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<p>Acidic soils are global hotspots of nitrous oxide (N<sub>2</sub>O) emissions, and biochar has been proposed as a promising mitigation strategy. However, most current evidence comes from short-term studies, and the legacy effects and underlying mechanisms remain poorly understood. Here, we collected acidic soil samples from three sites with and without biochar application, representing short-term (3 and 5&#xa0;years) and long-term (9&#xa0;years) legacy effects. Using microcosm incubations, isotope-based source partitioning, and microbial analyses, we evaluated N<sub>2</sub>O dynamics and their microbial drivers. The short-term legacy effects of biochar significantly reduced N<sub>2</sub>O emissions by inhibiting gross N<sub>2</sub>O production and enhancing N<sub>2</sub>O reduction. This was primarily attributed to reduced nitrification-derived N<sub>2</sub>O, increased <i>nos</i>Z gene abundance, and enrichment of taxa carrying the <i>nos</i>Z gene, such as <i>Rhodanobacter</i> and <i>Gemmatimonas</i>. In contrast, long-term legacy effects markedly increased N<sub>2</sub>O emissions because biochar suppressed N<sub>2</sub>O reduction more strongly than its production. This was linked to reduced <i>nos</i>Z abundance, increased fungal denitrification, and depletion of dissolved organic carbon and denitrifying bacteria. Together, these findings reveal that the legacy effects of biochar on N<sub>2</sub>O emissions diverge over time, driven by changes in microbial nitrogen cycling pathways. These results underscore the importance of incorporating temporal and microbial perspectives when evaluating the long-term climate impacts of biochar and developing sustainable soil management strategies.</p> Graphical Abstract <p></p>

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Divergent legacy effects of biochar on nitrous oxide emissions in acidic soils driven by altered microbial N pathways

  • 期刊论文

  • 出版模式：

    开放获取

  • 发表日期：

    2026年2月3日

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  • Shumin Guo,
  • Haiyan Lin,
  • Zhutao Li,
  • Zhaoqiang Han,
  • Jie Wu,
  • Xiaomeng Bo,
  • Mengxue Shen,
  • Zhiwei Zhang,
  • Shuwei Liu,
  • Jinyang Wang,
  • Jianwen Zou

摘要

Acidic soils are global hotspots of nitrous oxide (N2O) emissions, and biochar has been proposed as a promising mitigation strategy. However, most current evidence comes from short-term studies, and the legacy effects and underlying mechanisms remain poorly understood. Here, we collected acidic soil samples from three sites with and without biochar application, representing short-term (3 and 5 years) and long-term (9 years) legacy effects. Using microcosm incubations, isotope-based source partitioning, and microbial analyses, we evaluated N2O dynamics and their microbial drivers. The short-term legacy effects of biochar significantly reduced N2O emissions by inhibiting gross N2O production and enhancing N2O reduction. This was primarily attributed to reduced nitrification-derived N2O, increased nosZ gene abundance, and enrichment of taxa carrying the nosZ gene, such as Rhodanobacter and Gemmatimonas. In contrast, long-term legacy effects markedly increased N2O emissions because biochar suppressed N2O reduction more strongly than its production. This was linked to reduced nosZ abundance, increased fungal denitrification, and depletion of dissolved organic carbon and denitrifying bacteria. Together, these findings reveal that the legacy effects of biochar on N2O emissions diverge over time, driven by changes in microbial nitrogen cycling pathways. These results underscore the importance of incorporating temporal and microbial perspectives when evaluating the long-term climate impacts of biochar and developing sustainable soil management strategies.

Graphical Abstract