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Background and Aims <p>Food legumes contribute to sustainable agriculture by supporting nutritional security and soil fertility. However, the spatial distribution of soil organic carbon (SOC) content across croplands in China&#xa0;and its key driving factors in food legume systems remain not generalized.</p> Methods <p>To fill this knowledge gap, we conducted a large-scale soil survey across 456 sites spanning major food legume-producing regions in China and used random forest model combined with SHapley Additive exPlanations (SHAP) to identify the key factors correlated with SOC content.</p> Results <p>SOC content ranged from 1.3 to 52&#xa0;g&#xa0;C&#xa0;kg<sup>−1</sup>, with a mean of 12.1&#xa0;g&#xa0;C&#xa0;kg<sup>−1</sup>. Microbial properties, especially microbial biomass carbon (MBC) and <i>β</i>-glucosidase (BG) activity, were closely correlated with&#xa0;the SOC content, followed by soil physico-chemical properties (available iron, dissolved organic carbon, and clay content) and climatic factors (temperature and precipitation). Notably, SOC content was markedly higher at elevations above 1348&#xa0;m (18.0&#xa0;g&#xa0;C&#xa0;kg<sup>−1</sup>) than below this threshold (9.8&#xa0;g&#xa0;C&#xa0;kg<sup>−1</sup>). Structural equation modeling revealed contrasting elevation-dependent associations among the factors related to SOC content. At high elevation, cooler and drier conditions increased MBC content but constrained microbial activity, leading to higher SOC. In contrast, warmer and wetter conditions at low elevation stimulated both soil C inputs and microbial activity, but increased microbial decomposition partly offset these gains, limiting net SOC increases.</p> Conclusions <p>This study identified microbial biomass and enzyme activities as the primary factors of SOC content in food legume-based agroecosystems and demonstrated that elevation shapes distinct microbial and abiotic controls on SOC content at the national scale.</p>

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Elevation-dependent factors of soil organic carbon in food legume-based agroecosystems

  • 期刊论文

  • 发表日期：

    2026年7月1日

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  • Qi Liu,
  • Xuebin Xu,
  • Shuang Wang,
  • Liang Wei,
  • Yongfu Li,
  • Wenli Ling,
  • Xiang Wan,
  • Wu Xiang,
  • Zhenke Zhu,
  • Yakov Kuzyakov,
  • Qiong Liu,
  • Tida Ge

摘要

Background and Aims

Food legumes contribute to sustainable agriculture by supporting nutritional security and soil fertility. However, the spatial distribution of soil organic carbon (SOC) content across croplands in China and its key driving factors in food legume systems remain not generalized.

Methods

To fill this knowledge gap, we conducted a large-scale soil survey across 456 sites spanning major food legume-producing regions in China and used random forest model combined with SHapley Additive exPlanations (SHAP) to identify the key factors correlated with SOC content.

Results

SOC content ranged from 1.3 to 52 g C kg−1, with a mean of 12.1 g C kg−1. Microbial properties, especially microbial biomass carbon (MBC) and β-glucosidase (BG) activity, were closely correlated with the SOC content, followed by soil physico-chemical properties (available iron, dissolved organic carbon, and clay content) and climatic factors (temperature and precipitation). Notably, SOC content was markedly higher at elevations above 1348 m (18.0 g C kg−1) than below this threshold (9.8 g C kg−1). Structural equation modeling revealed contrasting elevation-dependent associations among the factors related to SOC content. At high elevation, cooler and drier conditions increased MBC content but constrained microbial activity, leading to higher SOC. In contrast, warmer and wetter conditions at low elevation stimulated both soil C inputs and microbial activity, but increased microbial decomposition partly offset these gains, limiting net SOC increases.

Conclusions

This study identified microbial biomass and enzyme activities as the primary factors of SOC content in food legume-based agroecosystems and demonstrated that elevation shapes distinct microbial and abiotic controls on SOC content at the national scale.