Biochar promotes the storage of organic carbon (OC) in soils. OC is unevenly distributed in soils among different particle-size fractions showing different structures, functions, and stability. The objective of this study was to investigate the biochar–soil interactions and the redistribution of soil C in different soil fractions based on a 2-year field experiment. Fractionation was done by particle sizes including coarse sand (250–2,000 μm), fine sand (53–250 μm), and silt/clay (<53 μm). Integrated spectroscopic techniques were employed to examine physical characteristics of biochar–soil interactions in different soil fractions. Application of biochar increased OC by 37%, 42%, and 76% in soil particle-size fractions of 53–250, <53, and 250–2,000 μm, respectively. This was supported by X-ray fluorescence spectroscopy analysis, which showed an increase of C contents by 5–56% with biochar addition. The highest increment in OC was found in coarse sand fraction, and redistribution of OC was detected depending on various soil particle sizes. Results of scanning electron microscopy combined with electron dispersive X-ray spectroscopy analysis showed the interactions between soil and biochar, which could be attributed to oxidized functional groups (OCO, CO, and CO) captured by the X-ray photoelectron spectroscopy. The long-term aged biochar could be beneficial to enhance soil quality by promoting OC storage and facilitating positive biochar–soil interactions.

中文翻译：

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生物炭影响土壤碳库并促进与土壤的相互作用：实地调查

生物炭促进土壤中有机碳 (OC) 的储存。有机碳在土壤中的不同粒径级分中分布不均，表现出不同的结构、功能和稳定性。本研究的目的是基于为期 2 年的田间试验，研究生物炭与土壤的相互作用以及不同土壤组分中土壤碳的重新分布。分馏按粒径进行，包括粗砂（250–2,000 μm）、细砂（53–250 μm）和粉砂/粘土（<53 μm）。综合光谱技术被用来检查不同土壤组分中生物炭-土壤相互作用的物理特性。应用生物炭使土壤粒径为 53-250、<53 和 250-2,000 μm 的土壤中的 OC 分别增加了 37%、42% 和 76%。这得到了 X 射线荧光光谱分析的支持，添加生物炭后，C 含量增加了 5-56%。在粗砂部分发现 OC 的最大增量，并且检测到 OC 的重新分布取决于不同的土壤颗粒大小。扫描电子显微镜结合电子色散 X 射线光谱分析的结果表明，土壤和生物炭之间存在相互作用，这可能归因于 X 射线光电子能谱捕获的氧化官能团（OCO、CO 和 CO）。长期老化的生物炭可能通过促进 OC 储存和促进生物炭 - 土壤的积极相互作用来提高土壤质量。扫描电子显微镜结合电子色散 X 射线光谱分析的结果表明，土壤和生物炭之间存在相互作用，这可能归因于 X 射线光电子能谱捕获的氧化官能团（OCO、CO 和 CO）。长期老化的生物炭可能通过促进 OC 储存和促进生物炭 - 土壤的积极相互作用来提高土壤质量。扫描电子显微镜结合电子色散 X 射线光谱分析的结果表明，土壤和生物炭之间存在相互作用，这可能归因于 X 射线光电子能谱捕获的氧化官能团（OCO、CO 和 CO）。长期老化的生物炭可能通过促进 OC 储存和促进生物炭 - 土壤的积极相互作用来提高土壤质量。