The book “Brief Compend of American Agriculture” published in 1846 mentions multiple uses mainly for nutrient (nitrogen) conservation disease suppression. Recent research could confirm the beneficial effects of biochar on soil fertility, increasing nutrient conservation, fertilizer efficiency and reducing disease severity in horticulture. Please visit the International Biochar Initiative website for a complete list of references.
Probably the oldest description of biochar use in agriculture comes from Japan. In 1697 “fire manure” was prepared by roasting organic wastes and mixing them with nutrient rich manures. Rice husk biochar has been used for several thousand of years, since the beginning of rice cultivation in Asia. As a result of these experience and research, carbonised materials are formally authorized for use as soil amendment material in Japan, which is using 27% of its national charcoal production for purposes other than fuel, more than 30% of which is used in agriculture.