NPK ratios?
J.E. Shields (Sun, 03 Feb 2008 04:42:23 PST)

Hi Rodger and all,

Well, I changed it back and forth a couple of times. I settled on "absorb"
because the kaolins can do an ion exchange, switching Ca++ for K+ in the
internal matrix of the clay. On the other hand, ion exchange phenomena are
probably best thought of as "adsorptions" as well, so (this morning) I tend
to agree with you. I have heard about the "different" clays of the North
American West, but I've not had any personal experience gardening in them.

Jim Shields
in central Indiana (USA)

At 06:55 PM 2/2/2008 -0800, you wrote:

On 31 Jan 08, at 9:09, J.E. Shields wrote:

Clays can adsorb ions on their surfaces and can absorb [sic; ITYM
"adsorb"] ions internally.

Not all clays. Lateritic clays have very poor adsorption powers,
hence the poor soils in the Oregon Coast Range (Ref: Roadside Geology
of Oregon), Africa, and the Amazon Basin.

For those of you on the Left Coast, there's a very nice exposure of
bright red lateritic soil on the east side of I-5 a little north of
Grass Pants, Oregon. Just a small cut with some erosion that exposes
the subsoil, but quite prominent because of the brilliant color.

--
Rodger Whitlock
Victoria, British Columbia, Canada
Maritime Zone 8, a cool Mediterranean climate

on beautiful Vancouver Island
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Jim Shields USDA Zone 5 Shields Gardens, Ltd.
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