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

MAN GA NESE 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.
IN TER PRE TA TION OF MAN GA NESE TEST
Manganese occurs in small amounts in all soils, chiefly 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 significance when made
just prior to planting, or during crop growth. A negative test at such
time indicates the desirability of applying manganese. Twenty-five
pounds of commercial manganese sulfate per acre is usually adequate to
correct any possible deficiency. It is doubtful if manganese is needed if
any positive test whatever is developed. Medium, or low, tests are of
little significance, except as indicating no manganese deficiency. High,
or very high tests are undesirable and indicate a need for lime.