LaMotte AMMONIA NITROGEN & NITRITE NITROGEN MODULE B - Manual (Page 2)

AMMONIA NITROGEN TEST
1. Use a transfer pipet (0364) to transfer four drops of the soil extract to a large
depression on a spot plate (0159).
2. Add two drops of *Ammonia Nitrogen Test Solution (5103WT). Stir with a
stirring rod (0519). Wait one minute.
3. Match color to a color standard on the Ammonia Nitrogen Color Chart (1302).
Record as ppm Ammonia Nitrogen.
INTERPRETATION OF AMMONIA NITROGEN TEST
A low test for ammonia in agricultural soils is to be expected in a fertile soil, unless
there has been a recent applicaion of nitrogenous fertilizer in forms other than the
nitrate. The rapidity of disappearance of ammonia from the soil in such cases is an
indication of the desired transformation of ammonia into the more available nitrate
compounds.
In forest soils, especially in the humus layers, ammonia is the most abundant available
form of nitrogen, and these organic horizons may produce very high ammonia nitrogen
concentrations if there is a satisfactory rate of nitrogen transformation.
NITRITE NITROGEN TEST
1. Use a transfer pipet (0364) to transfer fi ve drops of the soil extract to a large
depression on a spot plate (0159).
2. Add 2 drops of *Nitrite-Nitrogen Reagent #1 (5151WT).
3. Add 2 drops of *Nitrite-Nitrogen Reagent #2 (5152WT). Stir with a stirring rod
(0519).
4. Add 10 drops of *Nitrite-Nitrogen Reagent #3 (5153WT). Stir with a stirring rod
(0519). Wait one minute.
5. Match sample color to a color standard on the Nitrite Nitrogen Color Chart
(1310). Record as ppm nitrite nitrogen.
NOTE: If the deepest shade of orange represented on the chart is produced, the
test should be repeated on a diluted sample. Transfer one drop of the soil extract
to the spot plate (0159), and dilute it with four drops of *Universal Extracting
Solution (5173) and repeat steps 2-5 of the test. Multiply reading by 5. Record as
ppm Nitrite Nitrogen.
INTERPRETATION OF NITRITE NITROGEN TEST
In the production of nitrates in soils, nitrites are formed as an intermediate step. In soils
that are well drained and aerated, they are found in very small amounts. An excess
of nitrites, which is toxic to plants, may be found in poorly aerated soils and in soils
where there is a very large amount of nitrates, part of the nitrate concentration may
decompose to give nitrites. A high test for nitrite nitrogen, therefore, indicates a soil
condition which may be unfavorable to the formation of nitrates and toxic to plants.
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