Biochars

Biochar, also known as black carbon, is a product derived from organic materials rich in carbon (C) and is found in soils in very stable solid forms, often as deposits. Biochars can persist for long periods of time in the soil at various depths, typically thousands of years. The most common example is charcoal, derived from wood. Similarly, the Terra Preta soils of the Amazon Basin are one of the more widely known examples of biochar. -- An Introduction to Biochars and Their Uses in Agriculture