Symposium on Composting Mortalities and Slaughterhouse Residuals
May 24-25, 2005
Sheraton South Portland Hotel
Maine Department of Agriculture
Maine Department of Environmental Protection
University of Maine Cooperative Extension
Maine State Planning Office
Maine Department of Transportation
Maine Compost School
Maine Inland Fisheries & Wildlife
BioCycle, Journal of Composting & Organics Recycling
Cornell Waste Management Institute
U.S. Environmental Protection Agency
Conference proceedings prepared by:
University of Maine Cooperative Extension Knox-Lincoln County office
377 Manktown Road Waldoboro, Maine 04572-5815
Mark Hutchinson, Extension Educator: firstname.lastname@example.org
Jeanne S. Pipicello, Administrative Assistant: email@example.com
Plenary Session: Introductions and Keynote Address Are We There Yet?
Status of Mortality and Slaughterhouse Residuals Composting
Nora Goldstein, Executive Editor, BioCycle, Journal of Composting and Organics Recycling (presenter), 419 State Ave., Emmaus, PA 18049, ph. 610.967.4135, ext. 26; fax 610.967.1345, e-mail: firstname.lastname@example.org, http://www.biocycle.net
Robert Rynk, Environmental & Agricultural Engineering Consultant
Composting livestock mortalities has been practiced on farms for a number of years. Recently, however, the practice has received more attention as other management options for animal mortalities — rendering in particular — have become more costly and subject to end product market difficulties due to concern over “Mad Cow” disease. This situation has made composting a leading option for management of livestock mortalities and slaughterhouse residuals. Concurrent with the increased use of composting on farms is application of the practice to wildlife road kill. Composting methods developed for mortalities and slaughterhouse residuals, and used for wildlife, appear to be effective, both in terms of processing capabilities and cost-efficiencies. This talk will review the evolution of composting methods utilized, provide highlights of research findings, and discuss constraints, caveats and questions that remain to be answered.
Biosecurity/Diseases – Session Chair: Mark Hutchinson
Discoveries of Prion Degradation and a Safe Prion Surrogate Protein
Jason C.H. Shih
Department of Poultry Science
North Carolina State University
Raleigh, NC 27695-7608
Telephone: 919-515-5521; E-mail: Jason_shih@ncsu.edu
A bio-process called thermophilic anaerobic digestion (TAnD) was developed at NC State University for the treatment of poultry waste and production of biogas energy. During the operation, feathers mixed in the waste were completely degraded. This observation prompted a series of studies of feather degradation. A feather-degrading bacterium, the enzyme keratinase that hydrolyzes feather keratin and the gene that encodes keratinase were isolated. Genetic modification enabled the bacterium to over express keratinase and scale-up fermentation made the production of the enzyme in large quantities possible. Transmissible spongiform encephalopathies (TSE), including bovine spongiform encephalopathy (BSE), sheep scrapie, deer chronic waste disease (CWD) and human Cruesfeldt-Jakob disease (CJD) are caused by prions, made of very stable protein resistant to standard sterilizing processes and common proteases. Because of the structural similarity between prion protein and feather keratin, the keratinase was tested for its activity on prion degradation. Resulted from the collaboration with CIDC-Lelystad in the Netherlands, it was found that BSE and scrapie prions were indeed degradable by the enzyme to the undetectable level. This discovery indicated that the keratinase and other similar enzymes may be developed into a new enzymatic process that degrades prions and prevents TSE. To test and optimize the enzymatic process, a prion surrogate protein (PSP) as a safe bio-marker has been developed. PSP, genetically modified from yeast Sup35NM, has been cloned and over expressed in E. coli. Physical-chemically it behaves like prion protein, yet it is non-pathogenic and safe for laboratory and field tests. The combination of keratinase and PSP are believed to be a useful toolbox for prion degradation and TSE prevention. Keratinaseenhanced composting, monitored with PSP, could be an answer to the handling of contaminated animal mortalities. (Grants supported from FDA and JIFSAN)
Lessons Learned from Avian Influenza Outbreaks in Virginia 1984 – 2005
Eric S. Bendfeldt1, Robert W. Peer2, and Gary A. Flory3
Early developments in commercial hatchery technology, artificial incubation and brooding, marketing, diagnostic testing, and key infrastructure improvements from 1900 to 1950 contributed to the growth and present prominence of the poultry industry in the Shenandoah Valley and its importance in the agricultural economy of Virginia. In 2003, Virginia ranked 5th, 9th, and 31st in the nation for commercial turkey, broiler, and egg production. The value of Virginia’s turkey, broiler, and egg production was $692 million. The expansion and density of poultry production in the Shenandoah Valley has posed challenges to the industry and regulatory officials in the control of contagious diseases like avian influenza (AI). Poultry diseases were noticed, tested, and reported as early as 1928. The avian influenza outbreaks of 1984 and 2002 were particularly challenging and problematic due to the magnitude and urgency of the epidemic and carcass disposal issues. Many lessons were learned as a result of these outbreaks and the experience of trying to dispose of poultry carcasses through on-site burial, burial in sanitary landfills, incineration, rendering, and Ag-Bag composting. Each outbreak was certainly unique and offered many environmental and economic challenges. Virginia regulatory officials, as a result of these experiences, have encouraged the poultry industry to consider sanitary landfills and in-house or on-farm composting as rapid response tools of disposal and disease containment, particularly with low pathogenic avian diseases.
In 1984, an avian influenza outbreak cost Virginia poultry farmers and industry $40 million and resulted in the disposal of 5,700 tons of poultry carcass material. Approximately 88% of the material was disposed of on-site in burial trenches and the remaining 655 tons of carcass were disposed of in a local sanitary landfill (McClaskey, 2004). The cost of on-site burial and landfill was $25 per ton or $142,000. Neighbor concerns about contaminated groundwater from these sites and the discovery, during the excavation of a school building site in the late 1990s, of relatively intact carcasses affected future decisions of disposal actions. Eighteen years later, the poultry industry in the central Shenandoah Valley was affected by an even larger avian influenza outbreak. At the time of the outbreak in 2002, more than 56 million commercial turkey and chickens were being grown on over 1,000 poultry farms. On March 12, low pathogenic avian influenza was confirmed in a turkey breeder flock near Penn Laird, Virginia. One month later, more than 60 flocks tested positive. A total of 197 farms were infected with the virus and 4.7 million birds were destroyed to eradicate the virus. Turkeys accounted for 78% of the positive farms and bird losses (DEQ, 2002).
On-site burial was used for the first flock and assumed to be an acceptable method of disposal. However, several complaints about on-site burial and possible well contamination were raised by adjoining landowners. State authorities developed stricter criteria for on-site burial such as public disclosure of sites on deed records, a compacted clay layer, the burial of less birds and use of more cover, and the installation of monitoring wells in response to these concerns. As the disease progressed, many alternative disposal methods were researched, but five options were actually implemented: burial in sanitary landfills, controlled slaughter, incineration and air curtain destructors, in-house and Ag-Bag composting. Rendering was not used as a disposal method because of biosecurity risks associated with central collection sites and possible disease transmission.
Approximately 13,100 tons of infected poultry were landfilled. Two large landfills located over 160 miles from Harrisonburg accepted 7,900 tons, but transportation was expensive and problematic because of distance and a lack of enough trucks (Senne, Holt, and Akey, 2004). Tipping fees for landfilling the carcasses ranged from $45 to 89 per ton. With euthanasia, truck loading, and tipping fees, the actual disposal cost was $145 per ton. In 2004, a long-term contract was negotiated with two mega-landfills to accept carcasses at a cost of $75 per ton.
Table 1 Disposal Methods for Avian Influenza Infected Poultry and Quantity Disposed of by Method in 2002.
|Method of Disposal||Number of Birds||Percent of Total|
|Composting (Ag-Bag & In-house)||43,000||0.9|
Composting was implemented as a disposal technology for two flocks during the outbreak with limited supervision and success. In-house composting has not been considered a viable option by the industry because of this experience, the potential loss of production space and the perception that composting would not work on larger birds. Successful in-house composting of 5-pound broilers on the Delmarva Peninsula in 2004 proved the effectiveness of composting as a method of disposal and containment for an AI outbreak (Malone, 2004a; Malone et al., 2004b). Avian influenza was confined to 3 farms despite the high density of poultry farms in the area. In-house composting appears to be the most acceptable method of disposal because it limits the risks of groundwater and air pollution, high fuel costs, potential for farm-to-farm disease transmission, transportation costs, and tipping fees (Tablante et al., 2002).
State environmental officials and poultry industry personnel learned a number of important lessons from their experiences with the AI outbreaks in the Shenandoah Valley. The most significant was the value of a current prevention and rapid response plan. In the 18-years between the 1984 and 2002 AI outbreaks, there was a significant shift in accepted environmental practices which made the preferred disposal method from the 1984 outbreak unacceptable in 2002. Since the 2002 outbreak, the poultry industry has worked to develop a thorough plan for prevention and rapid response for future challenges and meets regularly to ensure that the plan is current. In the fall of 2004, Virginia Cooperative Extension, Virginia Department of Agriculture and Consumer Services, Virginia Department of Environmental Quality, Virginia Poultry Federation, Virginia Poultry Disease Task Force and the poultry industry initiated a research and demonstration project to evaluate the effectiveness of in-house composting of turkeys as another means of disposing of catastrophic losses and disease containment.
Other lessons learned by method:
- With proper biosecurity, transportation to and disposal at commercial sanitary landfills can be an effective disposal method.
- Disposal at smaller county or regional landfills poses many logistical difficulties and would not be recommended in most cases.
- Successful landfill disposal requires significant resources: track-hoe or similar heavy equipment, adequate lighting for operating after normal working hours, cleaning and disinfecting crews and equipment, double lining of transport vehicles to assist in the offloading of carcasses, stabilizing material for working in wet conditions, and an adequate communication system between the affected farm and the landfill.
- Transport trucks need hydraulics “wet lines” to operate dump trailers.
- Safety concerns need to be adequately addressed during the offloading of transport trailers.
- Litter and feed still need to be disposed of after the carcasses are removed from the houses – in 2002 over 5000 tons needed a $10/ton USDA incentive paid to recipients of this material because of the “stigma” of coming from an AI infected farm.
- Controlled Slaughter
- Impact on export and domestic markets needs to be addressed.
- Communication, biosecurity and pre-planning are critical for large-scale controlled slaughter.
- Contracting agencies need tight oversight of wood procurement, (quality and quantity), scheduling, and proper loading of the incinerator.
- A 3-sided portable metal loading platform, such as used for unloading biosolids, could be used to prevent runoff from stockpiled carcasses.
- Provisions need to be made for either recycling or disposing of large quantities of ash (6000 tons were generated in 2002 – approx.3 tons ash/ 1 ton carcass).
- On-Site Burial
- Public is more aware and concerned about environmental issues than they were in the 1984 outbreak.
- Groundwater contamination concerns need to be adequately addressed.
- New solid waste permitting requirements need to be followed.
- Ag-Bag Composting
- Specialized equipment requires permits for transportation and is difficult to move from site to site.
- Coordination is required to provide the necessary equipment, supplies and personnel.
- Many sites do not have the level ground required for the Ag-Bag’s use.
- Moisture content should be managed to prevent excessive moisture in the finished bags.
- Uniform mixing of the carcasses and the carbon source before loading the Ag-Bag is critical (and difficult to achieve).
- In-House Composting
- Compost piles need to be effectively constructed and managed to be effective.
- In-house composting can be accomplished within 4-weeks at which time the compost can be moved out of the poultry house for land application or further composting.
- In-house composting can be a cost effective and biosecure method disposal of carcasses.
- All of the litter and feed is managed with the carcasses.
- The volume of material is reduced in half.
The two major avian influenza outbreaks that affected the Virginia poultry industry in 1984 and 2002 presented unique environmental, economic, and policy challenges. The poultry industry has worked to develop a thorough prevention and rapid response plan for low pathogenic AI and meets regularly to ensure that the plan is current. The lessons learned will help industry, producers, and government agencies respond quickly and effectively to future diseases.
1 Extension Agent, Environmental Sciences, Virginia Cooperative Extension, 965 Pleasant Valley Road, Harrisonburg, Virginia 22801-0963 Phone: (540) 564-3080 Fax: (540) 564-3093 Email: email@example.com
2 Agricultural Program Coordinator, Virginia Department of Environmental Quality, Valley Regional Office, P.O. Box 3000, Harrisonburg, Virginia 22801 Phone: (540) 574-7866 Fax: (540) 574-7844 Email: firstname.lastname@example.org
3 Agricultural and Water Quality Assessment Manager, Virginia Department of Environmental Quality, Valley Regional Office, P.O. Box 3000, Harrisonburg, Virginia 22801 Phone: (540) 574-7866 Fax: (540) 574-7844 Email: email@example.com
Malone, G. 2004. In-house composting of avian influenza infected flocks. Proceedings 2004 Virginia Poultry Health & Management Seminar. Roanoke, VA. pp. 23-24.
Malone, G., S. Cloud, R. Alphin, L. Carr and N. Tablante. 2004. Delmarva in-house carcass composting experiences. Proceedings 2004 National Meeting on Poultry Health and Processing. Ocean City, MD. pp. 27-29.
McClaskey, J. 2004. Economic and Cost Considerations. Ch. 9 In: Carcass Disposal: A comprehensive review. National Agricultural Biosecurity Center Consortium
Senne, D.A., T.J. Holt, and B.L. Akey.2004. An overview of the 2002 outbreak of low-pathogenic H7N2 avian influenza in Virginia, West Virginia, and North Carolina. (Available on-line at http://library.wur.nl/frontis/avian_influenza/06_senne.pdf ) (Verified 27 April 2005).
Swayne, D.E., and B.L. Akey, 2004. Avian influenza control strategies in the United States of America. pp. 113-130. In: G. Koch (ed.) Proc. of the Wageningen Frontis International Workshop on Avian Influenza Prevention and Control. Wageningen. The Netherlands: Kluwer Academic Publishers. (Available on-line at http://library.wur.nl/frontis/avian_influenza/13_swayne.pdf.) (Verified 17 March 2005).
Tablante, N.L., L.E. Carr, G.W. Malone, P.H. Patterson, F.N. Hegngi, G. Felton, and N. Zimmerman. 2002. Guidelines for In-house Composting of Catastrophic Poultry Mortalities. Maryland Cooperative Extension Fact Sheet 801.
Virginia Department of Environmental Quality. 2002. Avian Influenza Outbreak Summary. VA. Dep. Env. of Qual. Harrisonburg, Virginia.
Foot and Mouth Disease, Equine Infectious Anemia: Biosecurity Considerations and Response Strategies
Submitted by: Don Hoenig, MDAFRR, 28 State House Station, Augusta, ME 04333, phone: (207) 287-7610, email: Donald.E.Hoenig@maine.gov
In this talk, I’ll be focusing on disposal of large numbers of animal carcasses in an emergency disease outbreak, drawing on experience in the UK in 2001 and also on our own avian influenza experience here in Maine in 2002.
Wildlife and Road Kill Issues – Session Chair: Jean Bonhotal
Assessing Pathogens in Road Kill
Jean Bonhotal, Ellen Harrison
Cornell Waste Management Institute
Dept of Crop & Soil Science
101 Rice Hall Ithaca, NY14853
Over 25,000 dead deer and numerous carcasses of other animals such as raccoons, coyote and fox are managed annually by NYSDOT. DOT maintains and operates a 15,656 mile highway system of interstates, expressways and collectors which comprises about 15 percent of NYS’s total of 111,000 miles of highway. The 25,000 dead deer managed annually by NYSDOT do not account for deer killed on county and local roads that must be managed by local highway departments.
Disposal options for these carcasses are limited and appropriate disposal is expensive. Carcasses are often left by the road or dumped into low areas. These methods are becoming less acceptable as rural areas become more populated and there is increased concern for environmental quality. Water quality can become compromised when animals decompose on or below ground. Current NYSDOT practices include contracting with service providers to pick up and dispose of the animals. This is becoming costly and inefficient and service providers do not always have a legal and environmentally sound plan for disposal. Contractors are paid between $30 and $80 per deer for pick-up and disposal (Rick McKeon, personal communication, NYSDOT) and in FY’s 20002002 this totaled just over $1.1 million. Landfills generally will not take carcasses and when they do it tends to be restricted, so the NYSDOT is left with limited and/or costly disposal options.
Over the past several years, the Cornell Waste Management Institute (CWMI) has worked with dairy farms to manage mortalities through on-site static pile composting. Workshops and demonstrations held at these sites have generated substantial interest in the process. The NYS Department of Environmental Conservation (NYSDEC), local and regional Departments of Health, Soil and Water committees and Natural Resources Conservation Service (NRCS) staff have attended workshops and become familiar with the process. Regional and local DOT personnel have attended workshops and indicated interest in trying composting to manage road-killed deer. In response, composting of road-killed deer is being piloted under CWMI guidance at several DOT facilities in NYS where it seems to be working well. These piles are easy to manage, do not generate odors, and the carcasses are transformed into compost. However, questions remain about the hygienic quality of the process and product as well as about worker health.
Passively aerated static pile composting is proving to be a good method of managing these wastes. It is simple, takes less time than dragging a carcass out back, uses equipment and materials used in daily operations and is cost effective. This method helps protect ground and surface water by keeping the carcasses out of contact with water and by reducing pathogens in properly managed piles and it reduces nuisance and odors.
The effectiveness of inactivating pathogens through composting is generally assessed by monitoring the reduction in indicator organisms. Salmonella and fecal coliform are the usual indicator organisms. These are the organisms that the USEPA requires for evaluation of the hygienic quality of sewage sludges. It is widely recognized that the sensitivity of different pathogenic organism to heat varies significantly and questions have been raised about the use of the current indicator organisms. Evaluation of the effectiveness of static pile composting to inactivate pathogens in road-killed carcasses requires identification of the pathogens that might be present and analysis of their sensitivity to inactivation by heating. That, combined with time/temperature data from the compost piles, will provide the information needed to assess the hygienic quality of the compost product.
Chronic Wasting Disease (CWD) is a prion disease that is of concern in wild populations. CWD has just been found in NYS, it was first found in a captive herd and with intensive sampling one wild animal (April 2005). There is no evidence to show whether CWD would be killed in the composting process. Compost temperatures are not high enough to inactivate prions, but it is possible that microbial and enzymatic activity could (Langeveld, et al; Kirill, et al.). Even if compost process does not inactivate prions, the end product (woodchips and bone) would be much more amenable to incineration than the untreated carcasses if incineration were required. Plans to manage the spread of CWD in wild deer populations are being developed up by NYS Dept of Environmental Conservation http://www.dec.state.ny.us/website/dfwr/wildlife/deer/currentcwd.html and NYS Dept of Ag and Markets (for captive herds)
Very little work has been done to assess the effectiveness of pathogen-kill in static pile mortality composting. The reduction of pathogens through composting due to elevated temperatures and microbial competition has been documented for intensively managed (frequently turned) compost piles handling other types of wastes. Even for turned piles, little information exists for carcass composts. Some research done in Ohio suggests regularly turned compost piles containing carcasses adequately kills common bacterial and viral pathogens (Keener et al).
Composting mortalities in turned piles requires more labor, machinery and management than static pile composting, thus increasing costs. It also provides the potential for release of odors if turned too early in the process. Static pile mortality composting is a more easily managed technique. By properly constructing the compost pile to allow for adequate natural aeration, mortality composting can be completed on intact animals with little or no turning. The process appears to be effective if the animals are enclosed in chunky carbonaceous material such as wood chips.
There is a need to evaluate the effectiveness of static pile composting of mortalities bulked with wood chips. Wood chips are an appropriate and easily available material for use in NYSDOT compost piles. Temperatures achieved in static pile composting suggest an adequate degree and duration of high temperatures to significantly reduce the survival of many pathogenic organisms, at least in the core of the piles. Preliminary investigations by CWMI at several piles in NYS indicate that temperatures of 140 degrees F are reached and that temperatures over 130 degrees are sustained for more than 6 weeks. However, temperature and pathogen kill in static compost piles have not been studied to the extent needed to provide confidence.
NYSDOT and local highway department staff who work with carcasses need health and safety information pertaining not only to carcass-borne pathogens, but also on tick-borne diseases such as Lyme disease, Rocky Mountain Spotted Fever, babesiosis and ehrlichisosis. Preliminary indications based on discussion with Cornell Vet College faculty indicate that ticks on deer have a relatively low infection rate at least for Lyme disease and that handling the carcasses would thus not be a major potential source of exposure. Ehrlichiosis is known primarily in the southern U.S. but has been reported in NYS and babesiosis is rare and is mainly coastal. However relevant data need to be gathered and assessed in order to develop appropriate guidance. Such guidance might address the life cycle, feeding behavior and data regarding infection coupled with advice on practices to minimize the risks of exposure and infection. This guidance would be relevant to all workers handling carcasses and not just to those engaged in composting.
An extensive study is underway to complete in depth literature searches, seed piles with indicator pathogens and provide more education on the composting process. Questions such as “What is the thermal stability/sensitivity of the pathogens that might be present in road-killed wildlife in NYS?”, “Are there worker health and safety issues?”, “When is the process finished?” and “Where can we use the finished product?” still need to be addressed.
Planning, Management of Chronic Wasting Disease Outbreaks in Wisconsin Science of a Transmissible Spongiform Encephalopathy (TSE) and Management Options for Disposal
By Joseph W. Brusca
Wisconsin Department of Natural Resources
3911 Fish Hatchery Road Madison, WI 53711
Phone (608) 275-3296
In February 2002 the Wisconsin Department of Natural Resources (WDNR) through routine sampling of wild white-tailed deer, learned that the herd in the southern portion of the state had contracted CWD. This was the first evidence of CWD infecting a free-ranging herd east of the Mississippi River. Colorado and several other western states have been involved with managing CWD infected elk and mule deer for years in both wild and captive herds. As of April 2005 CWD has been documented in free-ranging cervids in 10 states and 1 Canadian province and in captive reared cervids in 10 states and 2 Canadian provinces. TSE was well known in the devastating outbreak of Mad Cow Disease in Europe. TSE infected sheep in the form of scrapie has been common knowledge for decades. TSE also infects humans in the form of Creutzfeldt-Jakob Disease.
WDNR embarked on a very aggressive program to contain and eliminate CWD though several approaches. The first was to define the extent of CWD in the wild herd by sampling 40,000 animals of an estimated herd of 1.5 million in 2002. In addition, owners of captive herds were required to sample any animal that was killed or died on the farm. The results of that initial sampling indicated the geographic distribution of CWD was limited in the wild herd to an area of approximately 625 square miles in the southwest portion of the state. Several captive herds were also identified as having infected animals. The second strategy was to significantly reduce the concentration of wild deer in an area in what became known as the Disease Eradication Zone or DEZ to 5 deer per square mile. Deer density varies in this part of the state with the average of 40 deer per square mile.
Several teams were formed to cope with the strategy and operations of managing the disease. One of those teams was tasked with disposal of unwanted carcasses and CWD infected animals. The Initial strategy was to dispose of carcasses in an engineered landfill. Although this was the preferred alternative, it was quickly dropped from consideration in response to a flurry of media attention. Because of the persistence of prions in the natural environment, only two alternatives emerged as being acceptable to elected public officials. One was incineration and the other chemical digestion. Both of these alternatives had standing in the scientific community as acceptable treatments because the protein molecule chain was broken which has the effect of inactivating the prion. The problem faced in Wisconsin in 2002 was the throughput capacity of these alternatives would not be able to treat the large number of carcasses that were going to show up at our collection stations starting with the archery season in September. The Carcass Disposal Team developed bid proposals for handling carcasses and waste products from the fall hunt. We expected to generate waste from removal of heads for CWD sampling, butchered waste from hunters and meat processors, car killed deer and unwanted carcasses. What developed was a “frost and toast” option where carcasses were sampled and held in refer units (16 refrigerated semis) until test results allowed for sorting of positive and negative animals. This option was selected because the disease prevalence among all deer sampled in the DEZ was approximately 1.5-%. All negative animals could be landfilled. All CWD tested positive animals, butchered waste, heads and car-killed deer would be incinerated at a licensed pet crematorium. The 2002 season generated over 1.1 million pounds of waste (about 9,000 deer equivalents) at a disposal cost of $1 million.
In 2003 WDNR drafted legislation to allow for indemnification of publicly owned sewer plants and sanitary landfills that accepted DEZ harvested deer. The state legislature failed to act on the measure. The 2003 season was similar to the first with the “frost and toast” option selected as the preferred alternative with carcasses stored in refrigerated semis and sorting after test results were made available. The majority of the untested and positive tested waste went to Stericycle incinerators. A second option became available late in the fall season. The University of Wisconsin Veterinarian Diagnostic Lab (UWVDL) housed and operated a chemical digester purchased by USDA. The amount of waste handled through incineration and chemical digestion amounted to 633,000 pounds at a cost of $512,000 (including storage and sorting tested carcasses). Although the DEZ was expanded in response to the discovery of additional positive deer (1,153 square miles) the volume of waste was reduced by an increase in the number of deer retained by hunters during the 2003 deer season.
In 2004 the DEZ was expanded again to encompass additional positive deer along the Illinois border and portions of the Southeast Region of the State. A food pantry program was initiated so hunters could donate negative tested animals. The UWVDL digester took over the lion share of disposal needs with the crematorium used as backup. To date 382,000 pounds of waste were disposed of through chemical digestion and incineration. Over 200,000 pounds of venison were donated to food pantries. State contract costs for disposal and the pantry program amounted to $380,000 for the 2004 season.
CWD Waste Disposal Alternatives Analysis
Incineration is one of two scientifically accepted methods to inactivate prions. The incineration standard developed in Europe for Mad Cow Disease was complete combustion of the waste in the primary burn chamber at temperatures maintained at 1600 degree Fahrenheit with a secondary burn chamber and retention of 1 second of emissions at a similar temperature.
The second accepted method is chemical digestion. The standard for operating the digester at UWVDL is adding an equal amount of water (by weight) plus a 28% solution of potassium hydroxide to an adjusted pH of 10.5-11.5. The temperature is raised to 305 degrees F and maintained for 4 hours in the pressurized vessel. The capacity for each cycle of the digester is 4000 pounds of waste tissue. The effluent is trucked to the Madison Metropolitan Sewage District for disposal.
Composting is an effective method of volume reduction. However, the temperatures reached in compost operations are not effective in inactivating the prion resulting in a disposal problem of residual materials and remediation of the site once the facility is closed.
Rendering is another effective method of volume reduction. USDA promulgated rules that effectively removed rendering as a waste disposal alternative from a CWD designated area. The cost liability should a CWD positive animal go though the rendering process limited the industry to a dedicated plant. The cost of setting aside and operating a dedicated facility and the problem of wastewater disposal and end products eliminated this option from consideration because rendering is not consider effective in inactivating the prion. This approach was considered conservative by the industry since there has been no scientific evidence that CWD can cross over to cattle or humans.
Air Curtain Destructors were considered because of the initial low cost & throughput capacity. This option did not meet the incineration standards for maintaining temperature and there is no secondary burn chamber. The operation of ACD requires excellent control of start up and shut down procedures.
A dedicated landfill was given serious consideration. A request for proposal was sent out to design, construct and operate an engineered site with an artificial liner, leachate recirculation and lysimter monitoring system. The proposed site would have a capacity for 100,000 carcasses in a 4-phased configuration. The proposed site would be placed on state-owned property. The concept was abandoned because of time constraints and political fall out of exempting the siting process from local zoning.
Recommendations for Disposal of Waste from a CWD-Affected Area
Considering cost, worker safety issues, logistics, capacity to handle waste volumes and environmental considerations the author recommends disposal of untested waste from a CWD-affected area in a sanitary landfill. Waste sources would include carcasses, heads, butchered waste and car killed deer. Our experience in handling waste is that workers are at risk from physical injuries and pathogens from carcasses that are poor condition. The WDNR prepared a risk analysis of the fate of prion in a landfill that can be found on the following web site: http://www.dnr.state.wi.us/org/land/wildlife/Whealth/issues/Cwd/risk_analysis.pdf.
The analysis concluded that the risk associated with landfilling prions in an engineered site would pose minimal risk to spreading the prion through waste waster treatment plant’s solids spreading program. Placing the waste in the upper lifts of the fill allow for ample exchange capacity for the prion (prions are highly hydrophobic) to adhere to clay and waste particles before the prion encounters the leachate collection system. The sewer plants that treat leachate have little risk associated with prions entering the treatment system. Sewer plants that accepted landfill leachate and the concern by these plants that CWD waste would jeopardize their land spreading programs was the key issue in landfills refusing to accept CWD waste. The state of Wisconsin continues to work on indemnification legislation that would eliminate the financial risk for sewer plants and landfills that accept waste from CWD affected areas.
Relative Cost of CWD Waste Disposal Alternatives
Costs do not reflect storage, handling and transportation fees which are considerably higher for the incineration and chemical digestion options when looking at large volumes of waste. Costs are in dollars per ton.
CHEMICAL DIGESTION: $500
|Square miles in DEZ||625||1153||1634|
|Harvest for the season||9509||13694||15,600|
|No. of deer retained by hunters||4009 (42%)||10694 (78%)||12,750 (82%)|
|No. of deer disposed||5500||3000||650|
|No. of deer donated to food pantry program||0||0||2200|
|Total amount of waste generated for disposal (in tons)||688||316||307|
|Total cost of disposal contracts||$1,032,669 ($1500/ton)||$512,000 ($1620/ton)||$237,000 ($771/ton)|
|Total cost of pantry program||0||0||$143,000|
Carcass Composting –- Session Chair: Bill Seekins
Evaluation of Composting for Emergency Disposal of Cattle Mortalities in Iowa
Note: To see complete abstract, go to ABSTRACT FOLDER, CARCASS COMPOSTING FOLDER, Maine Livestock Disposal – pdf
Large Animal Mortality Carcass Composting Field Trials: 2001-2004
Maine Department of Agriculture
State House Station
28 Augusta ME
AUTHORS: B. Seekins, M.A. King, M.L. Hutchinson, N. Hallee
The Maine Department of Agriculture became aware of the outbreak of Foot and Mouth Disease (FMD) in Great Britain during the winter of 2001. The two Maine State Veterinarians and the Federal Veterinarian in Maine all spent time in England assisting with managing the crisis. Upon their returns to Maine, they reported on the devastation caused by the disease and the problems that resulted from trying to dispose of the thousands of carcasses. Their experience heightened the concerns already felt by the Department and by the Maine livestock industry about what would be done here if an outbreak occurred. A task force was established by the Commissioner of Agriculture to develop a plan of action to deal with such an emergency. One of the efforts of the task force was to evaluate the disposal options available and to develop a plan for implementing those best suited to the conditions in Maine.
The methods of disposal that were considered were:
When these options were evaluated, each was found to have a weakness, or concern.
As a result of these findings, the Maine State Soil Scientist, David Rocque suggested that the compost process should be tried using hot, active compost instead of sawdust or shavings as the compost media. The reasoning behind this suggestion was that hot compost would already have an active microbial population that was breaking down organic material. The heat and active microbes would create an environment that should be very hostile to pathogenic organisms such as the FMD virus.
The task force felt that this idea had merit and requested the assistance of the Maine Compost Team* (Compost Team) in evaluating this approach. The Compost Team was already planning to conduct animal carcass compost trials using farm based compost and so gladly accepted the charge. They determined that the most readily available source of active compost would be the large compost facilities that composted municipal waste water treatment sludges (biosolids).
* Note: The Maine Compost Team includes: Mark King, Maine Department of Environmental Protection; Bill Seekins, Maine Department of Agriculture and Mark Hutchinson, University of Maine Cooperative Extension. Neal Hallee, formerly of the University of Maine Cooperative Extension was also a member of the team at the time the trials began.
Literature on FMD virus survival suggested that the FMD virus did not survive beyond about 8 days in either liquid or solid manure if the manure was at or above 32°C (90°F). It also indicated that survival time was shortened significantly with every 2°C rise in temperature above this level. It was hypothesized that survival in a compost environment would be similar if it could be shown that the internal temperature in the carcass could be raised to this level and maintained for at least eight days.
DESCRIPTION OF PROJECTS
The Compost Team set up a demonstration/research project at Highmoor Farm, a research farm owned by the University of Maine. Several sets of trials were conducted at Highmoor and at other farm locations in the state. The first was done in the summer of 2001, trying different approaches for composting. A second trial was conducted in the winter of 20012002. This second trial focused on using the most successful of the approaches tried in the Summer Trials.
Summer Trials 2001
Four different approaches were tried during the Summer Trials. The initial trials began on June 5, 2001. Four dairy cows and two calves were used in the initial trials. These trials were set up to determine if there was any difference between just covering the carcass with active compost and completely surrounding it with compost and if placing the piles in a trench offered any benefits. The trials were set up as follows: Two were done in trenches, one with compost under and over the carcass and the second on the soil with compost as a cover.
Two others were done above ground. One used farm compost materials above and below the carcass, while the other used the municipal sludge compost above and below the carcass.
Monitoring consisted of daily visits to the site by a Compost Team member, who took and recorded temperature readings and made observations about odors, vector activity, moisture conditions and general pile appearance.
On September 6, 2001, the Compost Team dug into each of the trial piles to examine the condition of the carcasses. The amount and condition of the soft tissue was determined and the bones were examined for indications of decomposition.
General Results of 2001 Trials
Throughout the project, the piles were watched for signs of leachate escaping from the piles. No moisture was observed leaving the piles at any time. Odors at the compost site were minimal throughout the project. The odor that was detectable on site most of the time, was the relatively mild odor associated with the compost materials themselves, not the carcasses. Vector activity at the site was minimal. None of the sludge compost piles were dug into at any time during the project.
Temperatures in 2001 Trials
The temperature response within the carcasses was an important indicator, both of the suitability of each method for achieving the pathogen reduction and of the relative performance of each of the trials.
Figure 1 shows a comparison between the internal carcass temperatures for all four trials. Note that Trial 4 (carcass on a sludge compost bed laid on the turf) had the most rapid and highest temperature response of any of the trials. It quickly reached temperatures of over 140°F(65°C) and sustained temperatures over 130°F (55°C) for several weeks. Trials 2 (carcass laid on a bed of sludge compost in a trench) and 3 (carcass laid on a bed of farm based compost on the turf) had similar temperature responses, with both exceeding 120°F (52°C) for several weeks. Trial 1 (carcass laid directly on the soil in a trench) had the lowest temperature response of all the trials. The temperatures rose slower, but eventually exceeded 110°F (47°C) and maintained that temperature for several weeks. All four trials exceeded 90°F (32°C) for at least 8 days.
On September 6, Piles 1 and 2 had been in place for 13 weeks; Pile 3 had been in place 12 weeks and Pile 4 had been in place 6 weeks. At that point in time, Pile 3 had achieved the greatest degree of decomposition. Most of the soft tissue was gone and the larger bones showed signs of advanced decay. The large bones were pitted on the surface and were easily broken or sliced with a knife. Pile 1, which was the carcass laid directly on the soil, also had a layer of gooey odorous material at the bottom of the pile next to the soil. Pile 4 had a similar level of decomposition to Pile 2, even though it had been in place for only 6 weeks. (Note: Pile 3, the farm based compost, was moister than the other piles and so had better conditions for composting, even though it did not have the uniform mix and higher temperature of the sludge compost.)
Evaluation of 2001 Trials
All of the trials were successful at achieving the goal of 32°c for 8 days. Given this, any of the methods tried should be suitable for containing and reducing the survival time of the FMD virus. The trials using the bed of compost (either type) placed on the turf rather than in a trench worked better than the trials in trenches from both the point of view of temperatures achieved and rate of decomposition. In addition, odors associated with the above ground piles was less than those in the trenches. This was probably due to the greater amount of air that could infiltrate the piles.
The farm based compost laid out as a bed on the soil surface and a cover of farm based compost over the carcass would be the preferred approach for managing normal mortality. The preferred approach for managing a large number of carcasses from a disease outbreak, however, would be the use of sludge based compost as in Trial 4, where the compost is laid out as a bed on the ground surface and is used as a cover over the carcass.
Other Trials – 2001 – 2003
Following the summer trials at Highmoor Farm, the Maine Compost Team conducted a winter trial using the approach that proved to be the most successful during the summer trials. One cow carcass was composted on a bed of hot municipal sludge compost with a hot compost cover. The trial ran from December 2001 to February 2002. After exactly 10 weeks the carcass was exhumed. Almost 100% of the soft tissue was eliminated and significant deterioration of the bones was observed.
Three additional trials were conducted on other farms in Maine between 2002 and 2003. The first of these occurred on a game bird farm that had an outbreak of avian influenza. Hot sludge compost was used to break down the birds and to create an environment that would kill the AI virus. A trial was conducted on a working dairy farm as a demonstration for Farm Days. This trial showed that it was possible by using dry calf bedding to achieve temperatures over 130° F for several weeks. A third trial was conducted the following winter at a small diversified farm. In this trial, the pile was started with a frozen carcass in February. It demonstrated that even under these adverse conditions, the soft tissues could be eliminated in as little as 13 weeks.
Media Comparison Trials – 2004 – 2005
The most recent trials in Maine were again at Highmoor Farm. This was a much more ambitious project that used 8 different compost media and two types of animal carcasses. This set of trials was established to serve as a basis for developing best management practices (BMPs) for Maine farmers to use in composting mortalities on their farms. Observations were made about the environmental and nuisance impacts associated with each media material as well as the performance in terms of temperatures and rate of decomposition.
The original design called for 22 individual trials. Seven different media were to be used for composting cow carcasses and four were to be used for horse carcasses. Each combination of media and carcass type was to be done twice. As the trials progressed, the design changed slightly in response to early findings and the availability of additional media materials. These changes resulted in dropping three of the original piles and adding four others. The table below indicates the combinations of media and types of carcass used.
Table 1. Combinations of Compost Media and Carcass Type Used in 2004 Trials
|Heifer manure/bedding||X(1)||Only 1 trial due to lack of material|
|Woodchips||X(2)||Second trial included horse bedding around carcass|
|Municipal sludge compost||X(2)||X(4)||1st cow used fresh compost, 2nd used older compost|
|Leaf/manure mix||X(2)||1st cow used fresh compost, 2nd used older compost|
|Silage/bedding mix||X(2)||1st cow had 2/3 wet grass silage & 1/3 horse bedding; 2nd had 1/3 corn silage & 2/3 heifer bedding|
|Nviro Soil||X(2)||one used a woodchip base|
|Nviro Soil/Sludge Compost mix||X(1)|
Each trial was set up using the same methodology that proved most successful in the earlier trials. Each carcass was laid on an 18” bed of material and covered with 2 ft of material. (See photos #1 through 4.) All carcasses were vented prior to covering and had a 4 ft thermometer inserted into the abdomen to track internal temperatures. Thermometers were also placed in the compost media to read temperatures at the one foot and three foot depths. Temperatures were taken approximately 5 days per week throughout the summer, fall and early winter. Observations were also made of odors, animal activity, insect activity, leachate, pile structure changes and management activities. (A separate report details the findings associated with these observations.)
Temperature Observations 2004
Trials Temperature observations were made regarding peak temperatures achieved on all three thermometers in each pile, overall temperature profiles and number of days the internal carcass temperatures exceeded 130 °F. Compost media temperatures were also tracked for 1 and 3 ft depths in the piles.
Internal temperatures over 130° F
The most critical observation was felt to be the internal temperatures achieved in the carcasses themselves. Only seven of the 24 trials failed to achieve at least 130° F inside the carcass. For four of the seven, insufficient porosity in the media, either due to moisture or fine texture, was most likely responsible for not achieving 130° F. The other 3 all lacked energy due to a high C: N ratio or the compost mixture being too old. All of the trials that had sufficient porosity and relatively fresh materials, heated up sufficiently to achieve pathogen reduction, even in the core of the carcass. See Figure 2 for a break down of peak temperatures by media type. Seven of the trials actually achieved peak internal temperatures of over 140°F.
The duration of the high internal temperatures was also noted. Twelve of the trials maintained temperatures over 130° F for 10 days or more and eight sustained those temperatures for more than 20 days. These eight ‘top performers’ were:
Cow in fresh municipal sludge compost – 42 days
Cow in fresh leaf/chicken manure compost – 25 days
Cow in horse bedding – 34 days
Horse in fresh municipal sludge compost – 20 days
Cow in horse bedding – 40 days
Horse in fresh municipal sludge compost – 25 days
Foal in Nviro soil w/ woodchip base – 32 days
Cow in 1/3 silage, 2/3 horse bedding mix – 53 days
Figure #3 displays the results for all the trials.
Evaluation of 2004 Trials
In general, it appeared that the conditions achieved in the compost media made a bigger difference than the actual media itself. Some examples:
Municipal sludge compost performed very well in terms of both peak temperatures and duration of temperatures when it was relatively fresh i.e. had only been composting/curing for about 3 to 4 weeks. Older municipal sludge compost (over four months old) from the same facility did not have as much energy and so did not result in internal temperatures as high or for as long.
A spoiled silage/ bedding mix proved to be the best overall performer in all the trials while another spoiled silage/ bedding mix turned out to be one of the most disappointing performers. The one with the poor performance was mostly grass silage which was very wet and dense with very poor structure. Consequently, the air space collapsed out of the pile within a day or two, causing the pile to cool down and resulting in a number of other nuisance problems.
Two 400 lb. foals were buried in two piles of Nviro soil. (Nviro soil is a soil amendment made from municipal sludge, wood ash and lime.) One of these was the worst performer in terms of peak temperature achieved, only reaching about 102° F. The other was among the top eight performers, achieving temperatures of over 140° F and maintaining temperatures over 130° F for over a month. The difference was that the second carcass had a bed of woodchips underneath for better aeration.
One leaf/ chicken manure compost mix was among the poorest performers while another was among the top eight. The difference was that the first was a relatively new mix with a low C:N ratio that still had a lot of energy, while the second was several months old with a higher C: N ratio and no longer able to sustain the higher temperatures.
Animal carcasses can be successfully composted in a variety of media. The ability to achieve temperatures proven to kill most pathogens will depend more on the conditions in the media than on the source of the media. Those conditions that appear to be most conducive to rapid and sustained heating are:
Porosity – Piles with very fine textures or very wet materials fail to heat due to lack of oxygen. Piles with a very high porosity, such as wood chips, heat rapidly but are unable to sustain the high temperatures a long as materials with a little less air space. Textures with particles between ¼ inch and ½ inch appear to give the optimum results.
C: N ratio – As with all composting, piles with C: N ratios too high (over 40:1) tend to heat slower, in general than those with a lower C: N. One exception to this is the woodchip piles in which there is very little available carbon due to the coarse texture.
Age – Piles with materials that have been mixed and composting for several months do not have the amount of energy or activity needed to sustain the temperatures within the carcasses when compared to relatively fresh active compost piles.
Parker, J. 1971. The Veterinary Record. Presence and Inactivation or Foot and Mouth Disease Virus in Animal Feces. June. 659-662.
Photos: 2001 Carcass Compost Trials – Highmoor Farm
Pile #1 – Carcass placed in trench on soil
Pile #2 – Carcass placed in trench on bed of hot compost
Pile #3 – Carcass placed on bed of farm compost (no trench)
Pile #4 – Carcass placed on bed of hot compost (no trench)
Figure 2. PEAK TEMPERATURES FOR COW & HORSE CARCASSES IN DIFFERENT MEDIA
Figure 3. NUMBER OF DAYS OVER 130° F in COW & HORSE CARCASSES IN DIFFERENT MEDIA
Photos: 2004 Carcass Compost Trials – Highmoor Farm
New York State’s Implementation of Mortality Composting
Cornell Waste Management Institute
Dept. of Crop and Soil Sciences
101b Rice Hall
Ithaca, NY 14853
607/255-8444 (w), firstname.lastname@example.org
On-Farm Mortality — Current Situation
Until recently rendering plants have offered prompt, reasonably priced pickup of dead livestock at the farm. However, recent declines in prices of hides, tallow, meat and bone meal and the other useful commodities produced from animal carcasses have curtailed many rendering operations. In 2002, remaining plants are charging up to $70 for cows, $60 for pigs and $200 per horse to pickup animal carcasses from farms in their area. As a result, many livestock farms no longer have affordable access to rendering service.
Many livestock producers are unsure of what they should or could be doing to properly dispose of the occasional animal carcass. Brief anonymous surveys conducted in western New York and northern Pennsylvania reveal a widespread practice of improper mortality disposal. Animal carcasses left to decay naturally above ground or buried in shallow pits pose risks to surface and groundwater and endanger the health of domestic livestock, wildlife and pets. Likewise, land spreading of farm hospital pen wastes and fetal membranes may have implications for the biosecurity of the herd.
In the year 2001, there were 670,000 milk cows and 80,000 beef cows in New York State (Source: NYS Agriculture Statistic Service, www.nass.usda.gov/ny). With a typical death loss in dairy herds of two percent each year and beef herds of one-half percent per year, and a disposal cost of $30-70 per head, the state’s livestock producers could save over half a million dollars with an easily managed, low cost mortality disposal alternative.
Cornell Waste Management Institute has developed a 20 minute video, “Natural Rendering: Composting Livestock Mortality & Butcher Waste” and 10 page fact sheet and posters that are used to help teach farmers and butchers to implement these practices. Additional materials will be produced to address road kill.
Demand from farmers and butchers combined with CWMI expertise in the compost field made this program a natural fit. To date demonstration sites in 22 counties (serving 38 counties) have been set up with over 10,000 people in NY, VT and PA attending workshops 2001-05. Workshops generally consisted of presentation and pile openings in a 3-hour workshop. As workshops were set up hosts tried to ensure the local educators/ regulators were invited including NYS Dept of Environmental Conservation, Health Dept, NRCS, veterinarians, Cornell Cooperative Extension Agents and agriculture educators so they could enhance relationships and better understand the process.
Through workshops, tours and events CCE agents and others were trained to carry out local programs with technical support from CWMI. Display and demonstrations were utilized at trade shows like Empire Farm Days, fairs and conferences to raise the awareness of thousands of attendees. Newsletter, newspaper, and magazine articles will reach 16,500 producers throughout the Northeast Region. Cornell Waste Management Institute has posted the fact sheet and linked to other sites such as the Pro-Dairy web site. The “Natural Rendering”, program has received national awards from American Society of Agriculture Engineers, state and national agriculture associations and Outstanding New Extension Publication Award.
Impacts on Policy and Guidance
When composting mortality and butcher waste the process reduces odor, volume and pathogen. This is helping farms with their bio-security and has become part of CAFO plans. Research is currently on going for pathogen and use of the end product.
- NYSDEC promotes composting of mortality including road kill. They have a general mortality composting guidance in draft and they have released a report promoting road kill composting. New regulations will reflect these recent developments.
- NRCS has revised their national mortality standard. We also worked with NYS NRCS to revise (provide more detail) the compost and mortality standards to better suit NYS needs.
- NYS DOT Region 8 has written a guidance document to help their regions implement mortality composting.
Static Pile Composting Method for Mortality
The livestock and custom butcher industries need a convenient, socially and environmentally acceptable, biosecure way of disposing carcasses and butchering residuals. Landfills generally will not accept residuals or carcasses. The livestock farmer and custom butcher find themselves, in many cases, without disposal services or facing high disposal fees. Most people don’t realize that composting is a legal and acceptable way of disposing these materials. They fear that if regulators find out, they may be cited and fined. Regulators, on the other hand, fear that with the current disposal situation, farmers and butchers may cause serious problems with improper disposal. Composting can be accomplished in compliance with environmental regulations in many states, but check regulations before you start.
Composting provides an inexpensive alternative for disposal of all dead animals, butcher wastes and other biological residuals. The temperatures achieved during composting will kill or greatly reduce most pathogens, reducing the chance to spread disease. Properly composted material is environmentally safe and a valuable soil amendment for growing certain crops.
Composting animal carcasses is not new. Chickens, pigs, calves and occasional larger animals are composted. Ohio, Utah and Maryland have written resources and Maryland has a video on chicken carcass composting. Little information, however, is available to guide farmers that want to compost adult cattle or butcher residuals.
Static pile composting of dead, intact, fully-grown livestock and calves, aborted fetuses, placental membranes and butcher residuals is a practice that can fit into the management of livestock farms and butcher operations. The practice does require space on your land to construct the compost piles and takes from two to six months for the animal to decompose. Composting provides an inexpensive alternative for disposal of animal-based wastes.
- Picked up by rendering company within 48 hours after death or properly composted on the farm.
- Buried 6-ft deep in appropriate soils and buried more than 200 feet from a water body, watercourse, well or spring.
- Partially buried less than 6-ft deep or buried closer than 200 feet from a water body, watercourse, well or spring.
- Carcass is left outside for scavengers or to decay. Because of the cost of disposal, it will be tempting to dispose of carcasses by leaving them exposed in a woodlot to be scavenged. This is very risky from an environmental standpoint and that of disease transmission on your farm.
Animals showing signs of a neurological disease must be reported to authorities and disposed of in the manner they recommend. It is not clear whether prions, the agent that causes Bovine Spongiform Encephalitis (Mad Cow Disease), would be destroyed in the composting process. Animals that show signs of a neurological disease should not be composted. Animals under quarantine that die and those with anthrax, should not be composted.
Key Points of Static Pile Carcass Composting
- Select site that is well drained, at least 200 feet from water courses, sinkholes, seasonal seeps or other landscape features that indicate the area is hydrologically sensitive.
- Lay 24-inch bed of bulky, absorbent organic material containing sizeable pieces 4-6 inches long. Utility and municipal wood chips work well. Ensure the base is large enough to allow for 2-foot clearance around the carcass.
- Lay animal in the center of the bed. Lance the rumen to avoid bloating and possible explosion. Explosive release of gases can result in odor problems and it will blow the cover material off the composting carcass.
- Cover carcass with dry, high-carbon material, old silage, sawdust or dry stall bedding (some semi-solid manure will expedite the process).
- For young animals, layer mortalities with a minimum of 2 feet of carbon material between layers.
- Let sit for 4-6 months, then check to see if carcass is fully degraded.
- Reuse the composted material for another carcass compost pile, or remove large bones and land apply (see Use of Finished Product and Bones section). Site cleanliness is the most important aspect of composting; it deters scavengers, and helps control odors and keeps good neighbor relations.
Carcass and butcher residual piles should not be turned early in the process unless there are no neighbors that would be affected. Odor is a big issue most of the time. After 3 months, turning is an option and will speed the curing process.
Monitoring Compost Piles or Windrows
A log of temperature, odor, vectors (any unwanted animals), leachate (liquid that comes out of the pile), spills and other unexpected events should be kept as a record of the process. This will allow the composter to see if sufficiently high temperatures were reached and adjust the process if there is any problem. Also, odor can be an issue and compost piles are an easy target for complaints. When there is an odor problem, a compost pile may be blamed and may not be the cause.
Monitoring of the pile is done mostly by checking temperatures. Internal compost pile temperatures affect the rate of decomposition as well as the destruction of pathogenic bacteria, fungi and some seeds. The most efficient temperature range for composting is between 104ºF and 140ºF (40ºC and 60ºC). Compost pile temperatures depend on how much of the heat produced by the microorganisms is lost through aeration or surface cooling. During periods of extremely cold weather, piles may need to be larger than usual to minimize surface cooling. As decomposition slows, temperatures will gradually drop and remain within a few degrees of ambient air temperature. Temperature monitoring is crucial for managing the compost process. Thermometers with a 3-4 foot probe are available (see Thermometer Sources).
Pathogens are organisms that have the potential to cause disease. There is a wide array of pathogens found in our environment and pathogens may be elevated in compost operations. While there are currently no temperature regulations for mortality and butcher residual composting, following NYS DEC regulations currently applicable for biosolids is highly recommended to ensure adequate pathogen control and minimization in this type of composting.
If using an aerated static pile, the pile must be insulated (covered with a layer of bulking material or finished compost) and a temperature of not less than 131ºF (55ºC) must be maintained throughout the pile for at least 3 consecutive days, monitored 6-8 inches from the top of the pile.
Very little work has been done on documenting pathogen kill in composting of dead animals and butcher residual. Research at Ohio State University suggests that common bacterial and viral pathogens are killed in regularly turned compost piles containing carcasses. Static-pile composting is being recommended as a more easily managed mortality composting technique. By properly constructing the compost pile to allow for adequate natural aeration, mortality composting can be completed on intact animals without physically turning and mechanically aerating the pile. Degree and duration of temperatures achieved in static-pile composting are adequate to significantly reduce pathogen survival. Compost amendment variables, temperature and pathogen kill in static compost piles are currently being investigated.
Use of Finished Product and Bones
It is recommended to reuse finished compost as the base for the next pile. The remaining bones add structure to the base material for improved aeration. The composted material can also be used on hay, corn, winter wheat, tree plantations and forestland. Applying this compost to “table-top” crops directly consumed by people is not recommended at this time. In the future, testing and quality assurance standards may enable expanded uses or sale of the finished compost product. Nutrients in carcass and butcher residue composts are higher in N, P and K than compost containing only plant material, giving it more fertilizer value on and off farms.
When animal carcasses or butcher waste is composted, the large bones do not completely break down. Bones from immature animals degrade very quickly, but bones from mature animals take several seasons to breakdown. After the material is composted, bones can be reused as part of the base for the next compost pile. The bones that did not completely break down will add structure to the pile. Bones can be buried or disposed of in bone piles. Animal in the wild eat bones to meet calcium requirements.
When spreading the composted material, the bones can be removed and put in a hedgerow or forested land. Because they contain phosphorus and calcium, rodents will eat them; the smaller bones can be land spread and will disappear quickly. Smaller bones can be land spread, but large bones may splinter and can puncture tires. Also, avoid leaving skulls in the fields. Neighbors and the passing public may not fully understand the sight of a skull in the fields!
Economics of Mortality Disposal
Where available, the fee for pickup of dead animals ranges from $25-70/cow, $60/pig, and $200/horse. Some species are not accepted at all in rendering.
A Pennsylvania survey reports backhoe and loader rentals cost approximately $43.50 per hour. If we use one hour of labor at $10.00 per hour and about 0.6 gallons of fuel at $1.50 per gallon, the total cost for burial of a large carcass would be $54.40. Though carcass burial is permitted in New York, some states have outlawed the practice citing potential groundwater contamination. Burial at the recommended depth is also impractical in areas of shallow bedrock and when soils are deeply frozen.
The amount of carbon material (i.e., wood chips, sawdust, etc.) required to compost a full-grown cow is 12 cubic yards. Many of these materials can be used more than one time. Example: incorporating the residual bones and chips into the next season’s base material.
Presently, wood mulch is selling at about $550 per tractor trailer load, or $5.50 per cubic yard. The cost per carcass for the five cubic yard base would be $33. If we assume reuse of the composted material from other piles and a 30% loss of material during composting, the cost for the base would be $9.90 per carcass. The remainder would be used as cover on a new base of wood chips and mulch. Kiln-dried sawdust is selling for $550 per load, or $4.50 per cubic yard. If we used six cubic yards the cost would be $27. With a 30% loss of material during the process, the cost per carcass would be $8.10. The total cost of material per carcass would be $18.
If we estimate 30 minutes for preparation and covering, the cost for labor would be $5; fuel for a 100 hp tractor at 0.4 gallons or $0.60. Tractor and loader rental in the northeast as reported by Doanes is $28 per hour. The total cost for the material, equipment, fuel and labor would be $37.60 per large carcass.
As you can see, the cost of death is expensive in more ways than one.
Source: Bonhotal, J.F., Telega, S.L., and Petzen, J.S. 2002. Natural Rendering: Composting Livestock Mortality & Butcher Waste, Cornell Waste Management Institute, 12 page fact sheet and 3 posters. For the complete fact sheet and further information visit http://cwmi.css.cornell.edu
Observations of Static Pile Composting of Large Animal Carcasses Using Different Media
Submitted by: Mark A. King, Maine Department of Environmental Protection, 17 State House Station, Augusta, Maine, 04333, Mark.A.King@Maine.gov
Authors: M. A. King, B. Seekins, M.L. Hutchinson
During the summer of 2004, the Maine Compost Team, a collaborative interagency team including members from the Maine Department of Environmental Protection, Maine Department of Agriculture, and University of Maine Cooperative Extension, began a study to determine if large animal carcasses (bovine and equine) could be properly composted using a host of residuals that are commonly found on-farm and at various solid waste processing facilities.
We chose to conduct our trials at Highmoor Farm, a University of Maine owned agricultural research center located in Monmouth, Maine. Highmoor Farm operates as a “working” farm, focusing on fruit and vegetable production.
The entire site consists of 250 acres of hay fields, interspersed with various garden trials and apple orchard plots. Our study site consisted of an eight (8) acre parcel of hay field underlain by moderately well-drained soils with 0-8% slopes. The entire study area was surrounded by a dense mixture of hardwood and coniferous trees (Figure 1). This combination, soils with the ability to properly treat leachate losses and excellent visual-screening afforded by the tree buffer, gave us an opportunity to conduct our trials in a real-life situation.
A total of eight (8) separate trials, with up to four (4) variants each (two (2) horse carcasses and two (2) cow carcasses) were set up and allowed to run for a two to three month “active compost” period, without turning or disturbance. Compost piles were formed using a farm tractor and combinations of the following residuals (exact trial recipes are listed in Table 1, below): horse manure, poultry manure, leaves, sawdust shavings, wood chips, animal bedding, N-Viro© Soil, and, hot, immature municipal sludge compost. Once the pile base was formed with 18-24 inches of compost media, the carcass was added and then covered with an additional 24 to 36 inches of mixture.
Prior to final covering, the carcass abdomen was vented, in numerous areas, using a six-foot-long piece of re-bar. A four-foot thermometer was inserted into the abdomen to allow carcass temperature monitoring. Finally, the carcass was covered and two more thermometers were added to the pile at one foot and three foot depths.
|Table 1. Compost Trial Mixture Recipes|
|Trial||Pile Composition||Density (lbs./yd3)||C:N|
|C2B||Cow Manure (wet) + Horse Bedding||750||21|
|C4B||Wood Chips + Horse Bedding (core)||–||–|
|C5A||Sludge Compost (3 weeks old)||550||28|
|C5B||Sludge Compost (3 months old)||–||–|
|C6A||Hen Manure +Leaves||550||16|
|C7A||2/3 Silage + 1/3 Horse Bedding||700||18|
|C7B||1/3 Silage + 2/3 Horse Bedding||550||17|
|C8A||Sludge Compost + N-Viro© Soil||800||30|
|H5A||Sludge Compost (3 weeks old)||550||28|
|H5B||Sludge Compost (3 months old)||–||–|
Note: A “C” prefix in the trial column indicates a cow carcass trial and an “H” indicates a horse trial.
Each completed pile was sampled and tested for: bulk density (lbs. /yd3), Carbon to Nitrogen Ratio (C: N), and pile nutrients (N, P, K and Total C). Additionally, overall mixture quality was observed, focusing on pile texture and relative porosity. During the “active” compost period, temperatures were taken, on a daily basis, from the three points within each pile: one foot deep, three feet deep and within the core of the carcass itself. Finally, pile observations were made
regarding odor generation, animal (vector) scavenging activity/disturbance, and leachate generation. A field monitoring system (thermometer and rain gauge) was set up to provide data on ambient temperatures and precipitation volumes. This paper focuses on field observations noted during the course of the compost trials, including: pathogen reduction performance, odor generation, animal (vector) activity, and leachate generation.
Pathogen Reduction Performance
All but four (4) of the compost trials (N = 20) met or exceeded the EPA time and temperature standards for pathogen reduction (three consecutive days at 130° F). The trials using horse bedding (C1A, C1B, and H1B), municipal sludge compost (C5A, C5B, H5A, and H5B), one mixture combining 1/3 silage and 2/3 horse bedding (C7B), and one mixture using hen manure mixed with municipal leaves (C6A), performed exceptionally well, sustaining temperatures in excess of 130° F for greater than 17 consecutive days (range 17-53 days). Trial H1A (equine carcass in horse bedding) was the first study pile constructed, and consisted of a large draft horse. Although this pile never reached the pathogen reduction goal, it is important to note that it did manage to sustain 128° F for most of the active compost period. The trials using wood shavings (C3A, C3B, and H3A) had moderate success (averaging greater than eight consecutive days above 130° F). The remainder of the piles failed to reach target temperatures for a variety of reasons explained below.
Pile C2B (adult Holstein in 50% cow manure + 50% horse bedding) reached a maximum temperature of 116° F. This mixture had a very high bulk density (750 lbs. /yd3) which made it difficult to achieve a homogenous blend using the farm tractor bucket. As a result, this pile performed poorly due to inadequate porosity and texture, although it had a near optimal C: N ratio of 21.
Pile C6B (adult Holstein in 50% poultry manure + 50% municipal leaves) reached a high of 114° F. This pile, like C2B, was difficult to mix thoroughly (bulk density 300 lbs. /yd3), even though a manure spreader was used to enhance the mixing process. Additionally, C6B suffered due to the relative lack of “energy” afforded by the leaves and manure mixture. The municipal leaves had been stored on-site for several years, and were fairly decomposed when added to the manure, which was also about two months old. The combined mixture had a fairly high C: N of 52.
Pile H3B (adult horse in 100% wood shavings) reached a high of 111° F. This pile was formed in early August and never seemed to take-off. The final mixture had a bulk density of 250 lbs. /yd3 and a C: N ratio of 578. Although the texture and porosity allowed for ample aeration, the carcass did not provide enough nitrogen to “fuel” the compost process and overcome the high C: N ratio. Additionally, this pile was susceptible to cooling from heavy winds and drenching rain.
Pile C8A (50% N-Viro© Soil + 50% municipal sludge (three months old) achieved a peak temperature of 103° F. This mixture had a “high” bulk density (800 lbs. /yd3), a very fine texture, and poor porosity. This combination greatly inhibited self-aeration of the pile during active composting. Additionally, the relative high pH of the N-Viro© Soil (pH = 10-11) also served to inhibit microbial activity, resulting in a poor temperature response.
Odor Generation and Vector Attraction
Six of the compost trials (N = 20) experienced numerous odor releases (# >2) and animal disturbances (# > 2) during our study. This was especially true for the trials using recipes comprised entirely of wood chips or wood shavings. Additionally, the site was frequented by scavenging animals (vectors) due to a local farm dump, consisting of waste fruits and vegetables, located adjacent to our study area. The odorous piles proved to be very attractive to vectors, resulting in the need for diligent site management (Figure 2).
Pile C4A and C4B (adult Holsteins in wood chips) had the highest incidences of odor releases and animal disturbances (14 odor incidents and four (4) animal disturbances for C4A, and four (4) odor incidents and 5 animal disturbances for C4B). Both of these trials had a very low bulk densities (250 lbs. /yd3) and very coarse texture that self-aerated easily. These mixtures also had the highest C: N ratios recorded during the study (677) and very little fine textured material available to capture soluble nutrients or to provide energy for microbial activity. As a result, as the carcasses decomposed, anaerobic (odorous) gases escaped the pile unabated and proved to be irresistible to vectors. Additionally, flies and maggots were observed on numerous occasions on the surface of these piles. Our belief is that the lack of aerobically driven microbial activity in the pile, coupled with the lack of fine carbon particles (to help absorb leachate) and resultant low temperatures in the media surrounding the carcass provided an optimal environment for the maggots, allowing them to travel back and forth between the carcass and the pile surface without consequence.
Pile H1A (adult horse in horse bedding) and H3A (adult horse in wood shavings) also had numerous odor releases and animal disturbances (three (3) odor releases and five (5) animal disturbances for H1A, and six (6) odor releases and four (4) animal disturbances for H3A). Like the wood chip trials, both of these piles had relatively low bulk densities (H1A = 450 lbs. /yd3; H3A = 250 lbs. /yd3) and excellent porosity. Trial H1A, as previously noted, was the first pile constructed as part of this study. Because of the large size of the horse (lengthwise), the pile was constructed in a long rectangular shape. Initially, we believe that we had applied sufficient cover, but later found that as the animal decomposed and shifted, there was not enough cover material to maintain pile structure. Another confounding factor was venting of the animal. This carcass was punctured once in the abdomen to release trapped gasses. This proved to be insufficient, as the carcass continued to expand and contract as it released trapped gasses; resulting in further compromise of pile structure. As a result of the odor releases and lack of proper cover material, this pile was continually disturbed during the first couple weeks necessitating numerous rakings and additions of horse bedding. We finally decided to add a thicker coating of horse bedding, place snow fencing over the pile surface, and erect a snow fence around the entire pile as a “biosecurity” measure. Additionally, a scarecrow (with visual and auditory distracters) was added to help discourage on-site animal activity (Figure 3). These collective acts resulted in elimination of the vector problem.
Pile H3A experienced a somewhat different vector issue. This pile was formed in late August and almost immediately maggots were noted at the top of the pile surface. In fact, the maggots became so populous that the top of the pile literally appeared to be moving. Not long after the maggots appeared, the study site became populated with 10 to 20 wild turkeys. The turkeys, initially attracted by the adjacent dump site and an on-site hen manure stockpile, began feeding on the maggot-infested pile. Turkeys are notorious for tearing apart the ground as they forage. Pile H3A was no exception. Large portions of the pile face were torn away as the turkeys foraged for maggots (see Figure 2, above). Turkeys continued to disrupt the piles even after numerous re-coverings of the compost pile with horse bedding, and application of hot sludge compost to kill back the maggots. Therefore, we finally decided to obtain an “Animal Nuisance Control” permit from the Maine Department of Inland Fisheries and Wildlife to help discourage turkey scavenging at the study site.
The remainder of the piles had infrequent odor releases and incidental animal disturbances (animal tracks on pile surface or slight exploratory digging events). For most of these piles, surface raking and additional amendment placed over the chimney area (upper top of pile) was sufficient to suppress additional odor events and to discourage animal disturbances.
The final area of observation involved incidents of leachate generation following precipitation events. As with other factors, leachate incidents were most prevalent for the piles constructed entirely of wood chips (C4A, six (6) occurrences and C4B, eight (8) occurrences). Both of these piles exhibited pools of leachate at the base following rain events in excess of one inch. The leachate was usually pink to dark red during the first part of the active compost phase and brown to dark brown near the very end of the compost phase. The low bulk density and coarse pile structure (very few fines) of these piles, allowed precipitation to percolate down through; flushing nutrients as it exited. This continual loss of nutrients is of concern as it affects the overall quality of the finished product, as well as raising the potential for dissolved nutrients to leach to groundwater and/or enter nearby surface waters. Based on these observations, along with the odor and vector issues noted previously, we decided not to conduct additional wood chip trials using horse carcasses. The remainder of the piles experienced fewer than two (2) leachate episodes during the course of the study, and only following precipitation events in excess of two (2) inches.
The observations from this study indicate that on-site management is crucial throughout the composting event, especially during the first two weeks. Good site and carcass preparation facilitate carcass decomposition without causing nuisance odors, vector attraction issues, or generation of nutrient-rich leachate. Piles should be constructed using compost mixes with moderate bulk densities (300-550 lbs./yd.3), optimal C: N ratios (25 to 40), good texture (appropriate mix of fine and coarse particles) and optimal porosity and pile structure. Horse bedding and municipal sludge compost performed very well during our trials and are ideal for most carcass disposal situations. Carcasses must be vented in numerous locations to release trapped gasses and allow abdominal contents an opportunity to mix with compost ingredients. In many cases, carcass legs may be tied together, depending on state of “rigor mortis”, to help prevent extension out of pile as the carcass expands. Carcasses should be covered with 24 to 36 inches of cover material. This should be monitored during the first two weeks of composting, as carcasses slump, causing pile structure to collapse. Additional amendment may be needed, especially following pile collapse. Any occurrences of odors or maggots must be addressed before scavenging animals arrive. Covering with an appropriate amount of amendment will aid in reducing odor. Covering piles with hot, active compost will deter maggots. Likewise, leachate pools may also be amended and then re-incorporated into the compost piles.
In-House Composting of Turkey Mortalities as a Rapid Response to Catastrophic Losses
Eric S. Bendfeldt4, Robert W. Peer5, Gary A. Flory6, Greg K. Evanylo7, and George W. Malone8
4 Extension Agent, Environmental Sciences, Virginia Cooperative Extension, 965 Pleasant Valley Road, Harrisonburg, Virginia 22801-0963 Phone: (540) 564-3080 Fax: (540) 564-3093 Email: email@example.com
5 Agricultural Program Coordinator, Virginia Department of Environmental Quality, Valley Regional Office, P.O. Box 3000, Harrisonburg, Virginia 22801 Phone: (540) 574-7866 Fax: (540) 574-7844 Email:
6 Agricultural and Water Quality Assessment Manager, Virginia Department of Environmental Quality, Valley Regional Office, P.O. Box 3000, Harrisonburg, Virginia 22801 Phone: (540) 574-7866 Fax: (540) 574-7844 Email: firstname.lastname@example.org
7 Extension Specialist, Department of Crop and Soil Environmental Sciences, Virginia Tech, 426 Smyth Hall (0403), Blacksburg, Virginia 24061 Phone: (540) 231-9739 Fax: (540) 231-3075 Email: email@example.com
8 Extension Poultry Specialist, University of Delaware, 16684 County Seat Hwy., Georgetown, Delaware 19947 Phone: (302) 856-2585 Fax: (302) 856-1845 Email: firstname.lastname@example.org
An avian influenza (AI) outbreak in the central Shenandoah Valley of Virginia in the spring and summer of 2002 affected 197 poultry farms and had an estimated cost of $130 million to the poultry farmers and state economy. The total federal cost of avian influenza eradication in Virginia, including indemnity, was $81 million (Akey 2003; Swayne and Akey, 2004). Seventy-nine percent of the farms depopulated were turkey breeder and growout flocks. Five different methods were used to dispose of avian influenza infected poultry: on-farm burial, landfilling, incineration, slaughter, and composting (Ag-Bag and in-house). More than 3.1 of the 4.7 million birds infected or 13,000 tons were disposed of in landfills (DEQ 2002). Landfilling has been the preferred option for disposal because the infected flock can be removed from the poultry farm relatively quickly, which enables the farmer to begin cleaning and disinfecting the poultry houses. Drawbacks of landfilling include expense, transportation logistics, biosecurity risks, public perception issues, and environmental considerations. In 2002, turkey disposal costs exceeded $7.25 million with an average cost per farm of $30,175. The cost per ton with depopulation and disposal approached $145 not including the costs of additional litter handling at the farm.
Avian influenza depopulated poultry houses remained under quarantine on an average of 75 days each and for as long as 177 days (DEQ 2002). Composting was implemented as a disposal technology for two flocks during the outbreak with limited supervision and success. In-house composting has not been considered a viable option by the industry because of the potential loss of production space and the perception that composting would not work on larger birds. Successful in-house composting of 5-pound broilers on the Delmarva Peninsula in 2004 proved
the effectiveness of composting as a method of disposal and containment for an AI outbreak (Malone, 2004a; Malone et al., 2004b). Avian influenza was confined to 3 farms despite the high density of poultry farms in the area. In-house composting appears to be the most acceptable method of disposal because it limits the risks of groundwater and air pollution, high fuel costs, potential for farm-to-farm disease transmission, transportation costs, and tipping fees (Tablante et al., 2002).
The project objectives were:
- To test in-house composting as a method of disposal and disease containment for large birds (i.e., 17 to 40 pounds);
- To determine how quickly the in-house process could be completed;
- To test the effectiveness of carbon sources and rates;
- To compare the effectiveness of composting whole carcasses, shredded and tilled carcasses, and crushed carcasses;
- To demonstrate the composting process for farmers, industry and agency personnel.
The demonstration was initiated on December 2, 2004. Eight windrows (12’ wide by 6’ high), each representing a treatment, were formed. Each windrow contained 2500 to 3000 pounds of turkey carcasses weighing from 17 to 40 pounds each. An additional experiment was conducted to compare the effectiveness of crushing the carcasses versus whole birds and to determine the minimum amount of carbon material needed to prevent leakage and encourage composting at the highest possible density per square foot. The temperatures of all the windrows (i.e., at 10 and 30 inch depths) reached between 135 and 145 degrees F and maintained temperatures adequate for pathogen kill. The windrow with woodchips as the carbon source achieved the highest temperatures (Figure 1).
Carbon materials compared for their effectiveness in composting turkey carcasses included:
- Hardwood Sawdust;
- Aged, weathered woodchips with relatively high moisture;
- Built-up Litter;
- Starter litter or wood shavings from brooder house;
- Blend of starter litter and built-up litter.
The turkey carcass treatments included:
- Whole carcasses mixed and piled;
- Shredded and tilled carcasses, mixed and piled;
- Crushed carcasses mixed and piled.
The results of the research and demonstration are summarized as follows:
- After two weeks, few carcasses remained in any of the windrow treatments.
- All four carbon materials (i.e., hardwood sawdust, woodchips, built-up litter, and starter litter) were effective in composting the turkey mortalities.
- Temperatures of all the windrows (at 10 and 30 inch depths) reached 140 degrees and maintained temperatures adequate for pathogen kill.
- Woodchips reached and maintained the highest temperatures due to good porosity, varying particle size, and relatively ideal moisture content.
- The starter litter required that some water be added during the mixing process, but only enough to make the litter and mixture glisten.
- Shredding and tilling the carcasses increased the effectiveness of composting approximately 2 to 3 days by increasing the surface area to volume ratio and exposing the bones and marrow to further decomposition and releasing more moisture into the compost mix.
- Whole carcasses composted as well without tilling.
- Tilling the litter floor after depopulation to break up excessive caked or crusted litter helped to increase the composting process and prevent any seepage.
- Maintaining the base and cap on the windrow is essential to composting and preventing any carcasses from being exposed to the air which can prevent decomposition.
- An alternative to tilling and shredding the birds would be to crush the birds by running them over with a skid loader or tractor.
To determine the minimum amount of carbon material needed, an additional experiment was setup to simulate the worst case scenario (i.e., where a farmer had very little litter or carbon material available following a clean-out and was attempting to compost heavy toms (~ 35 to 40 pounds)). The treatments compared were crushed carcasses versus whole carcasses. These were mixed with a blend of starter and built-up litter to achieve a density 12.5 pounds of carcass per square foot (Table 1) above a 5 inch base layer and below a 5 inch cap.
Table 2. Average characteristics of different turkey types and population densities.*
|Bird Type||Age (weeks)||Weight (lbs.)||% Mortality||Population
|Size of House (ft2)||# of meat/ft2|
* The production goals and requirements for individual farms may vary from these averages.
The results from the experiment to determine the minimum carbon material needed for composting heavy toms are summarized as follows:
- Temperatures of 140+ degrees were achieved within 5 days for the crushed treatment and 16 days for the whole carcass treatment (Figure 2). Therefore, the poultry house could potentially become available 11 days sooner if the carcasses are initially crushed.
- With a 5 inch base layer and 5 inch cap (10” total), no seepage occurred at a density of 12.5 pounds per square foot and composting was promoted.
- Without crushing the carcasses, the whole birds tended to roll off the pile, require more labor, and take longer to begin composting.
- In the whole carcasses treatment, at least 0.8” of carbon material per pound of carcass was needed as a base and cap to adequately cover the carcass. More material, approximately 1” of carbon material per pound of carcass, was needed to promote composting.
- In the worst case scenario, where there is very little base litter (i.e., < 5”) and heavy toms in the poultry house, two tractor trailer loads of additional carbon material may be needed per house to promote composting. (In 2002, seven tractor trailer trucks were needed per house to haul carcasses off the farm to the landfill.)
A typical turkey farm affected with avian influenza in 2002 was as follows:
- 45,600 turkeys
- 22,800 – 14 week old hens, Avg. body Wt. 16 lbs.
- 22,800 – 4 week old hens, Avg. body Wt. 3 lbs.
- 352,000 pounds + 66,000 pounds = 418,000 pounds or 209 tons
- 14 Semi truck loads.
Cost estimates for in-house composting after euthanasia and depopulation:
- 2 skid loaders ~ $140 per house;
- 2 skid loader operators ~ $180 per house;
- 1 person knowledgeable of composting ~ $150 per house;
- 2 laborers ~ $120 per house for cleaning up litter and disinfecting skid loaders;
- 5 to 6 hours of operation per house including crushing the carcasses.
- 1 hour to clean and disinfect the skid loaders.
Cost estimates if no additional carbon is needed to compost the turkey carcasses:
- ~ $590 per house/ 104.5 tons of carcass per house = $5.65 per ton (if no additional carbon material is needed).
- ~ $700 for one 200’ roll of reusable compost fleece per house if a litter storage shed is not available.
Cost estimates if additional carbon is needed to compost the turkey carcasses:
- ~ $1000 per house for hardwood sawdust.
- ~ $590 per house for labor and equipment.
- 104.5 tons of carcasses per house.
- $15.22 per ton (if additional carbon material is needed).
- ~ $700 for one 200’ roll of reusable compost fleece per house.
Additional considerations for utilizing in-house composting as a disposal and disease containment method are summarized as follows:•
- Farmers and industry have expressed concern about the quality of the finished product and the presence of bones. In the research with heavy toms, only the upper part of the leg bones was visible. Other bones broke down during the compost process.
- Application of the final compost to tillable row crops like corn, small grains, and soybeans would be the preferred method of utilization.
- Applications to pasture or hay land would require a simple method of screening the bones such as through a box spreader.
- In 2002, moving the untreated litter from AI infected farms was a problem and stigma. An incentive payment of $10.00/ton of litter was needed and implemented to facilitate movement of 5000 tons of litter off farms.
- In-house composting could resolve some of these issues because composting reduces the volume of litter 40 to 60%, provides sufficient heat to deactivate most pathogens, and produces a quality final product that would not require an incentive payment to facilitate movement of the litter off farms.
Action items and potential research needed to make in-house composting the preferred option for disposal in a disease outbreak and catastrophic loss:
- Identify suitable compost sites on individual farms for final composting and curing;
- Identify and research which types of farms (i.e., broiler breeder, turkey breeder, double-deck houses) may need to compost outside of the house after euthanasia and depopulation;
- Evaluate biosecurity and farm-to-farm transmission concerns prior to bird and litter movement;
- Identify and secure several sources of carbon material (e.g., sawdust and woodchips) before an outbreak occurs. Sources might include county landfills, lumber mills, electrical power companies, tree trimming companies, and compost from wastewater treatment facilities.
- Negotiate a long term contract for at least enough carbon material to compost five average size farms in an outbreak (i.e., about 10 tractor trailer loads@100 cy./load).
- Encourage integrators to identify a site to stockpile carbon materials such as a county landfill or one of their facilities. 7) Request each integrator to designate a team or person to be trained for managing in-house composting in an outbreak and catastrophic loss.
In-house composting is an acceptable cost-effective method of disposal and disease containment. In-house composting has not been considered a viable option by the industry and farmers because of the potential loss of production space and the perception that composting would not work on turkeys. In-house composting of turkeys demonstrates that with a good base, cap, and proper disease monitoring, the compost could be turned and moved out of the poultry house within 3 to 4 weeks. This time would be comparable to the minimum down time experienced by farmers in the 2002 avian influenza outbreak. Each farm and type of flock would have to be evaluated, but with proper planning and training of farmers and industry personnel, in-house composting is an effective rapid response tool for managing catastrophic poultry losses.
Akey, B.L. 2003. Low-Pathogenecity H7N2 Avian Influenza Outbreak in Virginia during 2002. Avian Diseases 47:1099-1103.
Malone, G. 2004. In-house composting of avian influenza infected flocks. Proceedings 2004 Virginia Poultry Health & Management Seminar. Roanoke, VA. pp. 23-24.
Malone, G., S. Cloud, R. Alphin, L. Carr and N. Tablante. 2004. Delmarva in-house carcass composting experiences. Proceedings 2004 National Meeting on Poultry Health and Processing. Ocean City, MD. pp. 27-29.
Swayne, D.E., and B.L. Akey, 2004. Avian influenza control strategies in the United States of America. pp. 113-130. In: G. Koch (ed.) Proc. of the Wageningen Frontis International Workshop on Avian Influenza Prevention and Control. Wageningen. The Netherlands: Kluwer Academic Publishers. (Available on-line at http://library.wur.nl/frontis/avian_influenza/13_swayne.pdf.) (Verified 17 March 2005).
Tablante, N.L., L.E. Carr, G.W. Malone, P.H. Patterson, F.N. Hegngi, G. Felton, and N. Zimmerman. 2002. Guidelines for In-house Composting of Catastrophic Poultry Mortalities. Maryland Cooperative Extension Fact Sheet 801.
Virginia Department of Environmental Quality. 2002. Avian Influenza Outbreak Summary. VA. Dep. Env. of Qual. Harrisonburg, Virginia.
Funding for this research and demonstration project was generously provided by the Virginia Department of Agriculture and Consumer Services’ Division of Animal and Food Industry Services in cooperation with the Virginia Poultry Federation.
Composting Hog Mortalities in Nova Scotia: Environmental Impacts
L. Rogers1, R. Gordon1, A. Madani1 and G. Stratton2
1 Department of Engineering, Nova Scotia Agricultural College
2 Department of Environmental Sciences, Nova Scotia Agricultural College
A practical alternative to traditional methods of hog mortality management is practice that is best described as above ground burial with a biofilter (biopile) using composting techniques. This research is an attempt to determine the water quality impacts associated with managing hog mortalities using biopiles built on soil surfaces. A hog mortality management system was established at the Bio-Environmental Engineering Centre (BEEC) located in the AgriTECH Park (Nova Scotia Agricultural College) in Bible Hill, Nova Scotia, Canada.
Three different cover treatments (i. sawdust, ii. hog manure pack and iii. hog manure pack with tarp) over carcasses (700 through 900 kg dead-stock per surface area), replicated twice, were investigated over three trials (2001 through 2004). Leachate and surface runoff from biopiles were monitored with calibrated tipping buckets and water samples were collected during flow events and analyzed for various water quality parameters (E. coli., NO3–N, NH3-N, SRP, BOD5, etc.). The sawdust cover provided for higher temperatures and better carcass decomposition in both the primary and secondary phase compared to the other treatments. The sawdust cover had the lowest leachate and surface runoff volumes and lowest leachate and surface annual loads for SRP (0.186 and 1.18 kg ha-1yr-1), N03–N (10.5 and 4.87 kg ha-1yr-1), NH3-N (2.25 and 2.16 kg ha-1yr-1) and E. coli (8.17 x 107 and 4.19 x 108 CFU kg ha-1yr-1) compared to the other treatments. The sawdust cover end-product, however, had a lower nutrient content (3.04. to 3.42 g kg-1 N, 0.41 to 0.83 g kg-1 P and K 0.21 to 0.84 g kg-1 DM K) than the other treatments.
Final Disposition – Session Chair: Chuck Franks
BSE in Washington- Discovery, Response, and Disposal Issues
Primary Contact: Chuck Matthews (Washington State Department of Ecology, P.O. Box 47775, Olympia, WA, 98504-7775)
Kip Eagles (Washington State Department of Ecology, 15 West Yakima Avenue, Suite 200, Yakima, WA, 98902-3387)
On December 23, 2003, the U.S. Department of Agriculture (USDA) announced the first confirmed case of Bovine Spongiform Encephalopathy (BSE) in the United States. The USDA was responsible for tracking down related animals that might carry or be affected by the disease. Potentially adulterated meat and animal byproducts already in circulation also had to be traced. The discovery resulted in the destruction of a significant number of animals, rejection of U.S. beef and beef by-products by many trading partners from around the Pacific Rim and other regions, and concerns about the safety of rendered materials that may have been produced from the processing potentially contaminated animals. Many domestic consumers have also turned away from mainstream beef in favor of paying higher prices for meat from producers that have carved out a niche market of providing grain raised beef produced without growth hormones and antibiotics. There is debate as to whether this beef truly offers any real added protection against BSE specifically, but perception that this is the case by consumers appears to have solidified a place in the market for these producers.
Some countries continue to impose a total ban of U.S. beef and byproducts until all animals are tested for BSE prior to export. These bans continue to have major economic impact to the beef industry in the Pacific Northwest. The USDA and U.S. Food and Drug Administration (FDA) have imposed restrictions on what can be included in animal feed and on feed production facilities. Canada and the United States continue to wrangle over import restrictions of Canadian-born cattle and beef products into the U.S. Some estimate the economic impact on the Canadian beef industry of up to seven billion dollars. While federal officials from both countries debate whether to re-open the border to Canadian products, three additional animals have tested positive in Canada for BSE in the past year. In addition to the economic and political fallout, the announcement of a positive BSE test in the U.S. spawned a media feeding frenzy that fueled consumer distrust of the government agencies involved, accusations of a cover-up, and skepticism about the ability to guarantee the safety of U.S. beef in general. While disposal issues were responded to relatively quickly, the political and economic repercussions from the incident continues a year and a half later.
By the time the investigation was complete, about 650 animals had been destroyed and approximately 2000 tons of meat and bone meal (MBM) were identified as potentially adulterated and were prohibited into the marketplace. Responsibility for detailing disposal options for the animal carcasses and MBM fell on state officials from the Washington State Departments of Agriculture, Ecology, and Health. These efforts were conducted in cooperation with local jurisdictional health departments and landfill operators managing Subtitle D compliant
landfills in both Eastern and Western Washington. Similar efforts were made in Oregon in case the event expanded to such a scale that depopulation efforts widened into a substantial part of the Oregon herds or the needs for disposal overwhelmed capacity in Washington. After reviewing disposal options, a decision was made to landfill the carcasses and MBM. Because of concerns about the durability of prions, composting was quickly ruled out. Inadequate regional infrastructure existed to manage the materials through incineration in a timely manner. Due to the large volume of material, alkaline digestion was not a practical option at the time either. Once the decision was made to landfill suspect carcasses and MBM, state officials identified suitable landfills and issued standards and precautions that should be applied during burial.
Once the USDA concluded its investigation and identified animals and byproducts that would require isolation and disposal, state agencies were looked to for guidance on what state law allowed regarding disposal of carcasses and recalled MBM. Because of the potential regional nature of incident, state officials from both Washington and Oregon became involved in identifying suitable landfills in both states where the waste could be taken. There was a sentiment among some state officials that federal investigators could have been better served at the local level if federal official had communicated more openly about the scope of their investigation and the potential volume of material requiring disposal. State officials assumed the worst case in their initial efforts to identify landfills and get local health departments and landfill operators on board and prepared in the event their services became necessary. A list of eleven Subtitle D landfills on both sides of the Cascade Range was provided and ultimately pared down to five facilities in Washington and one in Oregon. State officials worked with operators to determine what volumes of waste could be managed at their respective facilities in order to be prepared for the worst case. One of the Washington facilities was dropped after determining it could not meet all the published guidelines issued by the Department of Ecology (Ecology). Eventually, questions about volumes were answered and all the material was disposed of at the Roosevelt Regional Landfill overlooking the Columbia River on the Washington side. This 1800 acre facility is located in Eastern Washington in a remote arid region of the state. The landfill sits atop a layer of clay and basalt. Depth to groundwater is at least 450 feet. Leachate produced is recirculated back into the landfill to promote the generation of methane which is collected and used to produce energy.
The guidelines published by Ecology were essentially for use by local jurisdictional health departments (JHD) and operators to ensure worker safety, thorough entombment of the material, and adequate control of leachate. The location of the animal trenches and MBM within the landfill was logged in the event the need to exhume the materials arises in the future. It should be noted that Washington State is one of a handful of states in the country where authority for solid waste facility permitting and oversight is delegated by statute to JHDs. Ultimately, it was the JHD that decided whether or not to allow burial of potentially infected animals and byproduct at a facility within their jurisdiction. Ecology’s published guidelines promoted the following:
- Disposal should occur only at lined Subtitle D landfill facilities
- The landfill should collect leachate in a closed system for recirculation
- The placement cell should have at least 20 feet of waste in place.
- Delivery of whole animals, offal, or recalled meat must be by appointment only. This allows preparation by landfill staff to immediately deal with disposal of the delivered waste. In the case of whole animals, it is more desirable to have them delivered to the landfill live and euthanized on site.
- Whole animals must only be disposed one layer thick. They must be immediately
- covered with at least three feet of regular garbage.
- Offal shall be placed on a 12-inch layer of Department-approved absorbent material such as a dry pulp sludge or dry soil. In certain cases municipal solid waste may be able to be utilized as absorbent material. This absorbent material is in addition to the twenty feet of waste required to be in place. The offal shall be immediately covered with at least three feet of regular garbage.
- Large quantities of recalled meat (typically shipped from central locations) shall be placed on in-place garbage and immediately covered with at least three feet of regular garbage.
- The disposal area for any of these wastes shall be covered with a minimum of twelve inches of soil at the end of the operating day. Alternative Daily Cover (ADC) cannot be utilized to cover this material at the end of the operating day.
(Since the Washington event, a concern has emerged regarding the suitability of placement of animals suspected to be infected with a prion-related disease such as BSE, Scrapies, Chronic Wasting Disease, in landfills that discharge leachate to waste water treatment facilities or surface waters. At the request of the Environmental Protection Agency’s (EPA) Office of Water, the Office of Solid Waste revised its guidance in November of 2004 for landfill disposal of animals potentially affected with CWD. The revision promoted limiting landfill disposal to facilities that recirculate leachate rather than discharge to a treatment plant or directly to surface water under a NPDES permit.)
Early in the week of January 6th, animals were trucked approximately 150 mile north of Mabton to a secluded closed processing plant in Wilbur Washington. Depopulation efforts occurred largely in secret and were performed by lethal injection. Carcasses were loaded into truck to be hauled south about 200 miles back south to the landfill. The operator, who was on call for this event, received a call at about 3:00 a.m. informing him that the carcasses were in route. The time of the call put the operator in the difficult position of securing a crew to bury the animals because the facility is about an hour’s drive from any of the communities where most of the workers lived and the region had experienced a snow storm that evening. As soon as there was adequate light to work, burial commenced at under gray skies, a shroud of fog, and a blanket of snow. The facility was closed to other customers that day.
By the time investigation and disposal were complete…
- A total of 449 animals were depopulated from the bull calf raising premises.
- A total of 131 at-risk animals were depopulated from the index premises in Mabton, WA.
- A total of 39 animals were depopulated from the facility in Mattawa, WA
- A total of 15 animals were depopulated from the facility in Connell, WA.
- A total of 20 animals were depopulated from a facility in Boardman, OR.
In addition to disposal of animal carcasses, approximately 2000 tons of recalled meat and byproducts were disposed of. Before these materials were allowed to be transported to Roosevelt Regional Landfill, Baker Commodities and Darling International were each required to submit a disposal plan and obtain approval from the FDA’s Center for Veterinary Medicine. These plans detailed the specific location of potentially adulterated products, quantities and types, transportation methods, contacts, and facility location.
- The discovery of BSE in Washington set in motion a sequence of events that exposed the need to plan for such incidents before they happen. Much of this planning is already taking place in states throughout the country under Homeland Security and other mandates. Officials need to understand risks associated with any animal disease that may require urgent response containment and perhaps mass depopulation ahead of the emergence of an incident warranting emergency response. Questions about necessary safeguards to protect human health and the environment, personnel protection, biosecurity, etc. in an emergency event should be answered and documented to help responders assemble necessary equipment and take appropriate precautions. Numerous animal diseases of concern have been identified and characteristics identified by national and international organizations. An understanding of disease characteristics such as how the disease spreads, it’s potential to affect humans and nearby animal populations, whether quarantine is required, whether immediate destruction is necessary all are critical to good response planning should an outbreak occur. How should the risks be communicated to the public? Such planning will go a long way towards swift and efficient responses and may also prevent an overreaction to the incident.
- It’s critical that agencies at all levels of government be prepared to work together in such a response. Planning noted above should clearly identify roles and responsibilities under specific circumstances. Communication between the federal investigators and state officials must be open, direct, and reliable. No less than seven state and federal agencies were directly involved with the response, in addition to numerous local agencies asked to assist in finding a solution to disposal issues. The need to communicate within agencies is as compelling as the need to communicate among agencies. Larger departments will frequently have many divisions within its agency that may have overlapping (and sometimes conflicting) responsibilities. Also, as with any emergency situation, elected officials at all levels of government will become involved out of concerns for constituents or simply to be seen as “on the job”.
- Poor communications and turf issues among involved agencies provide the media with fodder to fuel speculation about what is “really going on”. The speculation erodes public trust that officials are being truthful about the scope of the problem and efficacy of the solution. The behavior of officials towards media can be critical. Officials become discredited when the message is delivered with arrogance and when conflicting stories emerge from seemingly credible people. The public, when dealing with such conflicts, is far more likely to believe a story from a citizen asserting they had direct involvement who claims “cover up” over agency personnel who appear to deliver what is perceived a “company line” to protect the interests of the affected business over public safety.
- In retrospection, many state agency staff wonder if destroying the potentially infected cattle might have precluded an opportunity to study the development of the disease and advance the bank of knowledge about its transmission and symptoms in bovine animals among a typically bred population. Once isolated from commercial breeding and production, the animals posed very little risk to humans and to other animals. The focus of the response to the discovery of BSE was obviously on tracking down related animals and products as quickly as possible. However, once accomplished, there arguably was no real urgency to destroy them. Costs to maintain the herd and fears about possible impacts and future use of property hosting the herd would need to be considered, but the maintenance of the herd could provide deeper understanding of the disease.
- Finally, there was a sense that federal agencies should have relied more on the knowledge of state officials when seeking a disposal solution. Due to the nature of the business, solid waste staff in government and solid waste facility operators all understands the difficulty of the delivery of messages in the situation faced by the federal investigators. It is in no way uncommon that special situations arise that put the solid waste system in a situation of managing some of the less savory cast-offs of American society. It is unlikely that the disposal option eventually selected would have been different than what was ultimately selected, but the efficiencies of getting there would definitely have been improved. State solid waste professionals, both regulators and operators, routinely work closely together to ensure safe facility operations. Relationships exist that without question, could have been utilized and eased at least a portion of the anxiety and uncertainty of the situation experienced by all involved.
Agronomic Utilization of Compost — Growing Plants and Protecting the Environment
Harold M. Keener
Dept. of Food, Agricultural, and Biological Engineering, The Ohio State University, Wooster, OH. 44691, <email@example.com>
Many composts are marketed and priced based on their nutritive value, which is largely fixed (except for N) by the initial compost mix. This paper presents information on the chemical properties of composts generated from municipal and agricultural sources. In addition, it provides information on erosion control uses, plant responses to compost maturity, disease suppression from compost used in potting mixes, pathogen destruction and antibiotic breakdown during composting.
Chemical Properties of Composts During Utilization
During composting, the plant nutrients P, K, Ca, Mg, as well as heavy metals do not disappear appreciably from the system as the dry matter decomposes (unless leaching occurs). However, N is lost during composting via numerous pathways, with ammonia volatilization being the most common. Its loss is directly related to total N content of manure and by C/N ratio. Numerous studies have shown C/N ratios near 40 or above will minimize N loss (Michel et al., 2004). Also, if the compost mix starts with N < 1%, N is generally retained by the biomass as dry matter disappears from the mix such that N percentage in the compost increases. However, waste with high nitrogen content such as caged layer manure and biosolids generally have C: N ratios well below 40:1 for any reasonable level of amendment. To prevent N losses, unamended caged layer manure can be composted in an enclosed structure with high atmospheric NH3 to reduced N losses (Keener et al., 2002). A second approach is acid scrubbing and reintroducing the NH3 salt back into the finished compost. Still another approach has used alum (Eckinci, 2002) for controlling nitrogen loss, although it has been shown to reduce the solubility of P by >50 %.
Historically, mature compost has nutrient contents of approximately 2% N, 2% P and 1 % K (4.6% P2O5, 1.8% K2O). However, these values are greatly influenced by the starting compost mix, additives to mixes, and stage of stabilization. Also, reported nutrient values for compost are meaningful only if reliable samples have been taken. Discrepancies between initial mixes and final compost composition often arise with heterogeneous composts as noted by Keener et al. (2000) for compost made from blended materials. Since compost nutrient values can vary within the size ranges of the cured compost (Elwell, et al., 1994), screening can also be used to modify NPK levels in products. Table 1 is a summary of properties of compost from yard waste, biosolids, municipal solid waste (MSW) and livestock manures that have been studied along with paper mill sludge. These results illustrate how compost properties are related to initial properties of the compost mixes and length of composting time. It should be also noted composting may increase plant availability of macro and micronutrients, although biomass N is not as readily available as the NH3 form of N.
The US Composting Council (USCC, 2004) has developed detailed protocols for the composting industry to verify the physical, chemical, and biological condition of composting feedstocks, material in process and compost products at the point of sale. This protocol is called TMECC, Test Methods for the Examination of Composting and Compost.
Table 1. Chemical properties of compost made from yard waste, biosolids, MSW, animal manures, and paper mill sludge amended with yard waste, wood chips, sawdust or straw.
|Yard waste||Michel et al., 1996|
|Biosolids||Elwell et al., (1994)|
|bs/wc (< 0.375″)||14||21||4.26+0.09||2.17+0.05||0.77+0.02||5400+850||288+17|
|Bs/wc/l20 (< 0.375″)||12.4||21||3.60+0.02||1.44+0.04||0.71+0.01||3650+71||253+32|
|MSW||Keener et al. (1992)|
|kw/yw (4% inerts)||16.7||53||1.85+0.14||8.6+0.6|
|msw/cm (19% inerts, <0.375″)||19.3||31||2.01+0.04||12.8|
|so/le 1:1 (9% inerts)||32||54||2.3||12||0.35||0.91|
|Swine manure||Keener et al., 2001|
|Dairy manure||Wang et al., (2004),
Michel et al. 2004
|Poultry manure||Keener et al. (2002)|
|Chicken manure||Elwell et al., (1996)|
|Horse Manure||Keener et al. (2004)|
|Paper mill||Brodie et al., 1996|
|Ps/pl/wc (< 0.5 in.)||31.5||245||0.95||17.0||0.67||600||0.7|
1 br=brush, bs=biosolids, cb=cardboard, cm=caged layer chicken manure, dm=dairy manure, fw=food waste, gr=grass, hm=horse manure, kw=kitchen waste, le=leaves, msw=municipal solid waste, pl=poultry broiler liter, ps=paper mill sludge, sd=sawdust, sm=swine manure, so=store organics, st=straw, wc=woodchips, yw=yard waste.
2 <0.375″ indicates finished compost was screened to less than this size before analysis.
Composts prepared from wood industry wastes frequently have high C: N ratios and while technically “stable” may still immobilize N during utilization9. On the other hand composts from sewage sludges release significant levels of N early during crop production while a more mature compost from separated cow manure maintains a sustained level of N release over a longer time period (Chen et. al., 1996). Results (Wang et al., 2004) on dairy manure composted with sawdust or straw showed that a 100 day composting/curing time gave good growth responses. A growth trial (Wilkinson et al., 2004) conducted to identify the effect of cardboard/horse manure compost age on growth of cucumber seedlings (fig. 1) indicated that if fertilized at 200ppm N to overcome nitrogen immobilization, composting time should exceed 70 days. Results also showed the maturity or age of the compost in this study did not significantly affect the percent germination of cucumber seeds. In general total time for composting and curing will generally exceed 100 days to achieve well-stabilized, mature compost for use in potting mixes. For land application or other purposes, the time requirements could be less (See later discussion).
Allelopathy, described as chemical warfare between plants, needs to be considered in composting. Tree barks in particular may be sources of such chemicals that inhibit plant growth. Fortunately, allelopathic chemicals responsible for this effect in both softwood as well as hardwood barks are destroyed within a few weeks of composting of barks from most tree species (Still et al., 1976).
Organic acids in compost, especially the low molecular weight fatty acids, negatively impact emergence of seeds. In practice, producing compost in properly aerated systems so that anaerobic pockets are prevented during composting/ curing/ storage avoid toxicity caused by organic acids. For the case where acids exist in the cured compost, removing and allowing the compost to cure for 1-2 weeks in smaller aerobic windrows can eliminate the problem. Ammonium from immature low C/N materials (e.g. composted manure, food waste, sewage sludge) and soluble salts can also cause toxicity. Using mixtures with high C: N ratio alleviates these two problems. Table 2 provides guidelines on allowable soil soluble salt levels to avoid salt toxicity and fig. 2 shows how ammonium toxicity limits use of compost for growing plants.
Table 2. Allowable soil soluble salts (mMhos/cm) to minimize salt toxicity.
|Description||Saturated Media Extract||2 : 1 Dilution|
|Satisfactory if soil is high in organic matter but too low if soil is low in organic matter||Below 2||0.15 to 0.50|
|Satisfactory range for established plants but upper range may be too high for some seedlings||3 to 4||0.50 to 1.80|
|Slightly higher than desirable||4 to 8||1.80 to 2.25|
Land Application. Using composts for crop production requires attention to the source of compost and the timing, method and rate of application. Dalzell et al. (1987) recommended that mixtures of mineral fertilizers and composts should be such that at least 30% of the N is supplied by each source. However, composts made from biosolids often contain high concentrations of nitrate-N such that these composts require no mineral N additions (Chen et al., 1996). The timing of application versus when a crop is grown on the amended soil is important. Immature compost with a high C/N ratio should be applied several weeks ahead of planting to prevent immobilizing soil N and inhibiting crop growth. The method of application, i.e. surface applied or mixed into the soil, is controlled by whether N loss will be excessive from surface application and the tillage program for the crop production system. Lastly, rate of application is important. For crop production a minimum of about 2.5 Mg ha-1 (2.2 ton/acre) is required before benefits of compost application become evident. However, rates 10 times or more higher than the stated minimum rate can be equally effective if applications are not made annually but only every three or four years. If the compost contains heavy metals, application rates should not exceed the permissible levels based on the USEPA 503 regulations for biosolid compost (eg. Copper 67, Lead 13, Hg 0.76 lb/ac/yr.
Container Media. Utilizing compost in container media and soil blending is determined primarily by the compost effects on hydraulic conductivity, water retention and air capacity (Spencer and Benson, 1982). Compost addition should maintain air capacities above 25% as air capacity of a potting mix directly affects plant growth and has an impact on root rot severity. For example, observations in nurseries indicate that Phytophthora root rots do not occur in media that contain tree barks having air capacities > 25% and percolation rates > 2.5 cm/min. Since the ratio of compost to soil in land application is small, compost’s physical properties usually have only marginal effects on soil physical properties for land application.
Mulches and Top Dressings. Organic mulches and top dressings effect the soil’s ecology and plant health. They do this by controlling temperature swings, increasing water infiltration, reducing water evaporation, assisting in weed control, providing food for soil microbes, nutrients for the plants, etc. However, the effect they achieve depends on the materials particle size, available carbon, nitrogen and other nutrients.
Herms (2005) noted that ground wood pallets and composted yard waste mulches both increased soil organic matter and microbial biomass activity when used on rhododendron and river birch trees. However, the composted yard waste increased, while the ground wood decreased nutrient availability and plant growth. Only the yard waste compost suppressed root rot disease. Figure 3 shows organics in the landscape. Not all mulches have positive impacts and Hoitink (1998) noted dry composts and mulches cause problems for the user if nuisance fungi grow in them and produce spores that detach and stick to house siding.
Erosion Control, Filtering. Compost is being actively market for erosion control for use along roadways, riprap channels, stream bank stabilization and gabions. In addition it is being used for filter cells to control runoff, bioretention ponds and bioremediation projects. Tyler (2005) noted: Bill Stewart pioneered filter berms and erosion control using compost in 1993; Maine Waste Mgt. Agency tests compost against others in Kennebec County – 1994; Clyde Walton, Maine DOT one of first to spec. berms in DOT projects – 1996; and EPA cites innovative uses for compost for erosion control- 1997. Novel approaches, such as Filtrexx™ socks10 (Tyler, 2005), control soil loss, allow rapid establishment of cover vegetation, and avoids non-organic structures in the environment such as plastic filter fence.
Disease suppression using compost occurs by three mechanisms, general suppression, specific suppression and induced suppression. It has been found that general (Natural) suppression will occur in about 90% of mature composts. The diseases most frequently controlled are Phytophthora and Pythium root rots (fig. 4). The second area, i.e. specific disease suppression, occurs in about 20% of mature compost and Rhizoctonia root roots are often the disease one is attempting to control. The third area is induced systemic resistance. It occurs in about 2% of the compost naturally and confers the ability to control foliar diseases (fig. 5).
Producing disease suppressive compost. It is recognized that control of root rots with composts can be as effective as that obtained with fungicides (Hoitink et al., 1997). The ornamental plant industry now relies heavily on compost products for control of diseases caused by soil borne plant pathogens. However, composts must be of consistent quality to be used successfully for biological control of diseases of horticultural crops, particularly if used in container media.
Effects of chemical properties of composts on soil borne disease severity are important but often overlooked. Highly saline composts such as those prepared from dairy manure or hog manure (Keener et al., 2001) enhance Pythium and Phytophthora diseases unless they are applied months ahead of planting to allow for leaching. Compost prepared from municipal sewage sludge has a low carbon to nitrogen ratio. They release considerable amounts of ammonium nitrogen and enhance Fusarium wilt diseases (Quarles and Grossman, 1995).
9 Standards for compost stability generally have not yet been adopted but an oxygen uptake rate less than 0.1 and 1.0 mg hr-1 gvs-1 of compost volatile solids (vs.) have been proposed. Compost maturity has many meanings and is usually assessed through the potential for plant growth (Keener et al, 2000).
10 Use of product name or trademark does not mean endorsement by The Ohio State University.
More to come.