Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China.
Yucheng Comprehensive Experimental Station, China Academy of Science, Beijing, China.
Glob Chang Biol. 2018 Mar;24(3):987-1000. doi: 10.1111/gcb.13898. Epub 2017 Oct 16.
Agricultural soils are widely recognized to be capable of carbon sequestration that contributes to mitigating CO emissions. To better understand soil organic carbon (SOC) stock dynamics and its driving and controlling factors corresponding with a period of rapid agronomic evolution from the 1980s to the 2010s in the North China Plain (NCP), we collected data from two region-wide soil sampling campaigns (in the 1980s and 2010s) and conducted an analysis of the controlling factors using the random forest model. Between the 1980s and 2010s, environmental (i.e. soil salinity/fertility) and societal (i.e. policy/techniques) factors both contributed to adoption of new management practices (i.e. chemical fertilizer application/mechanization). Results of our work indicate that SOC stocks in the NCP croplands increased significantly, which also closely related to soil total nitrogen changes. Samples collected near the surface (0-20 cm) and deeper (20-40 cm) both increased by an average of 9.4 and 5.1 Mg C ha , respectively, which are equivalent to increases of 73% and 56% compared with initial SOC stocks in the 1980s. The annual carbon sequestration amount in surface soils reached 10.9 Tg C year , which contributed an estimated 43% of total carbon sequestration in all of China's cropland on just 27% of its area. Successful desalinization and the subsequent increases in carbon (C) inputs, induced by agricultural projects and policies intended to support crop production (i.e. reconstruction of low yield farmland, and agricultural subsidies), combined with improved cultivation practices (i.e. fertilization and straw return) since the early 1980s were the main drivers for the SOC stock increase. This study suggests that rehabilitation of NCP soils to reduce salinity and increase crop yields have also served as a pathway for substantial soil C sequestration.
农业土壤被广泛认为具有碳固存能力，有助于减少 CO 排放。为了更好地了解华北平原（NCP）从 20 世纪 80 年代到 21 世纪 10 年代快速农业发展过程中土壤有机碳（SOC）储量的动态及其驱动和控制因素，我们收集了两次区域土壤采样调查（20 世纪 80 年代和 21 世纪 10 年代）的数据，并利用随机森林模型分析了控制因素。在 20 世纪 80 年代到 21 世纪 10 年代期间，环境（即土壤盐分/肥力）和社会（即政策/技术）因素都促进了新管理实践（即化肥施用/机械化）的采用。我们的研究结果表明，NCP 耕地的 SOC 储量显著增加，这也与土壤全氮变化密切相关。表层（0-20cm）和较深层（20-40cm）采集的样本分别平均增加了 9.4 和 5.1 Mg C ha ，分别比 20 世纪 80 年代初始 SOC 储量增加了 73%和 56%。表层土壤的年碳固存量达到 10.9Tg C year ，这相当于中国所有耕地碳固存总量的 43%，而其面积仅占 27%。自 20 世纪 80 年代初以来，旨在支持作物生产的农业项目和政策（即低产农田重建和农业补贴）导致的脱盐和随后的碳（C）输入增加，以及改善的耕作实践（即施肥和秸秆还田），是 SOC 储量增加的主要驱动因素。本研究表明，NCP 土壤的修复以降低盐分和提高作物产量，也为大量土壤碳固存提供了途径。
