Aerobic emissions of N sub(2)O and N sub(2) from soil cores: Factors influencing production from super(13)N-labelled N sub(3) super(-) and NH sub(4) super(+)

Gas-stripping procedures, with air as the stripping and carrying gas, were used to investigate the effects of amendments on production in soil cores of N sub(2)O and N sub(2) arising from super(13)N-labelled NO sub(3) super(-) (denitrification) or NH sub(4) super(+) (nitrification). These cores had...

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Bibliographic Details
Published in:Soil biology & biochemistry 1995-01, Vol.27 (10), p.1299-1306
Main Authors: Speir, T W, Kettles, HA, More, R D
Format: Article
Language:English
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Summary:Gas-stripping procedures, with air as the stripping and carrying gas, were used to investigate the effects of amendments on production in soil cores of N sub(2)O and N sub(2) arising from super(13)N-labelled NO sub(3) super(-) (denitrification) or NH sub(4) super(+) (nitrification). These cores had been used previously to investigate ambient gas emission rates; the rates after amendment were compared with these "natural" emission results. Using super(13)NO sub(3) super(-), the results of amendment with H sub(2)O, glucose, NO sub(3) super(-), or glucose + NO sub(3) super(-), several hours before the experiment, were usually explicable in terms of effects on microbial numbers and soil O sub(2) status. However, results obtained immediately after amendments were made, before de novo enzyme synthesis or change of O sub(2) status would have occurred, were generally difficult to interpret. Amendments which included N sub(3) super(-) gave spuriously low N sub(2)O and N sub(2) emission rates, probably due to isotopic dilution. The immediate effect of amendments may vary from time to time and depend upon soil conditions at the time of sampling. Only glucose consistently stimulated gas emissions, presumably because it enhanced activity of the existing denitrifying population. Using super(13)3NH sub(4) super(+), amendment with H sub(2)O increased production of N sub(2), but not N sub(2)O, and amendment with glucose reduced emissions of both gases. The advantages and disadvantages of this super(13)N method for investigating the influence on N sub(2)O and N sub(2) production of various soil amendments, and the relationships of these results with those of more conventional studies, are discussed.
ISSN:0038-0717