Evolution of Maize Compost in a Mediterranean Agricultural Soil: Implications for Carbon Sequestration

Round 1

Reviewer 1 Report

English must be improved throughout. 

It is not clear what the authors consider as labile and slow compartment. It is necessary to clarify which chemically or physically measurable fractions the authors based on to separate labile and slow compartments.

Some important information was not included in the methodology (please see comments)

Discussions are not always based on the results or the evaluated variables. The authors establish statements without being based on measured data

The authors need to better explain the results based on the physical and chemical mechanisms of interaction of soil organic matter, from the application of the compost, with the specific chemical characteristics. They also need to express the importance of clay content throughout this process.

There is no clear conclusion.

Comments for author File: Comments.pdf

Author Response

All authors thank the reviewer for the constructive comments and suggestions. We hope the manuscript will now fit the journal and reviewer's quality standards. You can find attached the new MS file with marked changes, including the English review by the MDPI service and all suggestions.

• English must be improved throughout. 

The MS was revised by MDPI language edition service and later improved with the respective comments.

• It is not clear what the authors consider as labile and slow compartment. It is necessary to clarify which chemically or physically measurable fractions the authors based on to separate labile and slow compartments.

Labile and slow SOC compartments are distinct pools that are mainly differentiated by their degradability; fast or labile SOC fraction degrades fast (days or months) whereas slow or recalcitrant degrades slow (years) as described in Wang et al., 2022 and Zou et al., 2005. In this work we differentiate both fractions based in the calculated turn-over time using the double exponential decay model as described in Kniker et al 2013 using equation (1) that calculates two slopes (k) corresponding to the fast and slow C pools. Then the mean residence time for each fraction is calculated as in equation 2.

We have introduced the terms in the introduction and edited the text in the M&M section to make this clearer to the reader. Also a reference was added (Zou et al., 2005).

• Some important information was not included in the methodology (please see comments)

Texture data and depth of previous analyses were included in the text. An estimation of lignin and polysaccharide content is now included in Table 1.

• Discussions are not always based on the results or the evaluated variables. The authors establish statements without being based on measured data
• The authors need to better explain the results based on the physical and chemical mechanisms of interaction of soil organic matter, from the application of the compost, with the specific chemical characteristics. They also need to express the importance of clay content throughout this process.

Discussion has been improved based on data and new, relevant references. We have removed most of the assumptions based on chemical and physical soil properties as we have realized our basic analysis were not enough to assume so. We consequently added some further research notes at the end of the manuscript so these considerations are noted to be taken into account.

• There is no clear conclusion.

We apologize to this respect as this point has been appreciated by all reviewers. We have improved this section both in the manuscript and in regard to the abstract.

OTHERS: Other suggestions and clarifications annotated in the MS have been also addressed: Expressions such as “as expected” were deleted from the text. Also some parts have been rewritten more prudently.

Regarding significant differences in Table 3, The referee was right, there was significant differences between treatment AC-5% in C loss (mg) and the rest, this was now amended. Meaning of Afast, Aslow variables were included in Table 3 caption.

Note that the quality of all figures has been improved, and a new secondary graph with specific data has been added to the priming effect figure (figure 5).

Author Response File: Author Response.docx

Reviewer 2 Report

The series of questions and suggestions for improving the text are made available in the form of comments in the attached file, including:

- What is the hypothesis and purpose of the study?

- The experimental design is not clear, as it is written in a wrong way;

- Treatments, repetitions, analyzes carried out, need to be better described;

- The presentation of the results needs to be better detailed and discussed, as it is often confusing.

- The conclusions repeat the presented results and the author still tries to justify them, failing to extract the essence of the study.

- The conclusions should answer the objective of the study, which was highlighted in it.

Comments for author File: Comments.pdf

Author Response

All authors thank the reviewer for the constructive comments and suggestions. We hope the manuscript will now fit the journal and reviewer's quality standards. You can find attached the new MS file with marked changes, including the English review by the MDPI service and all suggestions.

The series of questions and suggestions for improving the text are made available in the form of comments in the attached file, including:

• What is the hypothesis and purpose of the study?

Thanks for pointing this out. Indeed, our manuscript was in lack of a proper hypothesis, which has now been added to the last part of the introduction.

• The experimental design is not clear, as it is written in a wrong way;

Excuse us for this, we have now rewrite this for clarity.

• Treatments, repetitions, analyzes carried out, need to be better described;

Also this part has been now revised and rewritten for better comprehension. Also a note was included in the Figure 1 caption to indicate that “Numbers after “T” indicates sampling time in months”.

• The presentation of the results needs to be better detailed and discussed, as it is often confusing.

Results and discussion has been improved based on data and new, relevant references. We have removed most of the assumptions based on chemical and physical soil properties as we have realized our basic analysis were not enough to assume so. We consequently added some further research notes at the end of the manuscript so these considerations are noted to be taken into account.

• The conclusions repeat the presented results and the author still tries to justify them, failing to extract the essence of the study.
• The conclusions should answer the objective of the study, which was highlighted in it.

We apologize to this respect as this point has been appreciated by all reviewers. We have improved this section both in the manuscript and in regard to the abstract.

Note that the quality of all figures has been improved (which we hope it is been notable along the manuscript; otherwise individual files are sent to the editor), and a new secondary graph with specific data has been added to the priming effect figure (figure 5).

Author Response File: Author Response.pdf

Reviewer 3 Report

1.The results and analysis of the abstract are not very logical and lack the final conclusion of the

manuscript.

2.The preface is very loose and illogical. It is necessary to combine some paragraphs to supplement some recent research progress

3.Because there was no information about replicates, I could not trust on data and some data had no error bar. The manuscript had no statistic analysis? Then, how can you conclude that was significant or not (for most figures and table).

4.The study area and experimental setup part is not clear and lacks logic. It needs to reorganize and organize the language

5.The quality of Figure 2 and Figure 4 is too poor, and it needs to be redrawn

6.There are too many conclusions.add perspectives. Try to provide some gaps for further research,this will enhance the novelty of the paper.

Author Response

All authors thank the reviewer for the constructive comments and suggestions. We hope the manuscript will now fit the journal and reviewer's quality standards. You can find attached the new MS file with marked changes, including the English review by the MDPI service and all suggestions.

2. The preface is very loose and illogical. It is necessary to combine some paragraphs to supplement some recent research progress

Thanks for noticing this and we apologize for such a confusing paragraph. The whole preface has been rewritten, adding new references.

3. Because there was no information about replicates, I could not trust on data and some data had no error bar. The manuscript had no statistic analysis? Then, how can you conclude that was significant or not (for most figures and table).

We have rewritten the data analysis part. All statistic test that have been used are now specified in each caption.

4. The study area and experimental setup part is not clear and lacks logic. It needs to reorganize and organize the language

We apologize for that, this part has been now revised and rewritten for better comprehension, including the figure of the experimental design.

5. The quality of Figure 2 and Figure 4 is too poor, and it needs to be redrawn

Thanks to the reviewer for noticing this. The quality of both figures, and generally of all of them, has been improved.

(Point 1) The results and analysis of the abstract are not very logical and lack the final conclusion of the manuscript & Point 6: There are too many conclusions.add perspectives. Try to provide some gaps for further research,this will enhance the novelty of the paper.

We apologize to this respect as this point has been appreciated by all reviewers. We have improved this section both in the manuscript and in regard to the abstract. We have removed most of the assumptions based on chemical and physical soil properties as we have realized our basic analysis were not enough to assume so. We consequently added some further research notes at the end of the manuscript so these considerations are noted to be taken into account.

Author Response File: Author Response.docx

Reviewer 4 Report

I think that manuscript is well conducted and presented. Discussed results fit with data presented. In any way I have some minor comments done in the pdf file attached.

Comments for author File: Comments.pdf

Author Response

All authors thank the reviewer for the constructive comments and suggestions. We hope the manuscript will now fit the journal and reviewer's quality standards. You can find attached the new MS file with marked changes, including the English review by the MDPI service and all suggestions made in the pdf file.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

After revision, the manuscript can be published

Reviewer 2 Report

Thank you for having accepted the suggestions inserted in the text in the form of comments, which improved the quality of the text to be published.

Reviewer 3 Report

The author has revised it as required, and it is suggested that the manuscript can be accepted.