[Terrapreta] Scientific American Story on Charcoal Decomposition

[Sean K. Barry]

Hi Duane, and other TP readers,

Thanks for the article.  It seems to me that the ecosystem of charcoal mixed with leaf litter INSIDE a plastic bag is not the same as charcoal-in-soil on the floor of a boreal forest.  Wardle also makes the common mistake of not differentiating fossil carbon from other organic carbon.  Emissions into the atmosphere of burned fossil carbon fuels does increase atmospheric carbon and GHG concentrations.  Organic carbon cycling occurs ubiquitously (estimated at ~120 Gtons yr-1) and DOES NOT INCREASE atmospheric concentrations of carbon.

Organic carbon found in leaf litter laying out on a boreal forest floor will decay and release carbon into the atmosphere within no more than 5 to 10 years, anyway.  Charcoal and increased microbial activity may speed that process up a bit.  But so what?! ... it is carbon that came from the atmosphere and is just recycled back.  The increased populations of soil microbes themselves contain large amounts of carbon in their cell structures.  Is that accounted for?  Charcoal-in-soil (rather than mixed with leaf litter INSIDE a plastic bag) will create more vigorous growth of plants in the soil containing the charcoal.  This has been demonstrated numerous times.  This enhanced plant growth equates to more CO2 uptake by the plants.  That is not taken into account by Wardle's charcoal-in-a-bag experiments either.

On balance, I think Wardle's experiments only suggest that charcoal increases microbial activity and growth INSIDE a plastic bag.  We actually could have probably predicted this.  It says nothing about charcoal-in-soil that is part of an entire ecosystem.

Regards,

SKB

  ----- Original Message ----- 
  From: Duane Pendergast<mailto:still.thinking at computare.org> 
  To: 'terra preta'<mailto:terrapreta at bioenergylists.org> 
  Sent: Friday, May 02, 2008 8:42 AM
  Subject: [Terrapreta] Scientific American Story on Charcoal Decomposition


  Google found this shallow story for me. I hope this is not a redundant posting. 



  http://www.sciam.com/article.cfm?id=charcoal-in-burned-forests-no-way-to-store-carbon<http://www.sciam.com/article.cfm?id=charcoal-in-burned-forests-no-way-to-store-carbon>



  Duane









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