Biochar can be made by burning hemp biomass (post cannabinoid extraction) in a controlled process called pyrolysis. Pyrolysis is achieved using a specialized kiln that creates high temperatures in a low oxygen environment.
The kiln deposits the carbon as biochar. Biochar literally is the carbon that the hemp had captured, hardened into a solid-state that can be added back into the hemp field.
In the field, it improves soil quality and remains sequestered in the soil carbon pool for thousands of years.