Carbon Footprint Assessment of Large-scale Pig Production System in Northern China: a Case Study
China raises 50% of the global live pigs. However, few studies on carbon footprint (CF) of large-scale pig production based on China’s actual production conditions have been carried out. In this study, life cycle assessment (LCA) method and actual production data of a typical large-scale pig farm in Northern China were used to assess greenhouse gas (GHG) emissions or CF associated with the whole process of pig production, including feed production (crop planting, feed processing, and transportation), enteric fermentation, manure management and energy consumption. The results showed a CF of 3.39 kg CO2-eq per kg of live market pig, and relative contributions of 55%, 28%, 13%, and 4% to the total CF by feed production, manure management, farm energy consumption, and enteric fermentation, respectively. Crop planting accounted for 66% of the feed production CF, while feed processing and transportation accounted for the remaining 34%. Long-distance transport of semi-raw feed materials caused by planting-feeding separation and over-fertilization in feed crop planting were two main reasons for the largest contribution of GHG emissions from feed production for the total CF. CF from nitrogen fertilizer application accounted for 33%-44% of crop planting, and contributed to 16% of the total CF. CF from transportation of feed ingredients accounted for 17% of the total CF. If the amount of nitrogen fertilizer used for producing the main feed ingredients is reduced from 209 kg/hm2 (for corn) and 216 kg/hm2 (for wheat) to 140 kg/hm2 (corn) and 180 kg/hm2 (wheat), respectively, the total CF would be reduced by 7%. If transportation distance for feed materials decreased from 325-493 km to 30 km, along with reducing the number of empty vehicles for the transport, total CF would be reduced by 18%. The combined CF mitigation potential for over-fertilization and transportation distance is 26%. In addition, use of pit storage – anaerobic digestion – lagoon practice can reduce GHG emissions from manure management by 76% as compared to the traditional pit storage – lagoon manure treatment method. This case study reveals the impact of planting-feeding separation and over-fertilization on CF of pig supply chain in China. Manure management practice of pit storage – anaerobic digestion – lagoon is much more conductive to reducing CF as compared to the traditional method of pit storage – lagoon.
This is a manuscript of the article Zhou, Yuanqing, Hongmin Dong, Hongwei Xin, Zhiping Zhu, Wenqiang Huang, and Yue Wang. "Carbon Footprint Assessment of Large-scale Pig Production System in Northern China: a Case Study." Transactions of the ASABE (in press) (2018). DOI: 10.13031/trans.12805. Posted with permission.