Temperature sensitivity of different soil carbon pools under biochar addition

The objective of this study was to investigate the temperature sensitivity of labile and relatively recalcitrant forest soil carbon (C) pools amended with biochar during short-term incubation. Biochars were prepared using sugar cane residue under pyrolysis temperatures of 300 and 700 °C (i.e., BC300 and BC700), respectively. Coarse particulate organic matter and acid hydrolysis residue were separated from a forest soil and treated as the labile and recalcitrant C pools of the soil, respectively. Temperature sensitivity of the soil C pools was characterized using the Q₁₀ values (i.e., the proportional increase in respiration per 10 °C rise). The increased Q₁₀ values of treatments in the earlier stage were attributable to instantaneously increased aromatic C content. The following decreased Q₁₀ values were related to the consumption of labile C. However, the two types of biochars led to similar Q₁₀ values in the same C pools at the later stage of incubation, which was closely related to the nearly humic-like component content in the dissolved organic matter. The different temporal distributions of Q₁₀ values were attributable to changes of aromatic C content and continuous consumption of labile components.