Originally published February 2012 in Experimentation Online.
Originally published February 2012 in Experimentation Online. In its modern guise, biochar is defined as any organic matter that has been heated in the absence or near absence of oxygen (like charcoal) but with the specific intention of applying it to soils, unlike charcoal, which is used as fuel. It is this limiting of oxygen whilst burning that causes organic carbon to mineralise into a stable solid form, rather than oxidising to form CO2 gas. The addition of char material to soils is thought to provide greater retentive capacity for nutrients, fertilisers and water and provide habitat space for micro organisms (Fig 2.) While in historic times the char would have been created by burning material in pits or kilns, the modern technique of pyrolysation is often done in purpose built machines, ranging from large industrial furnaces to small stoves. The input material or feedstock used to produce biochar can be any of a wide range of cellulous organic materials, from wood chips and rice husks to human waste. |
AuthorJohn Carson is a palynologist working mostly in the South American tropics and currently based at University of Reading. Archives |