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 aero bic and anaerobic composting of poultry manure with different amendmen ts were investigated through laboratory incubation experiments. The am endments include& four carbon (C) rich bedding materials (woodchip, pa per waste, cereal straw and peat), one acidifying material (elemental sulphur, S0) and two adsorbents (zeolite and soil). The loss of N thro ugh ammonia (NH3) volatilization from aerobic condition was about 17% of total manure N which was reduced by 90-95% under anaerobic conditio n. Under aerobic incubation systems, amongst the bedding materials exa mined, 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 6 0% 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 nitra te (NO3--N) in all composting mixtures suggesting little oxidation of NH4+ to NO3- (nitrification) occurred. The measurement of total N in t he compost at the end of the experiment showed a total loss of about 5 0 and 26% of manure N during aerobic and anaerobic incubations, respec tively, 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 volatiliz ation.