NITROUS-OXIDE AND CARBON-DIOXIDE EMISSIONS FROM PELLETIZED AND NONPELLETIZED POULTRY LITTER INCORPORATED INTO SOIL

While several studies have shown that the addition of animal manures t o soil can increase N2O and CO2 emissions, limited information is avai lable on the effect that manure physical characteristics can have on t hese emissions. This study compared N2O and CO2 emissions from poultry litter incorporated as pellets (5.5 mm OD, 7 mm long) or fine particl es (<0.83 mm) into Cecil soil samples. The soil-litter mixture was pac ked in acrylic plastic cylinders and adjusted to 55 or 90 % water-fill ed porosity (WFP). The cylinders were placed inside jars that were sea led and placed in an incubator at 25 degrees C for 35 d, with periodic air samplings conducted for N2O and CO2 analyses. At 55 % WFP, cumula tive emission of CO2 was similar for both litter types, but cumulative emission of N2O was slightly higher for pelletized (6.8 % of applied N) than for fine-particle litter (5.5 %). In contrast, at 90 % WFP, cu mulative emission of N2O was larger for fine-particle litter (3.4 % of applied N) than for pelletized litter (1.5 %). These results indicate that the effect of poultry litter physical characteristics on N2O emi ssions from incorporated applications can be expected to vary dependin g on the soil water regime.