Equine manure management: What goes in must come out

A 1,000-pound horse can produce 1,500 pounds of manure in a month. That is a lot of manure to manage.

Mary Kenna, livestock environmental management specialist at North Dakota State University said there are a couple reasons to manage manure from the horse herd. First, the manure contains many valuable nutrients. Kenna spoke in a recent NDSU Extension webinar.

Improper manure storage or land application can cause excess soil nutrients. This can sometimes lead to surface runoff or leeching. Leeching is when nutrients go down through the soil profile and the water becomes contaminated with the manure.

Another consideration with proper manure storage and management is controlling flies, bacteria, pathogens, rodents, weed seeds and internal parasites. Same goes with odors.

“Why would odors be important?” Kenna said. “Your neighbor, especially if you’re an urban area, may not appreciate your manure pile.”


Kenna said, according to Michigan State University Extension, a 1,000-pound horse is going to produce about 50 pounds of manure and urine a day. Add in even more if the horse is stalled and bedding is used.

That sounds like a lot, and Kenna said to also look at it in terms of volume. For those 2,000 pounds of manure, that measures 99 cubic feet per horse per month. Volume and pounds are important to recognize when stockpiling.

Manure stacking or stockpiling is one way to store manure, and horse owners need to contact the regulatory agency in their state for storage guidelines.

Picking an area for the stockpile is not one to be taken lightly, she said. Sandy soil will have a rapid permeability, meaning the nutrients are dissolved quickly through the soil profile. A clay type soil is more desirable because of the time it takes water to get through the profile.

Depth to groundwater and location to surface water is also important to recognize.

No matter if the stockpile is short-term or long-term, it shouldn’t be located in gravel pits or other excavations.

“If you see an area and you’re like, well I can’t use that for anything else, or nobody uses it for anything else, I’ll put my manure there,” Kenna said. “Don’t do that, because it’s probably not being used for something for a reason, very likely if it’s a pit, it’s going to become inundated with water.”

Manure shouldn’t be stored near surface water or where it can run into surface water. It shouldn’t be 50 feed from a private well or 100 feet from a public well. In some areas the manure can be covered with plastic or a tarp to reduce odor and fly problems.


One way of managing manure, while taking advantage of the nutrients is by composting. Kenna likes composting, especially for a horse operation because of one thing.

“First, manure comes out almost perfect,” she said. “It’s one of the easier products I think that we can compost.”

There’s a lot of horse manure available and if the weed seeds and pathogens can be removed and lower the nutrient loss, the nutrients become more stable.

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Composting also helps reduce the fly load and insects in general.

Flies lay eggs on the top couple inches of moist manure and hatch in as little as seven days. With compost, the material constantly gets turned causing disruption.

“We can constantly disrupt that flow,” Kenna said. “We can disrupt their life cycle and potentially lessen the amount of flies we have.”

Weed seeds

Paige Brummund, Ward County North Dakota, agriculture and natural resources Extension agent, also spoke during the webinar. During her section she discussed the importance of temperature is for killing weed seeds in the horse manure.

“Weed seeds consumed by the horse will germinate and produce more weeds, if not properly composted,” she said. “If that temperature reaches 140 degrees in your compost pile that most of our weeds are going to be killed in one to three hours.”

She said something to keep in mind is the entire pile is not going to be the same temperature at the same time.

“So again, most of the weed seeds will be able to be killed if you reach the correct temperatures,” Brummund said.

There’s no guarantee about killing all the seeds, but there’s a few options to control those weeds that do manage to germinate.

“Mow your pastures after you graze them, preferably, or should be before those weeds produce the seed head,” she said.

A cultural method to control weeds would be to maintain a thick healthy dense pasture so weeds are out competed by the desirable plants. This can be done through over seeding and proper grazing management.

“Horses are pretty tough on grasses and pastures,” she said. “They really like to chew them down and then that provides a good opportunity for weeds to come in and grow.”

The third option is chemical control using herbicides to control weeds. Brummund said the first step is to know what weeds are there in order to properly select herbicides.

“You’re going to want to apply those at the correct time,” she said. “It’s not as effective to apply herbicides to mature, tall, 3- or 4-foot tall weeds. It’s best to control them when they’re just a few inches in height.”

Use of the correct rate of herbicide is also important, and all the specifics are on the label.

“Always remember to follow that label. That label is the law,” she said. “If you need assistance with identifying what weeds they are and selecting what herbicides that will be able to effectively control them, you can certainly contact your county extension agent.”

If herbicides are used to control weeds and horses are consuming that pasture or hay on fields that have been sprayed, Brummund said, owners need to be aware that some herbicides have carry over and remain effective and active even in the manure and subsequent compost.

“So one option would be to spread that compost back onto the pastures or the hay fields to minimize killing any undesirable plants such as your vegetable garden or your shrubs or your trees,” she said. “Be aware that this is an issue for some herbicides that you may apply.”

Many states have a weed control guide put out by extension services, and this is a good resource for landowners to find weed control products for their area.

Kylene Scott can be reached at 620-227-1804 or [email protected].