I would like to determine the NH4-N in soils, and I would like a method rather than the steam distillation.
The most commonly used method state-side is METHOD 350.1
DETERMINATION OF AMMONIA NITROGEN BY SEMI-AUTOMATED
COLORIMETRY (http://water.epa.gov/scitech/methods/cwa/bioindicators/upload/2007_07_10_methods_method_350_1.pdf), which is performed on soil extracts (usually a 10:1 mass:mass 1M K2SO4 or 2M KCl). Lachat is a common maker of the colorimeter for the determination of NH4 in the extract solution. I've done this one by hand as well with an inexpensive spectrophotometer, but can't remember where I got the method (also based on indophenol blue reaction).
As Bryan stated, NH3 can be quantitatively displaced from soils by solutions of K salts and measured colorimetrically after reaction with phenol(s) and hypochlorite. The common choices are phenol itself and salicylate, and the methods are documented in compendia of "standard methods", e.g. from the American Public Health Association.
Dilip. i know this method, and i used it in my work. but my question about alternative method.
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