LaMotte MAGNESIUM & MANGANESE MODULE C - Manual (Page 3)

MANGANESE TEST
1. Use a transfer pipet (0364) to add 10 drops of soil extract to the large depression
on a spot plate.
2. Use the 0.05 g spoon (0696) to add one measure of Manganese Buffer Reagent
(6310). Mix with a clean stirring rod (0519) until the powder dissolves.
3. Use the other 0.05 g spoon (0696) to add one measure of *Manganese Periodate
Reagent (6311). Mix with a clean stirring rod for 20 seconds.
NOTE: The *Manganese Periodate Reagent will not dissolve completely.
4. Match the color in the spot plate to a color standard on the Manganese in Soil
Color Chart (1307-01). Record as ppm Manganese.
NOTE: Immediately clean the spot plate to prevent staining.
INTERPRETATION OF MANGANESE TEST
Manganese occurs in small amounts in all soils, chiefl y in insoluble combinations.
In some calcareous soils and acid soils, which have been heavily limed, practically
no manganese is present in active forms, and some crops are unable to obtain even
the small amount necessary to meet their requirements. Poor growth and a yellow,
chlorotic condition results.
On the other hand, strongly acid soils may contain injurious concentrations of active
manganese compound. Under some conditions liming is a corrective measure.
Manganese is changed by oxidation to less active forms, or may be leached from
the soil. Hence, tests are of most signifi cance when made just prior to planting, or
during crop growth. A negative test at such time indicates the desirability of applying
manganese. Twenty-fi ve pounds of commercial manganese sulfate per acre is usually
adequate to correct any possible defi ciency. It is doubtful if manganese is needed if
any positive test whatever is developed. Medium, or low, tests are of little signifi cance,
except as indicating no manganese defi ciency. High, or very high tests are undesirable
and indicate a need for lime.