Can Grazing Reduce Greenhouse Gas Emissions from Dairy Farms?

Authors: SEDOROVICH, DAWN - ENVIRON CORPORATION; Rotz, Clarence - Al

Submitted to: The Forage Leader
Publication Type: Trade Journal
Publication Acceptance Date: 2/10/2008
Publication Date: 12/15/2008
Citation: Sedorovich, D., Rotz, C.A. 2008. Can Grazing Reduce Greenhouse Gas Emissions from Dairy Farms? The Forage Leader, Winter Issue. p. 5-7.

Interpretive Summary: An interpretive summary is not required.

Technical Abstract: Greenhouse gases (GHG) have become a common topic the past few years as more concern is developing over global climate change and the potential impact of these gases on our environment. So do our farms emit GHG? If so, how much and does the use of grazing affect these losses? A study was conducted using computer simulated farming systems to answer these questions with an emphasis on forage-based dairy farms in the Northeast. Three production systems were simulated: full confinement, winter confinement with summer pasture, and animals outdoors year-round with summer pasture. All three systems were assumed to be well-managed dairy farms operated on productive soil. Dairy farms were found to be net emitters of GHG, and the amount of emissions varied based on the management of the farm. When compared based upon the emissions per cow plus her replacement, the year-round outdoor system emitted the least GHG, followed by winter confinement with summer grazing and the full confinement system. Although the all-grass system emitted less GHG per animal, it also produced less milk relative to the other two systems. Comparing net GHG emissions per unit of milk produced resulted in the lowest emissions from the full confinement system (50 lb CO2e/cwt milk). Another important consideration can be soil carbon sequestration. For the first 25 years or more after conversion to a perennial grassland system, GHG emissions can be substantially reduced through sequestration providing net farm emissions from the grass-based system substantially less than that of the crop-based systems (20 lb CO2e/cwt milk). It is important for research to continue investigating methods of reducing GHG emissions from various farm sources and improving carbon sequestration so that overall emissions from grazing systems can be reduced, providing another benefit to grass-based dairies.