Re: CULT: lime, soils, solubility

Some things I disagree with in Neil's post about lime, but we both agree
it's not a good idea to use slaked lime to raise soil pH in the garden.

Neil said:
<I would *never* use slaked lime in a garden>

Well, you got more sense than a lot of people Neil <g>.  Used to be
pretty common practice where I grew up to lime lawns with it, & some
folks used to use it in vegetable gardens.

<It is so strongly alkaline it burns--badly.  Any organic material will
be attacked by it and destroyed....>

We were warned to stay out of those yards until after it rained.  But
what you say doesn't quite match my understanding of how slaked lime
works.  It raises the pH, instantly, but has been used to <slow down>
decomposition of organic matter (and the accompanying smell!) in
outhouses and mass graves, as you say, by killing the bacteria, macro &
microfauna that decompose organic matter.  Not by causing them to
decompose.

<Granulated or pelletized lime has been treated so that it has a
structure  readily penetrated by moisture. It is perhaps even more
available than the  powdered  form which has a tendency to clump into a
solid mass, remaining visible for months as undissolved, undispersed
masses in the soil.>

This is so wierd - the pelletized lime and slaked lime tend to clump,
not crushed limestone.  Crushed rock is crushed rock, & stays that
way.?? Or did I misunderstand something here?

<Mg is so highly soluble that it leaches out of the root zone in very
short order unless adsorbed by clay--*adsorbed* meaning grabbed onto and
bonded chemically to the clay platelets. >

I think you've got Mg mixed up with K - Mg behaves almost the same as
Ca, is only slightly more mobile, whereas potassium is highly soluble
and rapidly leaches out.  Also, K and Na are smaller ions and when they
get between clay plate layers, the layers can collapse, more or less
permanently.  Ca and/or Mg between the clay layers is what is needed for
improving clay characteristics.  But that's all somewhat a separate
issue from altering pH.

Shall we bore everybody even more by getting into a discussion of
permanent and variable charges and different types of clay (again)?

--
Linda Mann east Tennessee USA zone 7/8
East Tennessee Iris Society <http://www.korrnet.org/etis>
American Iris Society web site <http://www.irises.org>
talk archives: <http://www.hort.net/lists/iris-talk/>
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online R&I <http://www.irisregister.com>

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