LaMotte SMART 2 Electronic Soil Lab - Manual (Page 77)

POTASSIUM
TETRAPHENYLBORON METHOD CODE M3639-46-65-SC
QUANTITY CONTENTS CODE
30 mL *Sodium Hydroxide, 0.1N *4004WT-G
5g *Tetraphenylboron Powder *6364-C
1 Spoon, 0.05g 0696
*WARNING: Reagents marked with a * are considered to be potential health hazards. To view
or print a Material Safety Data Sheet (MSDS) for these reagents see MSDS CD or
www.lamotte.com. To obtain a printed copy, contact LaMotte by e-mail, phone or fax.
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 beneficial
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, flavor, 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 lb/acre Potassium
METHOD: Potassium reacts with sodium tetraphenylboron to
form a colloidal white precipitate in quantities
proportional to the potassium concentration
measured as turbidity.
INTERFERENCES: Calcium and Magnesium at very high concentrations.
SMART2 SOIL MANUAL 1.07 77