Reducing nitrogen losses during simulated composting of poultry manure using adsorbents or chemical amendments

Ammonia emissions during composting of poultry manure can be significant, representing increased environmental pollution and decreased fertilizer value of manure. The objectives of this study were to measure NH3 volatilization losses during composting of poultry layer manure, and to evaluate the potential of different amendments to reduce NH3 losses using a laboratory composting simulator. The poultry manure was treated with various amendments which included two natural zeolites, clay, coir (mesocarp of coconut fruit), CaCl2, CaSO4, MgCl2, MgSO4, and Al-2(SO4)(3). The manure was composted for 49 to 56 d. Ammonia volatilized from the manure was trapped in a 0.3 M H2SO4 solution. The composts were weighed and analyzed for moisture content, total N and NH4+. The NH3 volatilization loss for the unamended manures ranged from 47 to 62% of the total manure N. A layer of 38% zeolite placed on the surface of the manure reduced NH3 losses by 44%, whereas 33% coir plated on the surface of the manure reduced NH3 losses by 49%. The 20% alum treatment reduced NH3 losses by 28%. Composting poultry manure with zeolites, coir, and alum produced composts with high NH4+ concentrations ranging from 17 to 53% of total N. The addition of 20% CaCl2 to poultry manure decreased NH3 volatilization but did not result in increased NH4+ or NO3- concentrations. The 38% zeolite Z1 and 33% coir-treated composts had total N concentrations of 17 and 31 g kg(-1), respectively. The zeolite and coir amendments were proposed to be the most suitable for reducing NH3 losses during composting of poultry manure.