Managing Your Manure Pile

Disposing of manure and soiled bedding is a mounting problem. If allowed to accumulate, raw manure serves as a vector for parasites and other organisms, attracts flies, and, if extensively amassed, increases the risk of thrush and other hoof-related problems. Fortunately, there are several ways to get rid of equine waste and here are some suggestions.

Composting

The most common and least costly method of handling manure and soiled bedding is through composting.

Tom Halbach, M.S. (agricultural geography), State Specialist – Waste Management, University of Minnesota, says that a good compost pile needs to be at least one cubic yard or larger to obtain proper temperatures, and optimally has about a 55 percent moisture content, a minimum of 5.5 percent oxygen throughout the pile, microorganisms, and a carbon-nitrogen (C:N) ratio of 30:1. Soiled bedding naturally contains microorganisms, a carbon-nitrogen ratio of about 32:1, and a moisture content of about 69 percent, notes Halbach. "This is close to the conditions we are trying to achieve."

After the materials are assembled into a mass, the compost pile heats up. Because the pile will be hotter at the center than the outer edges, the pile needs to be turned and mixed. The more it's turned, the faster it breaks down. "In general, four to eight turns during whatever time period you're going to be composting," is suggested, Halbach says. "If you're composting 180 days, you might turn it three or four times the first two months, and then less often as it gets older."

Temperatures at the center should be 122 to 150 degrees Fahrenheit; a temperature probe eliminates the guesswork. The EPA recommends 131 F for a minimum of 21 days, turning a minimum of seven times, to reduce disease pathogens, and 150 F for at least seven days to reduce weed seeds.

The porous, spongy consistency of straw usually provides sufficient oxygen within the pile, but sawdust, ground bedding, and other materials with a finer consistency pack too tightly, subsequently reducing oxygen levels and driving temperatures above 160 F. In that case, add a little extra straw to create more oxygen.

Piles that are too cool – below 122 F – break down slower and don't reduce parasites or weed seeds. Piles that are too hot – 160 F and above – begin killing the microorganisms. "By 176 degrees, we've killed all the microorganisms," states Halbach. "If the pile gets too hot, make the pile smaller. If it gets too cold, make it bigger." Five- to six-foot depths work best.

Moisture can be gauged by squeezing a handful of compost. "If it feels moist to the touch, but you cannot squeeze any water out of the compost, it's about right," says Halbach. "If you can squeeze water out, it's too wet. If it doesn't feel moist, it isn't."

Properly constructed and maintained piles break down between 90 to 120 days. Ill-maintained piles or those with incorrect mixes may take six to 12 months or more. "But even bad compost eventually turns into good compost in about four years if left alone," says Halbach.

Types of Compost Piles

• The simple vertical pile works well for one- or two-horse operations where manure and bedding is continually added to the top or sides of the mass. Frequent turning of the pile will hasten the composting process, but many prefer a less labor-intensive approach of building a new pile once or twice a year, turning the pile two or three times, then letting it take a year or so to mature.
• Windrow composting, where manure and bedding is piled horizontally, is good for those with large herds and sufficient room. Typically the windrow is a long row six to eight feet wide, about five to six feet tall, and anywhere from a dozen feet to several hundred feet in length. These piles are usually turned with a front-end loader or a tractor with an adapted implement that sticks out from the side while being pulled behind as it turns the pile.
• Bin composting works well when smaller amounts of material need to be composted, says Pat Millner, USDA research leader for the Soil Microbial Systems Laboratory, Agricultural Research Service Center, Beltsville, Md. "As you periodically add material to the bin, cover it with several inches of straw, old hay, or finished compost, then periodically turn the material with a shovel, pitch fork, or small bucket loader (if it will fit into the bin opening), to remix and promote reheating." Bins may or may not be covered to prevent rainfall collection.

Often a series of bins are used: Materials are piled into bin one until it's full, then turned into bin two for about two months, then turned into bin three for another two months. Some of the materials in bin one may be incompletely composted when turned into bin two; it will finish composting later in the other bins.

Piles should be sited at least 100 to 200 feet away from wells or water sources to avoid leaching during heavy rains, on a fairly flat site where water won't collect, and in an area where one can maneuver around the pile manually or with mechanical equipment.

Spreading

Folks with a lot of land may prefer to deal with raw manure by spreading it on croplands or unused pastures. "The advantage of direct land application of manure is that you retain up to 30 percent more nitrogen when applied and tilled into the soil," Halbach says. "On the downside, spreading doesn't deactivate weed seeds or aggressively attack pathogens." Some parasite eggs can live for years in the soil.

Manure should be spread uniformly and evenly to avoid concentrations of ammonia and salts that can kill the grass. Harrow or drag the area a couple of times a year to level the manure piles.

Opinions are divided on when horses can be turned out on spread pastures. "The general rule is that six months is enough for sunlight, temperature and surface microbial activity to deactivate most of the pathogens to the point that it's safe for most horses," says Halbach.

Horses that spend most of their time in the pasture do their own spreading, tending to defecate in one area and graze in another. "We have most of the Kansas State herd in a pasture setting, says Randel Raub, Ph.D. (animal science), Kansas State University. We don't overpopulate our pasture, so nature takes care of the manure problem. If your horse has enough room, manure disposal is taken care of by the elements and is not a problem." Although some suggest cleaning pastures to reduce parasite infestation, Dr. Raub points out that in adequately sized pastures, good de-worming programs may yield the same protection.

Hauling

Paying commercial haulers to cart away manure is the least labor-intensive but the most expensive method of disposal.

Although there may be an interest by local gardeners or nursery owners for hauling away or purchasing composted manure, fresh manure has limited value for many because it heats up and burns the plants it's applied to. It also may introduce additional weed seeds into a new environment.

Consult with your local cooperative extension agent to locate a hauler.