Masters in Manure

Credit: Thinkstock When managed properly, manure should be seen as valuable resource on a farm; when managed poorly, it can be a source of pollution.

A 1,000-pound horse will produce 35-50 pounds of manure alone on a daily basis. A ton of horse manure will contain 7-12 pound of nitrogen, 3-6 pounds of phosphorous and 3-9 pounds of potassium. Horses kept in stalls require 8-15 pounds of daily bedding; added to manure, the muck volume increases to 2-3 cubic feet per day amounting to approximately 12 tons per horse per year. So what’s a horse farm to do with all this waste? Balancing cost, health of animals, and environmental issues can be easier when waste is converted into a useable or saleable product for the farm.

When managed properly, manure should be seen as valuable resource on a farm. Nutrients entering the farm as feed or fertilizer are expelled as manure and can then be recycled as a source of nutrients for crops while improving soil quality. Organic matter from manure applied to pastures or crop land improves soil tilth (the condition of tilled soil) and water-holding capacity. Provided manure is applied at the proper rate, the soil can store nutrients for future plant uptake.

Poorly managed manure can be a source of pollution. Manure can create air quality concerns, introduce pathogens in water supplies, produce odors and dust, and increase the presence of vermin. Each farm should develop a management plan to provide for proper storage, use and/or disposal of manure.

Management planning is site specific as every farm is unique. Consideration must be given to farm land, equipment, and financial resources in addition to proximity to water bodies, neighbors’ concerns, potential erosion, manure storage and nutrient balance in the soil. It is important to understand that the value of manure varies. What animals are fed, their activity levels, the amount and type of bedding, and how manure is stored and handled all impact the benefits.

How manure is applied can also impact the value of nutrients retained for plant use. Not all of the nutrients in manure are immediately available for plant uptake. The amount of nitrogen available is based on the percentage of nitrogen in the manure (which varies if incorporated in the soil or surface applied) and is influenced by the rate of organic matter decomposition prior to spreading.

Sawdust or wood shavings are high-carbon materials that require a great deal of nitrogen to break down, tying up available nitrogen and rendering it unavailable to plants or crops. Composting will avoid this situation and will provide additional benefit. A well-managed compost pile reduces parasites, odors, bulk of material, kills off unwanted weed seeds and enhances soil productivity when applied to fields. Whether compost will be utilized on the farm or sold, this alternative to disposal of raw manure adds value and reduces cost to the business. Composting creates a more valuable soil amendment that will not affect soil pH, stabilizing nitrogen and reducing manure volume by 50%.

Adding compost to your land builds good soil structure and texture. Adding compost to heavy clay soil loosens the packed soil by enhancing pore spaces that carry air and water down into the plant root zone. Sandy soils, which tend to let water drain away too rapidly, are also improved with the addition of compost due to increased water retention of organic material. By increasing the soil’s moisture-holding capacity, compost also helps control erosion that would otherwise wash topsoil away.

Compost increases nutrient content and enhances nutrient availability to plants. This is beneficial for both pasture and crop fields. The benefits of adding compost will last for more than one season. The constant additions of compost results in the buildup of reserve nutrients in the soil which will likely reduce the need for added fertilizer. Compost also gradually changes soil pH levels that are either too low (acidic) or too high (alkaline). The pH level has a significant impact on nutrient availability. As the percentage of organic matter in the soil is increased with the addition of compost, the pH level is stabilized, thereby reducing the need to apply agents to adjust the pH of your soils.

Simply piling horse manure is not composting. Composting is the controlled conversion of the materials into organic soil amendments. Decomposition is a naturally occurring process. In composting, we are managing components of the process to speed it up, thereby affording us a useable product in much less time. The rate at which the material breaks down is influenced by the availability of air, moisture level, particle size, temperature,and the carbon/nitrogen ratio of the pile. These are all manageable components in composting.

Composting can take place under aerobic and anaerobic conditions. Aerobic composting implies decomposition is occurring in the presence of oxygen. Aerobic systems are generally more accepted since anaerobic systems are more likely to produce foul odors. Aerobic systems may not be completely free of odors, but they produce a minimum of objectionable odors when properly managed. Aerobic composting is more rapid than anaerobic composting and generates more heat during the process. This enhanced temperature is utilized to kill off most plant and animal pathogens and parasites.

A well-managed compost pile will be free of the odors often associated with an un-composted manure pile. Proper water content is required for composting. The microorganisms at work in the system require moisture; a system with 40-60% moisture keeps organisms working without creating the anaerobic condition that creates a strong odor resembling rotten eggs. If the compost feels like a freshly wrung out sponge, you have the proper amount of moisture. In decomposition, microorganisms break down organic materials like horse manure into smaller particles. The more surface area the faster the organisms can break down the material. Reducing particle size before it is added to the pile will decrease the time needed in the compost system.

Ideal temperature for a compost system is between 90 and 140 degrees Fahrenheit. This allows enough warmth to keep the system going without killing off the organisms working for you. A well-managed compost pile will reach temperatures high enough to kill fly eggs and larvae in manure. The high temperatures achieved through composting also kill worms and pathogens. This is especially important if you are spreading your manure in the same fields your horses graze on. To ensure killing off of unwanted organisms, at the end of the process you should allow the temperature to exceed 150 degrees Fahrenheit. Proper temperature is maintained by assuring adequate moisture and turning of the pile. Generally if the pile is too cold, it is due to a lack of moisture. The pile is turned because temperatures within the interior of the pile will be higher than the exterior. Size of the pile can also affect temperature, particularly in colder regions.

Spring is the preferred time to apply manure if your soil allows. Wet soils are susceptible to compaction or ripping up top soil so fields in wet conditions should be avoided. Cropland commonly provides the greatest flexibility in planning land application. Pasture spreading raw manure should be avoided due to the risk of infecting pastures with internal parasites. If applying to pastureland is necessary it is important to spread the manure four to five weeks before grazing.

It is prudent to take a soil tests to determine crop nutrient needs. Manure and compost tests can provide the actual nutrient value and coupled with regular soil testing will allow farms to balance nutrient availability with plant crop needs. Applying a thin layer will speed drying and discourage fly breeding.Manure should not be spread where and when there is any risk for water pollution, and there might be restriction for time of year spreading can occur in your state. Check with your local Cooperative Extension or Soil & Water Conservation District.

Proper field application requires proper equipment. Very small or limited-resource farms may need to get by a wheelbarrow and pitch fork. Others may be able to utilize small ground-drive spreaders; these are less effective if spreading fresh manure containing hay or straw. Both of these methods make it challenging to regulate rate of application. Spreaders with power take-off (PTO) give operators more control over rate as you can adjust travel speed and PTO speed. Whatever method is used it is critical to avoid heavy application rates as this can cause smothering of plants.

In situations where land application is not an option due to lack of acreage or having more manure than can be properly utilized; off-farm disposal options need to be considered. You may be able to marketing the manure or give it away. Gardeners are often willing to take or buy composted horse manure. Neighboring farmers might be willing to let you spread manure on their land. Look for local farms, nurseries and commercial compost operations that can use the manure.While expensive a dumpsters may be the best option when there is inadequate land for spreading.The dumpster should be placed on a concrete pad or other impervious surface that allows for the collection of any liquids that leach out. If you are faced with hiring a hauler to remove the manure, be aware that some states require hauler to be certified to haul manure off the farm and on to the highways. Check certification to avoid potential legal liability if there is an accidental spill by the hauler.

Lynn A. Bliven works in Agricultural Economic Development, specializing in beginning farmer outreach, local food systems and livestock production. She and her husband, Shawn, operate a farm in Rushford, New York, raising Hereford cattle and Shetland sheep along with their pleasure horses. Lynn is a Master Instructor and Clinician with the Certified Horsemanship Association. To become certified, get your facility accredited or find an instructor or barn near you visit or






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