permaculture

[Robyn Francis <robyn@permaculture.com.au>]

Thanks Toby - that's one of the clearest succinct explanations I've come
across. 

I've been following this thread and getting a bit frustrated by some of the
posts. I echo Toby's thinking on biochar.

Here's my take on how we use it here.

Some of my colleagues here in Oz have been doing research for many years and
we hold an annual biochar workshop at Djanbung with some the local bio-char
gurus and pioneers. We've been experimenting with making and adding small
amounts of biochar to the gardens here for the past 4 years and while no
rigorous scientific documentation and monitoring has been undertaken, we are
seeing positive results.

We use mainly woody weeds (not conducive to composting), excess stick wood
and 'waste' trimmings from the bamboo harvest for making biochar. We
pound/crush it so it's fine to pea size bits before adding to the garden and
find it's been improving soil structure by providing a greater diversity of
particle size in our very clayey soil. Our best results have been when we've
first soaked (i.e. activated) the biochar in compost tea. We add the biochar
when we add compost to the soil before mulching, and are now considering
mixing some into our compost heaps.

We have a clayey loam soil - more clay than loam - which has a tendency to
self compact, so every few years we break up the compaction by forking the
soil open (not turning it) in the veg garden before mulching and planting.
This is when we add fresh compost and biochar. We also add biochar when we
dig up root crops or tractor with the pigs so it gets down into the deeper
layers of topsoil.

Nutrient loss through leaching is a big challenge in high rainfall tropic
and subtropic soils. Biochar provides a stable 'habitat' to hold nutrients.
That's one of the key reasons why the terra preta soils were so productive
in the Amazon.

No one technique is a cure-all for everything, however wise use of biochar
definitely has a very positive role to play. I was initially quite sceptical
about the claims and am not one to jump on the latest fad-bandwagon, so I've
checked the issues, pro's and con's out fairly thoroughly.

I have nightmares about indiscriminate large-scale industrial biochar
production, but see that local biochar production through pyrolosis can turn
a lot of otherwise difficult to compost or productively use organic waste
into a durable carbon sink that improves the soil.

A local biochar enthusiast is making and selling neat little biochar stoves.
http://biochar-store.biocharproject.org/  I'm getting one next week for my
main cooking devise - will set it up on the veranda off my kitchen. I have
loads of small stickwood for fuel and I want to reduce, if not eliminate, my
use of gas for cooking. Our beautiful bioregion and many other parts of Oz
are threatened with Coal Seam Gas mining and some of Australia's best
farmland has already been polluted and compromised by fracking. I feel a
strong moral obligation to boycott this whole industry so the Biochar stove
gives me the perfect wood cooker with a net positive environmental impact.


Robyn


On 19/11/11 9:03 AM, "Toby Hemenway" <toby@patternliteracy.com> wrote:

> On Nov 18, 2011, at 11:31 AM, John D'hondt wrote:
>> 
>> I am well aware of the stability of charcoal but that it serves as living
>> space for microbes is pure nonsense. You can't have it both ways. If it 
>> were
>> good for microbes it would not be stable. It is one or the other and you
>> really can't keep your cabbage and eat it at the same time.
> 
> Well, you don't eat your house, either, even though it's made of carbon just
> as your cabbage is. They are different substances, with different functions,
> just as biochar and humus are.
>> 
>> And I also can't see it as a sink for soil minerals. As a slow sink for
>> mercury yes and organic pesticide molecules probably.
> 
> Yes, it is a sink for soil minerals. See, for example, "Black Carbon 
> Increases
> Cation Exchange Capacity in Soils" from the Soil Science of America Journal.
> Abstract is at
> http://www.biochar-international.org/node/157 though the article needs a
> subscription to view.
> 
> First, here's why biochar can house microbes and not break down. Microbes
> colonize surfaces. They do not always eat the surfaces they colonize. When
> they colonize gravel in reed beds, they don't eat the gravel. (Cred here: I
> ran a microbiology lab at a large biotech company. We used to colonize inert
> surfaces with microbes all the time, like porcelain and carbon fiber. They
> didn't eat it.) 
> 
> I'm seeing a fundamental confusion between the roles of humus and biochar 
> here
> that I hope to clear up. Humus feeds plants and microbes in two different
> ways, while biochar feeds them in only one way.  They both house microbes. 
> The
> first way humus feeds is by its ability to hold cations: positively charged
> nutrient ions such as calcium, iron, etc. These cations are not part of the
> humus; they are hydrogen-bonded to the oxygen atoms on the humus. The 
> cations
> are donated to the plant or microbe, and are recharged (returned) to the 
> humus
> by the breakdown of other organic matter. When organisms eat cations, the
> humus remains unchanged.
> 
> The other way microbes (not plants) are fed by humus is when the microbes
> break down the humus itself, extracting energy and carbon from the humus. 
> This
> results in degradation and loss of humus. New humus must be formed by a
> constant supply of new organic matter. Humus is always breaking down in this
> way, sometimes slowly if there is ample OM or few microbes, but fast if 
> there
> is a lack of OM. That's part of why OM must be constantly added to soil.
> Biochar lasts far longer than humus in soil where there is microbial 
> feeding.
> Humus is not as good a carbon sink as biochar.
> 
> Next,  biochar holds minerals in two ways. They can be directly adsorbed 
> onto
> the surface, and since it has so much surface, it can hold a lot of 
> minerals..
> Also, although the carbon in it is positively charged, and thus won't bond 
> to
> other +-charged cations, it raises CEC by adsorbing negatively charged
> substances in the soil, which then bond to cation nutrients. This is
> documented. It then releases the bound nutrients to microbes and plants the
> way humus does--and thus doesn't break down, just as humus does not in these
> cases. It also houses microbes but does not itself feed them carbon; the
> carbon has been largely stripped of the type of bond needed to fuel 
> microbes.
> Charcoal alone will not feed microbes or plants. There must be other OM
> present. This is why I am puzzled by this argument. Charcoal and OM work
> together, it is not a case of one or the other. Biochar provides a
> long-lasting carbon storage, unlike humus. And OM provides the food.
> 
> I hope not to hear the claim that biochar can't house microbes or donate
> nutrients any more. These are very well proven facts and have a very solid
> mechanism behind them.
> 
> I don't see biochar as a silver bullet. Like everything else, if made on an
> industrial scale, it be just as poor a product, and just as damaging, as
> industrial organic food or industrial medicine. But that is the fault of
> industrialization, not biochar.
> 
> Toby
> http://patternliteracy.com
>> 
>> 
>> 
> 
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-- 
Permaculture College Australia inc
Pathways to sustainability through
Accredited Permaculture Training
Certificates III & IV and Diploma of Permaculture
PDC and short courses

Robyn Francis 
International permaculture design and
sustainability consultant, educator & facilitator

Djanbung Gardens 
Permaculture Education Centre & Demonstration Farm
PO Box 379 Nimbin NSW 2480
02-6689 1755  /  0429 147 138
www.permaculture.com.au