The history of biochar dates back 2,000 years to a civilization in the Amazon Basin where extensive regions of dark, highly fertile soil known as terra preta – Portuguese for “black earth” – have been discovered and analyzed, revealing high concentrations of charcoal and organic matter, such as plant and animal remains. Found only within inhabited areas, the presence of terra preta indicates that humans were deliberately responsible for its creation.
Soil scientists theorize the ancient Amazonians used a “slash-and-char” process to develop this rich soil. With slash-and-char, plant material or crop remains were cut, ignited, and buried to smolder (rather than burn), which eventually produced char, now commonly referred to as “biochar” or “agrichar.” This process isolated most of the carbon in the vegetation, creating a particularly hospitable amendment, which in turn nurtured beneficial micro-organisms that transformed the degraded soil to extremely rich and stable humus.
For centuries the slash-and-char technique produced the fertile soil – often referred to as the “Secret of El Dorado” – that supported the agricultural needs of the Amazonians, which in turn, enabled their numbers to grow by the millions. From this ancient method modern scientists have developed the technology for producing biochar as a means to improve today’s soil quality, store carbon, and generate renewable energy.