LaMotte AST Series Professional Soil Test Outfits - Manual (Page 21)

PROCEDURE
Read Use of the Octa-Slide Viewer on page 5 before proceeding.
1.
Use a 1.0 mL pipet (0354) to add 1 mL of soil extract to a test tube
(0106). Dilute to 5 mL line with deionized water.
2. Use a 0.5 mL pipet (0353) to add 0.5 mL of *VM Phosphate (4410).
Cap and invert several times to mix. Wait 5 minutes.
3. Use the plain pipet (0352) to add 2 drops of *Reducing Reagent
(6405). Cap and mix. Solution should turn blue in 10 seconds.
4. Invert the sample once to mix. Insert test tube into the Octa-Slide
Viewer (1100). Slide the Phosphorus Octa-Slide (3423) into
viewer. Match sample color to a color standard. Record as lb/acre
Phosphorus.
NOTE: If sample color is darker than the highest color standard,
the sample must be diluted (see Sample Dilution Techniques,
page 7) and the test repeated.
PHOSPHORUS IN ALKALINE SOILS
A special extraction procedure is used for determining the available
phosphorus content of soils where the pH value is above 7.0.
1.
Use the 1.0 mL pipet (0354) to add 1 mL of *Special NF
Phosphorus Extracting Solution (6362) to the test tube (0701).
Dilute to the 15 mL line with deionized water.
2. Use the 1 g spoon (0697) to add 3 measures of the soil sample. Add
0.5 mL of Charcoal Suspension (5638). Cap and shake for 5
minutes.
3. Use filter paper (0465) and funnel (0459) to filter solution (see
How to Use a Funnel and Filter Paper, page 10). Collect the filtrate.
Follow the Phosphorus procedure above.
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