Soil Testing, more questions

To Sanet and Vaughan Jones:

I have been intrigued by the recent discussion of soil testing, and especially
by Vaughan Jones's response.  As someone who moved to the Colombia shortly after
an Ag degree from Ontario, I very quickly forgot my shaky knowledge of the
relationship between soil test results and the appropriate recommendations,
especially since I would not have been inclined to make any NPK recommendations
in the first place.  Nevertheless, soil testing seems to be one of those things
that everyone does, and follows religiously.  However, if I am not wrong, these
tests were really designed for an agriculture that sees the soil as a medium for
growth, not as a complex living organism.  The actual availability of nutrients
to the roots is affected by many other factors, and the conventional soil
testing procedures are at best imperfect indicators of what the health of the
soil is.  They answer questions such as how much NPK do I need to add to get so
many bushels of corn.

But are we not concerned about many other things in the soil, and are there
other indicators of "system health" that may be more effective, and more
practical?  I have not had much chance to study or understand the concepts
behind the use of refractometers, tissue testing, and so on, but there must be
something to it.

I was surprised that there was no reaction to  Vaughn's categorical dismissal of
soil testing as anything useful.  Vaughan, could you explain this further to us?
Could you expand on your views the use of tissue testing?

Ignacio Villa
9697 State Route 534
Middlefield, OH 44062