Marie Trydeman Knudsen, Teodora Dorca-Preda, Sylvestre Njakou Djomo, Nancy Peña, Susanne Padel, Laurence G. Smith, Werner Zollitsch, Stefan Hörtenhuber og John E.Hermansen
Three basic systems representative of a range of European approaches to dairy production were selected for the analysis, i.e. (i) low-land mixed crop-livestock systems, (ii) lowland grassland-based systems, (iii) and mountainous systems. As in previous publications, this study showed that when assessing climate change, eutrophication and acidification impact organic milk has similar or slightly lower impact than conventional, although land-use is higher under organic management. Including soil carbon changes reduced the global warming potential by 5–18%, mostly in organic systems with a high share of grass in the ration. The impacts of organic milk production on freshwater ecotoxicity, biodiversity and resource depletion were 2, 33 and 20% of the impacts of conventional management, respectively, across the basic systems considered. The study highlights the importance of including biodiversity, ecotoxicity and soil carbon changes in life cycle assessments when comparing organic and conventional agricultural products. Furthermore, the study shows that including more grass in the ration of dairy cows increases soil carbon sequestration and decreases the negative impact on biodiversity.