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Re: Laterite & Aluminum Silicate

> > 1) How probable is it that aluminum silicates could be leached from
> > soils under tropical conditions (i.e. mildly acidic water in large
> > quantities)?
> >
> 	I think it would be very slow.

Would it have a higher solubility than iron oxides?

> > 2) How reactive are aluminum silicates in clay form in the substrate
> > under low redox conditions and with possibly low pH (~6 pH) ?
> >
> 	The redox conditions are essentially irrelevant to this, because
> neither the Al nor the Si is going to change its oxidation state.
> Solubilities will be low.  What sort of reaction did you have in mind?

I'm concerned about the possibility of aluminum toxicity to plants.
This would be the situation where there are free aluminum ions which
would interfere with mechanisms for other nutrients being absorbed.
We know that aluminum silicates are very common in ordinary clays.
My suspicion is that if the solubility of those compounds is low even
under low pH, they will not release Al ions and thus not be a problem
for aluminum toxicity. There are other aluminum compounds like
aluminum oxide or hydroxide. Do they have higher solubility?