LaMotte STH Series - Manual (Page 4)

Multiple Sample Testing
When extracts from two or more samples are being tested
simultaneously use separate pipets for each extract. Mixing
samples will cause false test results. Multiple test tubes, pipets, and
spot plates have been provided to facilitate proper analytical
technique.
Test Methods
Color chart methods are used for all tests except for Potassium.
The reaction is performed in a tube or on a spot plate and the
resulting color is compared to a laminated color chart.
The Potassium test measures the amount of turbidity in a sample
relative to the potassium content.
Available Nutrients
All tests measure the portion of the nutrient in the soil that would
be “available” for the plant to use. Since extraction is not
complete, the amount that is measured is relative, dependent on
the extraction procedure.
Soil Sampling & Preparation
Carefully follow the soil sampling procedures discussed in detail in
the LaMotte Soil Handbook. For sampling greenhouse soils, the
following specialized procedure is recommended.
Collect greenhouse samples prior to watering. Remove any mulch
covering the soil, and then use a soil sampling tube or spoon to
take a sample from the entire plant rooting space, top to bottom.
A composite sample insures representative test results.
Thoroughly mix 8 to 10 individual samples, and then spread the
composite sample on a sheet of paper or plastic to dry. Allow the
sample to air dry overnight. Do not oven dry the sample. Sift the
dried sample through a wire screen mesh similar to as a window
screen.
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