Oh, Horse Manure!

If you have horses, you have manure. Dealing with the waste can be burdensome and sometimes costly for farm owners, not to mention some waste management methods are harmful to the environment. If you're looking for a way to improve your current method or start a new one, composting could be the answer.

On average, a horse produces about 50 pounds of manure per day; add bedding to the mix, and that amount nearly doubles. As urban sprawl continues to encroach on pastures, horse owners are forced to use less space to house and care for their horses, which can cause economic and health problems for horses and owners. With little or no room to spread manure as was done in previous generations, waste can begin to pile up.

This creates several problems. With neighbors building in close proximity to farms, owners have to worry about managing smells, unsightly manure piles, water runoff resulting in water quality problems somewhere down the line, flies, and other health issues. Often, owners resort to costly methods of having their manure hauled to a dump where the manure is entombed under anaerobic conditions. The carbon will eventually surface as methane gas, a potent green-house gas. Also, this uses valuable land fill space with a material that can easily be turned into a valuable soil amendment. Even worse, owners often dump manure in a hole on the back of the farm, allowing muck and chemicals to leach into waterways.

Composting is an economical way to dispose of muck, protect water sources, and end up with a product that has value.

If done correctly, composting horse manure will reduce the volume of material by more than half. High temperatures needed to break down manure will also kill fly larvae, parasites, pathogens, and weed seeds. If maintained properly, a compost pile can reduce odors and the chances of manure-contaminated runoff reaching ground water, provide a free source of natural fertilizer for pastures and gardens, and make property more pleasing for you and your neighbors. In this article, we'll discuss how composting works, and how you can use this simple process to turn manure into fertilizer.

How it Works

Composting utilizes aerobic microbes that thrive in an oxygen-rich environment. It's the biological oxidation of organic material into a fine-textured, humus-like material. Internal temperatures in an actively composting pile are high enough to destroy weed seeds, most pathogens, and parasite larvae. Composting reduces the bulk of the muck by half fairly quickly.

Aerobic microbes--microscopic bacteria and fungi that require oxygen--decompose manure, shavings, and/or straw under optimal conditions of temperature, moisture, oxygen, and carbon (C) to nitrogen (N) ratio (C:N), according to Kathy Corwin Doesken, research associate in the Department of Soil and Crop Sciences at Colorado State University (CSU). Aerobic microbes can't thrive in a typical manure pile because these piles settle over time, eliminating pore space and thereby the oxygen flow needed for the microbes to survive.

Anaerobic microbes (those that thrive in oxygen-free environments), however, are able thrive in the common manure pile. Those microbes will eventually decompose organic material, but at a much slower and less effective rate than aerobic microbes. Anaerobes also produce harmful byproducts such as ammonia sulfide and methane, which give off the unpleasant odor you associate with manure piles. Undesirable pathogens can also persist in anaerobic conditions. The basic principle of composting is to avoid these types of conditions that might cause problems to humans, horses, and the environment.

Composting Methods

There are several techniques used for composting manure. Deciding on the best method for your farm will depend on the number of horses housed there.

For small farms with one or two horses, it might be desirable to use several large bins to store and rotate the compost. Each bin should be approximately five feet wide, five feet deep, and five feet tall and capable of holding about four cubic yards of material. Be sure to base the size of the bins on any equipment that will be used to turn the compost. Multiple bins can be used to turn the contents from one bin into another.

Since composting organic material requires moisture, Steven Wisbaum, founder of the Champlain Valley Compost Co. located in Charlotte, Vt., and author of The Horse Owner's Guide to Composting, cautions that materials used for the bin's construction should be rot-resistant, such as non-arsenic pressure-treated lumber or recycled plastic lumber. Boards should contain enough space between them to allow significant airflow to aid in passive aeration. If the bins are going to be turned by hand, they should be small enough to be manageable. If using a loader to turn the compost, be sure the sides are wide enough to accommodate the bucket and that the back of the bin is sturdy enough to push against with the loader. Access to a water source is important, as is a roof or tarp to control the amount of water going into the pile.

Windrows are better suited for farms that house more than five horses. "The manure is piled into five- or six-foot-tall windrows, and the base is about 10 feet wide," says Ron Wallace, president of Equine Muck Management (EMM), which provides an on-site composting service to the Central Kentucky area.

To turn the windrows, Wallace uses a large turner and grinder machine to manipulate the windrows of compost and to allow air into it. "When the composting process is complete, these rows will only be about three feet tall," he explains.

"Ideally, windrows should remain moist to speed up the composting process," Wallace says. Our equipment is set up to do this (add moisture), but because of the climate that we are in, it isn't usually necessary."

Not adding water is not harmful because microbes can survive in the pile until moisture returns. However, adding moisture will speed up the composting process.

Air, Moisture, and Temperature

A pitchfork will suffice for turning small compost piles. For larger piles, a tractor loader, skid loader, or windrow turner might be necessary. Once your compost pile is built, Doesken suggests to begin monitoring internal temperatures with a compost thermometer (available online at www.Reotemp.com or www.Gardeners.com).

"The internal temperature will rise over a period of several days to about 140ºF or higher," explained Doesken. "This first phase is called the active, or thermophylic (heat-loving) phase. The heat generated results from the waste heat generated by active microorganisms. This is similar to the heat you generate when you work
out or chop wood. Heat generated in composting promotes the growth of the type of microorganisms that begin breaking down the organic material, and kills pathogens, parasites, and weed seeds."

When temperatures reach 150ºF or more, the pile should be turned, as temperatures above this level can actually limit the growth of useful microorganisms. When temperatures begin to decline, this is another time to consider turning the pile because it indicates that something is limiting growth. This is probably the lack of oxygen, but could also be moisture content.

To check the moisture content in the compost, Doesken says to squeeze the material in your fist. "If it sticks together, it is about 50% moisture and just right," she explains. "If free water can be squeezed out, it is too wet. If the material does not hold together at all, additional water should definitely be added."

Excessive moisture in compost creates problems, states Wisbaum. It can cause compost to leach harmful chemicals into the soil, and it can also displace oxygen within the pile, which creates an anaerobic condition that produces an unpleasant odor and phytotoxic (toxic to plants) substances.

If turning the pile is not practical at a particular time, waiting to turn will not ultimately have an adverse effect upon the composting operation. However, it might take more time for the process to occur. Usually a pile will need turning at least three to five times during composting.

"After turning, if the internal temperature does not rise appreciably, the second phase of composting, or mesophylic phase (at ambient temperature) has begun," Doesken explains. "At this point, microorganisms are still degrading the original material into compost, but do not produce heat as in the actively heating phase. These microorganisms are predominately fungi. You might even see some mushrooms appearing on the surface of your compost pile. This is a healthy occurrence and indicates that nature is taking its course."

Selecting a Site

Selecting an appropriate compost site is essential. Soil type, nearby waterways, and ease of access should be taken into consideration. The proximity of the compost to neighbors should also be considered because even well-maintained compost piles produce some odor initially.

Look for a high, level area on which to situate the compost pile; in low-lying areas the compost will turn into a soggy mess. Additionally, compost sites should be sloped slightly to avoid standing water. Compost sites should not be located within 100-200 feet of wells or water sources to avoid leaching during heavy rains.

The amount of space required will depend on the method used and the number of horses housed. Windrowing requires the most land; composting bins and static piles require less space. When selecting a location, be sure to leave about six to eight feet between rows or bins to operate equipment.

Wisbaum says a compost site should be located in an area with good drainage and a slight grade. In areas that get abundant annual rainfall, compost should be covered using compost covers that shed water and snow, but are permeable to oxygen and water vapor (unlike regular tarps). For more information on compost covers visit www.cvcompost.com/covers.htm.

Before choosing your compost site, it's a good idea to contact your local cooperative extension agency to determine if there are regulations that need to be addressed. Remember to check for agricultural grants that might help offset costs.

Companies such as EMM can help compost your manure on-site, eliminating the need for purchasing costly equipment required to turn larger piles. There are other companies that will remove manure from your farm or allow you to haul it to their off-site facility. They usually have strict rules prohibiting certain beddings (places that accept straw won't mix in shavings) and foreign debris. Be sure to check with the company before hauling to their site.

"Another alternative to hiring an outside contractor to compost at your site is to hire a professional consultant to help you set up your compost operation and provide training, so that you can operate it independently," suggests Doesken. Several consultants (such as O2composting in Snohomish, Wash.) specialize in designing compost facilities for equine farms.

The Finished Product

Composting the manure is only the first step. You need to think about how you will use the finished product. Will you use it yourself or sell it to neighbors?

Compost should be applied to plants and soils needing nutrients. It can be used as mulch around trees or fertilizer in gardens.

"Manure compost can be applied in one-half inch to one inch thickness around plants and on gardens and applied at 24 to 57 tons per acre. Unlike horse manure, compost also makes ideal topdressing for pastures," Doesken says. "It releases nutrients slowly, which eliminates the danger of digestive problems in horses grazing on pasture that has taken up excess nutrients from a quick-release chemical fertilizer. The addition of compost over time can increase the infiltration rate of water and increase the soil's water holding capacity, which will enhance pasture growth."

Take-Home Message

Disposing of manure and its attendant bedding should be done in an environmentally friendly manner to maintain your standing with your neighbors and improve your yard, garden, and pasture. Seek advice from local cooperative extension agents, professional compost consultants, or composting companies on the best, most economical way to turn your muck into something more pleasant. For more information on composting, visit CSU's web site at http://cwmi.css.cornell.edu/composting.html.

About the Author

Chad Mendell

Chad Mendell is the former Managing Editor for TheHorse.com .

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