State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China.
University of Chinese Academy of Sciences, Beijing, China.
ISME J. 2021 Sep;15(9):2561-2573. doi: 10.1038/s41396-021-00950-w. Epub 2021 Mar 12.
Understanding the effects of changing climate and long-term human activities on soil organic carbon (SOC) and the mediating roles of microorganisms is critical to maintain soil C stability in agricultural ecosystem. Here, we took samples from a long-term soil transplantation experiment, in which large transects of Mollisol soil in a cold temperate region were translocated to warm temperate and mid-subtropical regions to simulate different climate conditions, with a fertilization treatment on top. This study aimed to understand fertilization effect on SOC and the role of soil microorganisms featured after long-term community incubation in warm climates. After 12 years of soil transplantation, fertilization led to less reduction of SOC, in which aromatic C increased and the consumption of O-alkyl C and carbonyl C decreased. Soil live microbes were analyzed using propidium monoazide to remove DNAs from dead cells, and their network modulization explained 60.4% of variations in soil labile C. Single-cell Raman spectroscopy combined with DO isotope labeling indicated a higher metabolic activity of live microbes to use easily degradable C after soil transplantation. Compared with non-fertilization, there was a significant decrease in soil α- and β-glucosidase and delay on microbial growth with fertilization in warmer climate. Moreover, fertilization significantly increased microbial necromass as indicated by amino sugar content, and its contribution to soil resistant C reached 22.3%. This study evidentially highlights the substantial contribution of soil microbial metabolism and necromass to refractory C of SOC with addition of nutrients in the long-term.
了解气候变化和长期人类活动对土壤有机碳（SOC）的影响，以及微生物的中介作用，对于维持农业生态系统土壤 C 稳定性至关重要。在这里，我们从一个长期土壤移植实验中采集了样本，在这个实验中，寒冷温带地区的大量黑土被移植到温暖温带和中亚热带地区，以模拟不同的气候条件，并进行了施肥处理。本研究旨在了解施肥对 SOC 的影响，以及在温暖气候下长期群落培养后土壤微生物的特征和作用。经过 12 年的土壤移植，施肥导致 SOC 的减少量减少，其中芳香族 C 增加，O-烷基 C 和羰基 C 的消耗减少。使用吖啶橙单染法（propodium monoazide）分析土壤活微生物，以去除死细胞中的 DNA，并通过网络模块化解释土壤易变碳变化的 60.4%。单细胞拉曼光谱结合 DO 同位素标记表明，活微生物在土壤移植后具有更高的代谢活性，可利用易降解的 C。与未施肥相比，在温暖气候下施肥后，土壤 α-和 β-葡萄糖苷酶显著减少，微生物生长延迟。此外，施肥显著增加了微生物残体（由氨基糖含量指示），其对土壤抵抗性 C 的贡献达到 22.3%。本研究明确强调了在长期施肥条件下，土壤微生物代谢和残体对 SOC 难降解 C 的重要贡献。
