Biochar is comprised of stable carbon compounds created when biomass is heated to temperatures between 300 to 1000°C under low (preferably zero)oxygen concentrations.
The structural and chemical composition of biochar is highly heterogeneous, with the exception of pH, which is tipically > 7.
Some properties are pervasive throughout all biochars, including the high C content and degree of aromaticity, partially explining the high levels of biochar’s inherent recalcitrance.