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Titre :
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Denitrification in intact subsoil cores
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Auteurs :
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K. Castle ;
J. Arah ;
A. Vinten
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Type de document :
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article/chapitre/communication
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Année de publication :
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1998
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Format :
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p. 12-18
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Langues:
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= Anglais
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Catégories :
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AGRICULTURE, AGRONOMIE ET ELEVAGE
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Mots-clés:
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DENITRIFICATION
;
SOUS SOL
;
PRELEVEMENT D'ECHANTILLON
;
ESSAI AU LABORATOIRE
;
AEROBIOSE
;
ANAEROBIOSE
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Résumé :
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Intact, unamended subsoil cores taken from two contrasting field sites were incubated in the laboratory at 12 °C under aerobic (21% O-2) and anaerobic (1.1-5.5% O-2) conditions. Denitrification of N-15-NO3- diffusing into the cores across a semi-permeable membrane was estimated by: (1) direct observation of N-15- labelled N-2 and N2O and (2) mass balance following sectioning at the end of the experiment. The in situ denitrification potential (rates where the supply of NO3- is not limited by diffusion) was estimated using a finite-difference approximation to a diffusion reaction equation based on comparison of time and depth profiles of NO3- and Br- in the incubated cores. Potentials between 0.2 and 2.5 mg N kg(-1) day(-1) were obtained under low O-2 and natural C concentrations. These results indicate the potential for denitrification in glacial till subsoils to reduce NO3- leaching to ground or surface waters to levels unlikely to result in a pollution hazard. The major product of NO3- reduction in these subsoils was observed to be N-2, rather than the greenhouse gas and catalyst of stratospheric O-3 removal, N2O.
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Source :
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Biology and Fertility of Soils, vol.28
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