PONE-D-24-57959Black soil thickness prediction and soil erosion risk assessment in a small watershed in Northeast ChinaPLOS ONE

Dear Dr. xu,

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Sher Muhammad, PhD

Academic Editor

PLOS ONE

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Additional Editor Comments:

Two anonymous reviewers have reviewed the manuscript. The manuscript requires substantial revisions to address the issues in the present form. The Random Forest method's validation on a smaller range of observed values (30–60) as opposed to the entire range (10–130) covered by the kriging methods is one of the main concerns brought up by the reviewers. This disparity calls into question both the stated high R2 and the validity of the Random Forest results. To guarantee reliable comparisons, this approach must be tested across the entire spectrum. Furthermore, the wording "using raster calculations" in Table 1's description of precipitation data interpolation is imprecise. The paper should discuss the drawbacks of integrating coarse-resolution data with pixel sizes of 30 m and make clear how interpolation techniques affect the results. A comprehensive language evaluation is advised since the language has to be improved. The overall impact is limited by the study's unclear combination of soil erosion risk assessment and mapping the thickness of the black soil layer. A more unified process can result from including soil erosion as a variable in thickness mapping. The title has to be clarified, the units in the figures need to be formatted correctly, the novelty of this work needs to be better discussed with references to other research, and the sample approach needs to be clearly defined.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: No

Reviewer #2: Yes

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: No

Reviewer #2: Yes

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3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: No

Reviewer #2: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: No

Reviewer #2: No

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Thank you for the opportunity to review this research. The topic is important and the research approach is good, but I have some concerns about the execution and communication. I hope this can be revised to reach a broader audience though probably not in this journal.

My main concern pertains to Figure 4: All of the kriging methods show data points with observed values ranging from 10 to 130, matching the range of values reported in the paper. However, the Random Forest method only shows observed values ranging from about 30 to 60, and the linear regression is based on this small range. I don't think the overall results and much larger R^2 can be reliable if the Random Forest method is not tested against all of the observed values.

A secondary concern pertains to the methods used to interpolate the precipitation data listed in Table 1. The methods section should say more than "using raster calculations" (as on lines 139 and 142) and should discuss the relative accuracy or error inherent in combining data from much coarser resolutions with the 30m pixel size used in the study.

While the English usage is mostly understandable, there are minor errors throughout the paper that should be addressed. For example (not a complete list):

Check throughout the paper for the proper use of English articles (a, an, the): _the_ hydrologic cycle, _the_ Random Forest method, etc.

At line 45, please check the units and superscripts on line 45 (10^6 not 106, km^2 or ha?).

At line 108, what is "soil erosion, soil erosion ditch" (possibly gully formation?).

At line 116, rephrase the survey site description in better English.

At line 149, say Methods not Method and add a short introductory paragraph for this section.

At line 227, you say that the number of trees has a significant impact, but Table 4 shows that doubling from 50 to 100 trees only reduces the RMSE^oob by <2%.

In Figures 2 and 6, make sure units are given in parenthesis, not after a slash (which can mean "per"): (cm) not /cm, (%) not /%

Reviewer #2: This manuscript compared several models for predicting the thickness of black soil layer in a small watershed in Northeast China. Authors also explored the soil erosion risk using RUSLE model in the study area. Authors found that the random forest model outperformed the kriging models, with smaller RMSE and larger R². Soil erosion risk assessment revealed that areas with no risk and low risk accounted for 21.91% and 62.21%, respectively. The investigated topic is interesting and important for evaluating and protecting black soil in China. Nevertheless, this work has several major limitations: (1) the work on thickness of black soil layer mapping and soil erosion risk assessment has no linkage. The outcome of thickness map of black soil layer does not provide any useful information on soil erosion risk assessment in the current workflow. However, if you put soil erosion risk assessment as a starting point, then adding this variable as an input for thickness mapping, which is more logical. (2) the current knowledge has been poorly described, limiting the novelty of this work; (3) Please provide both out-of-bag validation and k-fold cross-validation results; (4) there are many mistakes regarding the grammars and duplicated sentences. Please carefully check the writing quality before the resubmission. In summary, this manuscript is not suitable to be published now, but can be reconsidered after re-submission.

Detailed comments:

Title: The use of “Black soil thickness” is confusing. Please consider the use of thickness of black soil layer.

Line 29: kriging methods (classical, ordinary, and simple) have been rarely used nowadays.

Lines 30-31: It is not clear how to connect the work on mapping thickness of black soil layer and soil erosion assessment.

Line 32: Please provide the values for RMSE and R2.

Line 45: 106 km2, 6 should be in superscript. Please use km2 for arable land as well.

Line 52: It is important to describe the definition of black soil layer. For most readers outside of China, it is not easy to understand the exact meaning.

Lines 57-60: As you stated here, soil erosion plays an important in shaping the thickness of black soil layer, so why not including soil erosion as an input for mapping thickness of black soil layer?

Line 61: It would be important to start the paragraph with the fact that soil thickness is the worst predicted soil information as summarized in the review by Chen et al. (2022). Therefore, there is a need to develop new methodology for soil thickness mapping.

Chen, S., Arrouays, D., Mulder, V.L., Poggio, L., Minasny, B., Roudier, P., Libohova, Z., Lagacherie, P., Shi, Z., Hannam, J. and Meersmans, J., 2022. Digital mapping of GlobalSoilMap soil properties at a broad scale: A review. Geoderma, 409, p.115567.

Lines 78-81: It is important to acknowledge previous studies on using machine learning model to predict soil thickness. Some relevant references are listed below, and you are explore more other interesting work as well:

Malone, B. and Searle, R., 2020. Improvements to the Australian national soil thickness map using an integrated data mining approach. Geoderma, 377, p.114579.

Liu, F., Zhang, G.L., Song, X., Li, D., Zhao, Y., Yang, J., Wu, H. and Yang, F., 2020. Liu, F., Wu, H., Zhao, Y., Li, D., Yang, J.L., Song, X., Shi, Z., Zhu, A.X. and Zhang, G.L., 2022. Mapping high resolution national soil information grids of China. Science Bulletin, 67(3), pp.328-340.

Lines 86-90: The current knowledge is missing before stating the objectives.

Line 102: N and E are missing after the coordinates.

Lines 114-123: Please specify the sampling design of the four survey routes.

Line 134: (1) for the equation.

Lines 137-142: Two sentences are replicated.

Line 148: In Table 1, why not using the National Soil Information Grids of China at 90 m resolution?

Lines 153-154: 500 trees would be more stable.

Line 167: In Figure 1, authors indicated the sites for model testing, but here you mentioned that OOB error was used. This is confusing.

Since the results would be changed if authors using the soil erosion map as an input. I stop here and would be happy to provide more comments in the next round.

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Reviewer #1: No

Reviewer #2: No

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PONE-D-24-57959R1Black soil layer thickness prediction and soil erosion risk assessment in a small watershed in Northeast ChinaPLOS ONE

Dear Dr. liu,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please submit your revised manuscript by May 16 2025 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org . When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols . Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols .

We look forward to receiving your revised manuscript.

Kind regards,

Sher Muhammad, PhD

Academic Editor

PLOS ONE

Journal Requirements:

Additional Editor Comments:

Dear Authors, Thank you for the revisions. The revised version has been reviewed by two reviewers, recommending a major revision before further consideration.

You are encouraged to address each of the reviewers’ comments and resubmit the revision. We are looking forward to receive your revised manuscript.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: (No Response)

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: (No Response)

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: (No Response)

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4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: (No Response)

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: (No Response)

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6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: (No Response)

Reviewer #2: This revised manuscript has been improved after addressing my previous comments, while many issues still need to be revised.

(1) the grammar should be greatly improved. Some examples are listed below: “Use the RUSLE erosion equation and soil thickness to create a soil erosion rating scale that integrates external factors and the soil's properties”, “The topography of the study area is high in the west and low in the east, high in the south and north, and low in the center.”.

(2) The reference 10 is not a review paper. Please have a check.

(3) Lines 104-110: The part is wordy, you can shorten it.

(4) Line 88: soil-forming environment should be corrected as soil-forming environmental covariates.

(5) Line 89: Malong is a typo. It should be corrected as Malone.

(6) Line 92: quantile random forests should be corrected as QRF since it has been defined in in Line 87.

(7) Line 131: Fig.1 not Fig 1. Please check similar typos in the manuscript.

(8) Line 183: There is no need to define RUSLE again.

(9) Lines 203-215: The problem is that OOB is for random forest, so how you applied for Kriging interpolation. Please make it clear.

(10) Table 5: R2 should be corrected as R2.

(11) You have two c in the figure caption.

(12) Line 307: Why used the section named “RUSLE result” here? Please check the format throughout the manuscript.

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean? ). If published, this will include your full peer review and any attached files.

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Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy .

Reviewer #1: No

Reviewer #2: No

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[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/ . PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org . Please note that Supporting Information files do not need this step.

Black soil layer thickness prediction and soil erosion risk assessment in a small watershed in Northeast China

PONE-D-24-57959R2

Dear Dr. liu,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Dinesh Panday

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Thank you for your thorough revisions. There is a minor suggestion from the reviewer, please address it before sending to production unit.

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Thank you for the opportunity to review this revised paper. The new version adequately addresses the prior reviewer comments and should be published.

If there is an opportunity for a very minor revision, please explain or spell out the abbreviation SEM (soil erosion modulus) in Table 6; ideally, the SEM and thickness categories would also be defined in the figure row/column headings or in the figure caption, not just in the text of the paper.

Reviewer #2: All the suggestions have been well addressed in the revised manuscript, and therefore it can be accepted for publication.

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean? ). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy .

Reviewer #1: No

Reviewer #2: No

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