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Pork Production: Best Management Practices
Table of Contents
Background and Overview
Best Management Practices
Environmental Impacts
Building an EMS
Alternative Technologies
Complete List of Links

Essential Links:

Ag 101 - Comprehensive Nutrient Management Planning
This is a summary of issues addressed by a CNMP.

Profile of the Agricultural Chemical, Pesticide, and Fertilizer Industry
This report is one in a series of volumes published by the United States Environmental Protection Ag...

Profile of the Agricultural Crop Production Industry
This report is one in a series of volumes published by the U.S. Environmental Protection Agency (EPA...

Profile of the Agricultural Livestock Production Industry
This report is one in a series of volumes published by the U.S. Environmental Protection Agency (EPA...

Best management practices (BMPs) refer to operating techniques and methodologies for reducing and/or preventing pollution before it occurs. BMPs for swine operations are a specific set of practices used by farmers to reduce the amount of soil, nutrients, pesticides, and microbial contaminants released to the environment while maintaining or improving the productivity of agricultural land. The following BMPs can help producers conserve and protect soil, water, and air resources by reducing pollutants from swine operations. Most technologies and practices work best in very specific situations and should be thoroughly researched before being implemented.

Facility Grounds
Animal Environment
Waste Management Systems
Land Application
Comprehensive Nutrient Management Planning
Feed Management
Crop Maintenance
Pesticide Application/Mgt.
Odor Control
Safety and Emergency Action Plans


housesBMPs for facility grounds are based upon minimizing environmental impacts to the surroundings. Specific examples include the following:

  • locating the facility as far as possible from surface water bodies
  • locating the facility in an area with sufficient soil drainage
  • having wind breaks and buffer strips around the facility
  • diverting rainwater away from areas where it could become contaminated
  • maintaining proper gravel cover and landscape gradient so water does not stand in access roads and around the production facility
  • scraping away manure in open feed lots to reduce buildup of solids, odors, and fly production
  • collecting runoff from lots in settling basins for subsequent land applications
  • immediately loading manure into a manure spreader and directly applying to the field
  • removing spilled feed promptly, and keeping feeder and watering equipment in good repair


Routine maintenance and good housekeeping practices are the simplest methods for maintaining a healthy environment for the animals. Other BMPs include the following:

  • constructing interior surfaces with smooth materials to reduce dust and grime accumulation and facilitate cleaning
  • maintaining adequate ventilation in the building to prevent buildup of dust, gases, moisture and heat
  • preventing liquids from collecting under animals and watering equipment by using slatted floors or other technologies
  • repairing leaking water lines immediately
  • maintaining clean and dry buildings
  • installing an under-floor ventilation system in confinement buildings where below-floor storage is used
  • covering feeders and extending feed downspouts to minimize dust
  • scraping off or flushing away manure in confinement areas on a frequency adequate to minimize odors
  • covering sumps at lift stations
  • pumping manure from accumulation areas to storage areas on a frequency adequate to prevent odors and overflow

For a list of daily checks for optimum animal house operations refer to the following:


lagoonEnsuring lagoons, settling basins and holding ponds are not undersized or poorly designed can prevent pollution. Examples of ways to optimize these waste management systems are listed below:

  • locating lagoons, settling basins, and holding ponds away from valley-type topography which can trap odors in low-lying areas
  • constructing lagoons, settling basins, and holding ponds so that wastes do not overflow or leach into groundwater and that odor is minimized, see the Odor Control: Anaerobic Lagoon section for additional considerations to minimize odor from anaerobic lagoons
  • covering the lagoon, settling basin, or holding pond to reduce release of surface odors
  • adding aeration, see the Odor Control: Aeration section for additional considerations to reduce odors using aeration
  • pumping or draining manure to a lagoon in small enough quantities to avoid slug loading to maintain a stable microbial population within the lagoon
  • maintaining sufficient storage capacity to prevent overflow of lagoons, settling basins, and holding ponds
  • using a pump and a solids separator to lower solid loading
  • removing sludge from the primary lagoon frequently enough to prevent overloading or carryover of solids to a second-stage lagoon
  • equipping lagoons and holding ponds with a free-board gauge to help determine when it is necessary to pump out and land-apply supernatant, and prevent overflows
  • dewatering lagoons no more than the minimum treatment volume level as indicated on the lagoon marker
  • filling new or emptied lagoons with water to the minimum treatment level before manure is introduced
  • For a checklist on conducting inspections of animal waste management systems, go to

Over the last five years, significant research and scientific experimentation have been conducted to identify environmentally sound and cost-effective options to traditional lagoon waste management systems. Refer to the Alternative Technologies section for a list of alternatives.


reelUsing manure generated by the hogs as a fertilizer can be environmentally beneficial. However, there are many opportunities to reduce pollution when applying the manure to the land. Consider the following application BMPs:

Developing a manure management plan: Refer to the Comprehensive Nutrient Management Planning Sectionfor a detailed example.


  • Ensure application times are compatible with crop rotations.
  • Apply manure early in the morning until early afternoon.
  • Apply manure on days with low humidity and little or no wind.
  • Prevent contaminated runoff by not applying manure during precipitation or when precipitation is imminent.
  • To prevent excessive phosphorus and potassium buildup, rotate manure application to different fields and apply to the lowest testing fields.
  • Irrigate cropless fields at low enough rates to allow liquid manure to be incorporated within 24 hours of application.
  • During the summer, broadcast manure on pastures or hay fields where nutrients can be used immediately. If manure must be applied to harvested wheat fields, incorporate the manure to reduce nutrient runoff potential.

Application Field Considerations:

  • Have sufficient land available to land-apply during various times of the year so that the application rate will be at or below agronomic rates.
  • Maintain grassed buffer areas to filter out solids and absorb nutrients at points where field and feedlot runoff may occur.
  • Locate land-application sites away from valleys.
  • Apply manure on fields that are not highly erodible.
  • Apply manure on land that is not frozen or snow covered.
  • Prevent contaminated runoff by not applying to land that is saturated or contains standing water.
  • Prevent contaminated runoff by not applying manure near a creek or river, or fields adjacent to these bodies of water.

Soil and Manure Testing:

  • Maintain regular manure and soil test programs to determine optimum application rate and priorities for spreading manure on a field-specific basis.

Record Keeping:

  • Keep records on each field where manure or commercial fertilizer are applied, on crop information, on soil and manure test results, and on pesticide and herbicide applications. Good records improve a producer's ability to evaluate how his crop management strategies are working on a field-specific basis.
  • Refer to this fact sheet for further guidance on land-application records and soil sampling at

Equipment Use and Maintenance:

  • Seal manure application equipment and cleaning disks used to incorporate manure if travel on public roads is necessary.
  • Apply liquid wastes at low pressures with little agitation if spreaders or sprayers are used to land apply.

Manure Injection:

  • Inject manure with a tank wagon equipped for manure injection.
  • Use injection equipment that leaves crop residue intact and creates a level surface to plant crops without further tillage.
  • Use nitrification inhibitors in liquid manure-injection systems to reduce nitrogen losses from applications made in the fall or early spring when nitrogen loss potential between application and crop uptake may be significant.

For additional land application BMPs that help to reduce odor from swine operations, refer to Odor Control: Land Application section.

Comprehensive Nutrient-Management Planning

In February 1998, with the release of then President Clinton's Clean Water Action Plan, the concept of Comprehensive Nutrient Management Planning was created by the U.S. Environmental Protection Agency and U.S. Department of Agriculture's Natural Resources Conservation Service. It is anticipated that the CNMP will serve as a cornerstone of environmental plans assembled by animal feeding operations to address federal and state regulations. EPA and NRCS guidelines for CNMP are given in Table 1.

Table 1. Summary of issues addressed by a CNMP as initially defined by EPA's guidance

Planning components of CNMP

Issues addressed

A manure-handling and storage plan

  1. Diversion of clean water
  2. Prevention of leakage storage plan
  3. Adequate storage
  4. Manure treatment
  5. Management of mortality

Land-application plan

  1. Proper nutrient application rates to achieve a crop nutrient balance
  2. Selection of timing and application methods to limit risk of runoff

Site-management plan

Soil conservation practices that minimize movement of soil and manure components to surface and groundwater

Record keeping

Manure production, utilization, and export to off-farm users

Other utilization options

Alternative safe manure utilization strategies such as sale of manure, treatment technologies, or energy generation

Feed-management plan

Alternative feed programs to minimize nutrients in manure


Further information on CNMPs is available from USDA/EPA Unified National Strategy for Animal Feeding Operations and (Louisiana State University, Swine Production Best Management Practices make hyperlink).


Appropriate management strategies that minimize manure nutrient excretion and maximize manure use efficiency in cropping programs can significantly improve the "bottom line" for most pork producers, especially producers who have crop acreage to maintain. Below are examples sited by Purdue University of BMPs for controlling nutrient flow from swine operations and improving the effectiveness of manure as a nutrient resource.

  • Evaluate diets and reduce feed nutrients. Adding phytase in low-phosphorus diets will enhance phosphorus, nitrogen, copper, zinc, and calcium use, and reducing crude protein and balancing amino acids can reduce nitrogen excretion.
  • Reduce water spillage or use wet-dry feeders to reduce manure volume and increase manure nutrient concentrations in liquid pit systems.
  • Consider phase feeding, split-sex feeding and grinding and pelleting feeds to enhance nutrient use and reduce nutrient excretion.
  • Refer to for a fact sheet titled "Feeding Strategies to Lower Nitrogen and Phosphorus in Manure."


To determine the amount of waste to apply, nutrient requirements of the crops to be planted must be known. In a waste management system, crops use the applied nutrients, prevent soil erosion, take up water, and provide food and habitat for organisms in the soil that further break down and use the waste products.

Without a crop to actively utilize nutrients and prevent erosion, applied waste could be washed directly into surface streams or leached into groundwater. Vegetative cover reduces the potential for runoff and erosion from an area. The root system in a cover crop holds soil together and provides a network of openings, or pores, for water to infiltrate (move into) the soil rather than run off. Crops for waste utilization are often selected only for their ability to take up large amounts of nutrients.

  • Base crop fertilizer needs on realistic yield goals and then take nitrogen credits from last year's legume crop (30 lbs nitrogen/acre for soybeans). Use commercial fertilizer only when manure does not meet crop needs.
  • Apply fertilizer with proper timing and placement for maximum plant utilization.
  • Incorporate manure to reduce nitrogen loss and manure runoff.
  • Put manure on non-legume crops to better utilize manure nitrogen.
  • When necessary, only surface-apply manure on fall cover crops or surface residues rather than tilled soil to minimize runoff.

For further guidance on crop selection and nutritional requirements go to In addition to nitrogen, phosphorus has recently become another nutrient of great concern. The Phosphorus Loss Assessment Tool (PLAT) helps producers handle phosphorus issues. To learn more about PLAT, refer to


Management practices such as pesticide selection, application method, pesticide rate used, and application timing influence pesticide movement. The following considerations will help ensure proper pesticide selection and application for swine producers:

  • Pesticides should be applied only when needed to prevent economic loss of a crop. In pesticide application, "the label is the law."
  • Before applying a pesticide, make an assessment of all environmental factors involved in all areas surrounding the application site. Carefully maintain all pesticide applications, not just restricted use pesticides.
  • Using chemicals at rates higher than specified by the label is ILLEGAL as well as an environmental hazard, because more pesticide is exposed to erosion, runoff, or leaching.
  • Poor timing of a pesticide application (application just before rain falls) can result in pesticide movement into water sources, as well as give little control of the targeted pest.
  • Consider creating buffer zones around sensitive areas such as streams and rivers, wellheads, and lakes or ponds where pesticide use will be reduced or eliminated. By buffering these areas, you may reduce water quality problems.
  • Limit the use of pesticides near roads, off-site dwellings, and areas of public gatherings.
  • Carefully calibrate application equipment at the beginning of the spray season and periodically afterwards.
  • Minimize spray drift by following label instructions and all rules and regulations developed to minimize spray drift (physical movement of spray particles at the time of or shortly after application).

For further guidance on minimizing environmental impacts from pesticide use refer to Louisiana State University, Swine Production Best Management Practices (BMPs).


The trend toward larger animal feeding operations, coupled with the influx of nonagricultural people into rural areas, has brought the issue of livestock odors to the forefront. Although water quality can be directly measured, odor strength and offensiveness can vary through personal perceptions. Total elimination of odor from animal feeding operations will probably never be accomplished. However, management practices and technology are becoming available that are capable of reducing odor. The following is a quick overview of some available practices and technologies. Most odor technologies work best in very specific situations and should be thoroughly researched before being implemented.

Information in this section was provided by the Nebraska Department of Environmental Quality and is located at For an abbreviated summary of information on controlling odors from confined-animal operations go to

Odors in Buildings:
Odors associated with livestock buildings are often overlooked for the more obvious odor source -- the waste storage structure. The following general housekeeping practices can go a long way to prevent odor from buildings:

    • Keep floors as clean and dry as possible to avoid anaerobic decomposition of organic material.
    • Avoid manure buildup, thereby decreasing odor sources.
    • Provide adequate ventilation to prevent buildup of dust, gases, moisture, and heat that may intensify odor.
    • Make sure building interior surfaces are as smooth as possible to facilitate cleaning and reduce area for dust and debris to accumulate.
    • Modify feed-delivery systems to release as little dust as possible. Odorants readily attach to airborne feed particles and dust, which can be easily released to outside air.
    • Clean exhaust fans and shutters regularly of dust and debris to maximize warm season ventilation.
    • Recharge, flush, or scrape under-floor manure storage areas as frequently as possible.
    • Cover recycle flush tanks.
    • Extend recharge pipes and fill-water lines to the bottom of the pit and fit them with anti-siphon vents in order to reduce agitation of liquids.
    • Cover outside collection and junction boxes, sump tanks, and storage basins, if possible.

Waste Storage Structures:
Properly designed and managed lagoons or holding ponds usually have low-odor potential. However, if an anaerobic lagoon is undersized or organically overloaded, it may be a significant odor source.

    • Make sure lagoons are large enough to consistently treat and store manure.
    • Fill new or emptied lagoons with four feet of water prior to introduction of manure so waste solids will be submerged. This gives different bacterial populations enough room to work and reduces the amount of complex and odorous compounds that will be released from the lagoon.
    • If possible, start loading new lagoons during the warmer summer months so that bacteria needed for proper lagoon function may become established.
    • Refrain from using harsh anti-microbial feed products like copper sulfate, which may disrupt the microbial population of the lagoon.

Land Application:
Application of liquid manure onto cropland may be a significant source of odors and nuisance complaints from surrounding neighbors. The following procedures may help alleviate those concerns:

    • Adjust sprayers and spreaders so the waste is applied at low pressures. High pressures can aerosolize the waste and allow for more air contact.
    • Apply wastes as close to the ground as possible. The higher the effluent is applied, the more air can mix with it and cause odors to be carried off the application site.
    • Apply manure during times when the air is warming and rising from the ground. This would normally be between the hours of 8 AM and 3 PM. Also, take into account prevailing winds, so odors won't be carried toward homes or businesses.
    • Avoid application on hot humid days (where odors will stay close to the ground), and on weekends or holidays.
    • Incorporation of the manure into the soil is a very effective technique of reducing odors. As soon as possible, incorporate manure if the soil type and costs aren't prohibitive.
    • Establish setback distances from neighbors.

Open Lots:
Odor from open lots is highly subject to climate change. Dust from feedlots is a primary concern because dust can absorb and concentrate odor compounds. Dust can also be carried long distances by wind and tends to stay closer to the ground than gaseous odor compounds. Other odors can come from decaying organic matter.

    • Lightly sprinkling pens with water or establishing shelterbelts has shown success in reducing the amount of fugitive dust leaving a facility.
    • Decaying manure produces more offensive odors that fresh manure. Keep pin areas free from puddles and fairly dry to inhibit anaerobic decomposition.
    • Clean pins regularly and land-apply the manure on cropland as soon as possible to prevent it becoming an odor source. Proper composting of the material can also reduce odors within a short period of time.

Facility Site Selection and Perception:
The primary method of reducing the number of odor complaints begins with selection of the site for the livestock waste control facility. Sites located near residences, commercial enterprises, recreational areas, or major roads are particularly prone to complaints. When selecting a site, also consider topography and prevailing wind directions.

?Trees and shrubs can help to reduce odor through air mixing and can add to the overall quality of appearance. See Facility Grounds BMPs for additional considerations in locating swine-production facilities.

Anaerobic Lagoon:
Improperly designed or managed lagoons can emit odorous gases like hydrogen sulfide and intermediate volatile organic compounds (VOCs). Conversely, correctly functioning anaerobic lagoons can treat wastewater with very little odor. As the size of a lagoon increases, potential for odors, rate of sludge buildup, and number of pathogenic organisms decrease, while nitrogen losses increase.

Lagoons operate more efficiently in warmer temperatures. They may produce considerable odor in the spring as bacterial populations are restored. Two main groups of bacteria exist in lagoons - acid-producing and methane-producing.

Acid-producing bacteria work at lower temperatures, breaking down organic matter into VOCs and volatile fatty acids (VFAs), both of which are odorous. Methane-producing bacteria, which flourish at higher temperatures, convert these complex odorous organic by-products into simple, nonodorous compounds like methane and carbon dioxide. However, methane-producing bacteria don't get started as early in the spring as acid-producing bacteria.

An anaerobic lagoon that is operating properly will have a pH of 7 to 8 (slightly basic). Overloaded lagoons tend to be more acidic (6.5 or less). This problem can be solved temporarily with a surface application of hydrated agricultural lime. Excessive additions of antibiotics or metals, like copper sulfate, to animal feeds may disrupt bacterial populations and cause odor.

Many lagoons exhibit a purple/reddish color on the surface. A naturally occurring, phototropic sulfur-oxidizing bacteria can cause this color. The color is a good sign that the lagoon is functioning properly and odor, ammonia-nitrogen, and soluble phosphorus are reduced. Research is being done at the University of Nebraska to determine how these bacteria reduce odor.

Manure Storage Covers:
Manure storage structures are often the focus of odor-control efforts. Therefore, many producers have covered them. Storage structures tend to be very large and covering them is not always economically feasible due to the high costs per square foot of material. However, several types of covers have been successful.

    • Geomembrane covers, like high-density polyethylene or reinforced polypropylene materials, can float or be supported through a structure on top of the storage unit. Geomembranes greatly reduce odors and eliminate the addition of rainwater into the structure. However, they do have their limitations. Producers need to find ways to remove rainwater from floating covers or they will become submerged. Also, biogas will collect under the cover. The gas could be vented and burned, or captured and used as an alternate energy source.
    • Biocovers consist of floating layers of chopped barley, wheat, flax, brome straw, corn stalks, or peat moss. Biocovers can greatly reduce odor from waste storage structures and cost less than synthetic covers. The drawback to biocovers is that they need to be replaced frequently, as the floating material sinks to the bottom and adds to the sludge build-up. They function best over semi-solid storages and are impractical in a lagoon setting because of the huge amount of material needed to cover it.

Solids Separation:

If a lagoon is odorous due to heavy organic overloading or is undersized, the producer can either increase the size of the lagoon or lower the amount of organic matter entering it. Solids separation can be done mechanically or through gravity (i.e., debris basins). This technology might be even more useful if recycled for flush water. The separated solids may be an extreme odor source.


In classic animal waste treatment systems, manure is treated anaerobically. Aeration adds dissolved oxygen to the treatment process, promoting growth of aerobic bacteria. Properly aerated, these lagoons have been proven to reduce odors, due to the complete breakdown of complex organic molecules like volatile fatty acids. However, aeration is costly - the addition of oxygen to water requires considerable energy use and equipment is expensive. Also, sludge builds up in the bottom of the lagoon faster in an aerobic system.

Anaerobic Digester:

Anaerobic digesters are designed to optimize waste degradation and capture the gaseous by-products, primarily carbon dioxide and methane. Methane can be used on-farm for heating through a furnace or in electricity production. Mesophilic digesters are the most common type and support a bacterial population in a temperature range of 700 to 1150 F. Higher temperature digesters are more efficient but are not as stable. Effluent from digesters can still be odorous without further treatment and nutrients aren't reduced substantially. High cost of the system, erratic biogas production, and remaining nutrient content may limit the building of digesters.

    • Biomass Filters:
      Biofilters can be used to treat ventilation air coming out of confined-animal production buildings. Biofilters provide a medium for growth of certain bacteria, which convert odorous compounds like VOCs, VFAs, and Nh2 into simple non-odorous compounds. Industrial biofilters can be very expensive, but biomass filters can be constructed and operated for as little as $0.22 per weaned pig produced. Buildings must use only mechanical ventilation, because naturally ventilated air can't be forced through the bacterial medium. The University of Minnesota has shown that biomass filters can remove up to 95 percent of the odor and 90 percent of the H2S with little resistance to air flow in the building.


Emergency action plans should be developed to meet current animal-manure management regulations. There are two primary safety concerns in manure storage and handling: environmental safety and personal safety. Every livestock facility should have an environmental emergency action plan available to all employees. The plan should be available and understood by all employees at the facility because accidents, leaks, and breaks could happen at any time. At a minimum consider the following:

- a plan to stop potential, uncontrolled releases of manure;
- phone numbers of those who can help stop any release;
- notification plan including agency phone numbers; and
- a cleanup plan.

  • Notification of local or state officials and local law enforcement officials is required in the event of a spill or other release.
  • If runoff results during manure application, stop applying immediately.
  • The five main gases produced by animal facilities are ammonia, methane, hydrogen sulfide, carbon monoxide, and carbon dioxide.
  • Hydrogen sulfide is the most dangerous of these gases. At high concentrations, it is lethal with just a few breaths.
  • Always use maximum ventilation during agitation and pumping from deep pits.
  • If one or more animals go down during agitation and pump out, shut off the pumps, but do not try to rescue the animals immediately.
  • Poor air quality in livestock facilities can cause long-term illness.

For extensive guidance on preparing an appropriate emergency action and safety plan go to or for an abbreviated version.


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Hub Last Updated: 3/18/2009