permaculture

[Alia Tsang <alia@dietrick.org>]

Dieter, you can always edit the wikipedia page. ;)

One thing that humus does for a soil is increase cation exchange capacity.
This provides sites for mineral nutrients (such as ammonium released by the
breakdown of new organic material) to bind to so that it doesn't get washed
out of the soil. It also makes the soil a better buffer, keeping mineral
and pH levels more stable, and helps the soil clump into nice, water
holding, microbe sheltering aggregates. These effects are a big part of how
humus boosts soil fertility.

John, speaking of hormone-like chemicals, a lot of microbes excrete plant
hormones. I'd bet the increased microbial activity in high organic matter
soils means there are some bacterial or fungal hormones boosting plant
growth too. Or maybe these hormones even become part of the humus.

And good point about burning - think about how much carbon they're losing
in that smoke! They're starving their microbes...

And just a little trivia for you, the structure of humic acid and fulvic
acid (two components of humus) aren't defined by a chemical formula,
they're "operationally defined" by how they're separated out of the humus.
Humus is treated with NaOH (lye, or another strong base) and they separate
the what's in the resulting liquid by acidifying it. Everything that
dissolves in the NaOH and stays dissolved when it's acidified is fulvic
acid, everything that was dissolved but falls out of solution when it's
acidified is humic acid. The actual chemical components of all this are
still being explored.

Alia


On Sun, Nov 13, 2011 at 10:48 AM, John D'hondt <dhondt@eircom.net> wrote:

>
> I could not agree more Dieter.
> We also though have an unfortunately simplistic paradigm developing in the
> big wide world that since carbon is black (as is obvious in diamond and for
> instance gasoline) and humus is dark to black then humus must be carbon and
> it is replaceable with other carbon sources like coal.
> I was sent an article only recently in which was claimed that the very
> fertile original American Prairie soil became black because the natives
> burned the bedjesus out of it regularly instead of that it developed over
> time by breakdown of organic matter into humus.
> My idea is that burning is the devil that makes good soil disappear and
> turn
> into subsoil and bedrock. I have been watching some of my neighbours burn
> every year for over 20 years and that has been the result.
> john
>
>
> > Peat, carbon or oil or must be particularly good examples of humus, if
> the
> > definition that “humus is organic matter that has reached a point of
> > stability to remain as it is for millennia” is correct. Yet all of these
> > have no or only very little fertility.
> >
> > Perhaps the trouble is that we want to perceive of humus as a substance,
> > whereas it may be more like a process. Do we get closer to what humus
> > actually is, if we narrow down its essence to a chemical substance such
> as
> > humic acid or to its individual N atoms? I don’t know! I know that the
> > fertility of my soil increases if I feed it with plenty of organic
> matter.
> > The response is almost immediately - already after a year or two there is
> > a remarkable increase in growth. Perhaps the increased soil activity also
> > taps stable humus that has been stored in the clay-humus complex for
> > millennia, but that is hard to tell. If it does the newly returned
> organic
> > matter probably also goes partly to replenishing this long-term
> storehouse
> > of fertility. Anyways, there is no doubt in my mind that the increased
> > fertility is due to the increased soil activity that occurs as a result
> of
> > the newly added organic matter.
> >
> > Cheers,
> > Dieter
> >
> >
> > --- On Sun, 11/13/11, John D'hondt <dhondt@eircom.net> wrote:
> >
> >
> > From: John D'hondt <dhondt@eircom.net>
> > Subject: Re: [permaculture] Humus
> > To: "permaculture" <permaculture@lists.ibiblio.org>
> > Date: Sunday, November 13, 2011, 12:14 AM
> >
> >
> >
> > There are quite a few nitrogens in humic acid which might account partly
> > for
> > the fertility it imbues but to me the structure of the molecule has
> always
> > made me think of a soil hormone, of something with a messenger function.
> > john
> >
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