LaMotte AST Series Professional Soil Test Outfits - Manual (Page 23)

IRON
Only small quantities of iron are used by plants, but it is essential to
growth as an activator in numerous enzyme systems. Since iron is more
soluble in acidic solutions, it will be more available in soils with a low
pH.
A bipyridal indicator, *Iron Reagent #2 Powder, reacts with iron at the
proper pH to produce a pink color. The resulting color is matched to a
color standard to determine the iron concentration.
QUANTITY CONTENTS CODE
30 mL *Iron Reagent #1 *4450-G
10 g *Iron Reagent #2 Powder *V-4451-D
1 Test Tube, plastic, w/cap 0106
1 Spoon, 0.05 g, plastic 0696
1 Iron Octa-Slide Bar, 2.5-50 ppm 3479
*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.
PROCEDURE
Read Use of the Octa-Slide Viewer on page 5 before proceeding.
1.
Fill test tube (0106) to 5 mL line with neutralized soil extract.
NOTE: See Neutralization of Soil Extract, page 15.
2. Add 5 drops of *Iron Reagent #1 (4450).
3. Use the 0.05 g spoon (0696) to add 1 measure of *Iron Reagent #2
(V-4451). Cap and mix until the powder has dissolved. Wait 5
minutes.
4. Invert the sample once to mix. Insert test tube into the Octa-Slide
Viewer (1100). Slide the Iron Octa-Slide Bar (3479) into viewer.
Match sample color to a color standard. Record as ppm Iron.
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.
23