LaMotte SMART 3 Electronic Soil Lab - Manual (Page 81)

SMART3 Soil 1.11 81
POTASSIUM
TETRAPHENYLBORON METHOD • CODE M3639-46-65-SC
QUANTITY CONTENTS CODE
30 mL *Sodium Hydroxide, 0.1N *4004WT-G
5 g *Tetraphenylboron Powder *6364-C
1 Spoon, 0.05g 0696
*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.
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.
APPLICATION: 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.
Test P
rocedures