State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Institute of Karst Research, Guizhou Normal University, Guiyang 550001, China; State Engineering Technology Institute for Karst Desertfication Control, Guiyang 550001, China.
Sci Total Environ. 2018 Dec 15;645:1296-1308. doi: 10.1016/j.scitotenv.2018.07.104. Epub 2018 Jul 22.
Agricultural management practices that increase carbon (C) sequestration and reduce greenhouse gas (GHG) emissions have been identified as attractive mitigation strategies. In this study, we evaluated the spatial-temporal dynamics of carbon footprints (CFs) in China and their driving factors aimed to analyze potential mitigation strategies. Our CF data comprised the GHG emissions and C sequestration of main crop production. The results indicated that from 2000 to 2015, the GHG emissions of main crop production reached 133.3 Tg CO-C equivalents (Ce) year and the soil C sequestration was 25.3 Tg Ce year, resulting in a CF of 108.0 Tg Ce year. In addition, the CF increased by only 1.9%, and 90.9% of the increase in GHG emissions was offset by C sequestration from straw return and fertilization. Moreover, the farm CF (FCF) and product CF (PCF) decreased by 9.7% and 30.4%, respectively, because the proportion of cropland practicing straw return increased by 26.4% and the improved efficiency of fertilization resulting from decrease in fertilizer use of 8 kg nitrogen (N) ha year. At the regional scale, GHG emissions increased by 9.1-65.0%, and the primary drivers underlying this change were fertilization, machinery operation and rice paddy CH flux in the northeast-northwest, north and south, respectively. However, the PCF decreased by 15.0-47.0% as soil C sequestration increased because of the decreased use of fertilizer and the implementation of straw return. The expansion of straw return and promotion of fertilization efficiency significantly mitigated 25.3 Tg Ce year emissions, indicating that these measures are important mitigation strategies and should be implemented specifically in different regions combined with other management practices. Our study provided a comprehensive method of calculating the CF of croplands and its driving factors in China and indicated potential mitigation strategies that would benefit policy selection for reduced emissions without influencing crop yields.
农业管理措施既能增加碳(C)固存,又能减少温室气体(GHG)排放,已被认为是有吸引力的缓解策略。本研究评估了中国碳足迹(CF)的时空动态及其驱动因素,旨在分析潜在的缓解策略。我们的 CF 数据包括主要作物生产的 GHG 排放和 C 固存。结果表明,2000 年至 2015 年,主要作物生产的 GHG 排放量达到 133.3Tg CO-C 当量(Ce)年,土壤 C 固存为 25.3Tg Ce 年,导致 CF 为 108.0Tg Ce 年。此外,CF 仅增加了 1.9%,而秸秆还田和施肥带来的 90.9%的 GHG 排放增加被 C 固存所抵消。此外,由于实行秸秆还田的耕地比例增加了 26.4%,施肥效率提高导致化肥用量减少了 8kg N/ha 年,农田 CF(FCF)和产品 CF(PCF)分别减少了 9.7%和 30.4%。在区域尺度上,GHG 排放量增加了 9.1%至 65.0%,变化的主要驱动因素分别是东北-西北、北和南地区的施肥、机械作业和稻田 CH 通量。然而,由于化肥用量减少和秸秆还田的实施,土壤 C 固存增加导致 PCF 减少了 15.0%至 47.0%。秸秆还田和提高施肥效率的扩大显著缓解了 25.3Tg Ce 年的排放,表明这些措施是重要的缓解策略,应结合其他管理措施,在不同地区具体实施。本研究提供了一种综合的方法来计算中国农田的 CF 及其驱动因素,并指出了潜在的缓解策略,这将有利于在不影响作物产量的情况下减少排放的政策选择。