Air Emissions and Animal Agriculture

Odor in manure storage

Sometimes farmers have more manure than they can spread on their fields, or they have to store it when it’s unsuitable to apply to land because the ground is frozen or too wet. When manure is stored, it can sometimes become a source for odor. However, where there is odor, there are methods to reduce it.

One technique that many dairy farmers use, but which could apply to all types of livestock, is to strain out the solid manure from the liquid manure. This is a lot like sifting gold out of the river. Usually the solid parts takes the longest to decompose and, therefore, result in odor. By removing them, the liquid manure can more readily break down. Some researchers found that this method cut the amount of odor in half in one swine barn. 

Another method to reduce odor is anaerobic digestion. While it seems technical, in its simplest form anaerobic digestion is a way to enhance a natural process by providing conditions suitable for complete decomposition of organic matter – manure – into low odor end products. Additionally, while the manure is being decomposed, it is stored in a tightly sealed system so no odor can leak out during the storage phase.

Some farmers put a lid on their manure to keep the smell from spreading – literally! Different types of covers can be used over manure storage pits and they range from being made out of polyethylene to straw.

Making sure the manure stays aerobic, which means the decomposition reactions inside it need to happen in the presence of oxygen, can also control odor. Some farmers purchase aerator equipment to supply oxygen, but this option can be rather costly. Another way to keep manure aerobic is to compost it. This is a better option for farms with solid manure, although it does require a high level of care and management.

Learn more:

National Air Quality Site Assessment Tool (NAQSAT)

Practices to Reduce Odor

Air Management Practices Assessment Tool (AMPAT)


Last Updated 11/02/2011