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veloped world is already declining and may continue to decline
in the future (Balmford
et al.
2005), potentially freeing up land
area that may be used to sequester carbon. Recent evidence
shows that carbon gains have occurred in agricultural land
abandoned after the collapse of the Soviet Union (soil gains of
0.47 t C per hectare per year, Vuichard
et al.
2009). This is
also known to be true of abandoned lands in Europe and North
America as it is in the early stages of succession and forest de-
velopment that carbon sink strength is strongest.
Biochar is a new and poorly understood technology and it
is likely that its effectiveness as a carbon storing strategy
will depend heavily upon economic and environmental fac-
tors. Research is still at a preliminary stage and large-scale
biochar deployment is inadvisable until these uncertainties
are resolved.
Biochar is an emerging technology in which organic materi-
als are reduced by pyrolosis at temperatures of 350–500ºC,
producing energy and a carbon rich charcoal that is returned
to the soil as a stable form of soil carbon. Research to date
has indicated that biochar may have the potential to seques-
ter significant amounts of carbon, while providing benefits
to soil fertility and nutrient retention (Lehmann
et al.
2006)
Nevertheless, the creation of biochar plantations should
be approached with great caution. While the use of biochar
could be realised in a number of ways including shifting cul-
tivation, charcoal production and the recycling of agricultural
wastes (Lehmann
et al.
2006) the most likely large-scale
source of biochar production is from the burning of biofuels.
To be justified as a carbon storage strategy, the amount se-
questered must exceed that produced in moving it between
its site of production, burning and application. In the case
of crop residues it must be ensured that biochar addition
provides a similar carbon gain to the simple return of these
materials at the site of production. The impacts of large-scale
biochar production on biodiversity and long-term agricultural
sustainability (e.g. nutrient depletion) are unknown.
Biochar: A Panacea?