This thesis addresses the influence of biochar discourses on the political practices in Brazil and the impact of biochar on soil organic carbon (SOC) stocks, thus contributing to the current debate on the potential of biochar to mitigate climate change. Biochar is the solid material obtained from the carbonization of biomass. Literature often suggests that biochar is recalcitrant material with a residence time in soil of thousands of years, which would make it a suitable candidate to sequester C. My findings show that there is no evidence that biochar is a reliable way for C sequestration in sandy soils under savannah environments. Biochar decomposition is highly variable, depending on charring conditions, soil and climate. These conclusions have a direct consequence for the development of policies on biochar, because we cannot ensure that biochar will sequester the same quantity of C for the same period at different geographical regions.