Determination of Nitrogen by Microdiffusion in Mason Jars. I. Inorganic Nitrogen in Soil Extracts

N. S. Saghir, Richard L Mulvaney, F. Azam

Research output: Contribution to journalArticlepeer-review

Abstract

Simple microdiffusion methods are described for determination of NH4 +, NO3 -, and NO2 -in soil extracts. These methods involve diffusion of NH3in a 473-mL (1-pint) wide-mouth Mason jar, the diffused NH3-N being collected in 3 mL of boric acid-indicator solution in a 60 mm (dia.) Petri dish suspended from the Mason jar lid, for quantitative determination by titrimetry (0.0025 M H2SO4). Magnesium oxide is used to liberate NH4 +; Devarda's alloy is used to reduce NO3 -and NO2 -to NH4 +; and sulfamic acid is used to eliminate N02 -Depending upon the volume of soil extract (10–50 mL), diffusion at room temperature (≥20°C) was complete in 18–72 h with orbital shaking, and in 24–86 h without shaking. The methods gave quantitative recovery of NH4 +, NO3 -, and N02 -added to soil extracts. A potential source of interference in the methods involving use of Devarda's alloy is the liberation of NH4 +-N from alkali-labile organic-N compounds.

Original languageEnglish (US)
Pages (from-to)1745-1762
Number of pages18
JournalCommunications in Soil Science and Plant Analysis
Volume24
Issue number13-14
DOIs
StatePublished - Aug 1 1993

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Soil Science

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