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Emission Spectrometry for Direct Measurement of Nitrous Oxide and Dinitrogen from Soil
Author(s) -
Eriksen A. B.,
HoltanHartwig L.
Publication year - 1993
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/sssaj1993.03615995005700030019x
Subject(s) - nitrous oxide , nitrification , nitrogen , denitrification , chemistry , environmental chemistry , fertilizer , soil test , soil water , environmental science , soil science , organic chemistry
Measurement of N 2 O and N 2 produced by denitrification is of current interest, from an environmental point of view and for the quantification of N losses. Our method for direct measurement of N 2 evolution from soil by 15 N emission spectrometry (ES) has been modified to measure both N 2 O and N 2 . Two different methods for reduction of N 2 O to N 2 before measurement by ES were tested: (i) by catalyst (Al 2 O 3 + 0.5% Pd) and high temperature (700 °C) in the gas sampling system (method I) and (ii) by high‐frequency discharge in the ES discharge tubes (Method II). By catalyst, 93% of 15 N‐N 2 O was reduced to 15 N‐N 2 , while 98% was reduced by high‐frequency discharge in the ES discharge tubes. The application of the two methods was tested by measuring the N 2 O and N 2 losses in closed cuvette systems after 15 N‐enriched KNO 3 was added to moist (85% of field capacity) and flooded soil. The nitrification inhibitor dicyandiamide was mixed into the moist soil to prevent loss of N 2 O as a result of nitrification. The same results were obtained when the N 2 O loss from moist soil was determined by using Method I, Method II, or gas chromatography (GC). The ratio of N 2 O/N 2 was 2.9 for moist soil and 0.2 for flooded soil 2 wk after application of 15 N‐KNO 3 . This method can measure both N 2 O and N 2 produced in soil from 15 N‐enriched fertilizer.