Ammonia nitrogen test nesslerization method – LaMotte DCL-20 Colorimeter User Manual
Page 11
AMMONIA NITROGEN TEST
NESSLERIZATION METHOD
QUANTITY
CONTENTS
CODE
30 mL
Ammonia Nitrogen Reagent #1
V-4797-G
2 x 30 mL
*Ammonia Nitrogen Reagent #2
*V-4798-G
1
Pipet, 1 mL, plastic
0354
*WARNING: Reagents marked with a * are considered hazardous substances. Material Safety Data Sheets (MSDS) are
supplied for these reagents. For your safety read label and MSDS before using.
A fertile soil may be expected to give a low ammonia nitrogen test reading, unless there has been a recent application of
nitrogenous fertilizer in forms other than the nitrate. The rapid disappearance of ammonia after fertilizer application
indicates the desired transformation of the ammonia to the more available nitrate compounds. In forest soils, ammonia is
the most abundant available form of nitrogen. If there is a satisfactory rate of nitrogen transformation, the humus layers of a
forest soil will produce very high concentrations of ammonia nitrogen.
RANGE:
0-150 lbs/A
METHOD:
Am mo nia forms a col ored com plex with Nessler’s Re agent in pro por tion to the amount of am mo -
nia pres ent in the sam ple. Ro chelle salt is added to pre vent pre cip i ta tion of cal cium or mag ne sium
in undistilled sam ples.
IN TER FER ENCES:
Sam ple tur bid ity and color may in ter fere. Tur bid ity may be re moved by fil tra tion pro ce dure. Color
in ter fer ences may be elim i nated by ad just ing the in stru ment to 100%T with a sam ple blank.
PROCEDURE
1. Use the 1 mL pipet (0354) to transfer 2 mL of soil filtrate into a clean colorimeter tube (0967) and dilute to the 10 mL
mark with deionized water. Mix and neutralize according to the procedure on page 10.
2. Select setting 1 on the “Select Wavelength” knob.
3. Insert sample into chamber and press the “30 Second Read” button. Adjust “100"%T with the ”Set Blank" knob.
4. Remove sample tube and add 12 drops of Ammonia Nitrogen Reagent #1 (4797), cap and mix.
5. With the 1.0 mL pipet (0354), add one measure of *Ammonia Nitrogen Reagent #2 (4798) to the tube, cap and mix.
Allow five minutes for maximum color development.
6. At the end of a 5 minute waiting period, insert sample into colorimeter, press “30 Second Read” button and measure
%T as soon as reading stabilizes.
7. Consult chart to find the concentration of Ammonia Nitrogen in pounds per acre.
AMMONIA NITROGEN CALIBRATION CHART (LBS/ACRE)
%T
9
8
7
6
5
4
3
2
1
0
80
0.0
0.5
1.5
2.0
3.0
3.5
70
4.5
5.5
6.0
7.0
8.0
8.5
9.5
10.5
11.5
12.0
60
13.0
14.0
15.0
16.0
17.0
18.0
19.0
20.0
21.0
22.0
50
23.0
24.0
25.5
26.5
27.5
28.5
30.0
31.0
32.5
33.5
40
35.0
36.0
37.5
39.0
40.5
42.0
43.0
44.5
46.5
48.0
30
49.5
51.0
53.0
54.5
56.5
58.0
60.0
62.0
64.0
66.0
20
68.5
70.5
73.0
75.5
78.0
80.5
83.5
86.0
89.0
92.0
10
95.5
99.0
102.5
106.5
110.5
115.0
120.0
125.0
130.5
137.0
0
143.5
151.0
AMMONIA NITROGEN CONCENTRATION CHART
%T
RANGE
POUNDS PER ACRE
58-100%
Low
0-24 lbs/acre
29-57%
Medium
25-68 lbs/acre
0-28%
High
Over 71 lbs/acre
11
1985-01 • 10/01