Greenhouse gas emissions associated with dairy manure produced in animal confinement facilities *

This review assesses potential greenhouse gas (GHG) emissions, including nitrous oxide (N2O), ammonia (NH3) and methane (CH4), associated with dairy cow confinement facilities and following application of manure collected from these facilities. When confined animals void their urine and dung in houses, sheds and barns, it is generally stored for some time before subsequent application to land. There are wide variations in animal manure/slurry storage and management systems that include differences in manure collection methods, amendments with litter or other materials, length of the storage period, the type of manure cover used during storage and the method and timing of land application. Each step in the management of these manures/slurries has its own set of physical and environmental conditions affecting the production and emission of GHGs, thus each step must be managed independently. As a consequence, GHG emissions from these systems differ widely. It is important to highlight that management of these manures/slurries should be viewed as a continuum, where potential emissions from one stage are directly influenced by the conditions and consequent emissions that occurred in the previous stages. Therefore, reductions in GHG production at one stage may result in increased production at a later stage unless all stages are well managed. It is also important to note that there are several GHGs (N2O, NH3 and CH4), and adjusting manure management practices to reduce one gas may increase the emission of another. Therefore, management of these emissions must be done with a holistic view of all the stages involved and with consideration of the total GHG footprint. * Chapter title changed when published to: Gaseous emissions from dairy manure collection in animal confinement facilities