Dear Authors,

Thank you for providing detailed responses to the two referee reports.

While both reviewers recognized the importance of the addressed topics and extensive data sets, the second reviewer raised many critical issues, including the organization and interpretation of data and experimental design. As you might remember, I had also suggested during the initial technical review that you would need a more consistent framing of your key hypotheses (refer to the original comment below).

(Comment during the technical review: It looks like that you have toned down the original hypothesis on the role of pyrite oxidation in some parts of the manuscript (e.g. goal statements at the end of Introduction), resulting in inconsistent descriptions of the major hypotheses. Please be consistent in providing major hypotheses throughout the manuscript, including Abstract, Introduction, and Discussion.)

Given many critical reviewer comments, a major revision would be required to reconsider your manuscript for publication in Biogeosciences. The revised manuscript might also be resent to the same reviewers for a second round of review. Some of your responses (particularly those to comments on refocusing major themes and experimental design) appear inadequate to justify your maintaining the current structure and data interpretation. In case you want to maintain the original structure, I would suggest that you provide at least your rationale in the discussion section.

I would like to ask you to make all the changes easily identifiable in a marked-up manuscript and a point-by-point reply to the reviewers’ comments. I would also suggest you to specify the line numbers of the revised parts when you respond to the reviewer comments.

Sincerely,

Ji-Hyung Park
Associate Editor, Biogeosciences

Dear Authors,

Thank you for revising your manuscript in response to the reviewer comments and suggestions. One of the two reviewers, who were involved in the first review round, provided very thoughtful, still quite critical comments on the revised manuscript. Please refer to the attached reviewer report.

I agree with this reviewer’s concerns that your responses to the original reviewer comments and the revised manuscript did not adequately address many of the raised issues, particularly those about the experimental design and the way to present an discuss rather qualitative results. Therefore, I need to reconsider your manuscript after another major revision that should fully address all the major and minor points raised by the reviewer.

I would like to ask you to make all the changes easily identifiable in a marked-up manuscript and a point-by-point reply to the reviewers’ comments. I would also suggest you to specify the ‘correct’ line numbers of the revised parts when you respond to the reviewer comments. The reviewer noted many errors in your previous responses (“a number (maybe all?) of the
line numbers of revised text referred to in the response to reviewers are incorrect, there are
typos in the quoted text revisions (e.g., response 50), and sometimes there’s no indication of
what revisions were made or where they can be found in the text (e.g., response 49)”).

Sincerely,

Ji-Hyung Park
Associate Editor, Biogeosciences

Dear Authors,

Thank you for your efforts to conduct additional statistical analyses and prepare detailed responses to the reviewer comments on your revised manuscript.

I am pleased to let you know that your manuscript can be published after some minor revisions (mostly technical corrections) as detailed below.

- Abstract, lines 20-22: Please provide "ranges" (either XX-XX or from XX to XX).
- Abstract, lines 30-31: This should be a concluding (or at least summarizing) remark. Please specify what "possible pathways of N2O production in spring and autumn periods" you would like to highlight.
- Conclusions, line 606: for grassland "also" during the autumn?
- Table 2: Please describe in the table caption what test was used and what significant differences (between what?) different letters represent.
- Fig. 1: To guide readers on the location of your study sites in Demark or Europe, please add more geographical information (e.g., any close city name, cardinal directions,,,) on the main site map

Sincerely,

Ji-Hyung Park,
Associate editor, Biogeosciences

Dear Authors,

Thank you for your efforts in the final stage of the long review process.

Please correct the incomplete expression in line 34 ("heterotrophic"): "heterotrophic denitrification"?

Sincerely,

Ji-Hyung Park,
Associate Editor, Biogeosciences