Dear authors,

you did a good job in responding to the reviewer comments. I am looking forward to seeing the revised paper.
Best regards
Cornelia

The authors revised the paper according to the reviewer comments and accordingly it improved somewhat. However, there is some work left before the paper may be published :

• The manuscript should be carefully proofread, e.g. in the first sentence it should be ‘….determine many crucial soil propertis and the cycling of carbon ….’ ; l.26 ‘derivied’ should be ‘derived’ ; P.2, l. 4 : ‘understanding of SOM formation’ ; P.6, l. 27 : ‘are relatively small components’ should be replaced by ‘contributing little to’, P. 8, l.7 : ‘aromatic matter’ should be replaced by ‘aromatic OM compounds’ ; P.12, l.11 : ‘on’ should be deleted.
• In the two sections giving the arguments for contradictory theories for stabilisation of aromatic C, authors should discuss all literature in terms of positive arguments for these research ligne. In the ‘Dissolved phase line of evidence’, the third paragraph on the importance of root origin of dissolved aromatics should be the third argument. In this paragraph it should be stated that all these arguments were obtained for acid forest soils under temperate climate or through laboratory analyses. Therefore, this line of evidence is difficult to use as a general argument.
• In the second section ‘solid line of evidence’, the contradictory argument mentioned in the last sentence (P.7, l.30-32) should be deleted, as it introduces a confusion to the reader.
• P. 8, l.29: the last sentence should be deleted, as it is a general statement. Instead it could be good to add a transition sentence introducing NMR as a method to quantify aromatic compounds.
• P.9 : Concerning the analytical bias introduced by HF treatment, the study by Eusterhues et al. (2007) , OG should be considered. It shows that the composition of HF soluble C is different for different soil types – thus not providing evidence of selective loss of specific C species.
• P.9 : the Bloch decay technique may lead in some cases to underestimation of O-akyl C, whereas the work of Knicker shows nicely that aromatic C, if not very condensed can be detected by CPMAS.
• The discussion about pyrogenic C should be moved to the process understanding part. The last sentence (P.9, l29-31) can be deleted.
• P.10, l.1 : a sentence is needed introducing the fact that process understanding may be limited by several different aspects related to our conceptual and experimental approaches.
• 4.2. Limits in process understanding : I think that this paragraph need to be better structured – temporal aspect as discussed in the beginning should be separated from spatial ones (probalby the last paragraph could be moved up a little); plant activity effects should be separated from the processes depending on pedology
• P.11, l.31 : ‘and methodological problems ‘ should be added after ‘the contradictions’
• P.12/13 : in the research strategies it shold be mentioned that the origin of aromatics in water and soil should be elucidated and specific stabilisation and destabilisation mechanisms studied (e.g. photooxidation ; binding of tannins to proteins….)

Dear authors,

you did a very good job in revising your manuscript - it reads very well know. I suggest two minor revisions: P.2, l.21 Lehmann and Kleber (2015) Nature could be added as a reference.
I do not quite understand the discussion on p.9, l.20-24: the peak at 56 ppm may not exclusively be derived from methoxyl groups, as amide C also contributes. Thus the observation discussed in the paragraph may not help very much towards your argument - I suggest to delete these sentences.
The subject of your paper moved somewhat away from aromatic lignin-derived C to a more general discussion on concepts about SOM stabilisation. In consequence I invite you to re-think your title. However, if you decide to keep it that is fine with me.
Best regards
Cornelia

Dear Authors,

Thank you for the detailed revision, your manuscript can now be published with some technical corrections. Please consider the suggestions made by Cornelia carefully. We are looking forward receiving the final version of the manuscript!

Kind regards,

Kristof Van Oost