LaMotte SMART 3 Electronic Soil Lab - Manual (Page 79)

SMART3 Soil 1.11 79
PROCEDURE
Press and hold 1. until colorimeter turns on.
Press 2. ENTER to select TESTING MENU.
Select 3. ALL TESTS (or another sequence containing 078 Phosphate ppb)
from TESTING MENU.
Scroll to and select
4. 078 Phosphate ppb from menu.
Use the 1 mL pipet (0354) to add 1 mL of the soil extract to a clean tube 5.
(0290) and dilute to the 10 mL line with deionized water.
Insert tube into chamber, close lid and select SCAN BLANK.
6.
Remove tube from colorimeter. Use 1.0 mL pipet (0354) to add 1.0 mL of 7.
*Phosphate Acid Reagent (V-6282). Cap and mix.
Use the 0.1 g spoon (0699) to add one measure of *Phosphate Reducing
8.
Reagent (V-6283). Cap and shake until powder dissolves. Wait 5 minutes for
full color development. Solution will turn blue if phosphorus is present.
At end of 5 minute waiting period, mix, insert tube into chamber, close
9.
lid and select SCAN SAMPLE. Multiply the result by 32 to determine the
phosphorus concentration in lb/acre.
Press
10. to turn colorimeter off or press
EXIT
to exit to a previous menu
or make another menu selection.
PHOSPHORUS IN ALKALINE SOILS
A special extraction procedure is used for determining the available phosphorus
content of Western U.S. alkaline soils where the pH value is above 7.0.
EXTRACTION PROCEDURE
Use the 1 mL pipet (0354) to add 1 mL of the *Special NF Extracting 1.
Solution (6362) to the test tube (0701) then add deionized water to the
graduation.
Add 3 one gram measures of soil using the 1 g spoon (0697) to the
2.
extracting solution in the vial.
Cap the vial and shake for a period of 5 minutes.
3.
Filter using the funnel (0459) and filter paper (0463). Collect all of the filtrate. 4.
Perform the Phosphorus test according to the Phosphorus procedure given 5.
above.
Test P
rocedures