A controlled kiln and manufacturing system for biochar production, including control systems and subsystems. An example controlled kiln (100) includes a drum (200), a lid (120) and a floor (250) together forming a combustion chamber configured to contain feedstock for conversion into biochar. A catalytic converter (700) may be operatively coupled with an outlet of the kiln (100). A conversion process completion detection subsystem may be operative to issue notifications. An example biochar manufacturing system includes at least one of the controlled kilns (100), a feedstock filling station (1010, 1020, 1030) for providing feedstock to kiln 100, a firing line (1040) for receiving the kiln containing feedstock, a tipping station (1050) for receiving biochar from the kiln, a biochar sizing station, and an automated handler (800) configured to move the kiln between the feedstock filling station (1010, 1020, 1030), the firing line (1040) and the tipping station (1050).