NPK ratios?
Sat, 02 Feb 2008 18:55:27 PST
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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