Abstract In recent decades there have been significant changes in land use and production orientation in certain marginal agricultural areas in the southwest of Spain. The abandonment of rainfed cereal crops and their change of use as natural pastures grazed by milk sheep, have led to an improvement in the profitability of the farms, greater industrialisation and a positive impact on rural development. This paper calculates the carbon footprint (CF) of farms in the context of life cycle assessment with the objective to identify the system that accounts for the lowest CF while maintaining adequate levels of profitability and revitalising the rural environment. The data were obtained through surveys carried out on dairy sheep farms of different typologies, ranging from the semi-intensive farms with small grazing areas, to the extensive farms with large areas of natural pastures. Findings could help farmers evaluate the environmental impact of their activities, while at the same time provide consumers with valuable evidence to be used in further marketing actions. Greenhouse gas emissions vary from 1.77 to 4.09 Kg CO2eq/kg of milk, where the lowest values correspond to the most intensive farms and the highest values to the most extensive and least productive farms. Enteric fermentation, followed by feeding, are the emissions with the greatest impact. Enteric fermentation reaches its maximum value (52.22 % of the total emissions) in the most extensive farms. On other hand, this study found that carbon sequestration varies between 0.09 and 2.04 kg of CO2eq/kg of milk, a figure that can considerably reduce the carbon footprint calculation and justifies its inclusion in the Life Cycle Assessment.

中文翻译：

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半干旱牧场的奶牛场：集约化和陆基放牧之间的碳足迹困境

摘要 近几十年来，西班牙西南部某些边缘农业区的土地利用和生产方向发生了重大变化。放弃雨养谷类作物并将其改作奶羊放牧的天然牧场，提高了农场的盈利能力，促进了工业化，并对农村发展产生了积极影响。本文在生命周期评估的背景下计算了农场的碳足迹 (CF)，目的是确定在保持足够的盈利水平和振兴农村环境的同时，碳足迹最低的系统。这些数据是通过对不同类型的奶羊养殖场进行的调查获得的，包括小牧场的半精养场、到拥有大面积天然牧场的广阔农场。调查结果可以帮助农民评估其活动对环境的影响，同时为消费者提供可用于进一步营销行动的宝贵证据。温室气体排放量从 1.77 到 4.09 Kg CO2eq/kg 牛奶不等，其中最低值对应于最集约化的农场，最高值对应于最粗放且生产力最低的农场。肠道发酵，其次是喂养，是影响最大的排放物。肠道发酵在最广泛的农场中达到最大值（占总排放量的 52.22%）。另一方面，这项研究发现碳固存量在 0.09 到 2.04 千克二氧化碳当量/千克牛奶之间变化，