Solve the Horse Manure Pile Problem

Eco-friendly solutions can help manage manure on your farm through horse manure composting, spreading horse manure and more.

Not long after Anna and Brian Smith of Camden, North Carolina, built their barn in 2007, they realized they had a problem. With four horses in residence, “The manure was really piling up,” says Anna.

Stacey Nedrow-Wigmore

Keeping horses will drain your checkbook, steal your time and sap your energy but horse manure is one item you’re sure to have in ever-increasing amounts. An average horse produces about 50 pounds of the stuff every day, or more than eight tons a year. Add a few more tons of soiled bedding, multiply the total times the number of horses you keep and just try not to feel overwhelmed. What will you do with it all?

“Unless it’s properly managed, horse manure can pose risks to the environment and to health,” says Virginia Cooperative Extension agent Carrie Swanson, who co-authored (with fellow agent Crystal Smith) an Extension publication on manure management (online at Here, with Carrie’s help, we’ll outline the top options for making your horse manure pile disappear.

Why It Matters

Back in the bad old days, most horse barns had a mountain of manure out back or, sometimes, out front. You don’t see that so often now, for reasons that include:

  • Parasites. Manure can contain the eggs of strongyles, roundworms and other internal parasites. If it’s not properly handled, the eggs (or larvae that hatch from them) can contaminate pastures, feed or water and infect other horses.
  • Pests. Manure piles are prime breeding grounds for stable flies, face flies, houseflies and several other types. They can also become cozy burrowing sites for rats.
  • Water quality. Excess nutrients and other contaminants can leach from poorly managed manure into streams, lakes and ponds, upsetting the ecological balance and causing environmental damage.
  • Regulations. There are federal regulations pertaining to manure management and water quality, as well as state and local regulations, Carrie says. “These may or may not affect horse operations, depending on the location,” she adds. “The regulatory agency also varies from state to state, but the county Extension agent should be able to explain local requirements.”
  • Aesthetics. The sight of a manure pile won’t do much for your property value or your relations with neighbors, and neither will the smell. A typical pile produces nasty byproducts like methane gas as the manure slowly molders inside it.

You can avoid or at least minimize these problems with a good manure management program. And because horse manure is a source of nutrients for plants, it can be a valuable resource. Managing horse manure can be complex, though, and what works for one barn may not work so well for another. Tailor your program to your situation.

Spread It

Manure contains nutrients for plant growth and can improve the condition of the soil so why not put it to work?

Good if: You have a lot of land, a tractor and a manure spreader.

How it works: Manure can go directly from your stalls to your fields, where over time it will break down and nourish the soil. Here are some dos and don’ts:

  • Spread thinly. Apply only what you need to improve your land, based on soil tests.
  • Spread manure in spring and summer, not when the ground is frozen or in rainy seasons when it may just wash away. (This means you’ll need to stockpile stall waste at times).
  • Don’t spread fresh manure on pastures where horses will graze anytime soon. It may contain parasite eggs that can survive for weeks or months, depending on conditions. It’ll do no harm on pastures that are being rested or grazed by other species, though. (A good deworming program, with fecal egg counts to monitor success, will minimize this risk.)
  • Don’t spread on floodplains or other areas where water runs seasonally or after rains, near wellheads and other groundwater sources, in areas where the water table is high or on slopes bordering streams and ponds.
  • Apply a nitrogen fertilizer if your fresh stall waste contains sawdust or wood shavings. Microbes that break down the wood products draw nitrogen from the soil, and that can stunt plant growth. Nitrogen fertilizer counteracts the effect. Or, to avoid the problem completely, compost manure before spreading it.

Tip: Contact your local Cooperative Extension office for advice on testing soil and developing a nutrient management plan, a plan that outlines your farm’s manure production, soil fertility and recommended manure application rates. Local soil and water conservation districts or a local branch of the Natural Resources Conservation Service can help you identify seasonal wetlands and other sensitive areas where manure shouldn’t be spread.

Compost It

Composting turns stall wastes into a ready-to-use, nutrient-packed soil enhancer.

“It’s the best green’ disposal option,” Carrie says. “This manure is a valuable resource and can reduce or eliminate the need for commercial fertilizer applications. Plus, properly composting your manure will kill weed seeds and parasite eggs.” You can use it directly on your land, and you’ll have no trouble giving away or even selling the excess to gardeners and farmers in your area. Setting up a composting system may cost some money (how much depends on the size and type), but it can generate income.

Composting is essentially managed decomposition, Carrie says. You get aerobic (oxygen-using) microbes to break down stall wastes quickly without smelly byproducts, generating heat that kills parasite eggs and weed seeds. These microbes, which are everywhere in the environment, can’t work their magic in a typical manure pile because the pile shuts out the oxygen they need. But they’ll work for you if you provide the right materials and conditions.

Good if: You want a low-cost, environmentally sound manure-disposal method and don’t mind investing some time and labor. Composting is an especially good choice if your land is in an environmentally sensitive area, a big consideration for Brian and Anna Smith in coastal North Carolina. “Our land is on the edge of a swamp, and we knew runoff from the manure pile would leach into the wetlands,” Anna says.

How it works: Compost systems can be designed for any size farm. Large farms often compost manure in windrows (long, freestanding piles). A three-bin system works well on many small horse farms. New stall waste goes in one bin while the microbes do their thing in a second, and finished compost cures in a third. Then you empty the third bin and start piling stall waste there, while the microbes get to work in the first bin and the contents of second bin cure.

How you build and maintain your compost system is key, Carrie says. These are the essentials:

  • Critical mass. As a rule, the base width of the pile should be twice its height–10 feet across and 5 feet high, for example. A pile must be at least 4 feet square and 4 feet deep to reach active composting temperatures.
  • Temperature. The microbes are active between 110 F and 150 F, and sustained temperatures of 130 F to 150 F in the pile interior will kill parasite eggs and weed seeds. A gradual drop in temperatures tells you that the microbes have finished their work. Monitor temperatures in the pile with a compost thermometer (from a garden store or online).
  • Oxygen. Introduce air by turning piles with a pitchfork or a tractor, weekly or when the internal temperatures fall above or below the active composting range. Or build static piles with perforated PVC pipes laid across the base, ends protruding, to draw in air. Composting takes longer this way, but static piles don’t need turning. Another option is an aerated static-pile system, with automated electric blowers that move air through perforated pipes under the piles. The initial cost is higher for this method, but it makes compost faster and takes less work than turned piles.
  • Moisture: Compost piles should be about as damp as a wrung out sponge; not soggy or dry and crumbly. Covering your piles will help keep moisture levels consistent. “Folks in very dry climates may need to add water to their compost piles,” Carrie says.
  • Carbon-to-nitrogen ratio: The amount and type of bedding that ends up in your piles determines this ratio, which affects composting speed. A good carbon-to-nitrogen ratio for compost is between 20:1 and 40:1. Horse manure with no bedding has a ratio of 25:1; oat straw, 48:1; wood products, 500:1. If you put lots of wood shavings in your piles, you slow down the action. With enough oxygen and moisture you’ll still make compost, but you can speed things up by using less bedding, switching to another type or adding nitrogen (in the form of urea) to your piles.

Compost decomposes more efficiently if the mix is uniform, Carrie adds. This is especially important with static piles, which aren’t turned. Some farms use a temporary storage area to mix material before adding it to the pile. “In very cold climates, composting in the winter months will take longer, and farms may have to allow for larger storage areas,” she says. “But the basic principles are the same.”

Tip: State and local regulations can affect composting operations. You may need to meet local planning and zoning requirements and get a state permit to sell compost commercially. Check with the local planning office and with your state department of agriculture, environmental protection or natural resources. Your Cooperative Extension office can also give advice on setting up a composting system for your farm.

Haul It Away

Trucking manure off site is the easiest solution, although it may not be the cheapest.

Good if: You have a number of horses but not much acreage or time to deal with manure.

How it works: You can load manure and stall waste into your own dump truck, if you have one, and then haul the full load to a commercial facility that composts manure. Some facilities charge a drop-off fee; others will take the load for free.

No such truck? Commercial services in many areas will provide a roll-off container for the waste and haul it away when the container is full. The service will help you determine how large a container you need and where to place it. Containers that hold 12, 20 or 30 cubic yards are typical. Fifteen to 20 horses will fill a 20-cubic-yard container in about a month. Fees vary, but the service can run several hundred dollars a month for containers that size.

Before you contract with a service, be sure the manure will go to a facility licensed to compost it. “Most of the time manure that is hauled off by commercial operations is composted and reused,” Carrie says. “Generally it does not end up in landfills.”

Tip: Contact conservation and environmental groups in your area to see if there are other haul-away options. These groups may be able to link you up with farmers who take manure, or biomass facilities that turn organic waste into energy–a new but growing use for stall waste. For example, Mid-Michigan Recycling picks up used shavings and manure for delivery to the Genesee Power Station in Flint, a facility that processes wood waste to produce electricity. (Details are online at

What’s Best for You?

It depends on your herd size and your resources, your acreage, equipment and budget. “If you’ve got one acre and two horses, you’re going to be generating more manure than the land can handle,” Carrie says. “But if those same two horses are on four acres, composting and applying manure back to the land might work well. If you’ve got twenty acres, you could probably skip the composting, apply directly to the fields and rotate the horses among several paddocks.” Your local Extension office is the place to go for individual advice, she adds. You can find more information and submit individual questions through the national Extension website,

For Brian and Anna Smith, the answer was an aerated three-bin composting system designed by O2Compost (, of Snohomish, Washington, that also provided how-to advice. The system is sized to handle manure output from six horses. To get the right mix for their compost, the Smiths use wood-pellet bedding in matted stalls. “The pellets aren’t as aesthetic as shavings,” Anna says, but they’re made of fine sawdust that breaks down much faster. She picks paddocks daily and adds that manure to the bins. (Only organic products are applied to the fields, so chemical herbicides and other long-lasting chemicals don’t wind up in the compost.)

It takes about 30 days to fill a bin. Then the blower system is switched on, and Brian monitors the temperature as the pile cooks for 30 days. After it cures for another 30 days, it’s moved to a storage area. The finished compost has a soil-like texture and an earthy smell. The Smiths sell it as Carolina Compost in tractor-bucket loads, recycled feedbags and cheesecloth packets that gardeners use to make “compost tea” for watering plants. Manure on their farm is no longer a polluting eyesore. It’s a source of income.

This article originally appeared in the December 2011 issue of Practical Horseman. 

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