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Evaluation of Nitrogen‐15 Tracer Techniques for Direct Measurement of Denitrification in Soil: III. Laboratory Studies
Author(s) -
Mulvaney R. L.
Publication year - 1988
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/sssaj1988.03615995005200050022x
Subject(s) - denitrification , nitrous oxide , chemistry , nitrogen , tracer , environmental chemistry , slurry , mass spectrometry , isotopes of nitrogen , soil test , fertilizer , soil water , gas chromatography , analytical chemistry (journal) , soil science , environmental science , chromatography , environmental engineering , physics , organic chemistry , nuclear physics
Laboratory studies were conducted to evaluate the assumption of isotopic uniformity that underlies mass spectrometric determination of dinitrogen (N 2 ) and nitrous oxide (N 2 O) evolved during denitrification in soil treated with 15 N‐labeled fertilizer. In these studies, a gas chromatograph (GC) and mass spectrometer (MS) were used to analyze replicate atmospheric samples containing N 2 O generated through oxidation of 15 N‐labeled NH 2 OH, evolved from 15 N‐treated soil slurries incubated at constant moisture content (1 kg H 2 O kg −1 ), or evolved from 15 N‐treated soil subjected to wetting and drying cycles. Both instruments gave almost identical values in analysis of N 2 O derived from a single pool of 15 N‐labeled NH 2 OH or from two pools having similar, but not necessarily the same, enrichments. The MS gave lower values for N 2 O derived from two pools differing markedly in their enrichment of 15 N. The values measured by GC and MS differed significantly (0.05 level) for about 50% of the soil atmospheric samples analyzed; however, the differences usually did not exceed 10% and probably resulted from analytical error rather than lack of isotopic uniformity in the NO − 3 denitrified, because in about half of these cases, the greater value was obtained by MS.