Horse Manure Management

The Nitrogen Enhancement System

AGF-212-03

Randall E. James, Ph.D.
Associate Professor
Extension Agent, Geauga County
Ohio State University Extension

Introduction

Ohio has a large number of horses stabled in suburban counties near each large city. Managing horse manure in suburban areas is often a problem because land, to properly store and utilize the manure for crop production, is limited. In addition, when horse manure is mixed with sawdust or wood chips, and spread on farm fields, it often stunts crop growth. Since farmers don't want to stunt their crops, the horse owner has few good options for disposing of manure. Frequently, it is simply stacked outside until the pile gets so big that a neighbor complains and the manure must be hauled to a landfill.

Why Does Horse Manure Stunt Crops?

Actually it doesn't; but sawdust or wood shavings do. These wood products are the most common bedding used for horses. When horse manure and sawdust (or shavings) are put on soil the microorganisms in the soil start to break them down. Unfortunately, these wood products have a lot of carbon that the microorganisms use for energy but not enough nitrogen to build protein. In other words, the microorganisms have an unbalanced diet and they need nitrogen. They find that nitrogen in the soil and they collect it more efficiently than plants do. In fact, they do it so well that the plants growing in the soil can't find enough nitrogen to grow properly. That's called an "induced nitrogen deficiency" and it stunts crops.

The Nitrogen Enhancement System

The horse owner or the farmer can add nitrogen fertilizer to the manure/sawdust mix or to the soil. The added nitrogen can be used by the soil microorganisms to break down the manure/sawdust mixture. Therefore, they won't need to steal soil nitrogen from the growing crops. The fertilizer should be added to the manure prior to spreading it on the soil. Another option is to work the fertilizer into the soil after the manure has been applied.

What Kind of Fertilizer and How Much?

Use only ammonium nitrate fertilizer with an analysis of 34-0-0 or ammonium sulfate with an analysis of 21-0-0. Other types of fertilizers (especially urea) can be lost into the air in a manure pile and do no good. Add about 10 pounds of ammonium nitrate or ammonium sulfate per ton of horse manure/sawdust mix. This is about 1/3 pound (about 1/2 cup) of ammonium nitrate or ammonium sulfate per 1,000-pound horse per day.

Add the ammonium nitrate as the stalls are cleaned. Simply pick a stall clean with a manure fork, then add about 1/2 cup of ammonium nitrate or ammonium sulfate (for a 1,000-pound horse) to the manure and bedding in the wheelbarrow or spreader. Adjust the amount of ammonium nitrate or ammonium sulfate if the horse is much smaller or larger than 1,000 pounds. For example, only about 1/4 cup of ammonium nitrate or ammonium sulfate per day would be needed for a 500-pound pony. Apply the ammonium nitrate or ammonium sulfate to the manure only after it has been removed from the stall.

Manure Storage

After the ammonium nitrate or ammonium sulfate has been added to the manure/sawdust mixture it can be held in proper storage for several months without losing the nitrogen. It can then be brought out of storage and spread when the field and crop conditions are best. Manure should be stored at least 50 feet from any drainage-way or water-course and a grass filter strip should be used to limit runoff. Check with your local Soil and Water Conservation District or the Natural Resource Conservation Service for technical help on a wide variety of resource management questions including manure application, utilization and storage. In some cases, the state or federal government may be willing to cost-share, with the stable owner, on the construction of a manure storage structure.

Application Rate

The amount of horse manure/sawdust that can be safely applied to a soil is based primarily on the nutrient needs of the crop, the soil nutrient levels, and the nutrient content of the manure/sawdust mixture. For more information on calculating manure application rates and managing manure systems see the following Ohio State University Extension publications:

These publications should be available through your local county office of Ohio State University Extension.

Once amended with ammonium nitrate or ammonium sulfate, horse manure and sawdust bedding can be beneficial for soils and crops. Like other organic materials, it contains nutrients for plant growth and can improve the general condition of the soil.


Composting Horse Manure1

E. A. Ott, E. L. Johnson, R. A. Nordstedt2

Management of horse farm wastes is an ever increasing problem for horse owners and horse facility managers. This is especially true where horses are stalled and land availability limited. Examples of the latter include race tracks, training centers, horse show complexes, public stables, and even some private horse farms.

In the past, these materials have been piled on unused land, deposited in ravines and eroded ditches, hauled to landfills, burned, and used as soil amendments for cropland. With the increasing emphasis on the control of environmental pollution, many of the above options are no longer acceptable. Alternative utilization or disposal procedures are essential. One of the most promising alternatives is the conversion of the materials to organic soil amendments via composting. Composted horse manure can be used to increase the organic matter content and thus the water and nutrient holding capacity of sandy soils in agricultural and home gardening settings. The material can also be used by plant nurseries as potting soil and is an excellent media for the production of mushrooms, fish worms, etc.

Horse stall wastes include feces, urine, bedding material, hay, and sometimes waste feed. Bedding materials make up a large portion of the waste and may include straw, wood shavings, sawdust, grass hay, peanut hulls, shredded paper and other locally available products. These products are characterized by their high organic matter content, bulky nature, high absorption ability, and low nitrogen content.

Composting is a method whereby the organic component of the solid waste is biologically decomposed under controlled conditions to a state in which it can be handled, stored, and applied to the land without adversely affecting the environment. A key phrase in the above definition is "under controlled conditions." This distinguishes composting from the biological decomposition processes which occur naturally, and it also differentiates composting from some objectionable practices such as open dumps, piles of rotting manure, and other accumulations of waste materials.

There are two types of composting systems, aerobic and anaerobic, and many procedures for accomplishing each. Aerobic composting implies decomposition in the presence of oxygen. Most commercial composting systems are aerobic, since anaerobic systems are more likely to produce foul odors. Even though aerobic systems may not be completely free of odors, they can usually be described as producing a minimum of objectional odors. Aerobic composting is more rapid than anaerobic composting; also, anaerobic composting does not result in an appreciable rise in temperature, while in most aerobic composting systems the temperature exceeds the thermal tolerance of most plant and animal pathogens and parasites. Weed seeds are also destroyed.

 

Factors Affecting the Rate of Composting

The rate at which the material breaks down is influenced by:

(1) Availability of air.

Two composting procedures are available. Anaerobic (lack of oxygen) composting is slow but requires very little management input. Manure piled outside will compost over a period of time. The procedure will require a year or more, and the results may not be uniform. Aerobic composting requires that the material be exposed to air on a regular basis. This is accomplished by turning the material 1 to 3 times per week. Aerobic composting is much faster than anaerobic composting and may require 30 to 60 days to complete. Equipment alternatives for aerating the material include a front end loader, rototiller or mechanical aerator.

 

(2) Moisture level.

Composting material should be 40 to 60% moisture. The material will feel wet but not soggy. Care must be taken to not add too much water as soluble nutrients will be lost and surface and ground water contamination could occur. If properly managed, composting can be done outdoors on well drained sandy soil, on a concrete slab or on a concrete floor under a roof.

 

(3) Particle size.

The smaller the particle size, the more efficient the composting procedure will be. Therefore, grinding may be appropriate for some types of materials. However, more frequent aeration may be necessary for smaller particle sizes.

 

(4)Temperature.

Microbial metabolic activity will generate considerable heat. The center of the pile may reach 130°C to 160°C. This heat is advantageous to the rate of composting and will destroy many life forms present in the material including plant seeds, parasite larvae and eggs, and some bacteria. Heat must be controlled since low moisture materials could ignite if they are in contact with hot compost.

 

(5) Carbon/nitrogen ratio.

Organisms require nitrogen for multiplication. Since some bedding materials are very low in nitrogen (Table 1) , additional nitrogen should be added to maximize decomposition rate. A C/N ratio of 15 to 30 will allow maximum fermentation rates. Organic nitrogen sources such as cottonseed meal grass clippings or additional manure can be added as a nitrogen source or inorganic nitrogen sources such as urea can be used.

 

(6) pH.

The composting of some materials may produce acids that lower the pH and stop the process. This is normally not a problem with livestock wastes, unless an unusual bedding material is used. The addition of ground limestone as a buffering agent will correct the problem.

Composting systems that are part of a horse farm or a nursery are generally considered to be an agricultural activity. If composting is a primary business, it is usually considered to be a manufacturing activity and appropriate land use regulations must be followed. Regardless of the type of operation, the site selected should minimize the possibility of ground or surface water contamination. Properly managed, a composting site should not produce fly or odor problems. However, visual impact may not be very favorable, so it should be screened from public view.

 

 

Tables

Table 1.

 

Table 1. Carbon to nitrogen ratios for manure and bedding materials.
 
Material
 

%N1


 

C/N ratio


 

Horse manure
 
1.0 - 2.5
 
17.5 - 42
 
Wood shavings
 
--
 
600
 
Wheat straw
 
0.53
 
76
 
Oats straw
 
0.60
 
65
 
Peanut hulls
 
0.74
 
54
 
C. Bermudagrass hay
 
1.10
 
35
 
Grass clippings
 
2.00
 
20
 
Cottonseed meal
 
6.60
 
6.2
 
Urea
 
45.00
 
--
 
1Dry matter basis
 

 


Footnotes

1. This document is SS-ANS-001, one of a series of the Department of Animal Sciences, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Date reviewed: March 2000. Please visit the EDIS Web site at http://edis.ifas.ufl.edu.

2. E. A. Ott, Professor, Department of Animal Sciences; E. L. Johnson, Associate Professor, Department of Animal Sciences; R. A. Nordstedt, Professor, Department of Agricultural and Biological Engineering, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611.


Horse Manure Management

by J.G. Davis and A.M. Swinker1


 

Quick Facts...

  • An average 1,000-pound horse produces 9 tons of manure a year containing valuable fertilizer elements.
  • Horse owners have a responsibility to manage the manure that is a byproduct of their industry.
  • Manure is commonly stockpiled prior to use. Adequate storage area allows for greater flexibility in timing of manure use.
  • Recordkeeping is an essential factor in land application of manure/compost.
  • The total fertilizer value of the manure produced by Colorado’s horses is estimated to be $10 million per year.

An average 1,000-pound horse produces 9 tons of manure a year (50 pounds per day) containing valuable fertilizer elements. (See Table 1.) Add to that an additional cubic foot of bedding material and you get 730 cubic feet/year from one horse. How the manure is stored and treated has a substantial impact on its value. The labor, storage and utilization costs for manure management can be considerable.
 

Colorado’s horse industry uses two principal feed management systems, according to a recent survey. The first system permits horses to graze full-time on pastures, and the manure is not collected or treated. Pasture manure usually is spread by harrow cultivation that promotes decomposition.
 

The second system confines animal feeding, which relies on intensive management, and the horses are kept in stalls or runs. The horses may be housed in box stalls and provided a bedding source for urine absorption. Alternatively, horses are kept in corrals or runs, and some runs are attached to stalls. Manure is managed in one or more of the following ways: 1) compost (manure is removed daily and composted); 2) stockpile (manure is removed daily and stored in piles); and, 3) daily land application (manure is removed daily and spread on cropland).

Marketing Plan

Horse owners have a responsibility to manage the manure that is a by-product of their industry. Develop a management plan for manure and soiled bedding. Use it on crop lands, arena surfaces, trail surfaces, and landscaping. If you don’t plan to use the manure yourself, develop a marketing plan so others can make use of it.
 

Contract or donate compost to crop farmers and community landscapers or parks, and neighborhood gardeners. Offer a discount to boarders if they dispose of manure. The people who come to watch others ride are another potential market for manure or compost sales. Before you can market the product, it must be completely and properly composted and free of foreign material such as pop cans, wire, and syringes.
 

Make an arrangement or contract with a landscaper, nursery or crop farmer. Be prepared to handle your own by-product. One option may be to deliver manure, at your cost, to a site where contractors do the composting. Pre-determine the bedding types they prefer in their compost mix.

Manure Collection

Confinement Housing (Stalls, Drylots, and Runs). Daily maintenance of horses in a confinement setting requires intensive labor. Horses housed in stalls and sheds require soft absorbent bedding. The most common bedding sources in Colorado are pine sawdust (80 percent), pine wood chips (17 percent), and straw (2 percent). Some other sources are shredded newsprint, peanut shells, peat moss, rice hulls, etc. Remove manure and soiled bedding on a regular basis and handle appropriately to prevent fly infestation and disease transmission.
 

Pastures. Manure management in pastures depends primarily on getting good distribution of manure across the pasture.To avoid manure concentration in isolated spots in a pasture, distribute grazing evenly. Rotational grazing is one of the best ways to achieve this goal; however, horse owners don’t usually have large enough pastures for rotational grazing.
 

On the other hand, pastures can be split, and the horses moved back and forth between both parts of the pasture to distribute the manure more uniformly. Availability of several watering facilities and moving feeding facilities periodically will encourage better manure distribution.
 

Avoid grazing during rainy periods when soils are saturated, to avoid soil compaction and manure runoff. Restrict access to streams to avoid manure deposition in or near water bodies. This can be done by fencing or providing shade away from the streams. Refrain from excessive stocking rates that lead to overgrazing. Damaging the grass stand increases manure runoff potential from pastures.

 

Storage and Treatment

Stockpiling. Manure is commonly stockpiled prior to use. Adequate storage area allows for greater flexibility in timing of manure use. Therefore, be sure you have a large enough storage area to accommodate the manure produced. Over time, the manure shrinks from decomposition and moisture loss.

Proper site selection for the storage area is important to safeguard against surface and groundwater contamination. Place stockpiles at least 150 feet away from surface water (creeks and ponds) and wells. Establish and maintain grass buffer strips between water bodies and manure piles. Construct a perimeter ditch or berm around the storage area, if needed, to prevent runoff onto or off of the area.
 

Composting produces a relatively dry end-product that is easily handled and reduces the volume of the manure (40 percent to 65 percent less volume and weight than the raw manure). Composting at proper temperatures can kill fly eggs and larvae, pathogens and weed seeds. Compost has less of an odor compared to raw manure and is more easily marketed. Composted manure acts as a slow release fertilizer and an excellent soil conditioner.
 

To be done right, composting requires an investment of time and money. Machinery required includes a tractor, a manure spreader and a front-end loader. Some ammonia-nitrogen is lost during the composting process, and an ammonia odor may result for a short period. When composting is done on a large scale, additional land and machinery requirements exist.
 

Microbes that drive the composting process require optimum conditions of temperature, moisture, oxygen, and carbon:nitrogen (C:N) ratio. The C:N ratio should be between 25:1 and 30:1; horse manure has an estimated C:N ratio of 50:1. With the addition of bedding material (high carbon content), the C:N ratio will be even higher. Therefore, N has to be added to the manure for it to compost properly. The addition of grass clippings, hay, or fertilizer [25 to 30 pounds N/ton of manure (75 to 90 pounds of ammonium nitrate or 50 to 65 pounds of urea)] should bring the C:N ratio into the optimum range. When microbes work properly, the compost temperature will be between 120 and 160 F. Cooler temperatures result from a lack of N. When the composting process is complete, the temperature will cool naturally.
 

It is important to have the right balance of moisture and air for the microbes to process the manure. The compost should be moist but not soggy, and may need to be watered or covered with plastic to maintain moisture. Aerate the compost by turning it regularly. The manure and bedding particles should be about one-half inch to one and a half inches in size. Composting does require effort, but the result is a more easily used and economically valuable fertilizer.

Utilization

Land Application. Recordkeeping is an essential factor in land application of manure/compost. It is critical to know how much manure/compost was applied to each field and when it was applied. Analyze manure/compost regularly and record the lab results for future reference. Note changes in nutrient value and factor them in when calculating future application rates.
 

Manual loading and land application are labor intensive and impractical for managing the manure generated by more than 25 horses. Consider mechanical loading and application with a bobcat or tractor-operated loader when the manure or the land application becomes large.
 

Apply the manure/compost uniformly to achieve an acceptable application rate. The finer textured and more uniform the manure, the easier it is to apply uniformly. Spreaders apply manure/compost at different rates depending on ground speed, PTO speed, gear box settings, discharge openings, and manure moisture and consistency.
 

Do not apply manure to land that is highly erodible, frozen or saturated. To protect water sources from manure runoff, do not spread manure within at least 150 feet of a water source (such as a well, creek or pond). Incorporate manure into the soil as soon as possible. Mixing the manure with the soil immediately reduces losses of manure nutrients to runoff and volatilization, and reduces odor problems associated with manure left on the soil surface.
 

Base the manure/compost application rate on crop N needs and available soil and manure N levels. Test your soil and manure for N levels at a certified laboratory. In general, the higher a crop yield goal, the greater the N requirements. Irrigated crops also tend to need more N. If yield goals are lower than those shown in Table 2, decrease the manure application rate and increase the land application area. If yields are higher, less land is needed. Soils high in organic matter and nitrate have higher available N in the soil and require less N.

Table 1: Average fertilizer content in horse manure (as-is basis).
N/ton
19 lb
P2O5/ton
14 lb
K2O/ton
36 lb

 

Table 2: Average manure application rates and land base (area) requirements for forages.
Forage
Yield
Annual Horse Manure Application
Land Base Needed
 
(tons/acre)
(tons/acre)
*(acres/horses/yr)
Alfalfa
2.0
15
0.6
Alfalfa-grass
2.0
10
0.8
Bentgrass
1.0
10
0.8
Big bluestream
1.5
5
1.8
Birdsfoot trefoil
1.5
12
0.8
Bluegrass
1.0
10
1.0
Bromegrass
1.5
10
1.0
Little bluestem
1.5
6
1.6
Orchardgrass
2.0
10
1.0
Red clover
1.5
10
0.8
Reed canarygrass
2.0
9
1.0
Ryegrass
2.0
11
0.8
Switchgrass
1.5
6
1.6
Tall fescue
2.0
13
0.6
Timothy
1.5
6
1.6
Wheatgrass
0.5
2
3.8
*The land base needed is the cropland requirement for manure application alone, not for grazing and forage needs. One ton = 2,000 lbs. One acre = 43,560 sq ft.

Landfill. Manure and compost are sometimes landfilled, dumped in gullies and used to repair roads. These are not recommended practices due to high runoff and leaching potential from gullies and roadways. If the areas are not vegetated and are waterways for storm runoff, the potential for runoff of manure nutrients into creeks and ponds is high. When excessive nutrients exist in surface waters, plant and algal growth becomes extreme, the oxygen supply is depleted, and fish can be killed.
 

Footing for Riding Arenas. An ideal arena surface provides resilient footing for optimum horse performance. Drain the arena well, maintain adequate depth to protect horses’ legs from contusions, and keep the arena absorbent to hold moisture efficiently and prevent dust. The arena surface also must be odor-free. Composted manure/bedding makes an ideal surface addition when mixed with river sand and wood products. Uncomposted manure and bedding results in ammonia fumes that can cause respiratory problems in horses. Surface depth of compost depends on soil type and climate; too much organic matter can hold excess moisture and may cause the horses to slip and fall.

Table 3: Maxium manure application rates to avoid soil salinity problems.
Manure EC*   Soil EC*  
 
1
2
3
10
84 T/A
56 T/A
28 T/A
20
30 T/A
20 T/A
10 T/A
30
18 T/A
12 T/A
6 T/A
40
12 T/A
8 T/A
4 T/A
*mmhos/cm; T = Ton; A = acre
EC = electrical conductivity measured in units of millimhos/centimeter. Note: The manure application rate should be based on N needs of the crop within this maxium range. This table assumes that manure is not incorporated, which is typical for perennial forage crops.

 

Precautions

Virtually no viral diseases are transmitted between horses and humans through fecal material, but some bacteria and protozoans (such as E. coli and Giardia) can be transmitted in this manner. Therefore, handle manure carefully to prevent disease transmission. In addition, horse manure runoff into waterways may produce fecal coliform contamination levels that can be potentially hazardous to fish and anyone who drinks that water.
 

Runoff. Runoff water from dry lots, pastures, and manure storage or compost areas carries pollutants (such as nitrogen, phosphorus, and bacteria) into surface waters. Avoid overirrigation of pastures. Build berms or trenches to prevent water from entering or leaving dry lots and manure storage and composting areas. Do not allow a creek or irrigation canal to pass through drylots.
 

Parasite Prevention and Control. Horses pick up parasites by ingesting grass, feed, or water that is contaminated with parasite larvae and eggs. The most common internal parasites of horses are the ascarids, strongyles (large and small), pinworms and bots.
 

Insect Control. Excellent fly-breeding conditions occur in mixtures of manure, spilled feed and decaying bedding. To help eliminate these areas, remove and spread the manure regularly and prevent accumulation of other wastes. Composting at proper temperatures inhibits fly development. Several pesticides can be used on manure piles to kill maggots. Cover manure stockpiles or compost sites to exclude flies and prevent their development.

Noncomposted manure piles can provide an ideal environment for the bumble flower beetle white grub. White grubs feed on decaying manure; however, these grubs do not damage home lawns. Therefore, there is no need to control them.
 

Mosquitoes require standing water to reproduce; therefore, it is imperative to prevent ponding of water in manure storage areas.
 

Salinity. Manure tends to be high in salts, which when land applied at excessive rates, contribute to soil salinity. Soil salinity causes plants to become water stressed or, in extreme cases, die. When manure is not soil-incorporated, as in applications to pasture, the salts accumulate on the soil surface unless they are leached into the subsoil. Irrigation or rainfall may move salts out of the topsoil and move them into deeper depths of the soil profile. If salinity levels in the soil and manure are known, use Table 3 to determine acceptable maximum rates of manure application for most forages to avoid excessive soil salinity (>4 mmhos/cm).

Weeds. A weed is an unwanted, out-of-place plant. Weeds compete with crops for limited resources of water, nutrients and light. Manure has contributed to weed problems where it has been applied to cropland. Use composted manure to avoid these problems. When manure is composted, the high temperatures achieved during the composting process kill most weed seeds. Some weed infestations may be the result of overgrazing, not due to manure applications.

 

Parasite Preventions and Controls

Deworm all horses on a regular schedule using an anthelmintic. Contact a veterinarian for anthelmintic recommendations.
 

Manure management:
A. Remove all manure from stalls, small corrals, and paddocks on a daily basis.
B. Compost all manure to a temperature of 145 F for at least two weeks to kill most parasite eggs, or compost at lower temperatures for longer periods of time.
C. Spread manure on pastures only after composting.
D. Manure that has not been composted should be spread only on crop land or other ungrazed, vegetated areas.


Pasture management:
A. Mow two to four times a year and chain harrow (drag) to break up manure piles and expose parasite eggs to the elements.
B. Don’t overstock.
C. Practice rotational grazing if possible.
D. Graze young horses separately from older horses; the younger horses have a higher susceptibility to parasites.
E. Follow horses with cattle or sheep before returning a pasture to horses. This interrupts the life cycles of horse parasites.
F. Deep harrow or plow pastures that are badly parasite-infested. Deep plow pastures and reseed every three to five years. This also helps break parasite cycles.
 

Feed and water management:
A. Use feeders, racks, bunks or mangers for feeding hay and grain. This will prevent feed from getting mixed with feces. Don’t feed off the ground.
B. Provide horses a clean, fresh drinking water supply.
C. Avoid water contaminated with feces.
 

 

Resources

Spencer, W., and D. Tepfer. 1993. 3.762, Economics of composting feedlot manure. Colorado State University Cooperative Extension.

Wilson, C.R., and J.R. Feucht. 1991. 7.212, Composting yard waste. Colorado State University Cooperative Extension.

Waskom and Davis. 1999. BMPs for Manure Management, Colorado State University bulletin no. 568a.


 

1J.G. Davis, Colorado State University Cooperative Extension environmental soil specialist and professor, soil and crop sciences; and A.M.Swinker, former Cooperative Extension horse specialist and associate professor, animal sciences. Reviewed 1/2002.

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Updated Thursday, December 04, 2003.


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