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  • From: Paul Cereghino <paul.cereghino@comcast.net>
  • To: permaculture <permaculture@lists.ibiblio.org>
  • Subject: Re: [permaculture] rock powders
  • Date: Fri, 17 Nov 2006 09:11:52 -0800

I am enjoying this strand, and it has made me want to brush up on chemical interactions in the soil solution!

Here is another scenerio studied by one of my cohort in school:
Phosphorus fertilization is promoted by the horticulture industry particular for flowering plants. Our damaged soils are typically low in calcium with low CEC. Excess soluble phosphorus immobilizes by bonding with available iron, resulting in iron deficiencies in some succeptible species.

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

(and a side note.. a local organic guru Steve Solomon made a precise critique of Fukuoka's continuous grain harvest system by noticing that he is farming on phosphorus rich soils.)

Thanks Lawrence for the tip on local quarries... duh!... I will check out my local rock crusher, their source of stone, and if they spray floculants (which i know little about) for dust control.

I feel compelled to make a plug for working carefully with your existing mineral base. Although we can manipulate the pools of various elements in the soil, I'd be willing to bet that the continuous availability of those elements is dependant on biological activity that increases the cycling of elements, and thier incorporation into soil food webs. And that 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 know all you folks are thinking about these things... but I know that our culture has a proclivity toward reducing complex things into consumer solutions... and so I take the soap box (no phosphate pun intended) only out of compulsion -- no patronization intended. The 'health and sustainability' market is just beginning to mature, and the snake-oil salesmen have always loved gardeners.

Anyone have any good resources on 'dynamic accumulators' of phosphorus or other elements?







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