Compared with the acidic soils, the neutral and alkaline soils showed
negative priming effect in the early stage of incubation. Biochar initially
exhibited a suppression of SOC mineralization (30.92, 44.86, 68.65 μg C
of 300BC, 500BC, 700BC amended soil S5 on the 7th day of the incubation,
respectively). The neural and alkaline soils amended with highertemperature-pyrolyzed
biochar resulted in a higher negative priming
effect. Adsorption of DOC to biochar was introduced to explain this negative
priming effect. The concentration of DOC in biochar-amended soil
significantly decreased (Fig. S6), suggesting the protection SOC from microbial
degradation and offset the excess CO2 release by co-metabolism.
Besides, as the smaller adsorption capacity and less stable structure of
300BC, negative priming effect switched to positive priming effect
over time (Fig. 3b).