[Terrapreta] charcoal degradation - uncertainties about its half life

[Andrew Zimmerman]

Mariska - It is generally assumed that charcoal (black carbon) is not 
very biodegradable because of its chemical composition (highly 
aromatic, with relatively little nitrogen, etc) and simply because it 
remains in the soil for long periods of time.  However, recent work 
(papers attached) has shown that microbes can indeed respire and 
abiotic reactions can breakdown this material to at least some 
extent, especially when more labile organic matter is also added (so 
called 'priming' effect).  In fact, my laboratory has found the same 
and is currently working on defining the properties of biochar and 
its remineralization rates better.  -AZ


At 01:21 PM 11/15/2007, mariska evelein wrote:
>Hello List
>
>A problem I stumbled across today is the half life of charcoal in 
>the environment.
>
>No one seems to have rigorous scientific proof that charcoal is 
>inert, but we are all assuming it is.
>
>According to the attached peer reviewed article (new directions in 
>black carbon organic geochemistry, masiello, 2004) there are some 
>serious gaps in how much black carbon is produced yearly and how 
>much of it we find in the environment, suggesting there is either a 
>problem with our scientific experiments, or there are other 
>processes that cause a black carbon loss that we haven't found out 
>about yet. Even a thousand year life span can't explain the carbon quantities.
>
>Does the fact that we find charcoal in our ancient soils mean that 
>this represents all the charcoal that was produced at that time? How 
>do we know that we are not only finding a fraction of what was once there?
>
>I would really like to believe that most the charcoal we put in our 
>soils will stay there indefinately, but am struggling to do so until 
>I find some peer reviewed evidence that proofs this.
>
>Can anybody provide me with this?
>
>Mariska
>
>
>
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___________________________________________
Andrew R. Zimmerman, PhD

Assistant Professor
Department of Geological Sciences
241 Williamson Hall
P.O. Box 112120
University of Florida
Gainesville, FL 32611
Office: (352) 392-0070
Fax: (352) 392-9294
azimmer at ufl.edu
www.clas.ufl.edu/users/azimmer/index.html

"The state of disequilibrium is one from which, in principle at 
least, it should be possible to extract some energy...."
                         -J.E. Lovelock, Gaia

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