[permaculture] Biochar

Toby Hemenway toby at patternliteracy.com
Thu Nov 17 12:23:08 EST 2011

Dieter, I don't see it in the stark either-or terms that you put it in. We're talking about two different goals and processes here--soil building alone via humus, and using biochar to provide heat while sequestering carbon and building soil in a different way. Obviously, the idea of clearing all biomass and pyrolizing it into charcoal is insane. But many people are going to use some sort of fuel for cooking or heating--in the developed world, we avoid the whole issue by using petroleum. But wood is still the most common heating and cooking fuel in the world. Efforts to convert wood-burning indigenous people to solar-users mostly fail; some cultures can't make the shift, as wood is embedded in their culture (I've seen shiny solar cookers converted into jewelry) so they are going to continue to use wood. Those are the people (and the lands) whom biochar would benefit the most. It would be stupid and unpermacultural to advocate making biochar just for its own sake, but we're talking about reducing wood consumption, building soil, generating a product, and creating usable and clean heat via biochar. Making humus from biomass only builds soil. So what you do with your biomass depends on what your goal is. If you are fortunate enough to have no need for heat, have plenty of wood, need soil built, and don't use a polluting or degenerative fuel, then you probably don't need any function from your biomass other than making humus.  

But if not, biochar is a terrific way to stack functions, to generate heat, keep air clean, and build soil at the same time.

We need to find some way to get carbon dioxide out of the atmosphere, without doing something stupid with this valuable resource like shooting in into deep underground fissures. Biochar provides a very multifunctional way to do that, getting the carbon out of the air but keeping in in a usable form. Just putting biomass into the soil does not sequester carbon; about 90% of the carbon is sent back into the atmosphere within a year, as opposed to biochar sequestering 30-40% of it for centuries. So in one sense, making humus out of biomass is far more damaging to the climate than making biochar, if I can play Devil's advocate for a minute. But anything is better than wasting biomass.


On Nov 17, 2011, at 2:40 AM, Dieter Brand wrote:

> My objection is that we can use a given biomass only once: we either return it to the soil to maintain humus and feed the microbes and other soil organism or we turn it into charcoal. 
> Humus is capable of providing both the living environment and the food for microbes.  There is no reason to assume that the microbes and other soil organisms in my soil would suddenly want prefabricated charcoal “apartment buildings” after having evolved without them for billions of years.  
> I live in a semi-arid climate on heavy clay soil.  The positive effect on fertility of adding biomass to the soil is immediately visible.  According to a figure I came across recently, there can be 10 tons or more of soil organisms in 1 hectare of rich soil.  These organisms need to be fed!  I return every ounce of biomass available in my place to the soil.  To turn biomass into charcoal would reduce the food I can provide to the soil organisms.  
> The last 100 years have seen an unprecedented destruction of biomass.  Many of our environmental, health and other problems can be directly or indirectly traced back to this destruction of biomass.  Not aware of the importance of biomass for maintaining humus and soil fertility, the public is likely to favor any plan to destroy even more biomass - considered a waste by most – that, like biochar or biofuel, promises a quick fix to our environmental problems and allows us to continue the wasteful lifestyle made possible by industrial methods.
> On a global scale it doesn’t matter if someone wants to try out charcoal in his backyard.  However, to have the effect on global warming that is claimed by biochar advocates, we need to turn biomass into charcoal on a large scale.  Added to the destruction that is already ongoing and the devastation caused by biofuel production, this will greatly reduce the future prospects for organic farming, which relies on feeding the soil with biomass.  
> Dieter
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