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<p>Organic amendments such as straw and biochar are widely applied to enhance soil fertility, yet their distinct contributions to soil organic C (SOC) stabilization remains poorly understood. Through a 180-day laboratory incubation experiment, we quantified and compared the effects of two straw amendment strategies—direct straw incorporation and straw-derived biochar application—on SOC stabilization across different soil types, with a focus on the underlying chemical and microbial mechanisms. This study revealed that biochar-treated soils exhibited significantly lower SOC mineralization than straw-treated soils. Furthermore, biochar-straw co-application demonstrated greater efficacy in suppressing C losses relative to straw alone, with reductions of 49% in sodic solonchaks and ~ 25% in cambisols. This reduction was attributed to biochar’s inherent resistance to microbial degradation, strong adsorption of ammonium nitrogen, and reduced dissolved organic C availability. These effects highlight biochar’s dual role as both a biologically inert C pool and an active regulator of soil nutrient dynamics. Notably, biochar application promoted SOC stabilization by increasing the aromatic-to-aliphatic C ratio (quantified as relative absorbance ratio of 1630&#xa0;cm⁻¹ to 2920&#xa0;cm⁻¹, rA1630/rA2920), indicating enhanced aromatic C accumulation while suppressing bacterial activity and aliphatic C formation. In contrast, direct straw incorporation stimulated microbial growth, increasing microbial residue C accrual, its contribution to SOC (~ 13%), and the fungal-to-bacterial residue C ratio, suggesting distinct SOC stabilization via microbial residue formation. Straw amendment significantly enhanced microbial residue C accumulation by ~ 20% relative to controls and biochar treatments, where biochar-treated soils showed microbial residue C levels similar to controls. Notably, under straw amendment, cambisols exhibited a 1.5-fold greater microbial residue contribution to SOC than sodic solonchaks. These findings demonstrate a fundamentally different SOC stabilization mechanisms: biochar enhances chemical stabilization through aromatic C enrichment, whereas straw fosters biological stabilization through microbial residue accumulation. Moreover, the ability of biochar to mitigate nutrient-induced SOC destabilization underscores its potential for reducing soil CO<sub>2</sub> emissions and advancing sustainable soil C management.</p>

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Interactive effects of straw and biochar amendments on soil organic carbon stabilization and bacterial community dynamics

  • 期刊论文

  • 发表日期：

    2025年10月2日

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  • Ninghui Xie,
  • Yuchuan Fan,
  • Ning Duan,
  • Lu Yang,
  • Mark Radosevich,
  • Ying Zhang,
  • Yongfeng Wang,
  • Jingkuan Wang,
  • Xiaolong Liang

摘要

Organic amendments such as straw and biochar are widely applied to enhance soil fertility, yet their distinct contributions to soil organic C (SOC) stabilization remains poorly understood. Through a 180-day laboratory incubation experiment, we quantified and compared the effects of two straw amendment strategies—direct straw incorporation and straw-derived biochar application—on SOC stabilization across different soil types, with a focus on the underlying chemical and microbial mechanisms. This study revealed that biochar-treated soils exhibited significantly lower SOC mineralization than straw-treated soils. Furthermore, biochar-straw co-application demonstrated greater efficacy in suppressing C losses relative to straw alone, with reductions of 49% in sodic solonchaks and ~ 25% in cambisols. This reduction was attributed to biochar’s inherent resistance to microbial degradation, strong adsorption of ammonium nitrogen, and reduced dissolved organic C availability. These effects highlight biochar’s dual role as both a biologically inert C pool and an active regulator of soil nutrient dynamics. Notably, biochar application promoted SOC stabilization by increasing the aromatic-to-aliphatic C ratio (quantified as relative absorbance ratio of 1630 cm⁻¹ to 2920 cm⁻¹, rA1630/rA2920), indicating enhanced aromatic C accumulation while suppressing bacterial activity and aliphatic C formation. In contrast, direct straw incorporation stimulated microbial growth, increasing microbial residue C accrual, its contribution to SOC (~ 13%), and the fungal-to-bacterial residue C ratio, suggesting distinct SOC stabilization via microbial residue formation. Straw amendment significantly enhanced microbial residue C accumulation by ~ 20% relative to controls and biochar treatments, where biochar-treated soils showed microbial residue C levels similar to controls. Notably, under straw amendment, cambisols exhibited a 1.5-fold greater microbial residue contribution to SOC than sodic solonchaks. These findings demonstrate a fundamentally different SOC stabilization mechanisms: biochar enhances chemical stabilization through aromatic C enrichment, whereas straw fosters biological stabilization through microbial residue accumulation. Moreover, the ability of biochar to mitigate nutrient-induced SOC destabilization underscores its potential for reducing soil CO2 emissions and advancing sustainable soil C management.