Biochar is a charcoal-like substance produced by heating organic matter such as wood or manure in low-oxygen conditions. It has a stable, porous structure that retains nutrients and improves soil properties like water retention and aggregation. Interest in biochar as a soil amendment stems from the discovery of fertile Dark Earth soils in the Amazon that were artificially enriched with charcoal by indigenous peoples. Research shows biochar can sequester carbon in soil for centuries while improving soil fertility and crop yields.

1. What is biochar?
Biochar.org
Biochar is the product of heating organic
matter such as wood, manure or plant
material to temperatures over 300oC in a
low-oxygen environment (pyrolysis) and is
similar to charcoal.
Biochar contains a high proportion of hexagonal carbon rings,
making it highly stable in the soil, and retains many of the
nutrients and minerals present in the original feedstock.
Interest in biochar as a soil amendment was
stimulated by the discovery of Terra preta
(Portuguese: Dark earth) in Amazonia. The
typical rainforest soils in the region are
poor, but large areas of fertile land had
been created by the early indigenous
peoples through the addition of organic
matter and charcoal.
Terra preta soils created many centuries
ago retain significant levels of stable
carbon and are still highly fertile.
This has stimulated research to establish
the role of charcoal (biochar) in
producing these properties.
Left-Crop yield with biochar and
fertilizer.
Right- Yield with fertilizer only.
(www.mcgbiocharpod.webs.com)
UK Biochar Research Centre
Biochar has been envisaged as having
four co-benefits:
• Climate mitigation by the long-term
sequestration of carbon in the soil.
• Energy production from oils , gases
and heat produced during pyrolysis.
• Management of organic wastes.
• Soil improvement.
Biochar has a highly porous structure and a
huge internal surface area. It has been
shown to improve water retention and
aggregation of the soil. Other benefits
include immobilisation of contaminants
(e.g. heavy metals ) and an increase in
beneficial soil micro-organisms.
Biochar removes carbon from the
natural plant/atmosphere carbon
cycle and stores it in the soil.
Evidence suggests that this carbon
will remain locked in the soil for
centuries to millennia, making a
significant contribution to the
reduction of atmospheric CO2
Plants remove CO2 naturally from the
atmosphere. Biochar locks some of this
carbon into the soil.
(International Biochar Initiative)
Philip Harries, Biochar Research Team, Swansea University. E-mail 450433@swansea.ac.uk
Left- typical Amazonian soil.
Right- Terra preta soil. (Bruno
Glaser)
Scanning electron
microscope image showing
the highly porous structure
of biochar