What information can you give me on composting poultry litter?
W.K.OklahomaAnswer: Thank you for contacting ATTRA with your request for information on composting poultry litter. I understand you are interested in composting existing poultry litter in empty broiler houses. I’ve compiled some information on the composting of poultry litter as well as composting in general that should help you in developing the best system and management of turning poultry litter to compost. ATTRA’s publication, Poultry House Management for Alternative Production contains an appendix which discusses the composting of poultry litter and is included below:Composting Poultry Litter (Appendix 2 in Poultry House Management for Alternative Production) — Poultry litter is an excellent feedstock for composting. Composting is controlled decomposition, the natural breakdown process of organic materials (Cooperband, 2002). Raw materials are transformed into biologically stable, humic substances that are an organic matter source with a unique ability to improve the chemical, physical, and biological characteristics of soil. In compost, nutrients are present in the same amounts but in a less soluble form, and compost has less odor than raw litter. However, some nitrogen (N) escapes during composting, so the phosphorus (P) is more concentrated in compost. Due to the action of microbes, volume of compost is reduced compared to the original litter. “Water and carbon dioxide lost during composting reduce the litter volume by 25-50 percent and the litter weight by 40-80 percent.” Composting occurs through the activity of microorganisms naturally found in soils, which colonize the material and start the composting process (Cooperband, 2002). During the active phase of composting, the temperatures in the pile get high enough to kill pathogens. The pile should be at least one cubic yard in order to retain heat. During this phase, oxygen must be replenished by aeration or turning of the pile. During the curing phase, temperatures lower, organic materials continue to decompose and are converted to biologically stable humic substances. Optimal conditions for rapid composting include a carbon to nitrogen ratio of 25-35:1, moisture content of 45-60 percent, available oxygen of more than 10 percent, particle size of less than1 inch, bulk density of 1,000 lbs/cu yd, pH of 6.5-8, and temperature of 130-140 F (Cooperband, 2002). If the carbon to nitrogen ratio is less than 20:1, the microbes have surplus nitrogen (N), which can be lost to the atmosphere as ammonia gas. Also the pH should be less than 7.5 to prevent ammonia formation. In order to compost poultry litter, additional shavings or carbon source may need to be added. If conditions are not optimal, anaerobic decomposition may occur, which produces foul-smelling sulfur and takes longer to compost. Composting bird carcasses (mortalities) is usually done in a bin. Referenced below is the publication, The Art and Science of Composting. The Art and Science of Composting was put together by the Center for Integrated Agricultural Systems and introduces some general points that are critical in properly managing compost. A publication entitled On-Farm Composting of Poultry Litter developed by the University of Tennessee Agricultural Extension Service is also referenced, and includes information specific to compost poultry litter. ATTRA’s publication, Farm-Scale Composting Resource List is another good resource.Some states have regulations on large-scale composting operations. For more information you can contact Jim Warram at the OK Department of Environmental Quality Waste Management Division (405) 745-7100. Compost testing can be done at most soil testing labs. The Soil, Water, and Forage Analytical Laboratory at Oklahoma State University provides compost testing as one of their services. They can be contacted at 405-744-6630, and also found on the web at www.soiltesting.okstate.edu/. Resources: Cooperband, L. 2002. The Art and Science of Composting: A Resource for Farmers and Compost Producers. Center for Integrated Agricultural Systems. University of Wisconsin, Madison, WI. 14 pg. Walker, Forbes. On-Farm Composting of Poultry Litter. University of Tennessee Agricultural Extension Service. 9 pg.