LaMotte STH Series - Manual (Page 7)

Extraction Procedure
The following extraction procedure uses *Universal Extracting
Solution (5173PS) to produce a single soil extract which is used
in all of the following tests: nitrate nitrogen, ammonia nitrogen,
nitrite nitrogen, phosphorus, potassium, calcium, magnesium,
sulfate, aluminum, iron, and manganese. The pH, chloride,
humus, and plant tissue tests use extraction procedures described
in the individual instructions for those tests.
The Extraction Tubes (0704) are marked at 7 and 14 mL. The
instructions below assume that a number of tests will be performed
with the general soil extract. Therefore 14 mL of extracting
solution and two level measures of the soil sample are called for in
Steps 1 & 2. If only a single test is to be performed (e.g., nitrate
nitrogen), fill the extraction tube to the 7 mL line (Step 1) and
add only one level measure of the soil sample (Step 2).
Procedure:
1. Fill an Extraction Tube (0704) to the 14 mL line with
*Universal Extracting Solution (5173PS).
2. Use the plastic soil measure (0819) to add two level measures
of the soil sample. Cap and shake for one minute.
3. Use a piece of filter paper (0465) and a plastic funnel (0459)
to filter the soil suspension into a second extraction tube
(0704). (Fold the filter paper in half and then in half again to
form a cone which is fitted into the funnel.) The filtrate in
the second extraction tube is the general soil extract for use in
the 11 individual test procedures listed previously.
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