Effect of soil saturation on denitrification in a grassland soil

Cardenas, Laura Maritza; Bol, Roland; Lewicka-Szczebak, Dominika; Gregory, Andrew Stuart; Matthews, Graham Peter; Whalley, William Richard; Misselbrook, Thomas Henry; Scholefield, David; Well, Reinhard

doi:https://doi.org/10.5194/bg-14-4691-2017

Articles | Volume 14, issue 20

https://doi.org/10.5194/bg-14-4691-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/bg-14-4691-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 14, issue 20

Research article

|

23 Oct 2017

Research article |

| 23 Oct 2017

Effect of soil saturation on denitrification in a grassland soil

Laura Maritza Cardenas, Roland Bol, Dominika Lewicka-Szczebak, Andrew Stuart Gregory, Graham Peter Matthews, William Richard Whalley, Thomas Henry Misselbrook, David Scholefield, and Reinhard Well

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Final revised paper (published on 23 Oct 2017)
Supplement to the final revised paper
Preprint (discussion started on 30 Jan 2017)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC1: 'Review', Anonymous Referee #3, 10 Feb 2017
- AC1: 'Responses to Reviewer 3', Laura Cardenas, 27 Apr 2017
RC2: 'Complex analysis for a simple process?', Anonymous Referee #1, 21 Feb 2017
- AC2: 'Responses to Reviewer 1', Laura Cardenas, 27 Apr 2017
RC3: 'review of manuscript "Effect of soil saturation on denitrification in a grassland soil"', Anonymous Referee #2, 22 Feb 2017
- AC3: 'Responses to reviewer 2', Laura Cardenas, 27 Apr 2017

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Publish subject to minor revisions (Editor review) (29 Apr 2017) by Yakov Kuzyakov

AR by Laura Cardenas on behalf of the Authors (30 Apr 2017) Author's response Manuscript

ED: Publish as is (08 May 2017) by Yakov Kuzyakov

ED: Reconsider after major revisions (18 May 2017) by Yakov Kuzyakov

AR by Laura Cardenas on behalf of the Authors (18 May 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (18 May 2017) by Yakov Kuzyakov

RR by Anonymous Referee #4 (13 Jun 2017)

RR by Yushu Zhang (22 Jun 2017)

Suggestions for revision or reasons for rejection

Nitrous oxide is a powerful greenhouse gas, the pathway of N2O production is important to model and mitigate N2O emissions, which would be changed due to differ in moisture contents. The authors seek to evaluate the roles of soil water filled pore space and nitrous oxide emission and its pathway. They established a laboratory incubation experiment in a relatively narrow range of moisture (70-100%), emissions of N2O, N2 and CO2, as well as the isotopocules of N2O, were measured. The authors found that denitrification as the main source of fluxes at the highest saturations, but nitrification could have occurred at the lower saturation, even though moisture was still high (71% WFSP). The results indicated that there are 2 N-pools with different dynamics: added N producing intense denitrification, vs soil N resulting in less isotopic fractionation.
Lots of studies have reported the relationship between the moisture contents and denitrification and N2O and N2 emission, and the effects of spatial heterogeneity and source processes on GHG. Whilst, the study conducted in a relatively narrow range of moisture is rare. These results could contribute to model and mitigate GHG emissions from agricultural soils. Additionally, the authors have revised the paper according the first 3 reviewers, which improved the paper a lot. In my opinion, this is an interesting paper, although it has some small problems should be revised. Thus, it can be accepted after minor revision. My suggestions were shown as follows.
Line 121 and 22, the authors hypothesized that, even at high soil moisture, a mixture of nitrification and denitrification can occur. However, the authors haven’t explain the base of this hypothesis.
Line 183, the incubation experiment lasted 13 days. The detail of incubation term should be described, “one day before amendment application and 12 days after ….”. Otherwise, the readers would be puzzled.
Line 268, in “Results” section, the results were described too much in details. In my view, the results which supported the conclusions could be described in details, whist, the other results may be described in brief. In fact, it is difficult for the reads to remember so much information and to find the important information for the conclusions.
Line 364 to 368, in “Results” just showing the results of the experiment. Thus, those sentences may be moved to “Discussion” section.
Line 385 to 389, move those sentences to Fig. 4 as a footnote.
Line 402, “2-pool dynamics” should be described.
Line 434, the topic of different paragraphs might be used as the subtitle in “Discussion” section, which might be easy for readers to understand and to follow authors’ thought. For example, in 4.1, “Nitrogen emission increasing with moisture contents” may be used as the subtitle of this section.
Fig. 1, take the figure of N2O, N2 or CO2 together, and then they would be easily compared.
Fig. 4, the icon of Fig. 4 should be described.
Fig. 5, “BD”, “ND” and “FD” should be described.

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RR by Anonymous Referee #6 (23 Jun 2017)

ED: Publish subject to minor revisions (Editor review) (23 Jun 2017) by Yakov Kuzyakov

AR by Laura Cardenas on behalf of the Authors (06 Jul 2017) Author's response Manuscript

ED: Publish as is (07 Jul 2017) by Yakov Kuzyakov

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Short summary

A laboratory incubation was carried out at different soil moisture levels to measure emissions of nitrogen gases and the isotopomers (position of ¹⁵N) of nitrous oxide. Flux variability was larger in drier conditions, probably due to nutrient distribution heterogeneity created from soil cracks and consequently nutrient hot spots. Denitrification was the main source of fluxes at higher moisture, but nitrification could have occurred under drier conditions (although moisture was still high).