These soils are mainly biochar, which is defined as a solid material obtained fromthermochemical conversion in an oxygen limited environment.

Quality, and especially toxicants, are problematic in biochar, so a number ofcertification schemes have been developed. For example, the European Biocharcertification and the International Biochar Initiative (IBI) have createdcertification program to ensure biochar meets certain minimum standards. Thequality of biochar is measured in these schemes by considering organic carbonlevels, ash content, and biomass.

Such schemes also consider the whole product lifecycle, such as carbon stability,metal contamination levels, economic viability, and sustainable provision offeedstock.