PELLETIZING AND SOIL-WATER EFFECTS ON GASEOUS EMISSIONS FROM SURFACE-APPLIED POULTRY LITTER

Several studies have shown that the application of animal manures to s oil can increase N2O and CO2 emissions. Little information is availabl e, however, on the effect that physical characteristics of the manure can have on these emissions. The objective of this work was to evaluat e the effects of physical characteristics of poultry litter (fine part icles or pellets) and soil water-filled porosity (WFP, 58 or 90%) on r ates and total amounts of N2O and CO2 emissions from surface applicati ons of poultry litter to soil. Poultry litter at 30.7 g N m-2 was surf ace applied to samples of Cecil loamy sand (clayey, kaolinitic, thermi c, Typic Kanhapludult) that were packed in acrylic plastic cylinders. Each cylinder was placed inside a jar that was closed with a screw-cap tid fitted with a rubber septum, and all jars were placed iu an incub ator at 25-degrees-C for 28 d. Periodic air samplings were conducted f or N2O and CO2 analyses. Maximum rates of N2O and CO2 emission occurre d within the first 4 d and were highest for fine-particle litter at 90 % WFP. Cumulative CO2 emission did not differ between treatments, but cumulative N2O emission was significantly lower for fine-particle litt er at 58% WFP than for the other treatments. Expressed as a percentage of the applied N, the N2O lost represented 0.2% for fine-particle lit ter at 58% WFP, and an average of 2.8% for the other treatments. These results suggest that for surface applications under the conditions of this study, pelletized litter may produce similar CO2 emission as fin e-particle litter, and may cause equal or larger emissions of N2O than fine-particle litter.