Comparing direct land use impacts on biodiversity of conventional and organic milk—based on a Swedish case study

PURPOSE: Halting the loss of biodiversity while providing food security for a growing and prospering world population is a challenge. One possible solution to this dilemma is organic agriculture, which is expected to enhance biodiversity on the farmland. However, organic products often require larger areas. This study demonstrates how we can quantify and compare the direct land use impacts on biodiversity of organic and conventional food products such as milk. MATERIAL AND METHODS: This study assessed direct land use impacts of 1 l of milk leaving the farm gate. Inventory data on land occupation were extracted from a life cycle assessment study of 15 farms in southern Sweden. Direct land use change data were derived from the FAO statistical database. Spatially differentiated characterization factors of occupation (CFOcc) and transformation (CFTᵣₐₙₛ) were calculated based on the relative difference of plant species richness on agricultural land compared to a (semi) natural regional reference. Data on plant species richness and regeneration times of ecosystems (for calculating transformation impacts) were derived from a literature review. To account for differences in biodiversity value between regions, a weighting system based on absolute species richness, vulnerability and irreplaceability was applied. RESULTS AND DISCUSSION: Organic milk had a lower direct land use impact than conventional milk, although it required about double the area. Occupation impacts dominated the results and were much smaller for organic than conventional milk, as CFOccof organic land uses were considerably smaller. For transformation impacts, differences between the two farming practices were even more pronounced. The highest impacts were caused by soymeal in concentrate feeds (conventional milk) due to large-scale deforestation in its country of cultivation (i.e. Brazil and Argentina). However, lack of reliable data posed a challenge in the assessment of transformation impacts. Overall, results were highly sensitive to differences in land occupation area between farms, the CFOccand assumptions concerning transformed area. Sensitivity and robustness of results were tested and are discussed. CONCLUSIONS: Although organic milk required about twice as much land as conventional, it still had lower direct land use impacts on biodiversity. This highlights the importance of assessing land use impacts not only based on area but also considering the actual impacts on biodiversity. The presented approach allows to quantify and compare hot- and coldspots in the agricultural stage of milk production and could potentially also be applied to other agricultural products. However, more research is needed to allow quantification of indirect land use impacts.