Potassium – LaMotte SMART 3 Electronic Soil Lab User Manual

Page 81

SMART3 Soil 1.11

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

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