A complete manure management system involves collection, storage (temporary or long term), and disposal or utilization.
Manure handling is a necessary evil of stable management with horse owners naturally preferring to ride rather than clean stalls. Making sure that stall cleaning and other manure handling chores are done efficiently can lead to more time spent with the horse. It is important to recognize that horses produce large amounts of manure that quickly accumulates! About 12 tons of manure and soiled bedding will be removed annually from each horse stall (housing a full-time occupant). Careful consideration of how this material is moved and stored is needed for efficient manure management. Getting the manure out of a stall is only the beginning. A complete manure management system involves collection, storage (temporary or long-term), and disposal or utilization. Associated issues such as odor control, fly breeding, and environmental impact are addressed in relation to horse facilities.
Manure management practices within horse facilities deserve careful attention. Since most horses are kept in suburban or rural residential settings, it is essential for horse owners to be good neighbors. Often, suburban horse facilities have limited or no acreage for disposal of manure and soiled bedding. Several alternatives for handling manure include land disposal, stockpiling for future handling, removal from stable site, and composting. Some stables have developed markets to distribute or sell the stall waste. Whether in a suburban or rural setting, proper manure management is based on simple principles that will virtually eliminate environmental pollution impacts and nuisances such as odor and flies.
Stall Waste Production and Characteristics
Manure includes both the solid and liquid portions of waste. Horse manure is about 60 percent solids and 40 percent urine. On average, a horse produces 0.5 ounce of feces and 0.3 fluid ounce of urine per pound of body weight every day. A 1,000-pound horse produces about 31 pounds of feces and 2.4 gallons of urine daily, which totals around 51 pounds of total raw waste per day.
Soiled bedding removed with the manure during stall cleaning may account for another 8 to 15 pounds per day of waste. The volume of soiled bedding removed equals almost twice the volume of manure removed but varies widely depending on management practices. So for each stall, about 60 to 70 pounds of total waste material is removed daily. This results in about 12 tons of waste a year per stall with 8.5 tons being manure from a 1,000-pound horse.
The density of horse manure is about 63 pounds per cubic foot (lb/ft3). Therefore, 51 pounds of manure would occupy about 0.81 cubic feet. The soiled stall bedding removed with this manure would be about twice this volume, so the total volume of stall waste removed per day per 1,000-pound horse may be estimated as 2.4 ft3. To put all these numbers in perspective, annual stall waste from one horse would fill its 12-foot by 12-foot stall about 6 feet deep (assuming no settling). Plan now for handling this material!
Barn chores include a daily cleanout of manure and soiled bedding, leading to a steady stream of waste to handle. There are several common stall bedding materials and each has different characteristics in handling, field application, suitability to composting, and acceptance for sales. Availability and cost of bedding materials in the stable area will probably have the greatest influence on bedding selection.
The manure management needs of pastured horses are different from those of stabled horses. The field-deposited manure is beneficial because it serves as a fertilizer. Substantial amounts of manure can accumulate where horses congregate around gates, waterers, favorite shade areas, feeders, and shelters. These areas should be cleaned weekly for better pasture management, parasite control, and to diminish fly breeding.
Manure collected from paddocks and pastures may be added to the stall waste stockpile.
Horse manure has been considered a valuable resource rather than a “waste.” Fertilizer value of the 8.5 tons of manure produced annually by a 1,000-pound horse is about 102 pounds of nitrogen (N), 43 pounds of P2O5 (phosphorus pentoxide [phosphate] = 43.7 percent P), and 77 pounds of K2O (potash = 83 percent K). The nutrient content of horse manure can also be represented as 12 lb/ton of N, 5 lb/ton of P2O5, and 9 lb/ton of K2O (nutrient values for any manure vary widely, so these are only guidelines). Traditionally, nitrate-nitrogen is the component that presents the most pollution potential since it moves freely in the soil. Most of horse manure’s nitrogen is contained in the urine.
These values are an average for horse manure (urine and feces). With the large amount of bedding material mixed with manure in typical stall waste, the fertilizer nutrient value would vary.
The stall waste will have to be stored somewhere whether temporarily or long term. Keep stored manure in a fly-tight area during the warm months or manage to prevent fly breeding and protect from rainfall and surface runoff. A well-built storage pad or container aids in waste handling and minimizes pollution potential from the pile. The pad can be as informal as a level, well-packed surface with a wood or masonry backstop or a covered structure with impermeable flooring. If topography permits, a below-grade storage container is a less objectionable structure as it keeps the manure contained to a small area, is out of view, can be covered, and is easily filled using gravity to dump waste into it. One side should be at ground level for emptying. Longer-term manure storages are often more substantial structures than short-term storages. Large quantities of manure require a storage designed with wide door(s), a high roof, and strong construction to allow cleanout with power equipment. Manure for commercial pickup can be stored in a container or dumpster. With any large or small manure storage, a tarp or other cover is recommended to minimize leachate production from rainfall.
Direct disposal involves the on-farm use of the stall waste via field application. Proper field application demands equipment such as a tractor and spreader so that the manure is applied in a thin layer over the soil. The thin layer is essential for drying the manure to discourage fly breeding and also spreads the nutrients for more optimal plant use. Weekly spreading in the summer will disrupt fly breeding and egg development cycles. To minimize pollution from runoff, do not spread manure on frozen ground or near waterways. It may not be possible to spread manure each week year-round, in which case the manure must be stockpiled. In cold climates, figure on 180 days of stockpile storage space. Manure application may be limited to preplanting and post-harvest dates for cultivated fields. Fields may not be accessible due to heavy snow accumulation or soil that is too wet to support equipment traffic.
Spreading manure in thin layers has been thought to reduce parasite numbers by desiccating the eggs. This does hold true under dry and extreme cold or hot conditions. Recent evidence suggests that spreading thin layers of manure on pastures can enhance grazing horses’ parasite exposure by spreading viable parasites over a larger area. The recommendation is to leave the manure piles in clumps and pick them up for disposal outside the pasture area.
Field application is based on fertilizer needs of the crop or pasture grass through soil sampling. The approximate fertilizer value of manure from bedded horse stalls (46 percent dry matter) is 4 lb/ton ammonium-N, 14 lb/ton Total N, 4 lb/ton P2O5 (phosphate), and 14 lb/ton K2O (potash). Fertilizer value of manure at 20 percent moisture without bedding is approximately 12-5-9 lb/ton (N-P2O5-K2O). Nutrient values vary widely, so use these values as guidelines and have the manure analyzed if more specific data are needed. The amount of organic nitrogen mineralized (released to crops) during the first cropping season after application of horse manure is about 0.20. Organic nitrogen must be released through mineralization before plants can use it. About 20 percent of the organic N from horse manure is available to the pasture grass the year of application. Organic N released during subsequent seasons is usually about 50 percent (second year), 25 percent (third year), and 13 percent (fourth year) of the first year mineralization.
Another manure disposal option is to contract with a hauler who will remove the waste from the stable facility. The waste can be used in a commercial composting operation or for other functions where the waste disposal is the responsibility of the hauler. Dumpsters are positioned at the stable for temporary stall waste storage (no trash or garbage); a full dumpster is replaced with an empty one. Dumpsters should be sized so that the contents are emptied at least weekly during the fly-breeding season. A concrete tank or pad is useful to contain any dumpster leachate.
A less formal “contract” disposal is to interest neighbors in free garden organic material. The key is to locate the organic fertilizer enthusiasts. Owners of small stables have had success with newspaper ads and locating “free” bagged manure at curbside. Empty feed sacks filled with horse manure are a useful package for manure distribution.
Keep It Legal
Various state and federal regulations for protecting environmental quality are aimed at manure management. Often categories of livestock (including horse) operations are defined that relate to their potential to cause environmental harm. When stable facilities and manure storage structures are properly designed, constructed, and managed, the manure is an important and environmentally safe source of nutrients and organic matter. Proper land application of manure will not cause water quality problems. The intent of regulations is to ensure that economically practical techniques are used in all aspects of manure handling.
Making manure management a more thoughtful and efficient chore benefits both the horse owner and their neighbors. Time spent planning for proper and easy manure disposal will pay back in many more hours spent enjoying the horses through decreased time and effort in stall cleaning and manure disposal chores. Maintaining good neighbor relations through fly and odor minimization will ensure the compatibility of horse stables within the neighborhood.
Courtesy of PennState Extension