LaMotte STH Series - Manual (Page 16)

Sulfate
Sulfur is essential to the formation of protein and affects various
aspects of plant metabolism. Sulfur-deficient plants are pale green
in color with thin, reedy stems. Negatively charged sulfate ions are
easily leached. The major sources of soil sulfate are fertilizer
containing sulfate compounds and atmospheric sulfur dioxide
carried into the soil by precipitation.
Procedure:
1. Use a transfer pipet (0364) to transfer five drops of the
general soil extract to a flat-bottomed turbidity vial (0242).
2. Add one drop of *Sulfate Test Solution (5171). Swirl gently
to mix.
3. Compare the turbidity of the sample to the turbidity standards
of the Sulfate Chart (1314). Lay the chart flat under natural
light and hold the turbidity vial one-half inch above the black
strip in the middle of the chart. View the black strip down
through the turbid sample and compare the resulting shade of
gray with the six standard shades. The test result is read in
parts per million sulfate.
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