Quote:
Originally Posted by malcolmf
I'm thinking that there should be a code for terra preta makers
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From what I've seen, terra preta nova makers need to be careful of their impact. Two kinds of impact:
- not having the intended effect (global warming mitigation and/or soil improvement);
- discrediting not only themselves but also the terra preta movement as a whole.
These are the rules I personally would observe:
I will ensure the regrowth of biomass to (at least) equal the quantity of feedstock that I use.
Otherwise there is no net reduction in atmospheric carbon.
I will not damage an existing carbon sink in order to obtain feedstock for char.
Otherwise I just rob Peter to pay Paul, or in this case to feed a pyromania habit. This limits feedstock to waste and purpose-grown biomass. But for example it is an incentive to keep hedges in trim and trees pruned.
I will not operate a charring process near habitation if it produces significant uncontained emissions of exhaust gases.
Otherwise emissions of CO2, CH4 especially, and N2O perhaps, will reduce or even negate the effect of removing carbon from the atmosphere. Furthermore, by not using gas feedback I roughly halve the efficiency of carbon fixation, thus wasting much of the feedstock. Not only that, emissions will quite literally get up the nose of the neighbours and, in sufficent quantity, would lead to a backlash against pyrolysis.
I will not damage an existing carbon sink in order to deposit char.
The same problem as robbing Peter above, but less obvious. If I disturb established covered land, such as pasture, to plough in char, I would destroy years of accumulated glomalin and subsurface biomass, and release their stored carbon through decomposition. A lot more carbon can be released than is added in the char.
I'm looking into one more, which is about how to manage the soil after adding carbon. Indications are that you should cover it with a mulch, use no-till methods (that is
a la Rodale not a la genetically modified crops), and be careful about what else you add. Otherwise either the carbon will enter into reactions and not stay in the soil, or no glomalin will accumulate, or both.
Terra preta nova seems not to be the simple, magical solution that some recent articles portray. I am however struck by the idea that, while the rules might be hard on one person acting alone, they will be easier on a co-operating group or voluntary organisation, which should be able to muster the resources. Friends of the Earth (etc), are you with this yet?
M
