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Re: [SG] Soil Testing Kits

Bobbi,
You said:
> Garden books always airily recommend having the local agricultural
> extension agent test your soil, which I suspect is a big hassle.
> Comments?
It is not a hassle at all.  In most states, the cost of an extension
service test for the standard NPK plus soil pH is between $5 and $10.  It
is probably the best investment you can make in your garden.  Seriously.  I
check mine every third or fourth year, and am now doing it bed by bed,
since I rotate crops across all of the beds (either seedlings out of my
breeding projects, or normal backyard veggies) and different crops take out
different things at different rates.

The inexpensive garden center kits work do OK.  But you have to know what
how
to do the interpretation.  The state soil testing labs have access to lots
of database information about soils in your state, and target the report
based on a lot more data than just the kit results.

I have experience with the Penn State lab --- actually earned tuition for a
semester of grad school back in the 80's by interpreting the test results
when they fell outside of the normal parameters.  The standard template is
for farm land in the normal PA crops, or for home gardeners --- the
software takes the data and spits out a report.  If you were raising an
unusual crop (back then, this would have included broccoli...), someone
(usually a grad student or young prof) does the interpretation manually.
What kinds of things ended up in my hands?  Unusual crops.  Strange test
patterns (sky high K values, for instance, when someone overdid garden
applications of wood ashes).  Greenhouse crops.  Soilless mixes (at least
back then).

The process in PA is this: call your agent.  Send them $5 (at least I think
that it is still $5).  They will send you a bag in which to put the soil.
Send the bag with soil to the University.  Get your results within 4 weeks.
 The results will tell you how much NPK are there as well as Ca and Mg, and
provide you with a relative scaling for each one (low, medium, high) based
on the nutritional needs run of the mill garden plants.  You can have them
estimate OM.  The normal test also tells you the soil pH and if you need
lime (and how much) for pH adjustment.

The reports from each state are a little bit different.  I do not know what
the folks up in West Lafayette do, but it has to be similar to PA's.  You
could send your soil to the PA lab, but the results would not necessarily
be as accurately targeted re the recommendations.  Yes, the chemical
results would be the same.  What they would mean in your soil type is
something that is best left to a local lab.

There are good instructions on how to take the samples.  That is probably
the most critical part of the process.

If you need any help figuring out what the test results mean, let me know.


Rick Grazzini
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