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  • From: Jody Troupe <jodyt2@mac.com>
  • To: permaculture <permaculture@lists.ibiblio.org>
  • Subject: Re: [permaculture] rock powders
  • Date: Fri, 17 Nov 2006 11:22:48 -0800

Paul Ereghino wrote:
>Excess soluble phosphorus immobilizes by bonding with available
iron, resulting in iron deficiencies in some succeptible species.

I just had a seminar last weekend and this was a topic we covered! I wish I
had my notes handy now to restate exactly what was said - but you are correct
about excess phosphorus in plants interfering in the chemistries of
animals/people. I'll have to look this up when I get home.


Paul Ereghino wrote:
>Another angle: Rock phospate (and thus all those phosphorus
products) is a limited resource only found in a few places on earth (florida,
morocco, ??).

Idaho, some islands off of Spain - and Saudi Arabia is supposed to have a
generous supply (figures). I'm not sure where else - but its on my list of
things to research because I was thinking exactly what you were... is this
another commodity? Who would own the major sources? Is it a resource that
would become controlled? I don't want to support that either. Its just that
right now, SRP is completely under the radar. I can't speak for rock
phosphate though. Is that something that might eventually be controlled? I
have no sense of the extent of ITS use.


Paul Ereghino wrote:
>Control of these resources is critical to industrial agriculture,
and
>perhaps all eurasian inspired agriculture is some soil types.
>Extraction of this non-renewable resource requires political
control,
>mining and energy intensive shipping. Why would those who support
local
>control, decentralization and reduction on energy dependance
promote
>this economy? I am wary of engaging in the scrabble for the last
easily
>extractable phosphorus on earth.

Thank you Paul for pointing out that local sourcing would OF COURSE be
important to permaculture. You are right. RBTI does acknowledge that
extremely well-made compost IS a substitute for SRP. Options ARE given -
home-grown substitutes - so you don't have to be reliant on commercial
offerings. Perhaps, if everyone knew how to make wonderful compost, there
wouldn't be much need for the soft rock phosphate. Though, its perhaps easier
for someone trying to treat a larger area to give it a jump-start with soft
rock phosphate than to try to generate a huge amount of compost. I would have
to research if there is faster recovery for depeleted soils through this
process than through compost, (I'm leaning toward yes but I couldn't say
that definitively at this point.) Fortunately, soft rock phosphate has a
decent life-span in the soil and it wouldn't need to be applied yearly.

Maybe this isn't the forum for such an amendment that has pockets of, but not
general, availability. But, as long as large-scale farming continues, the
benefits of improved soil seem worth pursuing. The improved carbon levels
would reduce leaching, working towards better aquifer quality... the balanced
mineral make-up would reduce their need for pesticides & herbicides, the
produce itself would be healthier, last longer... etc. These benefits would
be passed on to all the soils' inhabitants also, improving neighboring
soil... (like the post Ben recently submitted about 'Zai-holes' filled with
compost that drew beneficial organisms in - what a cool bit of info!) I guess
we're still back to the point that it isn't 'local' for everyone. Its at
least a step in a very good direction though - healthier land, healthier food
- there are a lot of positives, I think.


Paul Ereghino wrote:
>...stable humus so strongly mediates cation exchange and
phosphorus cycling that increasing the insoluble pool is less critical than
good cycling and
biological development in many soils. At some point rock powder
ammendment can be a side track if other factors are limiting plant health or
if the system
is producing 'well enough' such that the marginal return on rock
powders isn't ecologically justifiable. Rock powders obtained from far flung
surface
mining conglomerates, are energy intensive commodities -- and there
are local sources of waste phosphorus.

I'm not sure if this paragraph pertains to soft rock phosphate, but SRP
doesn't fall in the same category as other rock dusts. There is no
'break-down' time necessary and it is immediately available to plants. The
only reason there is a recommended 'reaction' time has to do with its
combining with calcium in the recommended method of application. The typical
method is to put down high-calcium lime (since MANY soils need calcium), and
then the SRP. A minimum of a two-week window is required before planting
young seedlings because of the tremendous energy release from the combining
of the calcium with the SRP. A month is considered even better. SRP is not
recommonded to be pre-mixed with the calcium before putting it down due to
the reactions/breakdowns that would begin before it hits the soil. Its
effects would be diluted.

Thank you for the commentary.
Jody

>




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