LaMotte AST Series Professional Soil Test Outfits - Manual (Page 22)

POTASSIUM
Potassium is found in great supply as a component of common minerals,
but slow solubility limits availability to plants. Although it is not part of
the actual plant structure, potassium is important in many biochemical
functions, including cell division and resistance to disease.
Potassium present in an alkaline solution combines with sodium
tetraphenylboron in *Potassium TPB Solution, to form a potassium
tetraphenylboron precipitate. The resulting turbidity is used to
determine the potassium level.
QUANTITY CONTENTS CODE
250 mL *Potassium TPB Solution *3825-K
1 Double Tube, Potassium 0796
2 Pipets, 1.0 mL, plastic 0354
*WARNING: Reagents marked with an * are considered to be potential health
hazards. To view or print a Material Safety Data Sheet (MSDS) for these
reagents go to www.lamotte.com. To obtain a printed copy, contact LaMotte by
e-mail, phone or fax.
PROCEDURE
1.
Use a 1.0 mL pipet (0354) to add 2 mL of soil extract to the round
tube (0796).
2. Use a second 1.0 mL pipet (0354) to add 2 mL of *Potassium TPB
Solution (3825). Wait 5 minutes.
3. Dilute to top line with deionized water. Cap and shake to mix.
4. Remove the cap and slowly insert the square tube with the collar.
The square tube will slide up and down through the collar and fill
with liquid.
5. Viewing from above, lower the square tube into the solution until
the black dot on the base can no longer be seen. Hold the round
tube at the top to avoid blocking the light.
6. Read the level of the liquid level in the square tube. Record as
lb/acre Potassium.
NOTE: To convert to potash, multiply result by 1.2.
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