MSU Extension Horses

Odor Management

As we continue through this 8 article series, we cannot forget the obvious that manure can produce odors. Understanding why manure smells, appropriate manure spreading times, and tips for success, will help any horse owner be a good neighbor and an excellent manager of manure!

Odor Management: why does manure smell?

So, what is it about manure that produces an unpleasant odor? In a previous article titled, "What factors influence the odors in manure", we can determine five different measurements and characteristics that contribute to the odor of horse manure:

• Concentration – Identified by the odor detection threshold (ODT); volume of non-odorous air divided by the volume of odorous air
• Intensity – the strength of an odor
• Persistence – how easily a full-strength odor is diluted below the ODT
• Hedonic Tone – the pleasant/unpleasantness of an odor
• Character Descriptor – the type of odor detected (floral, fruity, earthy, fishy, etc.)

Based on the characteristics and measures of odor within manure, it makes spreading manure on fields that much more important.

Odor Management: when should I spread manure?

While there is the option to spread manure any time throughout the year (though, not recommended during winter months), there are opportune times to spread and times that should be avoided if possible.

Good times to spread manure:

• In the morning when warm air rises and carries odors up away from the ground
• Breezy, cooler day as this disperses odors unlike warm, humid days intensify odors
• Helps to spread in the morning once everyone has left for work
• Incorporate manure within 48 hours (unless applied to alfalfa)
• Spring and late Fall as long as field and weather conditions permit

Times to avoid spreading manure:

• If wind is strong towards residential areas
• Weekends and holidays when the potential is increased for people to be home or having larger gatherings

Odor Management: keys to success

Along with appropriate manure application timing, there are a few other tips to ensure good standing with others in your community:

• Good neighbor relationships – this can make all the difference (let them know if you plan to spread)
• Studies have shown that neighbors who knew a producer tended to notice less odor when spreading manure (Penn State AN SC 418 Nutrient Management. Odor: generation and dispersion perception detection and measurement PA Act 38 odor regulations BMP review. 2016)
• Debris management – people sometimes smell with their eyes, so having a clean and aesthetically pleasing area, may help with odor issues
• Take advantage of vegetation barriers like trees or woodlots (or put some in place) around fields where you spread manure and/or store manure

Odor Management: what do the Manure Management and Utilization GAAMPs say?

The 2018 Manure Management and Utilization GAAMPs encourage the following practices related to odor management of manure:

• If building a new facility for horses or a manure storage, try not to locate in close proximity to neighbors
• Remove manure for stalls and paddocks into appropriate storage (locate away from neighbors as well)
• If stockpiling manure, consider a cover (tarp, straw, etc.), or a covered dry stack storage
• Composting can help reduce odors if done properly
• Fly control – reducing odor will help maintain positive neighbor relationships

It is important to plan ahead and consider how the odor from manure has the potential to be a nuisance. By following some or all of these practices, the odor of manure can be effectively managed, making you a star in your community and a place that everyone wants to visit!

In the last article of this Developing a horse manure management plan series – Part 8, the focus will be on emergency spill response and what to do in the event of a manure spill.