LaMotte SMART 3 Electronic Soil Lab - Manual (Page 72)

72 SMART3 Soil 1.11
PROCEDURE
NOTE: Place Dispenser Cap (0692) on *Mixed Acid Reagent (V-6278). Save this
cap for refill reagents.
Press and hold 1. until colorimeter turns on.
Press 2. ENTER to select TESTING MENU.
Select 3. ALL TESTS (or another sequence containing 064 Nitrate-N LR) from
TESTING MENU.
Scroll to and select
4. 064 Nitrate-N LR from menu.
Use the 1 mL pipet (0354) to add 1 mL of soil extract to a clean tube (0290) 5.
and dilute to the line with deionized water. Cap tube and mix.
Insert tube into chamber, close lid and select SCAN BLANK.
6.
Remove tube from colorimeter and pour off 5 mL into graduated cylinder or 7.
similar. Discard the remaining diluted extract.
Pour the 5 mL diluted extract from a graduated cylinder or similar into the
8.
tube. Use the graduated cylinder or similar to measure 5 mL of *Mixed Acid
Reagent (V-6278) and add to tube. Cap and mix. Wait 2 minutes before
proceeding to Step 10.
Use the 0.1 g spoon (0699) to add two measures of *Nitrate Reducing
9.
Reagent (V-6279). Cap.
Hold tube by index finger and thumb and mix by inverting approximately
10.
60 times a minute for four minutes. Wait 10 minutes for maximum color
development.
NOTE: At end of waiting period an undissolved portion of Nitrate Reducing
Reagent may remain in bottom of the tube without affecting results.
At the end of the 10 minute waiting period, mix, insert tube into chamber,
11.
close lid and select SCAN SAMPLE. Multiply the result by 100 to determine
the nitrate-nitrogen concentration in lb/acre.
Press
12. to turn colorimeter off or press
EXIT
to exit to a previous menu
or make another menu selection.
NOTE: For best possible results, a reagent blank should be determined
to account for any contribution to the test result by the reagent system. To
determine the reagent blank, follow the above test procedure to scan a distilled
or deionized water blank. Then follow the above procedure to perform the test
on a distilled or deionized water sample. This test result is the reagent blank.
Subtract the reagent blank from all subsequent test results of unknown samples.
It is necessary to determine the reagent blank only when a new lot number of
reagents are obtained.
To convert Nitrate Nitrogen (NO
3
–N) results to ppm Nitrate (NO
3
– ), multiply by
4.4.
Test P
rocedures