Chris Hogg wrote:
On Fri, 14 Mar 2008 17:38:48 -0000, "Donwill" popple @diddle .dot
wrote:

In acid soil and peat what are the acids that make it so?
Carbonic? a bit weak perhaps?
Nitric?
Wouldn't be Sulphuric.
Can't believe it would be Hydrochloric.
Any ideas, and where would it come from.
Don

The commonest soil acids are humic acid and fulvic acid. These are
organic acids with very complex structures, unlike some of the more
familiar organic acids such as acetic acid (vinegar) or fatty acids
such as cooking oils. They derive from decaying vegetable matter. Soil
scientists have studied them for years to try and understand their
structures, but AFAIK haven't come up with definitive results yet,
simply because the structures are so complex.

Humic acid can be extracted from peat, for example, by stirring it in
water with a few spoonfuls of baking soda to make it alkaline, and
letting it stand for a few days. Drain off the brown water that
results and add some vinegar or other acid to neutralise any remaining
baking soda, and a voluminous yellow-brown jelly-like mass will form.
This is 'pure' humic acid.

See also http://en.wikipedia.org/wiki/Humic_acid
and http://www.thekrib.com/Chemistry/humic.html


Humic acid was on sale at my local garden centre as a "soil
conditioner". Looks like coal dust and appears to be insoluble in water.
I read somewhere that it occurs naturally above coal deposits in parts
of the U.S. and Australia.