LOSSES AND TRANSFORMATION OF NITROGEN DURING COMPOSTING OF POULTRY MANURE WITH DIFFERENT AMENDMENTS - AN INCUBATION EXPERIMENT

The transformation of nitrogen (N) and its subsequent loss during aerobic and anaerobic composting of poultry manure with different amendments were investigated through laboratory incubation experiments. The amendments include& four carbon (C) rich bedding materials (woodchip, paper waste, cereal straw and peat), one acidifying material (elemental sulphur, S0) and two adsorbents (zeolite and soil). The loss of N through ammonia (NH3) volatilization from aerobic condition was about 17% of total manure N which was reduced by 90-95% under anaerobic condition. Under aerobic incubation systems, amongst the bedding materials examined, wheat straw and peat were found to be superior in reducing the NH3 loss by 33.5 and 25.8%, respectively. Loss of NH3 was reduced by 60% in manure amended with S0. Zeolite was a more effective NH3 (or NH4+) adsorbent than soil and reduced NH3 loss by 60%. The amount of 2 M KCl extractable NH4+-N was almost 1000 times higher than that of nitrate (NO3--N) in all composting mixtures suggesting little oxidation of NH4+ to NO3- (nitrification) occurred. The measurement of total N in the compost at the end of the experiment showed a total loss of about 50 and 26% of manure N during aerobic and anaerobic incubations, respectively, as against only about 17 and < 1% losses measured through NH3 volatilization. This suggested that the N loss through denitrification could be considerably higher than that occurred through NH3 volatilization.