title: The carbon footprint of pasture-based milk production: can white clover make a difference?
abstract: Carbon footprint (CF) calculated by life cycle assessment (LCA) was used to compare greenhouse gas emissions from pasture-based milk production relying mainly on (1) fertilizer N (FN), or (2) white clover (WC). Data were sourced from studies conducted at Solohead Research Farm in Ireland between 2001 and 2006. Ten FN pastures stocked between 2.0 and 2.5 livestock units (LU)/ha with fertilizer N input between 180 and 353 kg/ha were compared with 6 WC pastures stocked between 1.75 and 2.2 LU/ha with fertilizer N input between 80 and 99 kg/ha. The WC-based system had 11 to 23% lower CF compared with FN (average CF was 0.86 to 0.87 and 0.97 to 1.13 kg of CO(2)-eq/kg of energy-corrected milk, respectively, 91% economic allocation). Emissions of both N(2)O and CO(2) were lower in WC, whereas emissions of CH(4) (per kg of energy-corrected milk) were similar in both systems. Ratio sensitivity analysis indicated that the difference was not caused by error due to modeling assumptions. Replacing fertilizer N by biological nitrogen fixation could lower the CF of pasture-based milk production.
authors.affiliation: UCD School of Biosystems Engineering, University College Dublin, Belfield, Dublin 4, Dublin, Ireland.
authors.forename: M-J
authors.initials: MJ
authors.lastname: Yan
authors.forename: J
authors.initials: J
authors.lastname: Humphreys
authors.forename: N M
authors.initials: NM
authors.lastname: Holden
mesh_terms: D000821:Animal Feed / Q000592:standards; D000818:Animals; D058572:Carbon Footprint / Q000592:standards; D002417:Cattle; D003612:Dairying / Q000379:methods* / Q000592:standards; D005260:Female; D017752:Greenhouse Effect / Q000517:prevention & control; D008892:Milk / Q000378:metabolism; D029921:Trifolium