Dairy products play an important role in human nutrition, but at the same time, the dairy sector is a major contributor to global warming. The conversion from conventional to organic milk production could reduce the carbon footprint due to the elimination of synthetic fertilizers and strong reliance on closed on-farm nutrient cycling. We present one of the first studies to comprehensively estimate the climate-change impacts of the conversion to organic production of a large-scale dairy operation in central Germany. We used detailed farm data and a carbon footprint approach based on the IPCC tier-2 methodology to estimate greenhouse gas (GHG) emissions associated with feed production, animal husbandry, and animal rearing. Our results show that the carbon footprint per kg of energy-corrected milk (ECM) decreased by 9% during the first year of conversion to organic milk production. Conversely, livestock emissions per kg ECM increased by 12% in the first conversion year due to the increase in methane emissions from enteric fermentation, but this increase was more than offset by the decrease in emissions from feed production. Emissions from internal and external feed production per kg ECM decreased by 17% and 29%, respectively. Our study helps to understand how individual emission sources change as a result of a farm’s conversion to organic production. This research is important and timely, as the European Union is pursuing ambitious goals to increase the area under organic farming, although the impact of the conversion period on GHG emissions has been insufficiently studied.

乳制品在人类营养中发挥着重要作用，但与此同时，乳制品行业也是全球变暖的主要贡献者。由于消除了合成肥料并强烈依赖封闭的农场养分循环，从传统牛奶生产向有机牛奶生产的转变可以减少碳足迹。我们提出了首批研究之一，以全面估计德国中部一家大型乳制品企业向有机生产转变对气候变化的影响。我们使用详细的农场数据和基于 IPCC 二级方法的碳足迹方法来估算与饲料生产、畜牧业和动物饲养相关的温室气体 (GHG) 排放。我们的研究结果表明，在转换为有机牛奶生产的第一年，每公斤能量校正牛奶 (ECM) 的碳足迹减少了 9%。相反，由于肠道发酵产生的甲烷排放量增加，每公斤 ECM 的牲畜排放量在第一年增加了 12%，但这种增加被饲料生产排放量的减少所抵消。每公斤 ECM 的内部和外部饲料生产的排放量分别下降了 17% 和 29%。我们的研究有助于了解个体排放源如何因农场转向有机生产而发生变化。这项研究既重要又及时，因为欧盟正在追求雄心勃勃的目标，以增加有机农业的面积，