Comparison of Greenhouse Gas Emissions on an Organic and Conventional Dairy Farm in New Hampshire

Agriculture is responsible for 20 to 25% of total anthropogenic greenhouse gas (GHG) emissions globally. Emissions come primarily from enteric fermentation, manure management, and soil based emissions with management practices having a large effect on GHG emissions.;Organic and conventional dairy farms operated by the University of New Hampshire's Agriculture Experiment Stations (NHAES) were utilized as the study sites. Greenhouse gas fluxes were measured from: animals, housing, soil, feed and manure sites on the farms. Emission factors from soils that received animal excreta were lower than commonly cited values. The bedded pack produced significant quantities of N2O while the slurry lagoon produced significant CH4. A methods comparison test examined enteric fermentation, suggesting higher CH4 production than currently cited. A summary of preliminary results suggest that an organic dairy can be more efficient and produce less GHG per unit of energy corrected milk than a conventional dairy.