AI Insight
This global meta-analysis of 19 studies found that adding biochar to soil consistently reduces its thermal properties: thermal conductivity decreased by 17.6%, thermal diffusivity by 11.0%, and volumetric heat capacity by 8.3%. The effects were most strongly associated with changes in soil bulk density, with application rate and soil texture also influencing the magnitude of response. The coordinated changes across thermal properties indicate biochar causes structural reorganization of soil rather than affecting isolated parameters independently.
Why it matters
These findings are important for predicting how biochar amendments will affect soil temperature regulation, which has implications for both agricultural management and climate modeling. Understanding these thermal property changes is essential for accurately incorporating biochar effects into soil and land-surface models used for climate predictions and carbon sequestration strategies.
Understand the Science
⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Biochar amendments are increasingly applied to improve soil physical functioning and support carbon dioxide removal, but their effects on intrinsic soil thermal properties remain poorly characterised. We conducted the first global systematic meta-analysis of 19 independent studies, 231 control-biochar comparisons, and 529 property-specific effect sizes to test how biochar changes soil heat transfer and storage. Biochar reduced thermal conductivity by 17.6% (95% CI, -22.7 to -12.2), thermal diffusivity by 11.0% (-14.5 to -7.3), and volumetric heat capacity by 8.3% (-12.3 to -4.1). Gravimetric heat capacity showed no significant overall response (+3.3%; -7.6 to 15.4) but was supported by fewer studies. Negative responses were directionally consistent for thermal conductivity, diffusivity, and volumetric heat capacity. Moderator analyses showed that responses were most consistently associated with post-application bulk density and changes in bulk density, while application rate modulated response magnitude and soil texture constrained context dependence. Co-variation among thermal conductivity, thermal diffusivity, and volumetric heat capacity matched expected physical dependencies, indicating coordinated structural reorganisation rather than independent shifts in isolated parameters. These estimates describe intrinsic conductive and storage properties; field-scale soil temperature responses may also be modified by albedo, evaporation, vegetation, and surface energy balance. Improved integration of soil thermal measurements with moisture dynamics, structural changes, and carbon cycling is essential to accurately represent biochar effects in soil and land-surface models.