soil experiments?

Ross Koning Koning at ECSUC.CTSTATEU.EDU
Wed Aug 21 18:42:56 EST 1996

At  3:46 PM 8/21/96 -0700, SCHMID at wrote:
>Does anyone have any ideas for a token lab about soils, fertilizers and
>such?  I'm looking for immediate gratification sorts of experiments or
>observations, not long-term mineral deficiency studies. (The target
>audience is undergraduates with an interest in gardening.)

One I like is to do a Sudbury soil test.
I use the standard over-the-counter kit
from the garden/farm store.  It does
pH, N, P, and K tests.  I have the students
bring in their own soil samples (from home,
athletic fields, whatever).  To save on
costs (which isn't much anyway) and time,
I use graduated microcentrifuge tubes instead
of those supplied with the kit.  The soil
tests use 0.5 mL of soil and then (usually)
reagent up to the 1 mL mark on the graduated
tubes.  After the proper mixing, the tubes are
centrifuged for about 30 seconds (this is quite
sufficient for my Eppendorff machine to pellet
all the soil particles).  The supernatant is
compared with the color charts in the booklet.
I keep some small test tubes 10 x 75 mm or less
around to get a clearer view.  I have wash
bottles of dH2O around to wash out the tubes
for the next test.  I have students calculate
the amount of fertilizer to buy using some
of the procedures in the Sudbury direction book.

It is all very simple, takes about 1.5 hours
(if you don't give them time for calculations
in class), it is colorful and "practical."

PS: I have tried other brands of kits and find
them all to be unpredictable in at least one
of the tests.  The Sudbury kits have given
repeatable results and the kits have an extremely
long shelf life...I have not had a failure yet
in spite of some kits being two years old!

I also do the 2tsp/L Calgon soil particle size
determination in 100 mL grad cylinders, so that
the soil type can be determined.  If you do that
the day before, the sand, silt, and clay layers
can be measured and with some simple calculations
and a soil triangle the students can classify the
soil quite easily.  This can lead to discussions
of when to till, how much to water, how to fertilize
and so on.

My students really like the exercise and have found
it quite rewarding...especially the non-traditional
students.  Even the athletes like it because at ECSU
the students do quite a bit of field maintenance and
want to know about turf management!

The lab exercise is available on my web site under the
course Plants and Human Affairs (BIO 207).  The
address is in my signature file below.

Good Luck!


Ross Koning                 | Koning at
Biology Department          |
Eastern CT State University | Phone: 860-465-5327
Willimantic, CT  06226  USA | Fax: 860-465-5213

                Plant Physiology is Phun!

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  COOH        H2C=CH2         N  NH

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