Pyrolysis is a thermochemical decomposition process that involves heating organic material in the absence of oxygen to produce biochar. Biochar is the solid product leftover after pyrolysis and contains carbon. Indigenous people in the Amazon used various methods of biochar production through pyrolysis centuries ago which helped develop dark, carbon-rich soils that improved agricultural productivity. Various low-tech methods can be used to make biochar, including metal drums, cans, sheets, furnaces, and matting which allow containment of organic materials during pyrolysis.