields are not yet suitable for traffic in March and April and manure nitrogen is still available for plant uptake.

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. If a farmer is participating in the H2Ohio program, be sure to work with your Soil and Water Conservation District to be certain your cover crop mixture meets the necessary application rate(s) and also meets the requirement to live through the winter months.

A 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 or become a forage crop as wheat silage. It will capture large amounts of the available nitrogen from fall applied livestock manure. Dairy producers can spur growth with one or two applications of manure as the wheat grows next spring.

Cereal rye is the most commonly planted cool-season grass for capturing excess nitrogen. Because rye over-winters, research has shown it can capture and hold 25 to 50 lb/acre of nitrogen in the organic form as roots and plant tissue. 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. This is another cover crop that could be used as a forage crop in the spring.

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, such as setbacks, when applying manure. The goal should be to combine nutrient recovery and to protect water quality. Manure application rules in Ohio are influenced by watershed location. Check with your local Soil and Water Conservation District about the most current rules in your area.