LaMotte SMART3 Soil Operator's Manual page 105

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POTASSIUM
TETRAPHENYLBORON METHOD • CODE M3639-46-65-SC
QUANTITY CONTENTS
30 mL *Sodium Hydroxide, 1.0N
5 g *Tetraphenylboron Powder
1 Spoon, 0.05 g, plastic
*WARNING: Reagents marked with an * are considered to be potential health hazards.
To view or print a Safety Data Sheet (SDS) for these reagents go to www.lamotte.com.
Search for the four digit reagent code number listed on the reagent label, in the
contents list or in the test procedures. Omit any letter that follows or precedes the four
digit code number. For example, if the code is 4450WT-H, search 4450. To obtain a
printed copy, contact LaMotte by email, phone or fax.
Emergency information for all LaMotte reagents is available from Chem-Tel:
(US, 1-800-255-3924) (International, call collect, 813-248-0585).
Potassium is not a component of the structural makeup of plants, yet it plays a vital
role in the physiological and biochemical functions of plants. The exact function of
potassium in plants is not clearly understood, but many benefi cial factors, implicating
the involvement and necessity of potassium in plant nutrition have been demonstrated.
Some of these factors are: it enhances disease resistance by strengthening stalks and
stems; activates various enzyme systems within plants; contributes to a thicker cuticle
(waxy layer) which guards against disease and water loss; controls the turgor pressure
within plants to prevent wilting; enhances fruit size, fl avor, texture and development and
is involved in the production of amino acids (the building blocks for protein), chlorophyll
formation ( green-color), starch formation and sugar transport from leaves to roots.
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 test 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 tests will be somewhat lower.
RANGE: 0.0–500.0 ppm Potassium
METHOD: Potassium reacts with sodium tetraphenylborate to form a
colloidal white precipitate in quantities proportional to the
potassium concentration.
INTERFERENCE: Calcium and magnesium interfere at very high
concentrations. Check for stray light interference (see p. 69).
Smart3 Soil Test Procedures 9.18
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15
10 20
5 25
0 30
CODE
*4004WT-G
*6364-C
0696
POTASSIUM
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