Q. What production systems are commonly used?

A. Pork producers use a variety of production systems to raise hogs, which creates unique and different approaches to managing the manure. Typically, systems vary because of regional differences in climate, topography, and hydrology. For example, production systems and manure management methods used during a cold January in the upper Midwest may differ greatly from those used the same month in warmer, southern states.

Production Systems and Manure

Pastures and Drylots: Some hog enterprises consist of drylots or pastures in which manure cannot be collected easily for reuse. To the soil system, unconfined animals contribute manure nutrients that can be assimilated or otherwise used naturally by vegetation if animal densities are low enough to maintain pasture conditions. Hogs are fed on the ground or self-feeding troughs so that labor and land can substitute for capital. The trend in the last few decades, however, has been toward enclosed production facilities to better care for the animals and manage the manure more effectively.

Concrete-Slab-Floor Facilities: Two primary types of concrete-slab facilities are used in swine production: (1) units 100 percent roofed and (2) units 50 percent open or more. Bedding materials in the form of wood shaving, sawdust, or straw may be used in concrete-slab facilities. In solid form, manure and bedding are scraped and removed from completely roofed buildings in cold regions. Use of bedding is not as prevalent in warm areas and manure is handled as a slurry.

The other type of slab facility is a paved feedlot, 50 percent or less of which is under a partly open-sided, roofed building. The floor area slopes to a wide, shallow gutter at the low edge. Before being hauled directly to the field or stockpiled until spreading, manure is scraped mechanically from these lots once or twice a week in warm season and once every 1 to 3 months during winter.

Slatted-Floor, Enclosed Buildings: The environments of production facilities are controlled by either mechanical or natural ventilation systems with floor surfaces either partly or entirely slatted over manure collection gutters or pits. Because animals work the manure through floor slats, manure is separated quickly from the animal with minimal hand labor. Manure collected under the slatted floor either is removed infrequently by pumping or by gravity discharge to an outdoor holding tank or lagoon; or is removed frequently by mechanical scraping, pit recharging, or flushing with recycled lagoon liquid.

Q. Why are most pigs now raised indoors rather than in open pastures?

A. Hog farms are often very different than the traditional image many people have of pigs wallowing in a muddy pen. Years ago, pigs would lay in the mud to protect themselves from overheating and biting insects. Hogs today are raised in a variety of humane ways.

Many hogs, particularly those located in states with extreme weather, are kept indoors in buildings where the pork producer can control temperature, humidity and other environmental factors. These buildings are well-lit and clean, so the producer can better monitor and promote the health of the hogs.

Some modern operations use a combination of indoor and outdoor facilities. But most importantly, good care depends on the producer’s ability to properly manage and maintain housing rather than the type of housing used. Modern facilities typically provide a producer with the means to standardize production conditions and reduce production variation, making the operation more efficient. As a result, U.S. producers have been able to market the world’s highest quality pork products at the lowest production cost.

Q. Are modern production methods less sensitive to animal care?

A. In fact, the opposite is true. Producers realize the vital interest they have in raising healthy, well cared for animals because it quickly affects their bottom line. In short, healthy, unstressed animals are more profitable. And, profitable operations can afford to invest additional human and capital resources in finding better ways to care for animals.


Q. Are modern production methods less sensitive to animal care?

A. In fact, the opposite is true. Producers realize the vital interest they have in raising healthy, well cared for animals because it quickly affects their bottom line. In short, healthy, unstressed animals are more profitable. And, profitable operations can afford to invest additional human and capital resources in finding better ways to care for animals.

Pork producers finance hundreds of thousands of dollars in research to find better ways to care for animals. For example, studies show that pigs are more susceptible to diseases and less productive when they are subjected to stress from extreme heat or cold temperatures. As a result, producers learn how to monitor their herds to avoid or minimize the effects of temperature extremes. Research aimed at improving design of animal housing has resulted in better ventilation, improved manure management, and reduced disease and mortality rates.


Q. Do hog operations smell?

A. The human nose is capable of detecting numerous compounds that may be produced from manure handling or storage systems on pork operations. These compounds include ammonia and other nitrogen compounds generated by microbial decomposition.

Odorous compounds vary with location, production practices, season, temperature, humidity, time of day, and wind speed and direction. All compounds, however, represent elements and nutrients that occur naturally in the environment. For example, throughout the world, naturally occurring wetlands produce more methane than all agricultural land combined. Natural wetlands also produce hydrogen sulfide and other gases typical of anaerobic treatment processes used in pork production.

In general, odors from manure operations are generated by three sources: (1) buildings and holding facilities, (2) manure storage and treatment, and (3) land application. Odors generated by buildings and holding facilities are reduced most easily by keeping areas clean and well ventilated. Modern facilities that use underfloor manure holding systems generally reduce the levels of ammonia and hydrogen sulfide gas by keeping collection troughs and pits covered with water.

Lagoon treatment systems typically generate more odors during the initial start-up year because microbial activity has not yet reached its optimum efficiency. When these biological processes stabilize, treatment lagoons generate negligible odors. Most potential odor is generated by the lower, most anaerobic layers of a lagoon. If lower layers are allowed to decompose undisturbed, odors are minimized. The upper, more aerobic liquid layers of a lagoon generate significantly less odor. This upper, liquid layer can be siphoned off and applied to soil as fertilizer. When waters from that layer, or from a second-stage treatment lagoon, are properly applied to land as fertilizer, odor is minimized and dissipates rapidly.

The best way to control odors is to properly manage production facilities and take proactive measures to avoid problems. Proper management for odor control is a many-phased process for producers. Following is a list that summarizes preventative measures most often taken by responsible producers.

Location: Facilities are isolated and screened from roads and neighbors; separated by proper distance from neighbors and public areas; windbreaks and buffer strips are used.

Building Interiors: Building interiors are equipped with clean, well maintained ventilation systems to move fresh air; air exhaust hoods are used to help disperse odors; exhaust is directed away from sensitive outside areas like homes; interiors are well maintained, clean, and have low dust levels.

Building Exteriors: Buildings and fences are painted, clean, free of debris; exteriors are aesthetically landscaped, with well kept grass areas.

Manure Storage Systems: Systems have adequate capacity for the age and number of animals raised; location is out of public view and in compliance with local/state site requirements; windbreaks, fences or other visually-appealing elements are used; systems are well-maintained, clean, dry; some have a floating membrane; pumped out or handled when wind and weather conditions are most suitable.

Manure Application: Before application, wind direction, speed and distance to neighbors are considered; application prior to early afternoon is strongly recommended during warm weather to reduce odors; land application on calm, humid days is strongly discouraged; runoff is avoided by not applying manure on frozen ground; neighbors are notified prior to application; manure is not applied on weekends, holidays or at other special neighbor events or is incorporated or injected into the soil to reduce odor.

Other strategies: Deodorants, masking agents, and counteractants; dietary modifications and feed additives are used to reduce odor producing compounds in manure.

Producers recognize it is in their best interest to keep odors at a minimum. As a result producer-funded organizations, related pork industry businesses and government agencies sponsor numerous forums and educational workshops each year on odor management.

Q. Do new hog facilities affect property values?

A. New, large livestock facilities were strongly associated with higher nearby residential property values in an independent, scientific study paid for by the Minnesota Legislature and conducted by the researchers at the University of Minnesota. The study, the largest of its kind to date, looked at actual sales prices of 292 rural residential properties located near livestock facilities larger than 500 animal units (1,250 head of hogs). The study showed a mean price increase of 6.6% for a rural residential property near a new feeding operation of this size or greater.


Q. Do hog operations threaten wildlife species?

A. Modern pork operations do not threaten wildlife or their habitats. Agricultural production methods–including those used on pork operations–increase food yield while using less space, allowing greater areas of natural habitat to be protected. In fact, farm fields and fallow areas provide some of the last remaining large open areas for wildlife habitat and feeding. That includes areas for threatened and endangered species.

Large hayfields fertilized with manure provide natural food sources for many grazing wildlife species. These herbivores also benefit from wooded buffer zones that are sometimes used around manure storage systems. Buffer zones typically provide valuable forest and wetland habitats that may be destroyed with other types of development. Carnivorous species, such as owls and hawks, likewise benefit from open areas typical of pork production operations because these species feed on herbivore populations.

Q. What are the perceived negative economic effects of pork production?

A. Concerns typically involve quality-of-life issues like aesthetics, comfort, health, property values and housing development. In some areas of the country, citizen groups have organized to oppose new or expanded pork production facilities. The resulting debates, often emotional and contentious, have caused severe rifts between neighbors and among people in the community.

There is very little evidence, however, to support fears of deterioration in quality-of-life for communities that include pork production operations. For example, communities in North Carolina have experienced rapid growth in pork production at the same time tourism has increased. Rural economies grounded in pork production and related businesses have been able to thrive, increasing property values. Small communities can attract and keep young families by supporting growth of the pork industry because it provides opportunities for new businesses and good paying jobs.

As pork production methods become more familiar to the public, concerns should diminish. Responsibly managed pork operations promote economic prosperity, particularly in rural areas that may have few economic development opportunities.

Q. What are the economic benefits of pork production?

A. Pork production is a vital and growing part of the nation’s economy and the industry’s economic impact on rural America is especially significant. Annual farm sales usually exceed $11 billion, with the retail value of pork totaling about $30 billion. When the economic impact of wages and profits spent in other sectors is included, pork producers are responsible for generating more than $66 billion in total domestic economic activity.

Through direct, indirect, and induced effects, the pork industry supports over 600,000 jobs and adds nearly $27.4 billion of value to production inputs. Efficient production methods keep consumer pork prices in the United States among the lowest in the world. The pork industry also produces non-food items used in medicines, and cleaning agents. Pharmaceutical by-products include insulin, various hormones, materials used to dress wounds and burns, and replacement heart valves. Industrial by-products include cleaners, adhesives, proteins, dyes, insulation, crayons, chalk, lubricants, and leather.

The versatility of pork products makes production an appealing and potentially profitable business. The number of hogs produced in the United States now exceeds 93 million and the number of farms with hogs is more than 157,000 (USDA, December 1996).

Pork producers contribute to the economic viability of rural communities by supporting service and retail businesses from the farm gate to main street. As many small towns experience a gradual loss in population and tax base, areas that rely on pork production and related businesses often benefit from greater tax revenues, increased per capita incomes, stronger employment rates, and other factors that build economically stable communities.

Q. Are pork producers good stewards of natural resources?

A. Producers are very much aware that environmental conservation is in the long-term interest of their own business, the pork industry, and the nation. As residents of rural America, producers are committed to protecting their local environment for their families, neighbors, and communities. In short, good stewardship means good business.

As stewards of the environment, pork producers have funded and applied innovative research and technology programs to improve the quality of life in rural areas, prevent the degradation of environmental resources, and reduce odors and other potential problems associated with their operations.

The first edition of the “Guide to Environmental Quality in Pork Production,” has been cited by the U.S. Environmental Protection Agency as a model for use by other agricultural industries. Pork producers have worked with state and federal regulatory agencies to develop and present environmental workshops for more than 5,000 producers throughout the nation. These cooperative and educational efforts have improved operational efficiency while protecting the environment for future generations.


Q. How is manure applied on the land?

A. Land application is an important alternative for hog manure use. If applied properly, organic manure products can serve as sources of low-cost fertilizer for agricultural, horticultural, and silvicultural production systems. Organic materials also can be used as soil conditioners. The development and implementation of proper land application systems is extremely important to protecting surface water, groundwater, and air quality standards. Improved feed-ration design, manure solids separation for composting, and biological digestion are becoming increasingly important steps in the treatment sequence culminating in land application.

The contents of most anaerobic lagoons and settling basins are applied most economically to land by means of irrigation. Solids-free lagoon liquid is applied through single, small diameter, straight-bore sprinkler nozzles. Irrigation equipment is field calibrated periodically to verify that operating characteristics are unchanged.

In solid or slurry (semi-solid) form, manure is spread on the land and incorporated or injected into the soil. Soil incorporation is a mechanical process that mixes the soil with the manure. Soil injection is a mechanical process that places manure directly under the soil surface, so the nutrients can be better used by the cover crop. Injecting, or “knifing,” manure is the most effective way to reduce odor. Periodic spreading equipment calibration defines combination of settings and travel speeds needed to apply manure at an optimal rate.

Q. What are the differences between commercial and manure fertilizer?

A. The most environmentally significant difference between hog manure and commercial fertilizer is the relative concentration of nitrogen, phosphorus, and potassium compounds. Hog manure typically averages about 15 lb/ton of nitrogen, 30 lb/ton of phosphorus, and 10 lb/ton potassium. In liquid systems, the nutrient values are slightly higher 30 lb/1,000 gal of nitrogen, 32 lb/1,000 gal of phosphorus, and 25 lb/1,000 gal of potassium. In either liquid or nonliquid systems, other nutrients and minerals which are essential for optimum plant growth are present in trace amounts. In commercial fertilizers, concentrations of nitrogen, phosphorus, and potassium can be much higher in concentration per ton. Furthermore, the trace elements and minerals found in manure are not present in commercial fertilizers.

While manure is a good source of a wide range of nutrients, it can be bulky, wet, heavy, and difficult to manage. Producers must regularly collect, store, handle, treat, transport, and apply manure, and each of these activities requires a substantial investment of time, equipment, and money. The primary advantage of commercial fertilizer is that it is easier to handle because it comes in ready-to-use form.

Some producers are researching ways to convert manure to low concentration, commercially-available fertilizers that will not overburden the earth’s nutrient cycling processes–particularly aquatic nutrient cycles. This research is ultimately intended to convert manure into another value-added product. While promising, it has not yet resulted in a product that is economically feasible for commercial sale.


Q. What environmental regulations apply to pork production?

A. Areas of environmental regulation include: groundwater, surface water, air quality; animal and manure disposal; land and soil quality; and land use.

Typically, permits are required at state and local levels for construction of structures ranging from animal housing units to manure storage systems. Operating permits for manure handling also may be required.

As in other industries, pork producers must meet or exceed all local, state, and federal environmental worker health and safety requirements. In brief, pork producers are faced with a multitude of regulations at all levels of government.

Q. What kind of training or technical support is available to pork producers?

A. Environmental support and training are available through the pork industry and related agricultural associations, university extension services and programs sponsored by the U.S. Environmental Protection Agency and the U.S. Department of Agriculture. All of these resources provide pork producers with the latest research and information available on methods to improve environmental efforts.

In addition, producers can take advantage of a wide range of information from sources through the world-wide web. By taking advantage of developments in information technology, producers can access results of research conducted in Europe, Asia, and North America. Together, all of these information sources allow individual producers to research, plan, and implement a broad spectrum of initiatives to enhance their specific environmental efforts. A representative list of these resources is provided at the end of this publication.

Q. What human health and worker safety regulations apply to pork production?

A. Occupational Safety and Health Administration (OSHA) regulates pork operations that have more than 10 workers at any time during the year. Under OSHA regulations, workers who are exposed to certain compounds or other hazards must be trained in identification, documentation, handling, and emergency procedures. Part of these regulations apply to mixing and preparing feed materials and additives. Others cover potential gaseous hazards in manure pits and drain systems.

OSHA-required education and training can be supplemented with a variety of producer- and university-funded programs. Responsible producers voluntarily educate themselves because they understand that the health and safety of employees is vital to their community and long-term business development.

Q. What is the Environmental Quality Incentive Program?

A. Under the 1996 Farm Bill, four federal conservation cost-share programs were combined into the Environmental Quality Incentive Program (EQIP). EQIP is funded at $130 million in fiscal year 1996 and $200 million dollars thereafter. States must apply for funding based on environmental needs.

EQIP is expected to target improvements in three areas: wildlife habitat; land conservation; and protection of rural water quality. EQIP has two associated programs: the Conservation Reserve Program (CRP) and the Wetlands Reserve Program (WRP).

Under EQIP, pork producers may be able to apply for specific funding allocated for operational improvements that benefit the environment. Examples might include: improving manure management systems; installing more efficient and manageable animal housing; and applying new technologies to increase aerobic decomposition of manure. Although still in its early stages of development, EQIP has the potential to greatly benefit both pork producers and their communities.


Q. Is hog manure toxic or hazardous to the environment?

A. When managed properly, manure presents little risk to the public or to the environment. The U.S. Environmental Protection Agency defines a toxic substance as a chemical or mixture that may pose an unreasonable risk of injury to human health or the environment. Hazardous substances include those that present a threat because they are characteristically toxic, corrosive, ignitable, explosive, or chemically reactive. Based on these definitions, hog manure is neither toxic nor hazardous.

When manure decomposes, it produces ammonia and hydrogen sulfide, as well as a variety of organic compounds. These compounds, many of which are nutrients necessary for plant growth, are also produced through decomposition processes in natural wetlands and all of them occur throughout the environment as a result of various natural processes.

Compounds in hog manure–like the compounds in a compost pile–are easily broken down into various nutrient sources for plant uptake. Because hog manure contains only low concentrations of these compounds and nutrients, the products of decomposition are rarely, if ever, present at levels that are toxic or hazardous to local plant and wildlife habitats or human populations. The sound environmental management practices of today’s pork operations are designed to protect natural resources from excess nitrification, and high concentrations of manure when land applied.

Q. Are the elements found in hog manure contaminants or pollutants?

A. A contaminant is any substance or material that is not naturally present in the environment or that is naturally present at much higher levels. A pollutant is a contaminant that is present at levels that are high enough to make water unfit for its intended use.

The elements in hog manure if not managed correctly can be a contaminant or pollutant. Proper manure handling and management techniques avoid such problems by treating manure before it is applied to the land and by limiting its application to rates that can be used by plants in natural nutrient cycling processes.

Inorganic copper (Cu), zinc (Zn), and phosphorus (P) are added to animal diets as essential nutrients for growth. If not properly managed the potential for these elements to accumulate in soils from land application is possible. Some of these supplements, like Zn, is more likely to be beneficial to crops than harmful, and many diets tend to be low in Zn. Soil texture, soil pH, climate, and soil water holding capacity are all factors pork producers consider before applying manure to pasture land or cropland.

With continual manuring, soil aggregation eventually is improved, soil water-holding capacity is increased, and air exchange is enhanced. Additionally, the soil often becomes a better medium of aerobic biological activity. Manure application, if not excessive, thus tends to improve soil quality over time.

Q. How do production and manure management techniques affect ecosystems and the environment?

A. Elements in hog manure are all naturally occurring compounds that biodegrade or easily dissipate. When manure is loaded and treated at appropriate rates in lagoons or other systems and is then properly applied to crop and pasture land, the effects on air, water, and soil components of local ecosystems are negligible.

When manure is used as fertilizer, it completes a sustainable system. Manure nutrients are used by forage or agricultural crops, particularly corn. Forage crops are typically made into hay used to feed cattle. Corn is used to feed all livestock species.

Modern manure management and treatment systems do not overburden local watersheds with nutrients in agricultural runoff, and any changes in local air quality are short term, nonhazardous, and typically involve odors detected at parts-per-billion levels. Because compounds in hog manure are naturally occurring and are not applied in excessive amounts, they are cycled through the ecosystem in the same way as other nutrient sources. As in any operation, occasional accidental releases may occur, but these accidental releases involve only naturally occurring nutrients, which are easily absorbed and incorporated into the environment, producing minimal long-term effects.


Q. Does manure or odor present a public health risk?

A. No. Elements and nutrients in manure do not present a public health risk because all compounds occur naturally and none are released to the environment at concentrations detrimental to air or water quality. The human nose is sensitive enough to detect some of these compounds at parts-per-billion levels, which are well below the concentrations that produce human health effects. While odors from pork operations may occasionally be distracting or irritating, they do not pose a health risk.

Responsible pork producers employ various methods to minimize the effects of odor on the surrounding community. For example, producers monitor climate and wind speed conditions before manure fertilizer applications. They ensure liquids drawn from lagoons have received adequate treatment to minimize odors before land application. Most important, they understand being a good neighbor is essential to the continued success of their business. As a result, responsible producers plan ahead to avoid applying manure at times neighbors may be entertaining friends and relatives. Producers take proactive measures to avoid problems.

Q. Is manure a major cause of groundwater or surface water pollution?

A. Manure management systems that are properly managed do not contaminate groundwater or surface water resources. Properly constructed lagoons, particularly those with liners, thermal aeration systems, and other technologies, remove nutrients naturally present in manure before it is applied to soil or ground. The pork industry prides itself on its zero discharge standard.

Other sources typically contribute to elevated nitrate levels. They include naturally occurring background levels in wetland areas, human sewage systems, and runoff from commercial fertilizers.

Well depth and its proximity to operational areas significantly affected nitrogen levels in groundwater. When wells are placed and installed properly, natural attenuating factors in groundwater systems effectively reduce the nutrient and bacteria concentrations to safe, typically nondetectable concentrations.

Q. If a water source is found to be contaminated, is it possible to distinguish municipal human waste, commercial fertilizers, and livestock manure?

A. Elements and nutrients found in municipal human sewage, commercial fertilizers, and livestock manure are all naturally occurring compounds. When present in groundwater or surface water, these compounds may be indistinguishable. For example, sewage from a septic tank contains the same basic elements and nutrients found in manure. As a result, it is difficult to determine the source once compounds have impaired a watershed.

Modern groundwater and surface water monitoring techniques allow pork producers to manage manure systems to avoid any environmental impacts to local water resources. Groundwater monitoring wells placed near pork operations are able to detect any nutrients that may be leaching from treatment lagoons or other areas. Surface water monitoring also can determine if manure applications are affecting local stream quality.

Producers use such wells and sampling efforts to ensure their operations do not degrade local water quality. In the event of an accidental spill, these monitoring systems can determine the potential increased nutrient load resulting from the spill. That data can be used to establish cleanup and redemption goals.

Q. Are people at risk from high nitrate levels in potable water?

A. The primary human health effect of excess nitrate levels in drinking water is methemoglobinemia, or “blue-baby syndrome.” That condition is extremely rare and documented cases in the United States are particularly unusual.

Nitrites and nitrates are naturally occurring compounds that result from various biological processes. Those processes include microbial decomposition that is an essential component of nutrient cycling in natural ecosystems. Air itself is made up of about 70 percent nitrogen. Nitrogen cycling is essential for plants, wildlife, and atmospheric activity.

Although nitrates and nitrites may be dangerous to humans and wildlife in extremely high doses, pork production operations are rarely the primary contributing factor in groundwater or surface water contamination. Commercial fertilizer presents as much of a risk when overapplied or applied at the wrong time as does manure. When that happens, the plant is unable to use all the nutrient compounds and, as a result, groundwater or surface water can be contaminated.


Q. What is the risk of pathogenic transmission from hogs to humans?

A. The public is not at risk from any zoonotic diseases which are communicable among animals, particularly swine and humans. Farm workers, veterinarians, and slaughterhouse employees may, however, be suspectible to exposure throughout their daily activities. Although those who interact with the animals can potentially be exposed to zoonotic diseases, modern hygienic practices, producer and veterinarian knowledge of these diseases, and the development of antibiotics and vaccines minimize the already low risk for disease transfer from animals to producers. It is in the best interest of producers to maintain healthy animals and a safe working environment.

Pathogens present in water can be the result of feces or urine from various wildlife species such as deer, raccoons, opossums, rabbits, rats, mice, and squirrels as well as improperly applied livestock manure. Properly handled, stored, and applied manure will not jeopardize the integrity of surface water. For those pork operations permitted by state and federal agencies, the discharge of manure into lakes, streams or other surface water bodies is strictly prohibited unlike other non-agricultural permitted facilities which can and do. Public water systems are required to filter surface water sources and remove the risk of water contamination.

Q. Do waste spills occur when earthen manure storage lagoons collapse, equipment breaks, or people make mistakes?

A. 1. Structural collapses are extremely rare occurrences in livestock lagoons. Annual or more frequent operation inspections or construction-phase inspections are required by regulation in many leading pork production states like Iowa, North Carolina and Illinois. The National Environmental Dialogue on Pork Production recommends detailed recordkeeping by manure storage structure owners, and regular, periodic inspections of structures by appropriate regulatory agencies. Many state and local regulations prohibit the location of livestock lagoons in floodplains while many municipal lagoons are sited near streams and rivers which places them at additional risk for untreated sewage discharge during heavy precipitation events.

2. In 1996, North Carolina was hit with two hurricanes and a tropical storm. As a result, 68% of the municipal waste treatment systems in the state malfunctioned. Specifically, 122 systems reported the emergency discharge of 270 million gallons of raw sewage. Another 87 reported discharges of “unknown amounts.” In contrast, only 22 swine manure lagoons, less than 1%, experienced some sort of discharge.

3. In 1995, the Iowa Department of Natural Resources reported 5 fish kills related to swine manure. In 1997, the DNR reported 6. In the words of the IDNR, “there is increasing interest in this issue, (but) we do not necessarily think the number of fish kills is increasing.”

4. In 1995, the Iowa Department of Natural Resources reported 14 enforcement actions against all livestock operations. In 1996, 13 were reported. This equates to about 1 violation for every 8,000 livestock enterprises in the state.

5. Of the 10,140 miles of Iowa rivers and streams assessed by the Iowa Department of Natural Resources, only 3 percent were classified as not supporting designated uses because of pollution. For lakes, a water quality evaluation showed 91-percent of the 115 significant publicly owned lakes were either stable or improving. Only 9-percent were degrading.

6. The largest livestock spill in 1995 in North Carolina totaled approximately 25 million gallons. Municipal lagoons in the state spilled 10 times that much raw human sewage the following year.

Q. Are population equivalents, like a 2.5 million head per year swine operation having potential waste output greater than the city of Los Angeles, accurate?

A. 1. Population equivalents are sometimes used to characterize the potential for animal production systems to create water pollution problems. This is incorrect since modern manure handling systems are designed, operated and required to prevent discharge into water bodies. A concentrated pork production operation of this size is subject to Clean Water Act requirements that all manure be contained at the site in a manner that does not contaminate surface or ground water. Additionally, any manure which is land applied from such a site must be applied in a manner that does not contaminate surface or groundwater.

2. City waste treatment facilities are typically permitted to discharge millions of gallons of nutrient laden effluent streams or other surface waters which contributes to contamination of the surface water and wastes the nutrient resources. Only about 20 percent of all municipal byproducts and residues are recycled.

A 2.5 million head pork operation can provide enough nitrogen fertilizer for 335,000 acres of corn, in addition to providing enough pork for more than five million people. Nationwide, the value of swine manure as fertilizer is estimated at $2.50 to $3.50 per market hog sold. There are more than 15,000 publicly owned waste water treatment facilities processing more than 31 billion gallons of waste water each day. They discharge 3.2 billion pounds of nitrogen directly into surface water each year. This does not count discharges of raw sewage which frequently occur during times of heavy rain or equipment malfunction. EPA does not record these by-pass conditions.

3. Here’s how humans and pigs compare when they are compared on an equivalent pollutant mass loading basis for nitrogen, phosphorus and BOD (biological oxygen demand). A 3,600 head pig finishing operation is equivalent to 270 people for BOD, 1,580 people for nitrogen and 2,150 people for phosphorus.

4. The United States has approximately 330 million acres of cropland and 650 million acres of pasture and rangeland. This provides an ample base for land application of livestock manure. In only a limited number of counties nationwide does the supply of animal manure greatly exceed the cropland (not including forages, pasture and rangeland) available for manure use.


Q. Does manure pollute drinking and surface water with nitrates, parasites, bacteria and viruses?

A. 1. The most common cause of bacterial problems in drinking water wells is well deterioration. Many people use old wells; some were poorly constructed to begin with. In others, age has taken its toll, resulting in loose or missing caps, corroded or cracked casings, and other defects.

2. Available epidemiological data do not suggest any increase in the incidence of diseases caused by waterborne human pathogens such as Salmonella or Leptospira as a result of increased swine production in North Carolina. From 1989 to 1995, the hog population increased from 2.7 million to 7 million in the state, but the annual incidence of reported Salmonella infections remained unchanged. Most cases occur in populous, urban counties. Also, modern swine management practices in North Carolina appear to have virtually eliminated swine infection by toxoplasmosis.

3. An evaluation of 29 polluted wells in Sampson County, North Carolina (the second largest pork production county in the U.S.) was conducted using isotope analysis developed by North Carolina State University. The analysis can determine differences between industrial, human or animal waste. The isotope analysis showed two-thirds of the 29 wells were contaminated with synthetic fertilizer. The rest had more than one source of contamination, including septic pollution and organic nitrogen. Animal waste was a minor influence in only two wells.

4. Manure stored in the anaerobic condition, which is associated with many concentrated animal feeding operations, does not contain nitrates.

5. Because of cropping schedules, weather and the need to avoid soil compaction, most land application of manure slurry takes place in the fall of the year. However, seasonal nitrate levels in Midwestern streams typically peak in spring as a result of the soil mineralization process which generates nitrate nitrogen and the fact that precipitation is higher in the spring. Several states mandate training and certification for pork producers and employees who apply manure fertilizer, but not manufactured fertilizer.

6. Phosphorus concentrations exceed stream limits recommended by the EPA in 75 percent of urban streams sampled but only 25 percent of agricultural streams sampled.

7. Concentrated swine feeding operations are required to completely contain all manure at the production site to prevent movement of nutrients and pathogens to surface or groundwater. Producers are also required to land apply manure in a manner that prevents contamination of surface or groundwater.

8. EPA defines a toxic substance as a chemical or mixture that may pose an unreasonable risk of injury to human health or the environment. Hazardous substances include those that present a threat because they are characteristically toxic, corrosive or chemically reactive. By definition, hog manure is neither toxic nor hazardous.

9. Elements in hog manure do not present a public health risk because all compounds occur naturally and none are released to the environment at concentrations detrimental to air quality.

10. The occurrence of toxic forms of Pfiesteria is a complex process. Blooms in these dinoflagellate populations are responsible for the occurrence of “red tides” in coastal areas which are triggered by a combination of environmental factors, all of which must occur simultaneously. The factors include: 1) The presence of a large school of feeding fish. Large schools of feeding fish produce fresh excrement, which appears to be the stimulus for transformation of the dinoflagellate into toxic forms. 2) A nutrient-enriched body of water with elevated levels of nitrogen and phosphorus. 3) Moderate salinity. These organisms are only known to exist in estuaries, where fresh and salt water mix, generally at the mouth of a freshwater river that empties into a marine environment. While nationwide, pork production accounts for only 12-15% of all animal manure, the pork industry has taken the lead in developing manure management education programs and in seeking the development of science-based regulations to protect the environment.

11. The public is not at risk from any zoonotic diseases which are communicable among animals, particularly swine, and humans. Properly handled, stored and applied manure will not jeopardize the integrity of surface water. For concentrated pork operations, the discharge of manure into lakes, streams or other surface water bodies is strictly prohibited.

Q. Do inadequate waste management practices lead to water pollution?

A. 1. In some major pork production states, up to 80 percent of manure slurry from concentrated pork production operations is now injected directly into the soil at the root zone. This practice preserves the valuable crop nutrients in manure, virtually eliminates odor and runoff potential and places the nutrients where crops can use them. Hog manure is very valuable in restoring soil productivity and will bring soil back to a higher level of productivity than it had before because of the organic nutrient content.

2. A significant potential source of nutrients in ground and surface water is the use of private septic systems. It’s estimated 66 million Americans rely on septic systems for waste treatment producing up to 45 gallons per person per day of waste water. Septic effluent is typically deposited in trenches 18 to 24 inches below the surface, well below the root zone of most crops.

3. On a per acre basis, a septic system’s output can equate to application of total nitrogen of more than 700 pounds per acre, more than four times the amount typically applied from swine manure for corn production at 150 bushels per acre.

4. Urban land use activities can increase the risk of groundwater contamination, even when agricultural sources of nitrogen are lacking. Groundwater nitrate concentration is high (median of 8.9 mg/L) in heavily populated areas like Long Island, New York, even though nitrogen loadings from commercial fertilizer, manure and atmospheric sources are low according to the U.S. Geologic Survey. Septic systems and cesspools have been a major source of nitrate in groundwater for years. Public supply wells in Nassau County were abandoned almost fifty years ago because of nitrate contamination. Residential fertilizer contributed the equivalent of 182 pounds of nitrogen per acre in that urban county according to USGS, enough nitrogen to raise more than 150 bushels of corn to the acre.

5. U.S. Geologic Survey studies indicates nitrate levels in groundwater samples in the Northeastern United States increase significantly as population increases.

Q. Who can I contact if I have a problem or questions?

A. You can contact the following people with problems or questions:

Director, Environmental Programs – Allan Stokes

Responsible for the administration, communication and implementation of National Pork Board’s environmental programs including environmental research.

Producer Service Center