I have considered the referees comments and author responses and have decided that the manuscript should be reconsidered after major revisions. Reviewer 1 is very positive about the d15N data and the insights the paper contributes, but does make substantial constructive criticism of elements of the paper which require attention.
One point I am concerned about is the fatty acid analysis of microbial community composition which is raised by Reviewer 1, point 4. The authors do not used the widely used methodology based on Frostegard and others of PLFA analysis, but use a total fatty acid analysis and select single indicators for fungi and bacteria. For fungi this is usual, but for bacteria only using one indicator for gram positive bacteria means that no conclusion can be drawn about the relative abundance of bacteria and fungi in these peat samples, given that gram negative bacteria have not been accounted for, and a range of gram positive bacteria will not be accounted for with a single indicator. The references cited by the author indicate that this analysis should only be used for studies of particular bacterial isolates.
Given the limitations of the analytical approach used, the authors should remove the microbial community data entirely. Without this data, as reviewer 1 states, the d15N data are very interesting and novel, and therefore publishable in this journal.

I would request the authors to revise the manuscript in accordance with both reviewers comments and editorial comments above. The manuscript will then be reconsidered for publication
Yours sincerely
Jeanette Whitaker

The manuscript has been back to the same 2 reviewers for assessment. Reviewer 2 recommends acceptance and reviewer 1 suggests a few outstanding minor corrections whilst rating the quality of the manuscript highly. If you could consider these comments and respond accordingly the manuscript will then be returned to myself for editorial review and a final decision.
Best wishes
Jeanette Whitaker

Dear Dr Groß-Schmölders

Thankyou for your revisions in response to the 2nd set of reviews. I am pleased to tell you the paper is now accepted for publication, I believe this is a very interesting study.
Best wishes
Jeanette Whitaker
Executive Editor

Dear Dr Groß-Schmölders

Many thanks for submitting your paper to SOIL and for the positive way you have engaged with the review process. I look forward to seeing it published.

With best wishes

John Quinton
Executive Editor.