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Reply #19: Reality check [View All]

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HamdenRice Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Jun-08-07 08:56 AM
Response to Original message
19. Reality check
Edited on Fri Jun-08-07 09:04 AM by HamdenRice
I'm not sure that burning trees to bury the carbon has a net positive effect on carbon dioxide in the atmosphere. As the OP points out, when you make charcoal, about half of the carbon in the wood is released as carbon dioxide. If you bury the other half as charcoal, the net effect is that you have increased the amount of carbon dioxide in the air compared to the amount that was stored in the trees. In other words, a standing, in tact forest is a better carbon sink than a burned forest with half of the carbon buried as charcoal.

If you have ever seen video of an informal Amazonian charcoal maker, they are smokey, polluting little hells. I doubt that making charcoal for the purpose of burying it is good for the environment.

Also, this proposal seems to misunderstand slash and burn agriculture and tropical soils. It is true that tropical soils tend to be thin and acidic; but the land, taken in its entirety is fertile. That's because in temperate clients, the soil nutrients tend to build up in the soil as a result of winters when nothing is growing taking nutrients out of the soil. In tropical areas, where there is no winter die off, and the vegetation constantly grows, the nutrients are drawn into the foilage until there are no more in the soil, and they remain locked up in the foilage. Hence tropical farmers burn trees and foilage to release the nutrients into the soil to make them available to their crops.

There are good methods of slash and burn, called forest fallow. The farmer burns the forest, plants his crops and moves to a new field the next year, just as in bad slash and burn. But in good slash and burn, instead of a creating a frontier continuously moving into the forest, the farmer circles back after a few years of fallow. This is actually easier for the farmer because it is easier to slash and burn secondary forest (or bush) than primary forest, which has much bigger, older trees that are difficult to cut and burn. Forest fallow appears to have been the traditional form of slash and burn in much of South America and Africa.

The Amerinds of the S. American rain forest are believed to have engaged in forest fallow. A long term result of forest fallow would be a build up of charcoal in the soil. I suspect that terra petra was a by product, not a goal, of traditional agriculture.

Modern day Amazonian farmers engage in moving frontier slash and burn because of human institutions, not out of stupidity, greed or innate environmental destructiveness. In other words, the land tenure system discourages communities from circling back after a period of fallow.

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  -Terra Preta: The Benefits of the Incorporation of Charcoal into Soil AlecBGreen  Jun-07-07 10:51 AM   #0 
  - then further down the road it turns to coal....  madrchsod   Jun-07-07 10:58 AM   #1 
  - Not the same thing  Canuckistanian   Jun-07-07 11:19 AM   #3 
  - The more publicity Terra Preta gets, the better.  GliderGuider   Jun-07-07 11:13 AM   #2 
  - Ah, I was wondering if you would weigh in on this  Canuckistanian   Jun-07-07 11:23 AM   #4 
  - Good post, thanks  Canuckistanian   Jun-07-07 11:28 AM   #5 
  - yes and no  AlecBGreen   Jun-07-07 11:38 AM   #6 
     - Cool!  Canuckistanian   Jun-07-07 11:48 AM   #8 
     - I've made about 150 lbs since March. It's a pyromaniac's delight! nt  piedmont   Jun-07-07 07:14 PM   #16 
     - How do you make charcoal in a free-standing drum?  NickB79   Jun-16-07 01:22 PM   #45 
  - This really sounds like someting to be pursued aggressively!  kestrel91316   Jun-07-07 11:46 AM   #7 
  - ONE IMPORTANT THING  AlecBGreen   Jun-07-07 11:57 AM   #9 
     - Low tech time-release fertilizer.  formercia   Jun-07-07 06:28 PM   #14 
     - Presumably EPRIDA's process gets around this problem?  GliderGuider   Jun-08-07 11:16 AM   #26 
        - i know  AlecBGreen   Jun-08-07 11:34 AM   #28 
  - K & R - fascinating stuff!  MH1   Jun-07-07 02:05 PM   #10 
  - K&R  bahrbearian   Jun-07-07 02:56 PM   #11 
  - Tera Patrick unavailable for comment  paparush   Jun-07-07 03:03 PM   #12 
  - I think it's a great idea.  formercia   Jun-07-07 06:27 PM   #13 
  - When I first heard about charcoal as a soil amendment here, I was VERY skeptical...  piedmont   Jun-07-07 07:11 PM   #15 
  - K&R  petunia.here   Jun-07-07 07:48 PM   #17 
  - I just watched it - it's an excellent movie.  GliderGuider   Jun-07-07 11:20 PM   #18 
  - Reality check  HamdenRice   Jun-08-07 08:56 AM   #19 
  - Forests reach a steady state  GliderGuider   Jun-08-07 09:18 AM   #20 
     - I don't think you are seeing the balance here  HamdenRice   Jun-08-07 09:47 AM   #21 
        - I think you're both right  AlecBGreen   Jun-08-07 10:25 AM   #22 
        - one last point then I'll shut up  AlecBGreen   Jun-08-07 10:28 AM   #23 
        - Thanks for the post - more questions  blueworld   Jun-08-07 10:36 AM   #25 
           - not all trees are equal  AlecBGreen   Jun-08-07 11:32 AM   #27 
        - And I likewise think you're not seeing the balance.  GliderGuider   Jun-08-07 10:35 AM   #24 
           - Very interesting. Other plants grow even faster than vines.  phantom power   Jun-08-07 11:36 AM   #29 
           - not really  AlecBGreen   Jun-08-07 11:38 AM   #30 
           - Thanks for that explanation - it helped a lot!  Nihil   Jun-08-07 11:45 AM   #31 
           - You've changed the assumptions  HamdenRice   Jun-08-07 11:53 AM   #32 
              - Farming is exactly what would be done. But harvest after 5-10 years.  phantom power   Jun-08-07 12:07 PM   #33 
              - It does depend on your timeframe  GliderGuider   Jun-08-07 12:08 PM   #34 
                 - "your 50 year straw man"  HamdenRice   Jun-08-07 12:15 PM   #35 
                    - Fair enough.  GliderGuider   Jun-08-07 12:39 PM   #36 
                       - There's still something fishy about this, kinda like ethanol  HamdenRice   Jun-08-07 03:59 PM   #37 
                          - If all we were looking at was carbon sequestration, you would be right.  GliderGuider   Jun-08-07 04:16 PM   #38 
                          - But charcoal has no usable nutrients  HamdenRice   Jun-08-07 04:36 PM   #39 
                             - It appears to be much more active than just a conditioner  GliderGuider   Jun-08-07 05:11 PM   #40 
                             - The carbon in leaf litter will be mineralized (respired into CO2) within a year  piedmont   Jun-14-07 07:26 PM   #42 
                          - something fishy  AlecBGreen   Jun-08-07 06:23 PM   #41 
  - I have never heard of this idea, but it has several things to recommend it.  NNadir   Jun-14-07 09:56 PM   #43 
  - Hmmm, I could see this on a national level  NickB79   Jun-16-07 01:18 PM   #44 
 

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