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Background <p>Tea plantation soils serve as vital carbon (C) sinks rich in soil organic carbon (SOC), yet existing research primarily focuses on the 0–20&#xa0;cm topsoil, leaving a lack of systematic study of SOC mineralization characteristics and microbial regulatory mechanisms across the full 0–100&#xa0;cm soil profile. Therefore, we conducted incubation experiments with typical tea plantation soils to clarify changes in SOC mineralization, the SOC pool, the microbial community, and the functional genes (such as <i>GH48</i> and <i>cbh</i>I) and enzyme activities related to C decomposition at five soil depths (0–20&#xa0;cm, 20–40&#xa0;cm, 40–60&#xa0;cm, 60–80&#xa0;cm, and 80–100&#xa0;cm), and to elucidate their relationships, thereby revealing the mechanisms affecting SOC mineralization in different soil layers.</p> Results <p>The results revealed significant declines in SOC mineralization rate (from 842 to 431&#xa0;mg kg⁻¹), particulate organic carbon, water-soluble organic carbon, microbial biomass carbon, β-glucosidase (from 71.6 to 18.2&#xa0;µg g<sup>− 1</sup> h<sup>− 1</sup> at the end of incubation), cellobiohydrolase (from 0.229 to 0.091 mg g<sup>− 1</sup> 3d<sup>− 1</sup> at the end of incubation), <i>GH48</i> and <i>cbh</i>I gene abundances (decreased from 9.2 × 10<sup>7</sup> to 1.8 × 10<sup>7</sup> and 7.6 × 10<sup>7</sup> to 1.4 × 10<sup>6</sup> copies g<sup>− 1</sup> at the end of incubation, respectively), respectively with increasing soil depth. The decrease in the SOC mineralization rate with increasing soil depth was significantly associated with declines in the labile C fraction, C-decomposition-related extracellular enzyme activity, and functional gene abundance. Additionally, increasing soil depth significantly altered the microbial community structure and composition, particularly the relative abundances of dominant taxa such as Alphaproteobacteria, Bacilli, Sordariomycetes, Tremellomycetes, Mortierellomycetes, and Dothideomycetes, thereby further influencing SOC mineralization rate.</p> Conclusions <p>Our findings demonstrate that increasing soil depth significantly alters soil microbial community characteristics, particularly by reducing the abundance of C-degrading functional genes and enzyme activities, thereby lowering SOC mineralization rate and attenuating soil carbon emissions. These results underscore the importance of deep tillage during fertilization and the incorporation of pruning residue to enhance SOC sequestration in tea plantations.</p>

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Microbial community changes mediate the decline in soil organic carbon mineralization with depth in tea plantations

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月13日

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  • Shaobo Zhang,
  • Yifeng Xie,
  • Hongbing Zhang,
  • Junyan Lv,
  • Weizhen Wu,
  • Wenyan Han,
  • Gaodi Zhu,
  • Qiuhong Wang,
  • Claudien Habimana Simbi,
  • Rongxiu Yin,
  • Xin Li

摘要

Background

Tea plantation soils serve as vital carbon (C) sinks rich in soil organic carbon (SOC), yet existing research primarily focuses on the 0–20 cm topsoil, leaving a lack of systematic study of SOC mineralization characteristics and microbial regulatory mechanisms across the full 0–100 cm soil profile. Therefore, we conducted incubation experiments with typical tea plantation soils to clarify changes in SOC mineralization, the SOC pool, the microbial community, and the functional genes (such as GH48 and cbhI) and enzyme activities related to C decomposition at five soil depths (0–20 cm, 20–40 cm, 40–60 cm, 60–80 cm, and 80–100 cm), and to elucidate their relationships, thereby revealing the mechanisms affecting SOC mineralization in different soil layers.

Results

The results revealed significant declines in SOC mineralization rate (from 842 to 431 mg kg⁻¹), particulate organic carbon, water-soluble organic carbon, microbial biomass carbon, β-glucosidase (from 71.6 to 18.2 µg g− 1 h− 1 at the end of incubation), cellobiohydrolase (from 0.229 to 0.091 mg g− 1 3d− 1 at the end of incubation), GH48 and cbhI gene abundances (decreased from 9.2 × 107 to 1.8 × 107 and 7.6 × 107 to 1.4 × 106 copies g− 1 at the end of incubation, respectively), respectively with increasing soil depth. The decrease in the SOC mineralization rate with increasing soil depth was significantly associated with declines in the labile C fraction, C-decomposition-related extracellular enzyme activity, and functional gene abundance. Additionally, increasing soil depth significantly altered the microbial community structure and composition, particularly the relative abundances of dominant taxa such as Alphaproteobacteria, Bacilli, Sordariomycetes, Tremellomycetes, Mortierellomycetes, and Dothideomycetes, thereby further influencing SOC mineralization rate.

Conclusions

Our findings demonstrate that increasing soil depth significantly alters soil microbial community characteristics, particularly by reducing the abundance of C-degrading functional genes and enzyme activities, thereby lowering SOC mineralization rate and attenuating soil carbon emissions. These results underscore the importance of deep tillage during fertilization and the incorporation of pruning residue to enhance SOC sequestration in tea plantations.