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Manure Management Conservation Practices A Virtual Tour

Manure management is one of the most visible parts of modern animal feeding operations. It involves everything from adjusting an animal’s diet to collecting and handling the manure, all the way to storing, treating (if applicable), and disposing of or recycling it. Other farm wastes, such as wash water and wasted or spoiled feed are part of the waste handling system on a farm.

Anaerobic Digester (366)

Anaerobic digestion is a relatively uncommon, but effective manure treatment process. In anaerobic digestion, microbes break down manure in an anaerobic (without oxygen) environment and produce methane gas. The methane can be used to generate electricity. There are nearly 250 digesters operating on livestock or poultry farms in the U.S., according to the U.S. EPA AgSTAR database.

Natural Resources Benefits. Digesters (Photos 1-5) are considered beneficial to air quality since there is less odor from the system compared to uncovered manure storage structures. Anaerobic digesters also harvest methane, a greenhouse gas, and either reduce it to carbon dioxide or use it to generate renewable electricity. Anaerobic digestion does not change the amount of nutrients that must be managed in manure. Anaerobic digestion also results in water quality benefits related to nutrient runoff reduction. Technologies added to the digester system can remove phosphorus or nitrogen and convert it into a form that is economical to transport to areas that have not historically had as much manure application to fields.

Photos described clockwise starting upper left. Photo 1: A complete mix digester at a dairy farm in Pennsylvania. Photo 2: The digester at this dairy farm in Massachusetts treats manure and off-farm food waste. The heat is used to warm a greenhouse. Photo 3: The biogas storage facility for a digester in New York that accepts manure from several farms along with waste grease. Photo 4: This generator produces electricity from methane gas captured in a digester at a California dairy farm. Photo 5: is dairy in New Mexico uses an anaerobic digester and a constructed wetland system to treat manure.

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Composting Facility (317)

Composting uses naturally-occurring microbes and oxygen to heat and decompose organic materials. A composting facility is where this process is located. Composting results in a low-odor product that can be used as a fertilizer or soil amendment. For animal agriculture, composting is primarily a manure or litter treatment process. However, other common feedstocks for compost on farms are spoiled or wasted feed or hay, off-farm wastes such as lawn clippings or food wastes, and animal bedding. Some operations compost mortalities.

Natural Resource Benefits. A properly-designed compost facility (Photos 1-6) protects water quality by containing all runoff so it cannot reach water bodies or nearby wells or sinkholes. It should also prevent nutrients from leaching down through the soil beneath the facility. The location of the composting facility can preserve air quality or aesthetics by considering distance to neighbors and prevailing wind direction. Properly managed compost achieves high enough temperatures to kill most pathogens. Compost can provide a marketable product and potential revenue stream for a farm. One research project even highlighted a way to calculate the amount of carbon sequestered through compost application to range land for the purpose of selling carbon credits. Compost can be applied to crop fields or pastures as a nutrient source or soil amendment.

Photos described clockwise starting upper left. Photo 1: Wind rows of compost being turned on a large-scale dairy farm in California. Photo 2: Wind rows of compost on a large-scale dairy farm in California. Photo 3: A composting facility (with roof) on a small farm. Photo 4: Cows are bedded with composted manure solids on a dairy farm in California. Photo 5: Manure compost has many beneficial uses including those in landscape industry. Photo 6: Newly constructed composting facility on a small farm.

Recommend Resources

  • NRCS National Conservation Practice Standard Composting Facilities (317)
  • Cooperative Extension publications about manure composting. Search the Internet for “manure composting” and your state name and “Extension”. If no publications are found for your state, omit your state name and look at the publications available for other states.
  • NRCS fact sheet on the benefits as well as the economic and management considerations for composting
  • Example of a composting facility installed on a farm in Georgia

Dust Control from Animal Activity on Open Lot Surfaces (AC.) (375)

Open lots for animal feeding or housing can produce dust (particulate matter) under different conditions. Dust events are especially likely to happen in the early evening. Controlling dust (Photos 1-3) usually involves sprinkling water or effluent from runoff storage ponds onto the surface of the lot and/or roads to reduce dust emissions or other management techniques such as frequent manure harvesting.

Natural Resources Benefits. Preventing dust emissions from feedlots protects air quality and also improves human safety since significant dust events can reduce visibility on adjacent roadways. Reducing dust emissions also improves conditions for animal and employee health.

Photo 1: Feedlots can install sprinklers for dust control or to cool cattle on hot days. (Photo credit: Kay Ledbetter, Texas A&M AgriLife). Photo 2: Sprinklers in use to conttrol dust on a cattle feedlot. (Photo credit: Brent Auvermann, Texas A&M AgriLife). Photo 3: Frequent harvesting of accumulated manure on the pen surface reduces dust. (Photo credit: Kay Ledbetter, Texas A&M AgriLife).

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Feed Management (592)

This conservation practice refers to formulating animal rations, selecting feed ingredients, or using feed additives in such a way as to reduce nutrient excretion in manure.

Natural Resources Benefits. Feed management (Photos 1-4) can positively impact water quality by reducing the amount of nutrients in manure and reducing the risk of nutrient overloading or runoff/leaching. It can also improve air quality by reducing gas emissions from manure, such as ammonia. Greenhouse gas emissions (methane) can also be reduced through feed management.

Photos described clockwise starting upper left. Photo 1: An NRCS employee and a landowner examine dairy rotation on dairy farm in Stanislaus County, CA. Photo 2: NRCS staff inspect a newly-installed concrete pad in front of a silage pile. Photo 3: Sampling feed ingredients is an important part of implementing the Feed Management conservation practice. Photo 4: The different feedstuffs available to this cattle feedlot can be used to formulate rations that reduce nutrient excretion.

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Nutrient Management (590)

Nutrient management is defined by NRCS as the management of commercial fertilizers, manure, soil amendments, and organic by-products using the Four R's:

  • Right amount (rate)
  • Right source
  • Right placement (method of application) and
  • Right timing

The Four R’s ensure that the application to agricultural landscapes is an appropriate source of plant nutrients while protecting local air, soil, and water quality. For animal agriculture operations, the Four R’s apply when a farm uses their manure or compost on crop fields and needs to ensure the amount applied stays in balance with crop needs and prevents excess nutrient application. Nitrogen and phosphorus are the nutrients of greatest concern, with phosphorus being especially important to manage when manure or manure compost is used. Photos 1-7 show some of the different parts of manure nutrient management.

Natural Resources Benefits. This practice is especially important in protecting water quality by reducing the risk of excess or unused nutrients reaching ground or surface water through runoff or leaching. Learn more about manure and nutrient management…

Photos described clockwise starting upper left. Photo 1: Injection allows farmers to place manure just below the soil surface, minimizing disturbance and reducing runoff risk. Photo 2: Solid manure application. When applying manure, the goal is to achieve as much uniformity as possible across the field. Photo 3: Liquid or slurry manure can be applied to crop fields using a dragline hose. (Photo credit: Glen Arnold, Ohio State University). Photo 4: Agitation is important in order to apply manure nutrients as uniformly as possible. (Photo credit: Robb Meinen, Penn State). Photo 5: A farm worker in Wisconsin takes samples of manure for analysis from a pit. Photo 6: A farmer and an NRCS District Conservationist collect a sample of solid manure for nutrient analysis. Photo 7: Calibration can be done by driving over a series of plastic sheets, weighing the manure, and calculating amount applied per acre.

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Roofs and Covers (367)

Roofs and covers keep rain or snowmelt from entering the waste management system. Roofs can be used in animal agriculture operations for solid manure or litter storage, animal feeding areas, farm chemical storage, composting areas, or mortality composting areas. A cover is most likely to be used on a liquid or slurry manure storage structure. Gutters or other drainage are used to direct clean water away from the storage area. Photos 1-9 show several roofed, guttered, or covered manure storage, feeding, or agrichemical storage structures.

Natural Resources Benefits. By directing clean water away from or around storage areas, the potential for polluted runoff is reduced. Using this practice is especially important in wet climates or in areas that are prone to significant rain or snowmelt events or when waterbodies or wells are downslope. As a general rule of thumb, keeping manure dry should result in less odor and fly problems, but this is not the primary purpose for building a roof. Covers on a liquid or slurry manure storage area reduce odors and gaseous emissions such as hydrogen sulfide and ammonia. Covers can also be used as part of a digester system to capture gases, specifically methane, emitted from decomposing manure and use them for generating electricity.

Photos described clockwise starting upper left. Photo 1: The exterior of a roofed manure storage structure on a poultry farm in Texas. Photo 2: The interior of a roofed solid manure storage facility on a poultry farm in Texas. Photo 3: A roofed solid manure storage structure in Ohio. Photo 4: A manure storage cover is part of this anaerobic digester in Pennsylvania. Photo 5: Farm chemical storage. Photo 6: A roofed animal feeding area. Photo 7: This farm stored fertilizer in a roofed structure. Photo 8: A manure storage cover is part of this anaerobic digester on a dairy in California. Photo 9: A guttered roof protects the soil around a barn a directs water away from the animal lot.

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Vegetated Treatment Area (635)

A vegetated treatment area (VTA) is planted with perennial vegetation and used to treat wastewater or runoff. For animal agriculture operations, sources can be open lots, manure storage areas, compost facilities, parlor wash water or other process wastewater, and other areas. The VTA needs to be accessible for hay removal and regular maintenance. Maintenance is needed to maintain proper function and prevent gullies from forming.

Natural Resource Benefits. VTAs protect water quality by treating wastewater and removing potential contaminants such as nutrients, pathogens, sediment, or organic matter.

Manure being applied to a vegetated treatment area near in South Dakota.

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Waste Facility Closure (360)

Animal agriculture operations that cease operations, build a new manure storage facility, or change production systems (such as moving to a pasture-based system) may need to abandon an unused manure storage (or other waste storage) facility. Closure of a waste storage facility should be done in a way that utilizes the accumulated nutrients, reduces the risk to natural resources, and restores the area for other uses.

Natural Resources Benefits. This practice protects water quality by removing accumulated sludge or liquid (and its associated nutrients) and distributing them according to a nutrient management plan. Closing an unused manure storage facility protects air quality by removing a potential source of odors and gas emissions. It also removes a potential safety hazard for humans and animals/wildlife, reduces nuisances such as flies, and improves aesthetics of a site.

Photo 1: A Nebraska swine manure lagoon that is being prepared for closure. Photo 2: Removing the liquids from the swine lagoon being closed.

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Waste Recycling (633)

Waste recycling is reusing by-products or waste in agricultural production. For animal agriculture operations, this may include using food waste for animal feed or accepting off-farm wastes for composting or anaerobic digestion (Photo 38). This practice is often used in conjunction with Feed Management (592) and Nutrient Management (590).

Natural Resources Benefits. Recycling waste products is a key environmental stewardship principle that can (depending on the situation) improve water quality, air quality, reduce greenhouse gas emissions, and/or reduce landfill waste. It can provide a farm with a revenue stream through tipping fees, renewable energy generation, carbon credits, or value-added products.

This dairy farm accepts food waste. This building is where the waste is delivered and added to the anaerobic digester.

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Waste Separation Facility (632)

Animal manure can be separated into two parts, one that is mostly solid and one that is mostly liquid. This is commonly done by either mechanical separators (Photos 1 and 2) or by settling basins (Photo 3), which rely on gravity. Other methods are available. Mechanical separators are used more on farms that handle manure as a liquid or slurry or use an anaerobic digester. Settling basins are used mostly for slowing down runoff from open lots so that solids sink to the bottom and the liquid is transferred to the main manure storage facility. Settling basins are also used on dairies that bed cattle with sand (Photo 4). Separating the sand from the manure allows the sand to be reused and prevents it from entering the waste storage facility. Separation can extend the capacity of manure storage facilities by keeping solids out. Separation is also a critical step in many manure treatment options.

Natural Resources Benefits. There are several potential benefits of manure separation. One is that separated manure tends to emit less odor, improving air quality. Water quality can benefit when separation enables better nutrient management. For example, separated solids (which contain most of the phosphorus) can be economically transported outside of an area with high soil phosphorus levels and reduce the potential for negative impacts on water quality. As mentioned above, separation is also an important step in many manure treatment processes, some of which can be used to generate energy (through processes such as pyrolysis or gasification) and/or by-products (like composted solids or ash) that can be marketed off-farm, thus removing nutrients and providing a potential revenue stream for the farm.

Photos described clockwise starting upper left. Photo 1: Mechanical separation of compost solids produced by the anaerobic digester on a dairy farm Pennsylvania. Photo 2: A mechanical manure separator operating on a dairy in California. Photo 3: This structure is part of a closed loop water effluent system that uses sand separation on a dairy farm in Maryland. Photo 4: A settling basin under construction.

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Waste Storage Facility (313)

Storing manure in an engineered structure allows the farmer to postpone the application of manure until weather conditions are favorable and the cropping system can benefit from applied nutrients. In addition to manure, some farms also need to contain and store process wastewater such as dairy parlor or egg wash water. This waste stream does not generally include many manure solids (it is very diluted) but it usually includes cleaning chemicals. Photos 1-5 show different types of waste storage facilities.

Natural Resources Benefits. Having adequate storage allows farmers to plan manure application for appropriate conditions, which is when crops will use the nutrients applied. This reduces the chance that manure will be applied at high-risk times for runoff, such as when soils are frozen, snow-covered, or saturated. Human health and safety is protected when signs, fences, employee/family training, and other precautions are taken relative to manure storage structures.

Photos described clockwise starting upper left. Photo 1: Solid manure storage. Photo 2: A concrete slurry manure storage structure on a dairy farm. Photo 3: An earthen two-stage liquid manure storage system. Solids are settled out of the first stage with liquid pumped to the second. Photo 4: A round concrete slurry manure storage in Maryland. Photo 5: A steel slurry manure storage above ground tank (the shortest of the blue steel structures).

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Waste Transfer (634)

Transferring waste—whether it is manure, process wastewater, or other farm wastes—for storage or treatment is another conservation practice of importance to animal agriculture. This standard involves using pumps, pipes, or other conduits that are constructed to transfer waste. For manure management, this can include flush systems, conveyor belts, pipe to irrigation systems, or dragline hoses for manure application. This standard does not include using trucks, front end loads, or other vehicles to move the waste. Photos 1-5 show several manure transfer methods.

Natural Resource Benefits. A properly designed and managed waste transfer system efficiently moves manure or other wastes from where they are generated to the storage or treatment area. This protects water quality and improves the efficiency of the manure management system.

Photos described clockwise starting upper left. Photo 1: This grated inlet receives flush water from this dairy freestall barn and transfers it to the manure storage structure via pipes. Photo 2: A dragline hose can be used to apply manure up to 2 miles away from the storage structure. (Photo credit: Glen Arnold, Ohio State). Photo 3: Booster pumps maintain flow in dragline hoses whe application is farther from storage. (Photo credit: Glen Arnold, Ohio State). Photo 4: A conveyer belt system to transport manure from layer house to separate manure storage building. (Photo credit: Robb Meinen). Photo 5: A conveyer belt system deliver layer hen manure to a covered manure storage structure. (Photo credit Rob Meinen, Penn State).

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Waste Treatment (629)

Treating manure or other wastes from animal agriculture operations can include a wide variety of systems and technologies. Among those are nutrient extraction (Photo 1), thermal technologies such as gasification or pyrolysis (Photos 2 and 3), vermicomposting (Photo 4), or other innovative processes.

Natural Resources Benefits. The benefits of waste treatment vary somewhat depending on the process or technology used. Reducing the nutrient content of the waste stream (or concentrating the nutrients into a form that can be transported out of an area) has the potential to improve water quality. Many waste treatment technologies provide air quality benefits in the form of reduced odors or reduced gas emissions compared to raw manure storage systems. Greenhouse gas reductions and the potential to generate renewable energy are additional benefits.

Photos described clockwise starting upper left. Photo 1: This swine-turkey manure treatment system removes solids and nutrients, recycling water for washwater. Photo 2: An endothermic gasification system (under construction) that will produce methane for electricity generation and other products. Photo 3: An interior view of a vermicomposting vessel. Photo 4: This boiler combusts poultry litter to generate heat for the barns (Photo credit: Farm Manure-to-Energy Initiative).

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Waste Treatment Lagoon (359)

A lagoon is a constructed embankment or pit that confines and treats liquid waste. Photos 1-5 show several different manure treatment lagoons. Although many earthen manure storage structures are called lagoons, not very many of them actually are. A manure treatment lagoon is generally larger than a storage pond or structure. This is because the lagoon requires a treatment volume of liquid in addition to the storage capacity. This treatment volume allows for new manure to immediately undergo treatment via microbial activity. This treatment reduces the amount of solids and organic matter by converting them to gases. Some of this occurs in manure storage ponds but is, by design, more significant in lagoons. Lagoons can be either anaerobic (without oxygen except at the surface) or aerobic (an aeration system is used to mix oxygen throughout the contents). Treatment lagoons should be designed with safety in mind with posted signs or a fence to keep people out and should be designed with escape methods in case someone falls in.

Natural Resources Benefits. A properly designed and managed lagoon should be less odorous than a comparable manure storage. Otherwise, lagoons have similar benefits as an engineered manure storage in that having adequate capacity allows farmers to plan manure application for appropriate conditions, reducing the chance that manure is applied at high-risk times, such as when soils are frozen, snow-covered, or saturated. Water quality benefits when these situations can be avoided.

Photos described clockwise starting upper left. Photo 1: A swine manure treatment lagoon in Ohio. Photo 2: Obtaining a sample from a swine manure treatment lagoon in Iowa. Photo 3: This lagoon in Pennsylvania holds the liquid waste, to be used as fertilizer, after the solids are separated. Photo 4: This lagoon in North Carolina uses pumps new manure into the storage structure beneath the surface to reduce odors. Photo 5: A waste management system for a hog farm in Georgia.

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Footnotes: These materials were developed with funding from the USDA NRCS through an interagency agreement with the U.S. EPA

Photos, unless otherwise indicated, are courtesy of USDA NRCS or Jill Heemstra, University of Nebraska

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