Regional assessment of dairy farm environmental footprints

Authors: Rotz, Clarence - Al; Stout, Robert; HOLLY, MICHAEL - University Of Wisconsin; Kleinman, Peter

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/4/2019
Publication Date: 6/21/2020
Citation: Rotz, C.A., Stout, R.C., Holly, M.A., Kleinman, P.J. 2020. Regional assessment of dairy farm environmental footprints. Journal of Dairy Science. 130:3275-3288. https://doi.org/10.3168/jds.2019-17388.
DOI: https://doi.org/10.3168/jds.2019-17388

Interpretive Summary: Due to the great diversity in farm management across the nation, accurate assessments of the sustainability of the dairy industry are challenging. There is a need for objective, systematic assessments, particularly environmental assessments, that reflect the diversity of practices found on farms at regional to national scales. A methodology was developed and applied to the state of Pennsylvania, which used computer simulation of dairy farms throughout the state to quantify important farm-gate life cycle emissions and resource consumptions. Pennsylvania dairy farms were found to emit 1.6% of the greenhouse gas emissions and use 0.36% of the fossil energy and 0.77% of the fresh water consumption of the state. Perhaps the greatest concern of all environmental impacts is that of ammonia emissions where dairy farms may emit half that estimated for the whole state. This provides a methodology for application to larger regional and national scale assessments of dairy production.

Technical Abstract: There is a need for a comprehensive, yet in-depth assessment of the environmental impacts of dairy farms at regional and national scales to better track improvements being made by the industry. Using Pennsylvania as an example, a methodology using process-level simulation and cradle to farm-gate life cycle assessment was developed and used to assess important environmental footprints of dairy farms within a state. Representative dairy farms of various sizes and management practices throughout seven regions of the state were simulated with the Integrated Farm System Model. Impacts for the whole state were determined by totaling values among farms and regions based upon the amounts of milk produced by each. Pennsylvania dairy farms were determined to emit 4,555 ± 415 Gg CO2e of GHG with an intensity of 0.99 ± 0.09 kg CO2e/kg of fat and protein corrected milk (FPCM) produced. Fossil energy consumption was 12,324 ± 1,946 TJ for the state and 2.69 ± 0.42 MJ/kg FPCM. Blue (non-precipitation) water consumption was 64.1 ± 13.5 Tg with an intensity of 14.0 ± 3.0 kg/kg FPCM. A total of all forms of reactive N loss was 43.2 ± 5.0 Gg with an intensity of 9.4 ± 1.1 g/kg FPCM. These metrics represented 1.6% of the GHG emissions, 0.36% of fossil energy use and 0.77% of fresh water consumption reported for the state. Perhaps the greatest concern of all environmental impacts is that of ammonia emissions, where dairy farms accounted for about half the estimated emissions of the state. This provides a methodology for application to larger regional and national scale assessments of the dairy industry.