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Title: The effect of fertiliser application rate and soil pH on methane oxidation and nitrous oxide production
Author: Acton, Stuart David
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2007
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This study investigated the effect of fertiliser application on methane oxidation and nitrous oxide emissions. During this study a combination of 13C-CH4 and 15N stable isotope techniques were applied to laboratory soil incubations and traditional gas flux methodologies were applied to culture incubations. It was found that fertiliser application rate and soil pH were major influences on both methane oxidation and nitrous oxide emissions from an arable soil. Profiles of the main nitrous oxide producing processes were obtained, and it was shown that nitrification was the predominant source of nitrous oxide from most aerobic soil incubations and that soil acidification greatly reduced nitrous oxide emissions from nitrification. Additionally denitrification was shown to not be restricted to anaerobic conditions. Similar profiles were obtained for 13C soil incubations and the effect of increasing fertiliser concentrations on methane oxidation was determined. Methane oxidation was inhibited by fertiliser concentrations up to 20 g N m-2. However, above 20g N m-2 inhibition declined and there was no apparent effect of increasing fertiliser concentration on methane oxidation. Culture incubations aimed to determine the contribution of methane oxidising bacteria to nitrous oxide emissions and ammonia oxidation. Ammonia oxidation was observed in all methylotrophic bacterial cultures. Nitrous oxide production was only observed in Methylomicrobium chloromethanicum and Methylocystis parvus and it was not possible to determine if this nitrous oxide was produced via ammonia oxidation, nitrate reduction or via the reduction of nitrite produced during ammonia oxidation, in a process similar to nitrifier denitrification that has been observed in autotrophic ammonia oxidising bacteria.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available