LaMotte SMART 2 Electronic Soil Lab - Manual (Page 72)

PROCEDURE
NOTE: Place Dispenser Cap (0692) on *Mixed Acid Reagent (V-6278). Save
this cap for refill reagents.
1. Press and hold ON button until colorimeter turns on.
2. Press ENTER to start.
3. Press ENTER to select TESTING MENU.
4. Select ALL TESTS (or another sequence containing 67 Nitrite-N LR)
from TESTING MENU.
5. Scroll to and select 67 Nitrite-N LR from menu.
6. Use the 1 mL pipet (0354) to add 2 mL of soil extract to a clean tube (0290)
and dilute to the line with deionized water. Cap tube and mix.
7. Insert tube into chamber, close lid and select SCAN BLANK.
8. Remove tube from colorimeter and pour off 5 mL into a graduated cylinder
or similar. Discard the remaining diluted extract.
9. Pour the 5 mL diluted extract from the graduated cylinder or similar into
the colorimeter tube. Use graduated cylinder or similar to measure 5 mL of
*Mixed Acid Reagent (V-6278) and add to tube. Cap and mix.
10. Use the 0.1 g spoon (0699) to add two measures of *Color Developing
Reagent (V-6281). Cap and mix by gently inverting for 1 minute. Wait 5
minutes for maximum color development.
11. At the end of the 5 minute waiting period, mix, insert tube into chamber,
close lid and select SCAN SAMPLE. Multiply the result by 50 to determine
the nitrite-nitrogen concentration in lb/acre.
12. Press OFF button to turn colorimeter off or press EXIT button to exit to a
previous menu or make another menu selection.
NOTE: To convert nitrite-nitrogen (NO
2
–N) results to ppm nitrite (NO
2
),
multiply results by 3.3.
n
NITRITE-NITROGEN CONCENTRATION CHART
POUNDS PER ACRE RANGE
0.0-2.0 lb/acre Low
2.5-4.0 lb/acre Medium
4.5-10.0 lb/acre High
Over 10 lb/acre Very
High
72 SMART2 SOIL MANUAL 1.07