LaMotte STH Outfit - Manual (Page 8)

8
Nitrate Nitrogen
The role of nitrogen in plant nutrition is discussed in the LaMotte
Soil Handbook. For interpretation of test results see the LaMotte Soil
Handbook.
PROCEDURE
1. Use a 1 mL pipet (0354) to transfer 1 mL of the general soil extract
to one of the larger depressions on a spot plate (0159).
2. Add 10 drops of *Nitrate Reagent #1 (5146).
3. Use a 0.5 g spoon (0698) to add one level measure of *Nitrate
Reagent 2 Powder (5147).
4. Stir thoroughly with a clean stirring rod (0519). Allow to stand fi ve
minutes for full color development.
5. Match sample color with the Nitrate Nitrogen Color Chart (1315).
Record as pounds per acre nitrate nitrogen.
Potassium (Potash)
The role of potassium (potash) in plant nutrition is discussed in the
LaMotte Soil Handbook. For interpretation of test results, see the
LaMotte Soil Handbook.
When present in large amounts, ammonia salts will produce a precipitate
similar to that produced by potassium. If fertilizer containing ammonia
salts has recently been applied, or if the soil pH is below pH 5.0, perform
the Ammonia Nitrogen test (page 19) before performing the potassium
test. A high ammonia nitrogen test result will alert the operator to a
probable false high reading in the potassium test; actual potassium levels
will be somewhat lower.
It is important that the temperature of the test sample and the *Potassium
Reagent C (5162) be in the range of 20-27°C (68-80°F). On warm days,
prior to Step 3 below, cool both the test sample in the Potash “A” Tube
and the Reagent C container by placing them in cool water.
PROCEDURE
1. Use a transfer pipet (0364) to fi ll a Potash “A” Tube (0245) to the
lower line with the general soil extract.
2. Add one *Potassium Reagent B Tablet (5161A). Cap and shake
until dissolved.
3. Add *Potassium Reagent C (5162) until the Potash “A” Tube is
fi lled to the upper line. Allow the *Potassium Reagent C (5162)
to run slowly down the side of the tube. Swirl the tube to mix. A
precipitate will form if potassium is present.