billj at harborside.com
Fri Dec 21 04:47:35 EST 2007
I searched online for "purple dirt" and found several types, one formed
from amethyst mine trailings, one formed from silver mine trailings, and
another: soil contaminated with benzene. None of these sounds like
yours. Anything is possible on a tiny scale somewhere. Somewhere in
Utah, there's a soil that's blue from vanadyl sulfate, for example,
where the predominant mineral matter is vanadium-based. But how common
or relevant is that?
If you knew a little chemistry, you could predict the possibilities
without having to search the Internet for ad hoc examples.
There are only three reasons I can think of, but maybe Bev has another.
1. Young soils haven't had the time to have their supply of alkaline
metals leached out.
2. There are heavier, less common alkali metals. No CRC Manual with
me, of course, but I'll bet some might have not-so-soluble compounds
that can't leach as readily.
3. The most likely cause is ammonium ions resulting from the anaerobic
breakdown of nitrogenous material, thus this "muck" you spoke of. This
is "unstable" alkalinity, because the moment you aerate such a soil, a
different set of bacteria take over, converting the ammonium cations to
nitrite and nitrate anions.
Mind you, I'm no expert on soil science, as if anyone _really_ were. I
just happen to know that there are only so many types of positive ions,
and it's easy to go through the possibilities systematically.
Incidentally, we decided to leave tomorrow (Friday), and spend two
glorious nights in San Francisco, hopefully at the Lone Star Saloon,
then travel up the coast the rest of the way on a fairly rainless
Sunday, up north. Screw those Siskiyous. I don't mind driving on the
_inside_ lane up the coast. :)
S. Oregon coast
>Not necessarily. Bodega gets an average yearly rainfall of over 55 inches.
>Purple Dirt tests off the charts alkali.
>----- Original Message -----
>From: "Bill Jones" <billj at harborside.com>
>>Of course. But take away the plastic sheet from the greenhouse, and
>>after one year of leaching with 60" of rain, the alkaline deposits will
>>be gone, obviously. It should be obvious to anyone that there is indeed
>>a relationship between pH and rainfall levels.
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