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dc.contributor.authorBreuillin-Sessoms, F.
dc.contributor.authorVenterea, R. T.
dc.contributor.authorSadowsky, M. J.
dc.contributor.authorCoulter, J. A.
dc.contributor.authorClough, Timothy J.
dc.contributor.authorWang, P.
dc.date.accessioned2018-05-09T22:31:55Z
dc.date.available2017-04-20en
dc.date.issued2017-08
dc.date.submitted2017-04-05en
dc.identifier.issn0038-0717en
dc.identifier.urihttps://hdl.handle.net/10182/9322
dc.description.abstractThe atmospheric concentration of nitrous oxide (N₂O), a potent greenhouse gas and ozone-depleting chemical, continues to increase, due largely to the application of nitrogen (N) fertilizers. While nitrite (NO₂⁻) is a central regulator of N₂O production in soil, NO₂⁻ and N₂O responses to fertilizer addition rates cannot be readily predicted. Our objective was to determine if quantification of multiple chemical variables and structural genes associated with ammonia (NH₃)- (AOB, encoded by amoA) and NO₂⁻ -oxidizing bacteria (NOB, encoded by nxrA and nxrB) could explain the contrasting responses of eight agricultural soils to five rates of urea addition in aerobic microcosms. Significant differences in NO₂⁻ accumulation and N₂O production by soil type could not be explained by initial soil properties. Biologically-coherent statistical models, however, accounted for 70–89% of the total variance in NO₂⁻ and N₂O. Free NH₃ concentration accounted for 50–85% of the variance in NO₂⁻ which, in turn, explained 62–82% of the variance in N₂O. By itself, the time-integrated nxrA:amoA gene ratio explained 78 and 79% of the variance in cumulative NO₂⁻ and N₂O, respectively. In all soils, nxrA abundances declined above critical urea addition rates, indicating a consistent pattern of suppression of Nitrobacter-associated NOB due to NH₃ toxicity. In contrast, Nitrospira-associated nxrB abundances exhibited a broader range of responses, and showed that long-term management practices (e.g., tillage) can induce a shift in dominant NOB populations which subsequently impacts NO₂⁻ accumulation and N₂O production. These results highlight the challenges of predicting NO₂⁻ and N₂O responses based solely on static soil properties, and suggest that models that account for dynamic processes following N addition are ultimately needed. The relationships found here provide a basis for incorporating the relevant biological and chemical processes into N cycling and N₂O emissions models.en
dc.format.extent143-153en
dc.language.isoen
dc.publisherElsevier Ltd.
dc.relationThe original publication is available from - Elsevier Ltd. - https://doi.org/10.1016/j.soilbio.2017.04.007en
dc.relation.urihttps://doi.org/10.1016/j.soilbio.2017.04.007en
dc.rightsCopyright © 2018 Elsevier Ltd. All rights reserved
dc.subjectnitrous oxideen
dc.subjectnitrogen fertilizeren
dc.subjectsoil scienceen
dc.subjectNOBen
dc.subjectN cyclingen
dc.subjectN₂O emissions modelsen
dc.subjectAgronomy & Agricultureen
dc.titleNitrification gene ratio and free ammonia explain nitrite and nitrous oxide production in urea-amended soilsen
dc.typeJournal Article
lu.contributor.unitLincoln University
lu.contributor.unitFaculty of Agriculture and Life Sciences
lu.contributor.unitDepartment of Soil and Physical Sciences
dc.identifier.doi10.1016/j.soilbio.2017.04.007en
dc.relation.isPartOfSoil Biology and Biochemistryen
pubs.organisational-group/LU
pubs.organisational-group/LU/Agriculture and Life Sciences
pubs.organisational-group/LU/Agriculture and Life Sciences/SOILS
pubs.organisational-group/LU/Research Management Office
pubs.organisational-group/LU/Research Management Office/QE18
pubs.publication-statusPublisheden
pubs.volume111en
lu.identifier.orcid0000-0002-5978-5274


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