Abstract
Biochar application has been proposed as a promising strategy for enhancing soil organic carbon (SOC) sequestration and mitigating climate change. However, long-term field studies in temperate agricultural systems remain limited. This study synthesizes findings from a multi-site field trial across temperate Europe to evaluate the effects of a single biochar application (20 t ha⁻¹) on SOC stocks, soil physicochemical properties, and microbial activity over a 10-year period. Soil samples were collected at 0–20 cm depth from biochar-amended and control plots at three sites with contrasting soil textures (sandy loam, silt loam, clay loam). SOC content was measured using dry combustion, and carbon fractions were determined by wet oxidation. Microbial biomass carbon (MBC) and basal respiration were assessed. Results showed that biochar significantly increased SOC stocks by an average of 8.2 Mg C ha⁻¹ over 10 years, with the largest increases in clay loam soil. The stable carbon fraction (resistant to oxidation) accounted for 70% of the additional SOC. Biochar also improved soil water holding capacity by 12% and reduced bulk density by 5%. Microbial activity was initially suppressed but recovered after 3 years, with MBC increasing by 15% in the long term. Our findings confirm that biochar can contribute to long-term carbon sequestration in temperate agricultural soils, with effects modulated by soil texture. We recommend site-specific biochar application rates to optimize carbon storage and soil health benefits.
Keywords
Biochar, Carbon sequestration, Temperate soils, Soil organic carbon, Long-term field trial, Soil texture, Microbial activity, Soil health