Components of a manure-management system include collection, transfer, storage, possible treatment, hauling, and utilization (land application). Many factors should be considered when selecting a manure-management system for a specific operation. These include livestock type, age and size, feed rations, housing, bedding, labor requirements, land availability adjacent to the farmstead, cropping rotation, topography of farmstead and fields for planned manure application, proximity to waterways, proximity to neighbors, prevailing wind direction, and personal preference.
When on-farm manure-application areas are limited, the management plan must also include off-farm manure transport. Therefore, a manure-management system should fit the needs of each individual livestock operation. There is no single “best” system. Each has advantages and disadvantages. Proper implementation and management are the keys to a successfully operated manure-management system. A complete system should accomplish the following goals:
This chapter presents different options of equipment types and facilities for handling animal manures. System options for handling liquid, semi-solid, and solid manure for different livestock species are discussed.
Manure can be handled as a liquid, slurry, semi-solid, or solid. The amount of bedding or dilution water influences manure characteristics as discussed in Chapter 1, Manure Characteristics. Manure characteristics influence the collection, transfer, storage, and selection of spreading equipment.
Solid manure is a combination of urine, bedding, and feces with no extra water added, such as that found in a loafing barn, bedded pack, calving pen, or open lot with good drainage.
Semi-solid manure has little bedding and no extra liquid added. Little drying of semi-solid manure occurs before handling. Solid and semi-solid manure can be handled with tractor scrapers, front-end loaders, or mechanical scrapers. Conventional box or flail spreaders are common for land application.
Slurry manure is a combination of feces and urine with little organic bedding or dilution. Manure slurry can be transferred directly into storage with a mechanical or tractor scraper, or scraped to a reception pit for gravity flow or pumping into storage. If the storage facility is covered, the manure can be loaded out of storage onto a V-tank spreader.
Liquid manure has water added to form a flowable mixture that can be handled by solids-handling pumps. Liquid manure is usually less than 8 to 10% solids. Very liquid manure is usually only 1 to 2% solids and is common with flushing and lagoon systems. Liquid and slurry manure are handled with scrapers, flushing gutter, gravity-flow gutters, or storage under slotted floors. Liquids are spread on fields with tank wagons or by irrigation.
In most facilities, manure storage is needed to provide handling and spreading flexibility. The primary purpose of a storage structure is to provide flexibility in scheduling field spreading to avoid wet ground, poor weather conditions, growing crops, and conditions conducive to causing pollution.
Several collection and transfer methods are possible to manage manure. Selection considerations include facility type, labor requirements, investment, and overall manure management system. Open-lot and confined systems livestock housing have different requirements and options.
An open-lot system requires two manure-handling methods. Lot scrapings and open-front shelter manure packs are solid or semi-solid, and lot runoff is liquid. Solid manure from the shelter or lot can be moved to storage with a tractor scraper and front-end loader. Lot runoff contains manure, soil, chemicals, and debris and must be stored or treated as a component of the manure-management system. Runoff from roofs, drives (not animal alleys), and grassed or cropped areas without animal traffic is relatively clean and should be diverted from the manure system. See Chapter 5, Farmstead Runoff Control, for more details.
A confined system can store manure in a tank under the building or in outdoor storage. For an under-the-building storage tank, manure is transferred through a slotted floor or drain plug and collected in the tank. With outdoor storage facilities, manure is removed from the building to storage with a mechanical or tractor scraper, front-end loader, flushing gutter, or gravity-flow gutters or channels.
Slotted and expanded metal floors effectively transfer manure from the animal space to storage below a building. Expanded metal floors are also used in conjunction with below-building manure storage or gravity-flow channels. Concrete slats are the most durable, are suitable for animals of all ages, and are the most widely used flooring system for confined swine facilities.
Slightly crowned and tapered slats improve cleaning but may stress the livestock’s feet and legs. Slip-resistant surfaces provide better footing and longer wear. Slats are typically 4 to 10 inches wide. Wider slats provide better footing, but animals are usually dirtier.
Solid or semi-solid manure can be mechanically scraped. A mechanical scraper system has one or more scraping blades, a cable or chain to pull the scraper, and a power unit with controls. Common scraper systems are gutter cleaners, below-slat scrapers, alley scrapers, and elevator stackers. Mechanical scrapers allow more frequent removal of manure from the building and can reduce daily labor requirements. However, maintenance requirements can be higher because of corrosion and deterioration.
A small tractor with a back- or front-mounted blade or skid-steer loader can be used to scrape manure. Skid-steer loaders can clean in cramped areas, greatly reducing hand labor. Most have a low height and a turning radius of their own length, so they can work easily in tight quarters; however, some have a relatively low load-lifting capacity.
Front-end loaders remove solid manure from open lot surfaces, building floors, and storage facilities. Tractor loaders have a relatively high load-lifting capacity and are available in 1,000- to 4,000-pound sizes. Their relatively large turning radius usually limits them to straight runs and areas with few turns.
In a flush system, a large volume of water flows from one end of a building to the other, down a sloped, shallow gutter. The water scours manure from the gutter or alley and removes it to a lagoon or storage pond (Figure 4). Three types are common:
|
| Figure 4. Flush system with two-stage lagoon. (Source: Ohio State University Extension Bulletin 604, 1992 Edition, Figure 2.) |
Water may be recycled from a lagoon, holding pond, or earthen storage. If irrigating, producers may use fresh water for flushing rather than recycled water. In a flushing system, a pump transports either fresh or recycled water to a flush tank at the high end of the gutter. The flush tank periodically releases a large volume of water into the gutter. Flushing frequency is determined by animal type and size, gutter width, gutter slope, and flush-tank volume. Flush tanks can be automatic siphon tanks, manual flush tanks, tipping tanks, or gated flush tanks. Flush tanks should release the entire volume in 10 to 20 seconds.
Some systems use a large-capacity pump operated by a time clock to supply flush water instead of a flush tank. Pump flushing uses much more water than tank flushing.
Gutter slopes usually range from nearly flat to 5% to get the desired initial flush-water flow depth. Make the alley or gutter flat with no cross slope or only a slight crown, which will force the flow toward the curbs. Limit gutter length to 125 feet. If longer gutters are required, slope both ends of the gutter so they flush toward the middle of the building length. For more information about flushing system selection, design, and management, refer to MWPS 18, Livestock Waste Facilities Handbook, available from your local county Extension office.
Gravity-drain gutters are commonly installed in swine buildings under raised farrowing stalls, raised nursery decks, and slotted floors. These gutters have Y, U, V, and rectangular shapes. Manure and wastewater is allowed to build up in gutters. When gutters are full, usually in three days to two weeks, a drain plug is pulled and manure flows by gravity to some outdoor storage structure. Gravity-drain gutters use less water than flushing systems. Wastage from waterers usually provides the liquid necessary to make the manure flow out of the gutter. If gutters do not receive waterer wastage, additional water is required to provide enough liquid. To reduce the amount of fresh water needed, water from a lagoon can be pumped into the gutter to suspend solids and improve cleaning. However, recycled lagoon water may result in mineral and salt buildup in pipes and pumps.
A deep, narrow gutter gravity-flow system is nearly self-cleaning because manure flows rapidly when the plug is pulled. Deep, narrow gutters are located at the lower end of a solid feeding floor or solid floor under raised farrowing stalls or nursery decks (Figure 5). Some scraping of the solid floor section is required. For more information about the use and management of deep, narrow gutters, refer to MWPS 18, Livestock Waste Facilities Handbook, available from your local county Extension office.
 |
| Figure 5. Deep, narrow gutter. (Source: Ohio State University Extension Bulletin 604, 1992 Edition.) |
The Y-gutter is an adaptation of the deep, narrow gutter. The objective is to provide the cleaning action of the deep, narrow gutter with a sloped floor below slats or raised decks in swine buildings to promote a cleaner floor in the animal space. Side slopes of the upper channel are usually 1:1 or 0.75:1. Construction of Y-gutters is more complicated than for V- or rectangular-bottom gutters.
The V-gutter resulted from attempts to simplify construction of the Y-gutter (Figure 6). The bottom of the V-gutter can be a 6- to 8-inch PVC pipe cut in half or flat 6- to 8-inch concrete. The sides of the V-gutter appear to clean easier than the Y-gutter because manure solids have less time to dry on the upper slope. Cleaning action seems comparable to the deep, narrow channel and Y-gutter.
 |
| Figure 6. V-bottom gutter under a raised deck. (Source: Ohio State University Extension Bulletin 604, 1992 Edition.) |
Rectangular gutters are easier to construct and provide more storage capacity than the Y- or V-gutter (Figure 7). Cleaning action of rectangular gutters depends on the location of the drain plugs. Earlier versions had only one drain plug at the end of a sloping gutter, and solids tended to build up at the high end of the gutter. Recent designs leave the bottom flat with a drain plug at each end of the gutter. By alternating the plug pulled, draining the gutter two different ways has helped reduce solids buildup. An alternative approach is to locate drain plugs uniformly down the length of the gutter. Pull a different plug each time to clean solids from the gutter. In wide, flat-bottom gutters, cleaning is improved by dividing the gutter in the direction of flow into narrow channels 18 to 24 inches wide. Use channel dividers for all but the first 20 feet of the gutter and near the drain plug.
 |
| Figure 7. Flat-bottom gutter manure transfer. (Source: Ohio State University Extension Bulletin 604, 1992 Edition.) |
The reverse hairpin gravity gutter system, shown in Figure 8, is a modification of the original rectangular gravity-drain gutter. The primary difference is that the gutter is shaped like a horseshoe, and two drains are located at one end on opposite sides of a dividing wall. This approach simplifies drain line placement. A dividing wall is located down the center of the gutter, dividing it into two channels. The dividing wall extends to within 4 feet of the end farthest from the drains. In practice, two drain plugs are pulled in an alternating pattern every one to three weeks to reverse the flow of manure to the drain and reduce solids buildup. Gutter depth must be at least 18 inches although a gutter depth of 24 inches is preferred. Gutter length is limited to about 100 feet. Pumping 2 to 6 inches of recycled water back into the gutter will reduce ammonia odors, suspend solids, and improve cleaning. See AEX-114-96, Hairpin Gutters for Swine Facilities at: ohioline.osu.edu/aex-fact/0114.html.
 |
| Figure 8. Reverse hairpin flat-bottom gutter. (Source: Ohio State University Extension Bulletin 604, 1992 Edition.) |
Gravity-flow channels are rectangular-shaped channels with a flat bottom and a 6- to 8-inch-high dam at the discharge end. They have been used in tie-stall and free-stall dairy barns. The dam retains a lubricating layer under the manure, and the manure surface forms a 1 to 3% incline. Manure flows by gravity down the incline. Biological activity helps liquefy the manure and promote a constant flow. The manure flowing over the dam falls into a cross channel or discharge pipe. These systems can freeze in cold housing.
Channel width does not affect performance. However, limiting channel width to 36 inches can improve flow. Channel depth depends on channel length and manure-surface incline. For design, assume manure inclines 3%. Channel length is typically 40 to 80 feet and should not exceed 80 feet. If longer channels are required, increment the channel into steps. The overflow dam must be water-tight and can be concrete block, a steel plate, or pressure-preservative-treated wood. Removable dams allow for total clean-out but may be difficult to keep water-tight. Before putting animals in the barn, fill the gutter with 3 to 6 inches of water to form the lubricating layer. Limit the use of bedding.
Manure can be transferred to storage by gravity, piston pump, pneumatic pump, or centrifugal pump. System selection depends on the waste characteristics, bedding practices, available labor, and storage system.
Gravity-flow transfer uses the hydraulic head exerted by liquid waste to force the waste to flow (Figure 9). The transfer pipe size required depends on the manure characteristics. Very liquid wastes, such as swine manure and milking center wastewater, flow well through small-diameter (6- to 8-inch) pipes. Little or no bedding should be used. Larger-diameter (24- to 30-inch) pipes, discharging from a collection hopper, work well with dairy and beef manure with well-mixed sawdust or chopped straw bedding and a solids content of up to 8 to 12%. Pipe materials can be either SDR 35 PVC, smooth-wall polyethylene, concrete, or steel.
 |
| Figure 9. Gravity-flow manure transfer to storage. (Source: Liquid Application Manure Systems Design Manual, NRAES-89. Natural Resource, Agriculture, and Engineering Service, Ithaca, N.Y.) Used by permission. |
These systems work best when the pipe is installed on a uniform grade with a nearly flat slope (0 to 1%). Avoid horizontal bends in the pipe. Install the transfer pipe below the frost line to prevent freezing. To assure adequate hydraulic-head pressure for manure flow, the minimum head (elevation difference) between the scraped alley, or top of collection hopper, and the top of the maximum depth of the stored material should be 4 to 6 feet for transfer distances up to 125 feet. When manure from an outside lot is included, an additional small storage area for dry and frozen manure should be added, and the head requirement should be increased to 8 feet. For dairy facilities, the milkhouse washwater should be put in at the collection hopper to further liquefy the manure.
Gravity flow transfer of sand-laden dairy manure includes additional design considerations. The slope of the transfer pipe should be approximately 2%, the required head should a minimum of 8 feet, and the collection hopper functions as a temporary storage structure that is “flushed” every two to four days. The milkhouse washwater should not go into the collection hopper, because it may cause the sand to separate from the manure within the transfer system.
Bottom-load the storage facility because top-loading can result in cold-weather freezing problems. Keep the exit of the gravity-flow pipe at least 1 to 2 feet above the floor of the storage to reduce settled solids blocking the pipe. Be sure to cover the pipe end with at least 1 foot of liquid before winter freezing occurs. To reduce plugging, provide adequate clean-outs.
Another method of moving manure to storage is to collect the manure in a small concrete pit and then pump it to storage with a centrifugal chopper pump. Locate the pit for easy access. Size the pit for at least one-day storage, preferably several days. Select a pump that can handle manure with bedding and develop sufficient head pressure to pump manure from the bottom of the pit to the maximum level of the storage.
Pump selection depends on the solids content and required pumping pressure. Solids content varies with livestock species, housing type, and manure-collection system. If possible, settle out solids before pumping. Pressure requirements vary considerably, depending on the application. Irrigation of manure and wastewater may require high pressure to pump the material to the nozzle and spray it onto the land. Other typical applications may require only that manure be lifted 10 to 20 feet to storage or manure spreader.
Centrifugal pumps are not positive-displacement pumps because the impeller can slip in the liquid. Centrifugal pumps typically cannot handle manure with a solids content greater than 10 to 12%. Pump performance depends on impeller design. Closed impellers are more efficient with water and very liquid manure, but they cannot handle large solids percentages or large solid particle sizes. Open or semi-open impeller pumps can handle liquids with a larger solids content. However, in applications where fibrous, stringy material (such as hay or silage in a dairy lagoon) is present, use a cutter or chopper pump. These pumps have a cutting or chopping device (located just outside the pump inlet) that rotates with the impeller and shreds fibrous material as it enters the pump.
Positive-displacement pumps include screw pumps and piston pumps. Screw pumps handle manure with high solids content, but the manure must be free from hard or abrasive solids. Screw pumps should not be operated dry. Always add a small stream of water directly into the pump casing during operation. Piston pumps are used to move high-solids-content manure to storage. They are commonly used to transfer lot-scraping or tie-stall and free-stall barn manure to storage. Piston pumps generate very high pressures if the discharge pipe is plugged. Large-diameter (10- to 15-inch) pipes are typical and seldom plug; therefore, release valves are seldom used for manure transfer.
Manure pump characteristics are shown in Appendix C.
A manure-storage structure is often needed to provide management flexibility for scheduling appropriate land application that avoids wet soil, growing crops, fields already high in nutrient concentrations, and other conditions conducive to potential pollution. The storage facility must be sized to provide for manure bedding, washwater, and dilution water for the period that livestock manure cannot be spread and utilized. Open manure storage systems also need to store or treat rainfall that contacts the manure during the planned storage period and have reserve capacity to prevent release of a 24-hour, 25-year frequency rainfall event. Design storage facilities to minimize the potential for odors and contaminated runoff. Although higher in cost, a covered manure structure may be practical due to improved handling conditions, less excess water, and potentially fewer odors.
When planning manure storage facilities, consider all farmstead operations, building locations, well locations, future building expansions, and prevailing winds. Locate, size, and construct storage facilities for convenient filling and emptying. Provide all-weather access. Evaluate site and soil conditions carefully to avoid contaminating ground and surface water. Do not locate unlined storage facilities where leakage can cause ground water pollution, such as over shallow creviced bedrock, below the water table, or in pervious soils. For additional information or help in evaluating a site, contact your local Soil and Water Conservation District (SWCD) or the Natural Resources Conservation Service (NRCS).
Storage type depends on the manure characteristics. Manure can be handled as a liquid, slurry, semi-solid, or solid. The amount of dilution water or bedding influences the form and the choice of storage system.
Storage capacity depends on regulations, number and size of animals, amount of dilution by spilled and cleaning water, amount of stored runoff, and desired length of storage. Length of storage required may vary from farm to farm. Provide enough storage capacity and length of storage to allow spreading of manure when field conditions and weather permit. Plan for six to 12 months of storage capacity for liquid manure and at least three months storage for solid manure. Storage capacity of up to 12 months will provide more flexibility for scheduling field-spreading of manure. Table 9 provides a comparison of manure storage alternatives.
| Table 9. Comparison of Manure Storage Alternatives. | ||
| Manure Storage Type | Advantages | Disadvantages |
|---|---|---|
| Solid manure, roofed or covered (steel, concrete, timber plank) |
|
|
| Solid manure, not covered (steel, concrete, timber plank) |
|
|
| Slurry pit, reception pit, or roofed tank (earthen, concrete) |
|
|
| Below building pit (concrete) |
|
|
| Slurry pit or tank, not roofed (concrete, steel) |
|
|
| Earthen holding pond |
|
|
| Treatment Lagoon (earthen) |
|
|
| Runoff holding ponds (earthen, concrete) |
|
|
| Source: Adapted from MWPS-18, Section 2, Table 1-2, with modification for Ohio conditions. Used by permission. | ||
Liquid manure can be stored in below-ground tanks either under or separate from the building, earthen storage basins, or above-ground tanks. Plan for up to 12 months storage capacity and provide sufficient capacity for dilution water, rain, snow, and washwater. Dilution water results from livestock waterer leakage and spillage, washwater, and rainwater entering an open storage facility during the storage period. The volume of dilution water is highly variable and can range from 10% to more than 100% of the manure volume.
Planning for a liquid storage facility should include metered water usage for existing operations and realistic estimates for new facilities. Wastewater volumes in swine facilities are dependent on the frequency of barn cleaning and type of waterers used. Manure volume estimates inclusive of dilution water for swine facilities can be found in MWPS-18-S1, Table 7. Building ventilation and amount of salt in the feed rations also impact swine facility wastewater generation. Estimates of the volume of dairy milkhouse and parlor wastewater can be found in MWPS-18-S2, Table 2-6.
Below-ground storage tanks can be limited by depth to bedrock, water-table elevation, and, possibly, effective lift of a pump. Tanks must be designed to withstand all anticipated earth, hydrostatic, and storage loads, plus uplift if a high water table exists. Fill a newly constructed storage tank with 6 to 12 inches of water before adding manure to submerge solids and counter-balance any uplifting forces. For assistance with concrete tank design, contact the Natural Resources Conservation Service and MidWest Plan Service publications (see Chapter 12, Technical Services, for contact information). Protect tank openings with grills, covers, or both, and enclose open-top tanks with a fence at least 5 feet high to prevent accidental entry.
Earthen holding ponds are earth-walled structures at or below grade that provide long-term storage at a low to moderate cost. Holding ponds are intended for manure storage, not treatment, and can be an odor source. However, holding ponds for dairy manure do have a tendency to form a floating crust that contains odors until agitation. Holding ponds are designed to prevent ground and surface-water contamination and may or may not be lined. Planning for an earthen storage pond should always include a geologic exploration to a depth at least 5 feet below the pond bottom. Your local Natural Resources Conservation Service office can provide help in evaluating site suitability and provide design and construction quality-control services.
In general, steeper bank slopes conserve space, reduce the amount of rainfall runoff entering the pond, and leave less manure on the sides when emptying. Inside bank slopes of 2:1 to 3:1 (run:rise) are common for most soils. Outside side-slopes should be no steeper than 3:1 for easier maintenance. Make the embankment at least 12 feet wide to provide access for agitation, loading, and mowing equipment. Enclose earthen holding ponds with a fence at least 5 feet high to prevent unintentional access. Provide at least 40 feet of clearance between the earth basin and fence where agitation and loading equipment are used (Figure 10). The agitation and loadout ramps should be paved with gravel or concrete to prevent bank erosion, and the pond bottom should be paved with concrete at the agitation points to prevent scour. A holding pond designed for sand-laden dairy manure must have accessibility to the pond bottom for a loader and manure spreader. This is normally accomplished by constructing an access ramp sloped no steeper than 10:1. The ramp and pond bottom are lined with concrete.
 |
| Figure 10. Liquid storage system. (Source: Natural Resources Conservation Service (NRCS) Agricultural Waste Management Field Handbook. Used by permission.) |
Above-ground circular storage facilities are more expensive than earth storage basins and are usually not used to store runoff or dilute wastes. However, they are a good alternative where an earth basin or below-ground tank is limited by space, high ground water, shallow creviced bedrock, or where earth basins are not aesthetically acceptable. Above-ground storage facilities are usually 10 to 20 feet high and 30 to 120 feet in diameter. They are made of steel, reinforced concrete, and concrete stave. Locate or lock-out access ladders to reduce the risk of accidentally falling into the storage. Consider a ladder on the inside of an above-ground storage because the inside surface is usually very smooth and difficult to climb.
Determine storage capacity requirements when planning a manure-storage facility. Determine the capacity based on a working capacity, which includes manure storage, precipitation, runoff water, washwater, water wastage, agitation clearance, and remaining manure level after emptying.
Plan to store precipitation from a 25-year, 24-hour-duration storm unless the storage has a roof. Provide at least 1 foot of additional freeboard in the storage and plan on a remaining manure depth, after emptying, of 12 to 24 inches when determining the storage depth (Figure 11).
 |
| Figure 11. Liquid manure storage pond. (Source: Natural Resources Conservation Service (NRCS) Agricultural Waste Management Field Handbook. Used by permission.) |
Manure can be stored and handled as a semi-solid or solid if ample bedding is added or additional water is excluded. Semi-solid manure has excess liquids drained off and some bedding added to increase solids content. Solid manure has a relatively large amount of bedding added to give it a stackable consistency. Semi-solid manure can be stored in either an above-ground roofed storage or an outside structure with a picket dam to drain off rainwater (Figures 12 and 13).
 |
| Figure 12. Manure storage structure with picket dam. (Source: Natural Resources Conservation Service (NRCS) Agricultural Waste Management Field Handbook. Used by permission.) |
 |
| Figure 13. Picket dam details. (Source: Natural Resources Conservation Service (NRCS) Agricultural Waste Management Field Handbook. Used by permission.) |
The emptying and hauling schedule from a solid or semi-solid storage is more flexible. Storage length and capacity can vary from a few days to several months. With semi-solid or solid manure storage, manure can be hauled whenever time allows without planning ahead to agitate the storage as is required with liquid storage facilities. Also, less total storage capacity is needed for a given storage length because less water is added. Plan for at least three months storage to allow flexibility for hauling manure when conditions are appropriate.
A drained storage facility allows semi-solid manure to be stored uncovered outside and maintain semi-solid handling characteristics by draining off rainwater. Divert all excess lot water away from the manure storage. A picket dam is often used to hold the manure solids and remove rainwater; it does not reduce the water content of the manure. Vertical picket-walls with vertical slots not exceeding 3/4-inch wide between planks allow continuous drainage of liquid from the manure. With proper drainage, the manure will not absorb rainwater and become more soupy. The drainage water from these storage facilities contains manure, chemicals, and debris and must be collected and contained, or treated. A concrete trough along the storage facility perimeter directs drainage water to a liquid storage facility or treatment area.
Where the site is not well suited for storage or treatment of the runoff, a roofed storage facility is better. This system provides an aesthetically pleasing structure that appears to be another building on the farmstead, rather than a manure-storage facility (Figure 14).
 |
| Figure 14. Roofed post-and-plank storage. (Source: Ohio State University Extension Bulletin 604, 1992 Edition.) |
Solid-manure storage is an option where adequate amounts of bedding are used to make the manure a stackable solid. Solid manure can be stored on an open or covered stacking slab with or without retaining walls. Retaining walls around the stacking slab reduce the total area required for the storage (Figure 15). Provide at least one or two sturdy walls to buck against for unloading. Walls are usually post-and-plank, concrete, or masonry block.
 |
| Figure 15. Solid manure stacking slab. (Source: Natural Resources Conservation Service (NRCS) Agricultural Waste Management Field Handbook. Used by permission.) |
Prevent surface runoff water from entering the storage. Slope the entrance ramp upward to keep out surface water. Any rainwater that falls on the storage must be collected and contained or treated. If the slab is enclosed by walls, install picket dams to drain excess water. Collect and store drainage water in a storage tank, earth basin, or holding pond. Slope the slab about 1/8 inch per foot toward the picket dam or drain. Start stacking at the high end of the slope.
Provide for convenient filling with a tractor-mounted manure loader or scraper, elevator stacker, or piston pump. Unload with a tractor-mounted bucket. Locate the storage for year-round access so manure can be spread when field conditions and weather allow.
Adequate storage provides convenience and flexibility to spread manure under appropriate weather and soil conditions. Provide a minimum storage capacity of three months. For better management and hauling flexibility, plan for six months or more of storage capacity. Determine the storage capacity based on animal manure production, amount of bedding used, any stored liquids (rain, snow, runoff), and availability of fields for manure application. Stored liquids should be only a small fraction of the storage capacity because successful solid and semi-solid storage facilities require excess liquids to be drained off. To estimate the required storage volume of manure and bedding, add the manure production volume to half of the bedding volume added in the barn. Bedding volume is usually halved because it compacts during use.
Drain excess liquids. If animals have access to an outdoor lot and manure from the lot is not added to the solid or semi-solid storage, assume half the daily manure production volume when estimating storage capacity. Additional capacity is needed for drainage water, lot runoff, and possibly lot scrapings.
Additional planning and design considerations for waste storage facilities are available in Ohio Natural Resources Conservation Service (NRCS) Conservation Practice Standard 313, Waste Storage Facility. NRCS conservation practice standards are available at: http://www.oh.nrcs.usda.gov/technical/ohio_eFOTG.html.
Mechanical Separation of Manure Solids
Adapted from Natural Resources Conservation Service (NRCS) Animal Waste Management Field Handbook, Chapter 10, pages 62-64. Used by permission.
Animal manure contains material that can often be reclaimed. Much of the partly digested feed grain can be recovered from manure of poultry and livestock fed high grain rations. Solids in dairy manure from animals fed a high roughage diet can be removed and processed for use as good quality bedding. Some form of separation must be used to recover these solids. Typically, a mechanical separator is employed. Separators are also used to reduce solids content and required storage volumes.
Separators also facilitate handling of manure. For example, solid separation can allow the use of conventional irrigation equipment for land application of the liquids. Separation eliminates many of the problems associated with the introduction of solids into waste storage ponds and treatment lagoons. For example, it eliminates the accelerated filling of storage volumes with solids and also minimizes agitation requirements.
Several kinds of mechanical separators can be used to remove by-products from manure. One kind commonly used is a screen. Screens are statically inclined or in continuous motion to aid in separation. The most common type of continuous motion screen is a vibrating screen. The total solids (TS) concentration of manure to be processed by a screen should be reduced to less than 5%. Higher TS concentrations reduce the effectiveness of the separator.
A centrifuge separator uses centrifugal force to remove the solids, which are eliminated from the machine at a different point than the liquids. In addition, various types of presses can be used to force the liquid part of the waste from the solid part.
Several design factors should be considered when selecting a mechanical separator. One factor is the amount of liquid waste that the machine can process in a given amount of time. This is referred to as the throughput of the unit. Some units have a relatively low throughput and must be operated for a long time. Another very important factor is the TS content required by the given machine. Centrifuges and presses can operate at a higher TS level than static screens.
Consideration should be given to handling the separated materials. Liquid can be collected in a reception pit and later pumped to storage or treatment. The separated solids will have a TS concentration of 15 to 40%. Typically, solids should be composted to kill pathogens and control disease before they are used for bedding. While a substantial amount of nutrients are removed with the solids, the majority of the nutrients and salt remain in the liquid fraction. In many cases, water drains freely from piles of separated solids. This liquid needs to be transferred to storage to reduce odors and fly breeding.
A planner/designer needs to know the performance characteristics of the separator being considered for the type of waste to be separated. The best data, if available, would be that provided by the separator manufacturer. If that data is not available, the manufacturer or supplier may agree to demonstrate the separator with waste material to be separated. This can also provide insight as to the effectiveness of the equipment.
The housing system influences the amount of bedding or dilution water used, which influences manure characteristics. Manure characteristics influence selection of collection, transfer, storage, and spreading equipment. The components of solid and liquid manure systems for dairy are shown in Table 9 and Appendix D. Also consider rainwater runoff from barn lots. Procedures for handling runoff are discussed in Chapter 5, Farmstead Runoff Control. Alternative handling systems for dairy manure are shown in Appendix D.
Solid handling is used by many dairy operations with comfort-stall barns as well as free-stall barns with added bedding. Storage length varies from a few days with a daily haul system to three months or more. An alternative liquid-handling system is required for milking-center waste. See Chapter 6, Land Application of Manure.
Solids storage can be a stacking slab or covered storage. Provide at least one or two walls to control leachate, ease load-out, and reduce required floor area. A roofed storage keeps out precipitation so manure can be handled as a solid or semi-solid. A picket dam structure for storing solid or semi-solid manure can be used to remove rainwater that falls on an uncovered storage, but does not reduce the manure’s water content. Do not expect to put a slurry in and get a solid out. The vertical slots in the plank fence allow rainwater runoff to drain away. Transfer manure and load the storage with a tractor-mounted front-end loader, elevator stacker, and solid piston pump. Unload the storage with a front-end loader. Manure can be spread as a solid or semi-solid in a box or flail spreader.
Sand-laden manure scraped directly from the free-stall barn can be stored in a covered storage facility and loaded into a “V” box spreader with a tractor-mounted front-end loader. The storage facility must include an access ramp sloped not steeper than 10:1.
Liquid handling is used in many dairy facilities with free-stall housing. Free-stall manure is commonly collected and removed from the barn with a tractor-mounted scraper, mechanical alley scraper, flushing system, or slotted floor. Depending on site conditions, manure can be stored in earth basins, below-ground tanks, or above-ground tanks. Common methods for transferring liquid dairy manure to storage include gravity, large piston pump, pneumatic pump, and centrifugal chopper pump.
Free-stall manure with sawdust or chopped straw bedding can be transferred to storage by gravity. In general, four to six feet of elevation drop between the floor of the barn and full storage level is adequate for manure to flow over 100 feet. Terrain that slopes about 10% away from the barn for 250 to 300 feet can provide enough head pressure for both filling and emptying a liquid storage by gravity. A gravity pipe used to empty a storage pond must be equipped with two valves to prevent an accidental release. One valve should be located near the pipe inlet below the frost line, and the other located near the pipe outlet. Each valve needs to have an independent power source and be dual acting (able to apply pressure to flow in either direction).
A piston-type pump provides convenient transport of manure to a storage structure. A key factor in the design and operation of any liquid-storage structure is provision for agitating the waste prior to irrigating or loading the tank spreader. Without complete agitation, solids will accumulate in the structure, reducing storage capacity, and the nutrient concentrations of the manure will be non-uniform. Allow for solids accumulation that cannot be completely removed when determining the required storage capacity.
When placed in a storage structure, undiluted manure from cattle usually will develop a crust of floating solids. This crust helps control odors and should not be disturbed until the manure is agitated just prior to field spreading.
The principal advantage of the flush system for collecting manure is that it can be automated. To minimize the amount of water to be field spread, some means of recycling clarified wastewater for flushing may be desirable. Separation of solids from flush water can be used to reduce the solids in the recycled flush water. Separated solids can be hauled and land applied or reused as bedding if dried or composted to remove excess moisture and reduce volume.
In skim and haul systems, most if not all of a farm’s manure and wastewater streams are put directly into an outdoor storage facility. The premise behind these systems is that given some dilution and time, gradations of material will develop in the storage facility that allow a portion of the contents to be readily removed as a liquid. The remaining material is removed using equipment designed to handle solid manure. Some producers opt for this type of system because, compared to the alternative systems, a skim-and-haul system usually:
However, management of these systems at clean-out time is usually more demanding than for alternative systems. Successful operation and management of a skim-and-haul system requires consideration of the entire manure-management system, including application.
Sand bedding can be separated from the manure prior to storage by mechanical separation or gravity settling of flush system manure. Gravity settling requires the manure to be diluted to less than 5% solids content, and mechanical separation requires a constant water flow of 1 to 5 gpm during operation. The decision to choose sand separation must consider the economic feasibility and additional water requirements.
Source: Michigan State University Extension Bulletin E-2561, Storing and Handling Sand-Laden Dairy Manure, by R. R. Stowell and W. G. Bickert, 1995. A much more complete discussion of skim-and-haul systems and sand separation can be found in this excellent Michigan State University Extension bulletin.
Handling alternatives for beef cattle manure can be divided into solid and liquid options. Alternative handling systems for beef manure are shown in Appendix D. In Ohio, the typical cow/calf beef operation provides housing and bedding during winter and early-spring months. Solid-manure handling systems are commonly used with cow/calf operations and confined feeder operations.
The common housing system for feeder beef cattle is an open-front shelter with an earthen or paved lot. Many feedlots are unpaved and require more total lot area for effective management. Paved lots are recommended to reduce the required lot area and ease manure collection and runoff control.
Open-lot systems require two manure-handling methods. Lot scrapings are either solid or semi-solid, and lot runoff is liquid. Move solid manure from the lot to storage with a tractor scraper and front-end loader. Lot runoff contains manure, soil, chemicals, and debris, and must be collected as part of the manure handling system. Divert clean runoff away from manure and animal areas to reduce the total volume of liquid to be handled. See Farmstead Runoff Control in Chapter 5.
Beef cattle can be fed in solid or slotted-floor confinement buildings. Liquid manure-handling systems are common with confinement housing. Manure storage can be a concrete tank under the building or an outdoor earthen or concrete storage. Remove manure from the building with a tractor or mechanical scraper, or by gravity flow.
Swine manure can be handled as a solid, semi-solid, or liquid. Alternative handling systems for swine manure are shown in Appendix D. Additional bedding or drying is required to handle manure as a solid. Solid manure handling is common for shed and lot systems used for swine gestation and finishing. Where shed and open-lot systems are used, solid storage for lot scrapings and shed manure are required, along with facilities for controlling runoff (Figure 16).
 |
| Figure 16. Open-lot manure handling system. (Source: Ohio State University Extension Bulletin 604, 1992 Edition.) |
Slurry and liquid manure handling are more common in larger swine-production facilities. Liquid handling requires less time and labor to collect, transfer, and store manure. Manure can be stored below the partial or full-slotted floor in deep pits, in an outdoor below-ground or above-ground storage facility, or treated in an anaerobic lagoon.
A primary objective in swine manure handling is to minimize the accumulation of noxious gases and odors. Pit ventilation can be used to reduce odors and gases within the building. The stored manure must be agitated before removal to facilitate removal of settled solids. Failure to sufficiently agitate will result in decreased storage capacity because of accumulated settled solids. The effects of agitation are limited to a radius of about 40 feet; therefore, access ports should be located so that all manure is within 40 feet of a port. (From MWPS-18 Section 2, page 3 and figure 1-1.)
Removing manure from the building to outdoor storage can also reduce odor and gas accumulations within the building. However, uncovered swine manure storage facilities are odorous and should not be considered in sensitive locations. Where odor control is important, an anaerobic waste-treatment lagoon is often recommended.
Manure can be removed from the building with manual or mechanical scrapers, gravity-flow gutters, and flushing gutters. Mechanical scrapers are often used in shallow gutters below slotted floors.
In a flush system, a large volume of water flows from one end of a building to the other down a sloped, shallow gutter. The water scours manure from the gutter and removes it to a lagoon. There are two types:
A modification of the flush system is pit recharge. This system uses a single or two-stage lagoon for storage. A water depth of one to two feet is maintained in an under-floor storage or gutter after emptying. Use a flat-bottom gutter or slope less than 1%. The gutter is drained every three to four days and refilled with water from the top of the lagoon. Size the refill line to fill the gutter in four hours or less. A recharge sump pit can be placed on the outside of the lagoon.
Hoop Structures (Adapted from MidWest Plan Service, Hoop Structures for Grow-Finish Swine, AED 41.) Used by permission.
Hoop structures are a low-cost alternative pig housing system that is gaining attention in the upper Midwest. Hoop structures use treated wood posts and tongue-in-groove siding for 4- to 6-foot side walls. Steel tubes or trusses are fastened to the top of the side walls to form an arch. The arch is covered with a UV-resistant polypropylene tarp.
For a finishing operation, an earthen floor that is heavily bedded covers about 75% of the building area. The remaining 25% of the floor area is designated as the feeding and watering area and is covered with concrete.
Finishing pigs are placed in the structure at a stocking density of approximately 12 square feet per pig. Common bedding materials are shredded corn stalks, long straw, sawdust, and wood chips. Typical bedding usage (for wheat straw) is approximately 225 lb per pig for the finishing period. Summer bedding usage ranges from 140 to 170 lb per pig, and winter usage averages from 225 to 285 lb per pig. The building is cleaned and disinfected between finishing cycles.
Hoop structures can also be used for gestation barns. Further information for this application is found in MidWest Plan Service, Hoop Structures for Gestating Swine, AED 44.
Poultry manure has a higher total solids content than most other manures. Dilution with water increases the potential for odor, so handling the manure as a solid is usually preferred. Handling alternatives for hen, broiler, and turkey manures are shown in Appendix D.
Most cage layers are housed in high-rise poultry facilities. A deep pit is used in the cage layer house to minimize odor and insect problems, eliminate water pollution potential, and maximize the potential value of the manure. The manure “cones” under the cages in a well-managed high-rise layer house and is typically stored from nine to 18 months. These management objectives can be achieved by keeping the manure as dry as possible. Note the following guidelines:
These guidelines should help keep manure moisture levels low enough to avoid significant odor and insect problems when used with other insect control methods. Dry poultry manure (25% moisture) is also more easily handled for transportation and field application.
The primary difference between cage layer manure and broiler and turkey manure is that the broiler and turkey manure is diluted with litter material. This usually results in a manure-containing mixture that is easier to handle, because it is drier and has fewer problems with odor and insects than manure without litter. Good ventilation in the poultry house and tilling of the litter between flocks will help control moisture levels. Avoid water spillage on the litter or runoff drainage into the building.
When using broiler and turkey manure as a fertilizer, consider the dilution of the manure with the litter material. Analysis of the used litter for nitrogen, phosphorus, and potassium is essential to determine the amount of this manure to apply in a particular crop situation. In most cases, dilution of the manure with litter means that a higher application rate can be used than for cage layer manure.
Composting or ensiling of used poultry litter for feeding to ruminants may be an option where drugs used in broiler- and turkey-growing diets do not interfere with rumen function or result in tissue residues in the ruminant animal. Proper composting of used poultry litter can also yield a stable product for use as a fertilizer, soil amendment, and mulch in gardens, greenhouses, and production of specialty crops.
For more information, refer to Ohio State University Extension Bulletin 804, Poultry Manure Management and Utilization, available from your local county Extension office.
Horse manure is best handled as a solid. Plan horse housing and manure management carefully to avoid difficulties with neighbors and health officials. Review local zoning and health regulations if housing horses in a suburban area. Flies and odors are the most common complaints. See Chapter 9, Insect and Pest Control, and Chapter 8, Odor and Dust Emission Control.
Successful management requires daily clean-out and removal of wet or soiled bedding to a container or storage facility or for field spreading. Fresh bedding is added after removing manure and soiled bedding to ensure clean, dry conditions. Regular cleanup reduces odors and insect breeding. Because of individual horse stalls, manual cleaning with a fork or shovel and wheelbarrow, tractor loader, or trailer is common. Simply adding fresh bedding and allowing manure and soiled bedding to accumulate in the stall results in dirty animals, an excellent fly-breeding environment, and generally unhealthy conditions for horses.
Protect the manure storage from rainfall and surface runoff. The type and size of manure storage depend on the amount of manure to be stored. A horse produces about 0.75 cubic feet of manure per day per 1,000 pounds of body weight, plus bedding. Storage facilities can be covered boxes, concrete or pressure-preservative-treated lumber sheds, covered piles, or covered trash receptacles. The required storage volume needs to be sufficient to store the manure between planned removal intervals.
Open manure piles are not recommended. However, if used, they need a minimum separation distance of 300 feet to neighboring residents, and the manure should not accumulate more than 30 days. These piles should be on a paved pad, with all-weather access, where runoff from the pad is filtered through a vegetative buffer. The pad needs to be located where it is protected from flooding and upstream runoff.
Note the following recommendations when planning a manure storage-and-handling system for horses:
Land application of manure is the most practical method of utilization; however, since both sawdust and wood-shaving bedding are very high in carbon, the soil can become depleted of nitrogen which stunts crops. Ammonium nitrate (34-0-0) or ammonium sulfate (21-0-0) added to the manure at a rate of 1/2 cup per 1,000-lb horse per day can be used to balance the carbon/nitrogen ratio of the land-applied manure. See Ohio State University Extension Fact Sheet AGF-212-03, Horse Manure Management — The Nitrogen Enhancement System at , ohioline.osu.edu/agf-fact/0212.html.
Disposal or utilization of horse manure can be a challenge for horse owners with no available cropland. Producers with limited land resources are encouraged to seek off-site partners for manure utilization
Horse manure-bedding mixture can be used as an amendment for composting raw dairy or swine manure. Composted manure can be used in specialty markets such as greenhouses, gardens, and nurseries. See Chapter 4, Treatment and Utilization Options for Livestock Manure, for more information on composting.
Horses on pasture generally spread their manure over the pasture, where it is recycled naturally. The pasture must be managed to maintain vegetation and control soil erosion and surface water runoff. Access to streams should be limited. The animal density should not be greater than one-half acre per horse. Exercise lots and corrals need to be surfaced to prevent erosion and contaminated runoff.
Proper manure management is as important for the horse owner with only a few horses as for large horse farms and boarding stables. Seek competent help when planning a workable, environmentally safe manure-handling system.
Horse facilities are generally exempt from township zoning regulations, but they may not be exempt from municipal zoning or subdivision regulations when the facility is on less than five acres. Horse owners should always check with all applicable local regulations before locating a facility in a non-agricultural land-use area.
Sheep are most commonly housed in bedded pens with a manure pack. They can also be raised on slotted floors or expanded-metal floors that allow manure to pass through to a pit. Sheep manure is about 75% water and is usually handled as a solid. It is difficult to dilute or mix the manure with water because solids from mature sheep float to the surface. Liquid handling is practical only for early-weaned lambs on a liquid diet. Typical sheep manure management systems are shown in Appendix D.
Sheep manure can collect on the barn floor, on the lot, or in a pit. Sheep housing should be constructed for easy clean-out with a tractor scraper and loader. Manure collected in a pit can be removed with a cable scraper or front-end loader. Sheep manure is often stored in the building or below-floor pits until field spread.
If separate manure storage is needed, plan for about one-half cubic foot per day per 1,000 pounds live weight for raw manure. Add half the volume of bedding for bedded-pack housing. Cover the storage to keep out excess water. A conventional box spreader is used for land application of sheep manure. Feedlot runoff from open-lot production can be controlled with settling basins, holding ponds, and infiltration areas. For more information, see Chapter 5, Farmstead Runoff Control.
Livestock waste-management facilities should not be located in a floodplain unless adequately protected from inundation or damage. They should never be located in a regulatory floodway designated on a Flood Insurance Rate Map provided by the Federal Emergency Management Agency (FEMA).
Information on floodplains, flood frequencies, flood inundation maps, and floodplain management is available from the County Floodplain Management Coordinator, the Ohio Department of Natural Resources Division of Water, the local SWCD/ NRCS office, and Flood Insurance Rate Maps (FIRM) provided by FEMA.
Animal manure should not be surface applied to land subject to flooding, except at those times of the year when flood risk is nearly zero. Follow the guidelines discussed in Chapter 6, Land Application of Manure. See also Chapter 7, Safety and Manure Handling.