Fire-derived organic carbon turnover in soils on a centennial scale

Pyrogenic Carbon (PyC), the residue of an incomplete combustion of plant biomass, is considered as a carbon (C) sink due to its assumed stability in soil. Our meta-analysis of studies on PyC degradation challenges the assumption that PyC persist in soil for several thousand years. The turnover time for PyC estimated here ranges from decadal to centennial time scales, and is not slower than decomposition of bulk Soil Organic Matter (SOM) and differs with initial biomass, pyrolysis temperature and climate. Thus, using PyC as a strategy for offsetting carbon emissions requires caution and further research.