[Terrapreta] New Scientist: Burying trees to fight climatechange

[Peter Read]

I recollect this being called "pickling logs" in the early 1990's
Deep burial would release large quantities of carbon through oxidation of disturbed/exposed soil organic matter - one aspect of the concern over 'carbon debt'  raised in the recent science paper by Fargione et al.
Avoiding soil disturbance though low- or no-till cultivation is part of developing understanding of best practice land use improvement.
A thing I have wondered about is, suppose you just scatter biochsar on the soil surface, does it get carried down by rain, bugs, worms etc ?  One proposal form pastoral land is to feed biochar to mixing into cattle cake and then let nature do the rest.  Any ideas on how well that would work?
Cheers
Peter
  ----- Original Message ----- 
  From: Sean K. Barry 
  To: terra pretta group ; Laurens Rademakers 
  Sent: Saturday, May 03, 2008 2:19 PM
  Subject: Re: [Terrapreta] New Scientist: Burying trees to fight climatechange


  Hi Lorenzo,

  I suspect that burying trees "deeply" into the ground would require more energy than putting charcoal into or onto the topsoil.  There would be NO agricultural benefit for having the tress buried into the ground and there would be NO energy harvested from that carbon rich biomass.

  So, burying trees by comparison to charring biomass and adding the charcoal to the soil seems to not take advantage of some pretty worthwhile benefits;  improving food agricultural production, harvesting needed renewable energy instead of continuing to burn fossil fuels, and doing all of this while also sequestering carbon into soil for thousands of years.

  Regards,

  SKB
    ----- Original Message ----- 
    From: Laurens Rademakers 
    To: terra pretta group 
    Sent: Friday, May 02, 2008 8:11 PM
    Subject: [Terrapreta] New Scientist: Burying trees to fight climate change


    Original here (subscription required):
    http://environment.newscientist.com/channel/earth/mg19826542.400-burying-trees-to-fight-climate-change.html

    Mongabay's summary:

     Could cutting down trees and burying them help fight global warming? An article in this week's issue of New Scientist suggests so. 

    Ning Zeng, an atmospheric scientist at the University of Maryland in College Park, tells New Scientist that thinning forests and burying "excess wood" in a manner in which its didn't decay could sequester enough carbon to offset all of our fossil-fuel emissions. 

    "Zeng gives an example of a plot of 1 square kilometre (100 hectares), with the excess wood from 1 hectare of woodland buried deeper than 5 metres and down to 20 metres," writes Richard Lovett of New Scientist, referring to Zeng's research published in Carbon Balance and Management. "He calculates that this could sequester 1 tonne of carbon per hectare - using that land to grow trees would sequester 1 to 5 tonnes, depending on the age of the forest and the type of tree." 

     "He estimates that offsetting all of the world's current emissions would be achievable with a workforce of one million people - substantially fewer than those already employed in the forestry industry in the US alone," Lovett continues. "Even so, to offset all our emissions, most of the world's forests would have to run a wood burial scheme." 

    New Scientist notes that Zeng's idea is not a new one - ancient indigenous groups used a similar approach known as biochar to enrich the nutrient-poor soils of the Amazon rainforest. 

    "More than 500 years ago Amazonian people were creating almost pure carbon by smouldering their domestic waste and letting it work its way into the soil. This earth, known as terra preta ('black earth') remains to this day," Lovett writes. "Ancient farmers had no idea that they were sequestering carbon, of course, but they did know that adding biochar to the soil hugely increased its quality." 

    Lovett cites a modern example in hydrothermal carbonization, a process which chars organic material under pressure. He says the technique could eventually be used on an industrial scale and may qualify for carbon credits, assuming it could avoid generating methane, another potent greenhouse gas. 

    http://news.mongabay.com/2008/0430-soil_carbon.html

    -----------------------------------------

    Interesting concept. We could use an economic comparison of biochar systems in agriculture as compared to Zeng's idea of just burying the trees deeply into the ground.

    Cheers, Lorenzo




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