Greenhouse gas emissions from dairy farms

The reduction of greenhouse gas emissions Is becoming more important world-wide. Although research suggests that farmland can serve as a sink for carbon, agriculture is also an important source of emissions. As a sector, agriculture is reported to be the greatest contributor of nitrous oxide and the third greatest contributor of methane In the U.S. Thus, strategies must be designed to reduce or eliminate net emissions of greenhouse gases. Before these strategies can be developed, we must first understand typical emission ranges from each source at the farm level in order to focus on the processes with the greatest emissions. Sources on dairy farms include soil, growing crops, feed storage, animals, and manure In animal housing facilities, during storage, and following field application. Other countries, particularly In Europe, have quantified emission ranges, although these data are less established within the U.S. An extensive literature review was conducted to determine the major processes contributing to greenhouse gas emissions from dairy farms and to quantify typical emission levels. From these typical levels, emissions were estimated for a representative dairy farm. This review and farm analysis will help direct modeling efforts by determining the important physical processes that drive emissions of carbon dioxide, methane, and nitrous oxide in dairy production. The review also expands the knowledge base of researchers, farm planners, and policymakers as they work to develop and maintain sustainable farming systems.