Re: CULT: trace elements

I wrote:
> << When this book was written, sulfur deficiencies  (or rather growth
> responses to sulfur additions) were being reported in  more and more areas as
> deposition of air pollutant sources of sulfur  decreased.>>
and Anner Whitehead asked:
> Those aren't quite the same thing are they? Just wondering about sulfur and
> pH.......

No, they aren't the same, but back in the old days before 1974 when that
book was written, most air pollution was loaded with sulfur.  There has
been a tremendous reduction in sulfur emissions in this country over the
last few decades, but not as much for nitrous oxides.  Both contribute
to acid rain.  Acid rain mostly has a strong effect on soils (like
Gunnar's in Sweden) with little natural buffering capacity.  But it
can/does increase leaching of some nutrients in lots of soils.

Soil pH is extremely important in regulating availability of nutrients. 
Some are only available (soluble) at higher pH's and vice versa.  Boron
is one that is more available in more acid conditions, but that also
makes it more readily removed by high rainfall (hence potential for
deficiency in highly leached sands).  These nutrients also form
complexes with different kinds of clays in various ways - seems like I
remember some can be bound between the lattices of some clays and be
'unreachable' by plants etc etc.  

The soil book I cited is very readable and has lots of fascinating stuff
in it.  It was a standard text for introductory soil classes and is
probably still widely available.  In this country anyway.

Linda Mann east Tennessee USA
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