Global Warming Assessment of Dairy Farms: A Case Study of Organic and Conventional Fluid Milk in Thailand

The international trade in organic food has obviously increased potential in the past decade. The present study was conducted to assess and compare the first global warming impact of fluid milk production in Thailand associated to two systems, namely organic and conventional farms, by applying LCA for a case study approach. The assessment was based on a cradle-to-farm gate, with 1 kg of fat- and protein-corrected milk (FPCM) as a functional unit (FU). The environmental impact was evaluated according to International Dairy Federation or biological allocation. The results showed that the global warming values of organic farms (2.366–2.783 kg CO2 equivalent/kg FPCM) were 47% moderately higher than those of conventional farms (1.253–1.474 kg CO2 equivalent/kg FPCM). The main contributors to the global warming impact were feed consumption and CH4 emission, accounting for 33.41% and 33.19%, respectively. The highest global warming impact was found in the stages of lactating cow. Another interesting finding was lack of local organic feed with a relatively high impact on transportation stage. Based on biological allocation, the global warming impact was increased over 12.652–13.107% by the mass allocation method, whereas economic allocation exhibited no effect on the global warming impact. A sensitivity analysis result indicated that the organic farm was economically feasible as an alternative to conventional farm. The substitution of conventional farming with organic farming of 10–50% led to an annual global warming impact in Thailand of 8–30% higher than that of conventional farms.