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Determination and Isotope‐Ratio Analysis of Different Forms of Nitrogen in Soils: 4. Exchangeable Ammonium, Nitrate, and Nitrite by Direct‐Distillation Methods
Author(s) -
Keeney D. R.,
Bremner J. M.
Publication year - 1966
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1966.03615995003000050016x
Subject(s) - nitrite , chemistry , nitrate , ammonium , distillation , ammonium nitrate , sulfamic acid , soil water , nitrogen , environmental chemistry , steam distillation , inorganic chemistry , nuclear chemistry , chromatography , organic chemistry , soil science , environmental science
Methods of determining exchangeable ammonium, nitrate, and nitrite in soils which do not require extraction of the soil sample are described. The soil sample is treated with 2M KCl (5 ml/g of soil) and analyzed directly by steam‐distillation methods involving use of magnesium oxide for liberation of ammonium, ball‐milled Devarda alloy for reduction of nitrate and nitrite to ammonium, and sulfamic acid for destruction of nitrite. The methods are rapid, specific, and precise, and they permit nitrogen isotope‐ratio analysis of exchangeable ammonium, nitrate, and nitrite in N 15 ‐tracer studies of nitrogen transformations in soils. Results of soil analyses by these direct‐distillation methods are practically identical to those obtained by extraction‐distillation methods.