Biochar offers environmental benefits, such as enhanced soil aggregation and carbon sequestration. However, its effect on soil aggregation and organic carbon and nitrogen sequestration across soil textures remains unclear. In this systematic review, the results of 534 experiments reported in 100 peer-reviewed articles were analyzed. The results show that biochar addition enhances macroaggregate formation, improves aggregate water stability, and enriches organic carbon and nitrogen in different-sized aggregates compared with un-amended controls. When comparing clay and loam soils to biochar, clay soils respond more effectively to biochar than did loam soils. Specifically, the size distribution of clay aggregates responded to biochar input, whereas the organic carbon within different-sized aggregates of loam soil significantly increased. The benefits of biochar are attributed to the reduction in clay bulk density (−10.9 %) and the increase in microbial biomass carbon (+32.4 %), as well as enhanced organic matter input from plant biomass (+28.3 %) in loam. Long-term experiments (> 3 yr) revealed more macroaggregate-associated organic carbon in both loam and clay soils. Based on the results of this assessment, the optimal application conditions of biochar in loam and clay soils are as follows: in loam soils with initial organic carbon levels of 5–10 g·kg−1, biochar should be applied at a rate of 10–20 t·ha−1 to maximize large macroaggregate formation; in clay soils, an application rate of 20–40 t·ha−1 of biochar is recommended. Overall, biochar improves aggregate stability and carbon and nitrogen contents, with distinct responses in clay and loam soils.

中文翻译：

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生物炭对不同尺寸粘壤土团聚体聚集体和碳氮保留的影响：荟萃分析


生物炭具有环境效益，例如增强土壤聚集和碳封存。然而，它对土壤聚集和土壤质地中的有机碳和氮封存的影响仍不清楚。在本系统评价中，分析了 100 篇同行评审文章中报告的 534 项实验的结果。结果表明，与未修正的对照相比，生物炭添加增强了大团聚体的形成，提高了团聚体水分的稳定性，并丰富了不同大小的团聚体中的有机碳和氮。将粘土和壤土与生物炭进行比较时，粘土比壤土对生物炭的反应更有效。具体而言，粘土团聚体的粒径分布对生物炭的输入做出了响应，而壤土不同粒径团聚体中的有机碳显著增加。生物炭的好处归因于粘土体积密度的降低 （-10.9 %） 和微生物生物量碳的增加 （+32.4 %），以及植物生物量输入的增加 （+28.3 %）壤土。长期试验（> 3 yr）显示，壤土和粘土中大团聚体相关有机碳含量较高。根据评估结果，生物炭在壤土和粘土中的最佳施用条件如下：在初始有机碳水平为 5-10 g·kg-1 的壤土中，生物炭应以 10-20 t·ha-1 的施用量施用，以最大限度地形成大团聚体;在粘土中，建议生物炭的施用量为 20-40 t·ha-1。总体而言，生物炭提高了团聚体稳定性和碳氮含量，在粘土和壤土中具有明显的响应。