Composting poultry litter may result in substantial nitrogen losses during composting process. During aerobic decomposition, the uric acid is broken down to produce ammonia, which results in an increase in the pH of the composting material. With a pka of 9.2, as the pH of the composting material increases, the ammonium-ammonia balance moves toward increasing concentrations of volatile ammonia, with the resulting loss of NH3 to the air.
How much of the nitrogen is lost during the composting process? Kithome et al. (1999) reported that up to 30% of the N in poultry litter was volatilized after a few days of composting, and that up to 62% of the nitrogen was volatilized as ammonia after 25 days. DeLaune et al. (2004) reported up to 56% loss of nitrogen as ammonia during 68 to 92 days of windrow composting turkey litter including bedding. Tiquia and Tam (2000) reported that more than 59% of the initial nitrogen was lost as ammonia during forced aerated composting of poultry broiler litter.
In a 180 day windrow (5 m wide by 2.5 m high windrows) composting trial with five turns of the composting material, up to 82% of the initial nitrogen in poultry litter was lost as ammonia volatilization or N leaching (Delta Farmers Institute 2004). They reported 53% of the nitrogen was lost in the first 39 days of composting. They also used uncovered composting piles during the rainy season in southcoastal BC (up to 1 m rain between October and March). They concluded that the C/N ratio of poultry litter is too low for composting not to result in relatively large nitrogen losses.
Increased amounts of carbon potentially reduce ammonia losses. Delta Farmers Institute (2004) reported that ammonia losses were reduced by building larger piles, adding 40% yard trimmings compost to increase the C/N ratio and minimizing pile turnings. Mohan and Kovilpillai (2012) reported that addition of carbon such as coir, sawdust and straw reduced ammonia losses by 31 to 48% during composting of poultry layer manure.
Even with additional of carbon to poultry litter, reducing ammonia loss is difficult. Kithome et al. (1999) concluded that reducing ammonia losses during composting of poultry manure is costly and that poultry manure should perhaps best be utilized for field production in its uncomposted state. This will not be possible with Good Agricultural Practice Guidelines requiring manure to be composted to reduce pathogens. Keener et al. (2011) reviewed the composting process for poultry litter and concluded that “the most applicable system for broiler litter for producing a low moisture, high N product would be an in-vessel system with forced aeration, mechanical turning and a high ammonia concentration in the ambient environment surrounding the compost. Such a system would not fully compost the broiler litter, but lead to a stabilized, dry product with high nitrogen content (12-15% N loss) that could be marketed to nurserymen and gardeners, as well as general farmers.”
DeLaune, P.B., P.A. Moore, Jr., T.C. Daniel and J.L. Lemunyon. 2004. Effect of chemical and microbial amendments on ammonia volatilization from composting poultry litter. J. Environ. Qual. 33: 728-734.
Delta Farmers Institute. 2004. Poultry litter & compost resource stewardship practices on the Fraser River Delta. Agriculture Environment Partnership Initiative Project # 01-054.
Keener, H.M., M.H. Wicks, F.C. Michel and K. Eckinci. 2011. New technologies and approaches for composting broiler manure. Paper presented at the First International Poultry Meat Congress, Antalya, Turkey. May 12, 2011.
Kithome, M., J.W. Paul and A.A. Bomke. 1999. Reducing nitrogen losses during simulated composting of poultry manure using adsorbents or chemical amendments. J. Environ. Qual. 28: 194-201.
Mahimairaja, S., N.S. Bolan, M.J. Hedley and A.N. Macgregor. 1994. Losses and transformation of nitrogen during composting of poultry manure with different amendments: An incubation experiment. Bioresource Technology 47: 265-273.
Mohan, P. and B. Kovilpillai. 2012. Addressing the challenges of ammonia loss from poultry droppings through indidgenous carbon wastes. International Journal of Environmental Science and Development 3: 400-406.
Tiquia, S.M. and N.F. Tam. 2000. Fate of nitrogen during composting of chicken litter. Environ. Pollution 110: 535-541.