Like all animals, hogs generate manure. How we handle and treat that manure—and protect nearby water sources from runoff—is a critical element of the extensive environmental management systems we employ at our farms. We’re proud of the manure management programs at our hog production IOCs, which we believe are among the best of any U.S. farming operations. Below are answers to some of the most frequently asked questions about the process.
Q: How much manure does a typical hog produce?
A: The average market hog produces between 300 to 350 gallons of manure during its lifetime. That number includes the water used to clean animal pens. The manure and the water move through slatted floors into containment structures below. (By comparison, the average adult in the United States generates 14,600 gallons of wastewater—including water for showers, washing clothes and dishes, and other cleaning—a year.)
Q: Do pigs wallow in their own manure?
A: This is a common misconception. In modern farms, slatted floors and routine flushing keep animal pens clean, and the barns are maintained by farm employees.
Q: Where does the hog manure go?
A: The manure goes into several types of treatment systems that vary depending on several factors, including the location and type of the farm. The majority of Murphy–Brown’s farms use anaerobic treatment lagoons, which have been designed and certified by professional engineers to treat and store the manure. Although the surfaces of the lagoons are exposed to the air, they are anaerobic below the liquid surface. Lagoon sizes vary depending on the animal production on the farm. These lagoons allow the solids and the associated nutrients in the manure to break down naturally over a period of six to 12 months. Think of the lagoons as a “stomach” for our farms, where naturally occurring anaerobic organisms digest the materials. With this treatment system, we achieve up to 95 percent reductions in volatile solids and 85 percent reductions in biological oxygen demand (a common measure of the amount of oxygen necessary for bacteria to break down organic material in water). What remains is an anaerobically digested, low-solids effluent product that is highly suitable for use as an organic fertilizer and is applied for that purpose. Learn more about our treatment systems and the crops produced on our farms (PDF).
Q: How do Murphy–Brown and its subsidiaries manage these treatment facilities?
A: Our Environmental Management System requires daily checks on the status of all lagoons, weekly inspections, and regular internal audits. The results of all these efforts are recorded, and we make sure that each farm has enough land available to utilize the manure to grow a variety of crops. Our technical specialist staff prepare detailed and comprehensive nutrient management plans that specify the land area needed and types of crops to be grown.
Q: Are the treatment systems regulated?
A: The Federal Clean Water Act prohibits hog farms and other livestock operations from discharging manure or any wastewater to "waters of the state" at any time. All our treatment systems and those on contract farms required sign-off by state and federal regulators when they were built. In addition, all our farms are regulated by state and/or federal water quality permits. These permits not only make comprehensive nutrient management plans enforceable under law, but also require that we keep extensive records demonstrating compliance. Government inspectors visit our farms regularly (up to twice per year) to ensure compliance. Our internal requirements go well beyond regulatory compliance and record keeping; all of our farms are certified to ISO 14001 standards.
Q: Are there other location-specific regulations?
A: Yes. Local, state, and federal setback requirements ensure that hog farms are located in areas that minimize impacts to neighbors as well as risks to local water sources. Setbacks vary, but examples include requiring farms to locate lagoons no less than 2,500 feet from schools, hospitals, parks, and other public spaces; or 500 feet from any public water supply well.
Q: Are the anaerobic lagoons the best system available?
A: They are for certain locations and climates but not in all places. We utilize a variety of manure management technologies depending on regulatory requirements and regional climatic conditions. Our companies have invested millions of dollars over the past 15 years to evaluate different manure management technologies and will continue to monitor emerging technologies. A few years ago, we sponsored research at North Carolina State University that analyzed 18 different treatment technologies; the researchers concluded—and we agreed—that anaerobic lagoons are the best technology for Murphy-Brown’s existing North Carolina farms today.
Q: What other types of systems do Murphy–Brown and its subsidiaries use?
A: Lagoons aren’t feasible in colder climates, so, in these locations, farms use slurry store systems to maximize the nutrient content of the manure. The manure is stored in tanks or in-ground concrete pits for eventual application to crops as a slurry.
Q: Is there any data to show whether treatment lagoons pose risks to the environment?
A: As part of a legal settlement in North Carolina a few years ago, we agreed to a risk ranking of Murphy–Brown farms for any threats to public health and/or the environment. An independent, third-party engineering firm is in the process of evaluating the farms. While the evaluation is not yet complete, early indications show that the risks from the treatment lagoons are very low.
Q: How do Murphy–Brown and its subsidiaries ensure that manure applied to fields won’t wash away with the rain?
A: Murphy–Brown and its subsidiaries apply the fertilizer at controlled application rates and only at times when ponding and/or runoff will not occur, and detailed records of all applications are kept and inspected by state regulators. Employees must inspect the fields before, during, and after manure application to make sure that no runoff occurs. In North Carolina, for example, operators carry pagers that alert them to developing weather events and are required to shut down land application when developing weather systems are within 30 minutes of the farm. This precipitation alert system has been used in North Carolina for the past three years and may be expanded to other areas.
Q: Is it better for the environment to raise hogs outdoors?
A: While some outdoor systems disperse manure across large areas, many outdoor animal producers have little or no containment to control manure runoff during rainstorms and have animals located near creeks. In addition, untreated manure is deposited on the ground all year long. Modern production systems have storage systems so that manure does not need to be applied during rainstorms or in seasons when crops are not growing.
