LaMotte MAGNESIUM & MANGANESE MODULE C - Manual (Page 2)

EXTRACTION PROCEDURE
1. Fill a test tube (0755) to line 7 with *Universal Extracting Solution (5173).
2. Use the 0.5 g spoon (0698) to add four level measures of soil to the test tube. Cap
and shake for one minute.
NOTE: When adding samples with high concentrations of carbonates to
*Universal Extracting Solution (5173), swirl tube to mix for 30 seconds before
capping to allow gases to escape.
3. Fold a piece of fi lter paper (0465) in half, then in half again. Press corners
together to form a cone. Place in funnel (0459). Pour extract solution into funnel,
collecting extract. This clear extract is used for the test.
MAGNESIUM TEST
1. Use a transfer pipet (0364) to add ten drops of soil extract to a large depression on
a spot plate (0159).
2. Add one drop of *Magnesium Test Solution (5140). Stir with a stirring rod
(0519). Solution will turn pale yellow.
3. Add one drop of *Manganese-Magnesium Solution #2 (5145WT). Stir with
a stirring rod. Compare to color standards on Magnesium in Soil Color Chart
(1306). Continue adding *Manganese- Magnesium Test Solution #2 one drop at a
time until sample color matches a color standard. Record as ppm Magnesium.
NOTE: It usually requires 2 drops of *Manganese-Magnesium Test Solution #2
to cause color change.
INTERPRETATION OF MAGNESIUM TEST
Soils giving a very low test should be treated with dolomitic lime or fertilizers, such as
double-manure salts, which contain considerable magnesia. Soils giving high, or very
high, magnesium tests, with low calcium tests, should receive applications of gypsum
or high calcic lime, in order to prevent calcium defi ciency, due to over-balance of
magnesium.