Nitrogen oxides and ozone fluxes from an oilseed-rape management cycle: the influence of cattle slurry application

Vuolo, Raffaella M.; Loubet, Benjamin; Mascher, Nicolas; Gueudet, Jean-Christophe; Durand, Brigitte; Laville, Patricia; Zurfluh, Olivier; Ciuraru, Raluca; Stella, Patrick; Trebs, Ivonne

doi:https://doi.org/10.5194/bg-14-2225-2017

Articles | Volume 14, issue 8

https://doi.org/10.5194/bg-14-2225-2017

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

https://doi.org/10.5194/bg-14-2225-2017

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

Articles | Volume 14, issue 8

Research article

|

02 May 2017

Research article |

| 02 May 2017

Nitrogen oxides and ozone fluxes from an oilseed-rape management cycle: the influence of cattle slurry application

Raffaella M. Vuolo, Benjamin Loubet, Nicolas Mascher, Jean-Christophe Gueudet, Brigitte Durand, Patricia Laville, Olivier Zurfluh, Raluca Ciuraru, Patrick Stella, and Ivonne Trebs

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Interactive discussion

Status: closed

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

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RC1: 'Review Nitrogen oxides and ozone fluxes following organic and mineral fertilisation of a growing oilseed-rape', Anonymous Referee #1, 03 Aug 2016
- AC1: 'Answer to Anonymous Referee #1', Benjamin LOUBET, 22 Sep 2016
RC2: 'Review', Anonymous Referee #2, 16 Aug 2016
- AC2: 'Answer to Anonymous Referee #2', Benjamin LOUBET, 22 Sep 2016

Peer-review completion

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

ED: Reconsider after major revisions (28 Sep 2016) by Mathew Williams

AR by Benjamin Loubet on behalf of the Authors (02 Nov 2016) Author's response Manuscript

ED: Referee Nomination & Report Request started (08 Nov 2016) by Mathew Williams

RR by Anonymous Referee #2 (24 Nov 2016)

Suggestions for revision or reasons for rejection

With the revised version, the authors have considerably improved the manuscript. However, there are still some issues that need further revision before the manuscript can be published (see detailed comments below).

MAJOR COMMENTS

It needs to be considered, that the Supplementary material is not an integral and equally valid part of the peer-reviewed manuscript. Therefore, information that is necessary for understanding the discussion and conclusions must not be placed in the Supplementary material but has to be included in the main manuscript. This concerns the following comments 1 and 2.

1) Supplementary section 6 should be integrated in Section 3.3.2 of the main manuscript. The latter is named 'Seasonal dynamics ...' but presently contains only one sentence (Line 260) about seasonal variations, although this is one major aspect of the presented dataset. In contrast, the overall flux statistics presented in Lines 240-250 could be shortened.

2) Fig. S5 and the corresponding text in supplementary section 7 need to be integrated into the main manuscript, in order to make the discussion in Section 3.8.2 understandable.

3) In Section 3.8.2 the authors should probably differentiate more between (a) empirical explanations of the observed ozone deposition velocity by measurable driving parameters like e.g. the parameterisation of Stella et al. and (b) identification of real physical/chemical adsorption and destruction processes like e.g. gas-phase chemical reactions with NO and various VOCs (above soil or within soil pore-space) or heterogeneous chemical and physico-chemical reactions at dry and wet soil surfaces.

4) Line 505ff.: Instead of assessing the significance of agriculture for total NOx emissions from this single site and crop, it would be much more useful to compare the observed NO emission factor to comparable emission factors used in national or international inventories (e.g. EMEP, IPCC, etc.).

5) Line 508: The value ~5.6 t N-NO ha-1 is clearly erroneous (concerning value and/or units ha-1). 0.27% of 80 kg N ha-1 yr-1 multiplied by 26 Mha results in an annual total of 5600 t N-NO for the entire country.

6) Line 508-512: The argumentation is contradicting here. First it is said that the annual total of agricultural NO emissions is "several hundreds of thousand" times smaller than the other emissions; and then it is argued that if concentrated within a few weeks in spring and autumn, they can nevertheless be important. A concentration of the annual emission to a few weeks (say 2-3 weeks) increases the relative magnitude (compared to other emissions during these weeks) only by a factor of 20, which is still much smaller than a factor of "several hundreds of thousand"

7) Figure 5b: It would be most interesting to see the effect of the chemical correction on the NO2 deposition velocity.

MINOR COMMENTS AND LANGUAGE CORRECTIONS

- Line 15 (abstract): Replace "Mean NO emissions" by "Cumulated NO emissions"

- Line 19/20: This statement about the ozone deposition velocity is incomplete. It 'was significantly larger' than ...?

- Line 84: write more precisely "...none over an arable crop."

- Line 85: This sentence needs rephrasing. It is not the question whether the gases are interacting (they do so according to general chemical and physical laws). Better write "...whether the reactions between NO, NO2 and O3 significantly influence their fluxes above crops and ..."

- Line 99: It is not clear what 'adapted' means here. Better use e.g. 'suitable' or 'adaptable'.

- The numbering of the (Sub-) Sections in Chapter 3 is obviously not correct. E.g. there is no Section 3.4 or 3.5

- Line 276-278: This argument should be related to the chemical correction and derivation of the surface fluxes in Section 3.8.1 and Fig. 8 later in the manuscript. Does the chemical correction of the NO fluxes lead to diurnal cycle that is more in phase with temperature?

- Line 282-284: These statements are contradicting: 0.09 nmol m-2 s-1 is not smaller than the previous result of 0.07 nmol m-2 s-1!

- Line 287: Correct to "...flux distributions ..."

- Line 288: Change to "...the ones for the whole period"

- Line 295: "Following the slurry application" is quite unspecific. Please specify the length of the time period attributed to this event.

- Line 297: What is the difference of this emission factor (0.27%) to the one in Line 295 (0.25%)? Maybe Lines 295-296 are obsolete?

- Line 309: " the soil was only humidified ... and occurred ..." This formulation is syntactically incorrect and needs rephrasing.

- Line 359-360: It is quite unusual to present correlation coefficients in %. In addition it is not fully clear whether the normal correlation coefficient or the squared correlation is meant here.

- Line 387f.: This statement needs rephrasing. The gaseous transfer in the soil is always driven by molecular diffusion. Here, the important assumption is that the soil surface deposition is quantitatively limited by molecular diffusion in the soil pores. I thus suggest to modify to: "...if molecular diffusion in the soil pores is the main limitation factor"

- Line 394: Replace "to the mast" by "to the EC measurement height"

- LIne 408-410: This sentence can be omitted because it is a repetition of statements that have been introduced before.

- Line 418: "O3" is misplaced here.

- Line 427: Correct to "using the Stella et al..."

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RR by Anonymous Referee #1 (28 Nov 2016)

Suggestions for revision or reasons for rejection

I think this is an excellent study, with the MS including particularly detailed discussion of the underlying processes which have driven the fluxes measured. I think this adds to our knowledge of NO, NO2 and O3 fluxes and would be of interest to the readership of Biogeosciences. Whilst I find the scientific updates to have been well implemented in general, for example I am impressed by the detail given for the response to the influence of the surrounding roads (3.7) I think that some minor changes will still be required before publication. There is still no mention of the statistics in the methods section. I think that this is essential if the reader is to make an informed decision about the drivers of flux increases. What has been tested against what? What was the magnitude of change and what is the statistical output? Also, whilst I understand that it is not always easy to generate perfect scientific prose, I think that the scientific English should be improved. I have listed a few items which need to be corrected below, but I suggest that the paper be re-read with spelling and grammar in mind.
Specific comments below, though this list is not exhaustive:
21: at all time(s)
70 and others: nowadays – is not a very scientific term
73: is this a quote – “”?
83-98: The section reads very much like a list
128: on the oilseed rape field
131: French for December is included
136: ~monthly -> approximately monthly
169: equation has been included in the main text
232: (Paris) – items in brackets must be elaborated upon, or not put in brackets.
243: NO fluxes were slightly negative part of the time - reword
248: and were mostly negative (deposition) – again brackets
257: during bare soil periods - reword
350: stats in brackets in discussion, not enough detail and no statistical output
421: numbered bullets very long – bullet points are unusual and if included, very brief

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RR by Anonymous Referee #3 (29 Nov 2016)

ED: Publish subject to minor revisions (Editor review) (12 Dec 2016) by Mathew Williams

AR by Benjamin Loubet on behalf of the Authors (06 Jan 2017) Author's response Manuscript

ED: Publish as is (26 Jan 2017) by Mathew Williams

AR by Benjamin Loubet on behalf of the Authors (03 Feb 2017) Author's response Manuscript

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Short summary

Atmospheric nitrogen oxides (NO and NO₂) are a threat for the environment and human health. Agricultural soils are a large but uncertain source, partly due to a lack of direct fluxes measurements. We quantified NO, NO₂ and ozone (O₃) fluxes above an oilseed rape crop rotation. We found that 0.27 % of nitrogen applied was emitted as NO, whose emissions were favoured by fertilisation under dry and warm conditions. We found significant interactions between NO, NO₂ and O₃ even above bare soil.