Higher-temperature-pyrolyzed biochar-amended neutral or alkaline
soils adsorbed much more CO2 from the atmosphere. In S4-S6
(pH N 7.0), the highest IC/TC ratio was observed in 300BC-amended
soil, CO2 release from inorganic carbon significantly decreased
for 500BC and 700BC treatments (p b 0.05). Since H2CO3 was
the unique form that dissociated immediately into CO2 and H2O at
pH b 4. When the pH was higher, the equilibrium between CO2 and carbonates
promoted the formation of carbonates (Maestrini et al., 2015),
thus to adsorb more CO2 from the atmosphere and might lead to an
under-estimation of the CO2 evolution (Blagodatskaya and Kuzyakov,
2008).