biochar in the carbon-richh solid resideu obtained by the pyrolysis of biomass. Biochar can be used as a carbon-negative soil enhancer. the study at hand deals with the assessment of the biochar stability in the soil and its potential effect on CO2 production out of soil organic carbon by soil microbiota. furthermore, different physicochemical characterezation techniques will assessed in terms of their use in predicting the biochar in soil stability, given any type of biochar.