Determination of ammonium in kc1 extracts of soils by the salicylate method

Abstract

A method is described for the direct estimation of NH4+-N in 2M KC1 extracts of soils based on the emerald green color formed when NH3and salicylate react in the presence of NaOCI at high pH.-The reagent concentration, solution pH, and time and temperature of color development specified are those giving maximum molar asorptivity. Precipitate formation observed when KC1 extracts containing divalent cations were treated with color developing reagents was eliminated by addition of 1 mL of 6% EDTA to complex Ca2+and Mg2+. Free EDTA or complexed Ca2+or Mg2+did not markedly affect color development or molar absorptivity. The proposed method efficiently recovered NH4+-N added to 2M KC1 extracts of soils and studies showed that the proposed method and two other procedures differing in principle gave similar values for NH4+-N in extracts of 5 soils. The proposed method is a simple, rapid, accurate, and precise technique for the colorimetric determination of NH4+-N in KC1 extracts of soils. Copyright © 1983 by Marcel Dekker, Inc.