LaMotte STH Outfit - Manual (Page 5)

5
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 (1504). 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 a window screen.