Making Bio-char is halfway between a bonfire and charcoal making. The brash is burnt in a kiln with a restricted air supply then put into sealed drums to cool before combustion is complete. The result is a fine powder consisting of carbon and ash. This locks up a considerable proportion of the carbon which would have been released into the air (as carbon dioxide) if it were burn in the open. Bio -char makes a great addition to compost as the carbon particles absorb nutrients which, when it is mixed into the soil, are slowly released to plants.
Clockwise. 1) Filling the kiln. 2) Well alight. 3) The volatiles have burn off. 4) Putting into drums to cool. 5) Tina preparing sausages for cooking on the embers.
