As a dynamic process in the soil, soil aggregation has a direct impact on several vital functions, including microbial activity, greenhouse gas emissions, water storage, and nutrient availability. Biochar as a recalcitrant soil amendment could potentially regulate soil functions, especially aggregation. However, there have been conflicting studies regarding the effectiveness of biochar, its variations, and how it interacts with various soil conditions to affect aggregate status. In this regard a thorough meta-analysis was conducted, considering six categories of significant variables: soil texture, soil organic carbon (SOC), application rate, pyrolysis temperature, feedstock type, and various biochar use methodologies as well as various soil aggregation indices as impacted factors. Based on the results, wood-based biochar showed the highest efficiency above straw and manure-based biochar with a positive effect size of 15.4 % and 17.7 % for mean weight diameter (MWD) and macro-aggregate. The highest geometric mean diameter (GMD) was obtained from biochars pyrolyzed at 550< °C with 19.9 % effect size. Also, low pyrolysis temperature (<450 °C) resulted in the maximum formation of micro-aggregates with a positive effect size of 14.9 %. The moderate application of biochar (10–20 t ha) resulted in the lowest micro-aggregates (−8.9 %) and the highest macro-aggregates (24.2 %). The single application of biochar resulted in a positive effect size in the case of macro-aggregate (17.2 %) significantly higher than the combined application of biochar with fertilizer (8.1 %). The highest MWD (12.8 %) and GMD (7.1 %) were obtained from biochar-treated soils with loamy texture. Also, the high availability of SOC (2<%) caused the highest macro-aggregate formation with a positive effect size of 28.2 %. Expanding our knowledge of biochar capability and soil functions could change soil aggregation scenarios, as the variety of biochar pyrolysis processes and its application strategies could directly modify soil's dynamic structure, through inducing functional groups, carbon linkage, and soil particle rearrangement.

中文翻译：

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深入了解土壤和生物炭的变化及其对土壤团聚体状态的贡献——荟萃分析


作为土壤中的动态过程，土壤团聚对多种重要功能有直接影响，包括微生物活动、温室气体排放、水储存和养分利用率。生物炭作为一种顽固性土壤改良剂，可能会调节土壤功能，尤其是聚集作用。然而，关于生物炭的有效性、其变化以及它如何与各种土壤条件相互作用以影响团聚状态的研究相互矛盾。在这方面，进行了彻底的荟萃分析，考虑了六类重要变量：土壤质地、土壤有机碳（SOC）、施用量、热解温度、原料类型、各种生物炭使用方法以及各种土壤聚集指数影响因素。根据结果​​，木质生物炭的效率高于秸秆和粪肥生物炭，平均重量直径 (MWD) 和大骨料的正效应大小分别为 15.4% 和 17.7%。在 550< °C 下热解的生物炭获得了最高的几何平均直径 (GMD)，效应大小为 19.9%。此外，低热解温度 (<450 °C) 导致微聚集体的最大形成，其正效应大小为 14.9%。适度施用生物炭（10-20 吨公顷）导致微团聚体最低（-8.9%）和宏观团聚体最高（24.2%）。生物炭单独施用对大骨料的正效应大小（17.2%）显着高于生物炭与肥料联合施用（8.1%）。最高的 MWD (12.8%) 和 GMD (7.1%) 是从生物炭处理的壤质土壤中获得的。 此外，SOC 的高可用性 (2<%) 导致了最高的宏观聚集体形成，其正效应大小为 28.2%。扩大我们对生物炭能力和土壤功能的了解可以改变土壤聚集情况，因为生物炭热解过程的多样性及其应用策略可以通过诱导官能团、碳键和土壤颗粒重排直接改变土壤的动态结构。