Biochar is charcoal that is produced by pyrolysis of biomass in the absence of oxygen; it is used as a soil amendment. Biochar is defined by the International Biochar Initiative as "The solid material obtained from the thermochemical conversion of biomass in an oxygen-limited environment".

Biochar also brings agricultural benefits by boosting soil's fertility and its ability to withstand drought or flooding; it can also rid soil of heavy metals and other pollutants. Adding biochar to 10 percent of global cropland could sequester the equivalent of 29 billion tons of CO2.