"Martin Brown" wrote in message
...
In message , Franz Heymann
writes

"Martin Brown" wrote in message
...
In message , Franz Heymann
writes

My point was that I do not understand what process can determine
the
amount of arbitrary organic matter in a sample by simply shaking
a
suspension of the sample in a liquid and looking for a colour
change.

Probably something like: a fairly powerful oxidising agent, a
catalyst
and a suitable indicator.

I am sincerely doubtful whether *all* organic compounds would
respond
identically to such a group of agents.

Oh. I can assure you that *all* organic compounds will respond the
same
way to sufficiently powerful oxidising agents - ending up as CO2.
The
problem is that most of these chemicals are far too dangerous to be
used
in a soil test. PTFE and a few other designer molecules might
resist
attack at room temperature but ultimately even they give up the
ghost.

I was talking about responding by imparting a characteristic colour to
a test fluid.

It may be more specific than that - targeting
the acidic peaty component that is guaranteed to rot and change
volume.

That would be a pH meter. That does not measure "total organic
content", and would give wildly misleading results in limestone
country.

There are more cunning ways to measure humic acids.

I don't doubt that. By the way, I don't like the catch-all term
"humic acids".

I still think it is a scam.

I am pretty sure the test being sold is supremely irrelevant to
gardening, but if the Organic(TM) suckers want to buy into a
spurious
chemical test of "goodness" then so be it.....

Agreed

Franz