AMMONIA VOLATILIZATION AND CARBON-DIOXIDE EMISSION FROM POULTRY LITTER - EFFECTS OF FRACTIONATION AND STORAGE TIME

In many poultry producing areas, the amounts of poultry litter generated exceeds the amounts needed for application to soil, as fertilizer, at environmentally safe rates. To reduce the amounts of litter produced, Ndegwa et al. (1991) proposed fractionating the litter to generate a fine fraction that could be used as fertilizer, and a coarser fraction that could be recycled into poultry houses as bedding material. Because the fine fraction may need to be stored for several months before land application, knowledge of the changes that occur during storage would be important from the point of view of litter utilization. The objective of this study was to monitor water and inorganic nitrogen (N) contents, as well as potential ammonia (NH3) volatilization and carbon dioxide (CO2) emission in samples of whole litter and fine fraction stored in an unheated building for 16 weeks. Potential NH3 volatilization and CO2 emission were measured at unamended water contents and at a water content of 0.5 kg kg-1. Water and inorganic N contents of the whole litter and fine fractions showed some fluctuations during the first 4 weeks, but remained relatively stable from weeks 4 to 16. At unamended water contents, potential NH3 volatilization and CO2 emission were relatively low and similar for the whole litter and the fine fraction. Also, potential NH3 volatilization remained stable whereas CO2 emission decreased with time. Increasing the water content to 0.5 kg kg-1 significantly increased potential NH3 volatilization and CO2 emission in the whole litters and fine fractions, with larger increases usually observed in the fine fractions. At 0.5 kg kg-1, both potential NH3 volatilization and CO2 emission decreased with time. These results suggest that the fine fraction and the whole litter should be stored at relatively low water contents to prevent N losses through NH3 volatilization and possibly denitrification.