The impact of silicon-modified biochar on carbon sequestration pathways in saline-alkali soil under different pyrolysis temperatures
摘要
Soil organic carbon (SOC) plays a critical role in ameliorating saline-alkali soils characterized by poor aggregate structure. This study explicitly clarifies how SiBC interacts with pyrolysis temperatures to alter SOC stabilization pathways compared to BC, quantifying the shifts between nutrient-mediated and soil property-driven retention mechanisms.
MethodsThis study investigated the effects of applying BC and SiBC, pyrolyzed at 300, 500, and 700 °C, in a 120-day incubation experiment at a 3% application rate.
ResultsSiBC amendment exhibited superior remediation efficacy compared to BC. Specifically, soils treated with SiBC enhanced cation exchange capacity by 21.02%–56.40%, significantly surpassing the BC treatments. Furthermore, SiBC application increased mineral-associated organic carbon (MAOC) by 27.5%–39.6%. The low-temperature S+SiBC300 treatment exhibited the highest dissolved organic carbon (143.07 mg kg⁻¹) and aggregation stability indexs (MWD and R> 0.25). Structural analysis revealed that the SiBC was enriched in oxygen-containing functional groups, which facilitated aliphatic carbon retention in the soil. Partial least squares path modeling identified aggregate stability as the primary driver of SOC stability.
ConclusionOverall, the application of low-temperature SiBC was optimal for aggregate-mediated physical protection, whereas high-temperature SiBC was advantageous for long-term stabilization via organo-mineral associations. These findings reveal that SiBC could restore soil health and promote agricultural sustainability in degraded saline-alkali agroecosystems.