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<p>To elucidate the mechanisms by which long-term straw return regulates soil organic carbon (SOC) sequestration and aggregate-associated carbon accumulation across contrasting soil textures (clay loam vs. sandy loam) under wheat-cotton cropping system. A 10-year field experiment was conducted using a randomized block design with nine straw input rate treatments in two soil types: clay loam (Nanjing) and sandy loam (Dafeng). SOC dynamics and aggregate-associate carbon distribution were analyzed at 0–10&#xa0;cm and 10–20&#xa0;cm depths. SOC increased linearly with straw inputs in both soils. However, clay loam exhibited carbon stabilization in silt and clay fractions (&lt; 53&#xa0;μm) at high application rates, while sandy loam had linear carbon accrual across all aggregate classes without saturation signals. Logarithmic saturation was observed in dissolved organic carbon (R²=0.709) and microbial biomass carbon (R²=0.664) in the 0–10&#xa0;cm layer of clay loam. Persistent linear accumulation occurred across all labile carbon fractions in sandy loam. Hierarchical carbon saturation phenomenon emerged in clay loam aggregates after 10 years of straw return. These differential responses were attributed to the active mediator role of labile carbon pools in regulating aggregate carbon saturation processes. Straw return enhances SOC sequestration without reaching whole-soil saturation threshold, but texture-specific mechanisms govern carbon stabilization. These findings provide a mechanistic basis for optimizing straw return strategies depend on soil texture.</p>

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Effect of Straw Input on Soil Carbon Sequestration in Clay Loam and Sandy Loam Soils in a Wheat-cotton Cropping System

  • 期刊论文

  • 发表日期：

    2025年7月21日

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  • Zhaorui Cheng,
  • Li Zha,
  • Guowen Fang,
  • Qiang Li,
  • Zhiguo Zhou,
  • Yali Meng

摘要

To elucidate the mechanisms by which long-term straw return regulates soil organic carbon (SOC) sequestration and aggregate-associated carbon accumulation across contrasting soil textures (clay loam vs. sandy loam) under wheat-cotton cropping system. A 10-year field experiment was conducted using a randomized block design with nine straw input rate treatments in two soil types: clay loam (Nanjing) and sandy loam (Dafeng). SOC dynamics and aggregate-associate carbon distribution were analyzed at 0–10 cm and 10–20 cm depths. SOC increased linearly with straw inputs in both soils. However, clay loam exhibited carbon stabilization in silt and clay fractions (< 53 μm) at high application rates, while sandy loam had linear carbon accrual across all aggregate classes without saturation signals. Logarithmic saturation was observed in dissolved organic carbon (R²=0.709) and microbial biomass carbon (R²=0.664) in the 0–10 cm layer of clay loam. Persistent linear accumulation occurred across all labile carbon fractions in sandy loam. Hierarchical carbon saturation phenomenon emerged in clay loam aggregates after 10 years of straw return. These differential responses were attributed to the active mediator role of labile carbon pools in regulating aggregate carbon saturation processes. Straw return enhances SOC sequestration without reaching whole-soil saturation threshold, but texture-specific mechanisms govern carbon stabilization. These findings provide a mechanistic basis for optimizing straw return strategies depend on soil texture.