| Three studies were conducted to better understand the emissions of N 2O and CH4 from composting liquid swine manure. One study quantified the emissions of these gases from a liquid swine manure storage, to provide a comparison, while the other two examined the N2O and CH4 emissions from composting liquid swine manure under forced aeration using lab scale and farm scale composting systems.; Nitrous oxide was not detected from the liquid manure storage. Methane emissions were variable among the seasons, increased with manure agitation/pumping, and was found to have a yearly mean emission flux of 245 mug of CH 4 m-2 S-1. Greenhouse gas emissions from composting were not found to be related to any chemical or physical characteristics of the compost. Aeration did not influence N 2O emissions from either the lab scale or farm scale. Methane emissions were strongly influence by aeration at the farm scale, with mean CH4 emissions from non-aerated compost 24 times higher than from aerated compost. Annual greenhouse gas emissions from composting were estimated to represent 74.3 and 205% of the emissions from liquid manure storage. |
