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  • Haiyang Yu1,‡,
  • Biyun Feng2,‡ and
  • Yuanyuan Dong2
  • et al.

Reviewer 1: Anonymous Reviewer 2: Naveen Dixit Reviewer 3: Anonymous

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The article titled "How to minimize the impact of biochar on soil salinity in dry regions? Lessons from a data synthesis" aims to perform a meta-analysis of biochar effects on soil salinity (using EC as the proxy) in Mediterranean, arid, and semi-arid climates, and in glasshouse/incubation experiments that simulate dry and saline conditions. The meta-analysis includes 40 studies from 14 countries. 

  1. Line 18: The number of studies reported in the Abstract does not match the number given in Materials & Methods. Please check and correct both places.
  2. Line 30: The sentence about “low-salt biochars” is wrong — biochar is more commonly alkaline rather than “low salt.” Please check the intended meaning and correct the wording.

 

  1. Lines 36–48 (Introduction): The biochar background is too brief and unclear. Add more environmental context — for example: appropriate application rates, using biochar alone or combined with other practices, and its effects on greenhouse gases (e.g., how biochar can change methanogenic communities and reduce CH4 and N2O while maintaining yield). Include a recent reference to support these points.
  2. State the aim and specific objectives of the study clearly and concisely.
  3. Add a world map figure showing the locations of the included studies. Consider using colors or symbols to show differences (e.g., soil texture, feedstock type, or climate).

 

  1. Figure 1: The results show biochar pH, animal stock, and biochar EC had larger effects than other factors, but this is not mentioned in the Abstract. Please highlight these important findings in the Abstract.
  2. The discussion needs improvement. The authors should explain possible mechanisms for why salinity increased or decreased with biochar (give plausible reasons and cite recent studies). Expand interpretations rather than just restating results.
  3. Conclusion: Add clear suggestions for future research — practical gaps or specific questions scholars should address.

Author Response

The article titled "How to minimize the impact of biochar on soil salinity in dry regions? Lessons from a data synthesis" aims to perform a meta-analysis of biochar effects on soil salinity (using EC as the proxy) in Mediterranean, arid, and semi-arid climates, and in glasshouse/incubation experiments that simulate dry and saline conditions. The meta-analysis includes 40 studies from 14 countries. 

1. Line 18: The number of studies reported in the Abstract does not match the number given in Materials & Methods. Please check and correct both places.

Response: Thank you for your comment. We checked and corrected both places in lines18-90 and 94-95 in the new no-marked version of our MS.

 

2. Line 30: The sentence about “low-salt biochars” is wrong — biochar is more commonly alkaline rather than “low salt.” Please check the intended meaning and correct the wording.

Response: Thank you for your suggestion. We checked and corrected the wording: “lower-EC biochar” in line 30 in the new no-marked version of our MS.

 

3. Lines 36–48 (Introduction): The biochar background is too brief and unclear. Add more environmental context — for example: appropriate application rates, using biochar alone or combined with other practices, and its effects on greenhouse gases (e.g., how biochar can change methanogenic communities and reduce CH4 and N2O while maintaining yield). Include a recent reference to support these points.

Response: Thank you for your suggestion. We added a recent reference to support these points: “A recent study has demonstrated that long-term application of biochar (for at least four years) can not only enhance crop yields by 11%, but also reduce methane and nitrous oxide emissions by 14% and 21%, respectively, while increasing soil organic carbon content by 53% [4]” in lines 40-43 in the new no-marked version of our MS.

Reference: Yang, J. R., Xia, L. L., van Groenigen, K. J., et al. Sustained benefits of long-term biochar application for food security and climate change mitigation. Proceedings of the National Academy of Sciences of the United States of America, 2025, 122: e2509237122.

 

4. State the aim and specific objectives of the study clearly and concisely.

Response: Thank you for your suggestion. We restated the aim and specific objectives of the study clearly and concisely: “This study conducted a meta-analysis using EC as the proxy to evaluate the effect of biochar on soil salinity under Mediterranean, arid, and semi-arid climatic conditions, as well as under simulated dry and saline conditions in glasshouse or incubation chamber experiments. We hypothesized that: (1) biochar would increase soil salinity in arid regions; and (2) the effects would vary with application conditions. The findings are expected to contribute to a better understanding of how biochar influences soil properties in arid environments, thereby informing practical guidelines for its standardized application” in lines 74-80 in the new no-marked version of our MS.

 

5. Add a world map figure showing the locations of the included studies. Consider using colors or symbols to show differences (e.g., soil texture, feedstock type, or climate).

Response: Thank you for your suggestion. We added a world map figure showing the locations of the included studies in lines 97-100 in the new no-marked version of our MS. However, due to technical limitations, we were unable to distinguish the differences in climate, soil, and biochar types among various studies using colors.

 

6. Figure 1: The results show biochar pH, animal stock, and biochar EC had larger effects than other factors, but this is not mentioned in the Abstract. Please highlight these important findings in the Abstract.

Response: Thank you for your suggestion. We highlighted these important findings in the Abstract: “However, this effect was highly dependent on pedoclimatic conditions, soil pH, biochar feedstock types, pH and EC, irrigation practices, and management factors” in lines 21-23 in the new no-marked version of our MS.

 

7. The discussion needs improvement. The authors should explain possible mechanisms for why salinity increased or decreased with biochar (give plausible reasons and cite recent studies). Expand interpretations rather than just restating results.

Response: Thank you for your constructive suggestion. We improved the discussion about possible mechanisms in lines 255-259 in the new no-marked version of our MS.

 

8. Conclusion: Add clear suggestions for future research — practical gaps or specific questions scholars should address.

Response: Thank you for your suggestion. We added some suggestions for future research in lines 381-382 in the new no-marked version of our MS.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Review Report:

Manuscript ID: agronomy-3948758

 

Title: How to Minimize the Impact of Biochar on Soil Salinity in Dry Regions? Lessions from a Data Synthesis.

The title looks good; just replace “Lessions” with “Lessons.” As a suggestion, “Drylands” would be a better word choice than “regions.”

Abstract: The abstract is clear and concise and includes information about the selection of biochar and other practices used to minimize saline effects in drylands.

Introduction: It is suggested that the authors include the sources of biochar and the corresponding changes in soil salinity (with values) in the introduction section. This addition would help readers better understand the context and could also increase the citation potential of the article.

Methodology: The methodology is clear and sufficient for this work. My only question is why the authors limited their article selection to studies published up to 2020 instead of including those available up to 2025.

Results: The results are well explained and clear, showing good connection between data and objectives, and helping readers easily understand the main findings.

Line 159: biochar; fix it to Biochar.

Discussion: The discussion is relevant to the results; however, the authors did not address how seafood shell powder and peanut shell biochar can increase soil salinity. It is suggested that the authors review existing literature to find explanations for these outcomes and include them in the discussion section. This addition would help make the statements clearer rather than leaving them unexplained.

The manuscript is clear, well-structured, and focused on the role of biochar in mitigating soil salinity. The methodology is sound, though including recent studies up to 2025 would strengthen the review (just a suggestion, otherwise it’s OK). Results are well explained and connected to objectives, but the discussion should clarify why seafood shell powder and peanut shell biochar increased soil salinity, supported by relevant literature.

Author Response

Title: How to Minimize the Impact of Biochar on Soil Salinity in Dry Regions? Lessions from a Data Synthesis.

The title looks good; just replace “Lessions” with “Lessons.” As a suggestion, “Drylands” would be a better word choice than “regions.”

Response: Thank you for your constructive suggestion. We replaced them in lines 2-3 in the new no-marked version of our MS.

 

Abstract: The abstract is clear and concise and includes information about the selection of biochar and other practices used to minimize saline effects in drylands.

Response: We are extremely grateful to you for your positive comments on our work.

 

Introduction: It is suggested that the authors include the sources of biochar and the corresponding changes in soil salinity (with values) in the introduction section. This addition would help readers better understand the context and could also increase the citation potential of the article.

Response: Thank you for your suggestion. We added this section in lines 40-43 in the new no-marked version of our MS.

 

 

Methodology: The methodology is clear and sufficient for this work. My only question is why the authors limited their article selection to studies published up to 2020 instead of including those available up to 2025.

Response: Thank you for your suggestion. Actually, this was one of our earlier works. We decided to submit it now. We did not collect any relevant articles from 2020 onwards. However, the current dataaet is already sufficient to support our conclusion. If we had enough time, we could reorganize this part of the content to verify our conclusion once again.

 

Results: The results are well explained and clear, showing good connection between data and objectives, and helping readers easily understand the main findings.

Response: We are extremely grateful to you for your positive comments on our work.

 

Line 159: biochar; fix it to Biochar.

Response: Thank you for your careful and thorough review. We fixed it to biochar in line 168 in the new no-marked version of our MS.

 

 

Discussion: The discussion is relevant to the results; however, the authors did not address how seafood shell powder and peanut shell biochar can increase soil salinity. It is suggested that the authors review existing literature to find explanations for these outcomes and include them in the discussion section. This addition would help make the statements clearer rather than leaving them unexplained.

Response: Thank you for your suggestion. We added some explanations for these outcomes in section 4.2.

 

The manuscript is clear, well-structured, and focused on the role of biochar in mitigating soil salinity. The methodology is sound, though including recent studies up to 2025 would strengthen the review (just a suggestion, otherwise it’s OK). Results are well explained and connected to objectives, but the discussion should clarify why seafood shell powder and peanut shell biochar increased soil salinity, supported by relevant literature.

Response: We are extremely grateful to you for your positive comments on our work. We added some explanations for these outcomes in section 4.2.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Please see my comments in the attached document.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

Please see my comments in the attached document.

Author Response

The authors developed a meta-analysis of several studies conducted in dry climates, evaluating the short-term effects of biochar application on soil salinity. The overall results demonstrated a significant increase in soil electrical conductivity due to biochar addition; however, the effects were dependent on the properties of the raw materials and soil management practices.

The authors were able to identify the conditions that most influenced the increase in soil salinity, including biochar raw materials, application rates, initial soil characteristics, and irrigation management. Furthermore, they identified some soil and biochar variables that were the most influential factors.

Thus, the authors were able to formulate recommendations to minimize the risk of salinization caused by biochar application.

Response: We are extremely grateful to you for your positive comments on our work.

 

Specific comments

  1. a) It is recommended that the manuscript be written carefully in the authors' original language and then translated by a competent specialized translator (a native speaker, preferably).

Response: Thank you for your suggestion. We have enhanced the language polishing.

 

  1. b) The authors acknowledge the limitations of the study in section 4.3. They therefore should emphasize the potential novelty of the study, demonstrating a possible detrimental effect of biochar, given that there is a bias in publications to highlight the benefits of biochar predominantly.

Response: Thank you for your constructive suggestion. We emphasized the potential novelty of the study and a possible detrimental effect of biochar in section 4.3.

 

  1. c) Authors should report the main effects of excess soluble salts on soil structure and in terms of osmotic, toxic, and nutritional impact on plants.

Response: Thank you for your suggestion. We added some suggestions for future research in line 340-343 in the new no-marked version of our MS.

 

  1. d) Table and figure titles should contain information about the context of the work, so that they can be interpreted even when presented in isolation. Furthermore, the information should be given as briefly as possible and separated from the title, preferably using a contrasting font.

Response: Thank you for your suggestion. We changed them in lines 98-100, 109, 239, 245, and 318 in the new no-marked version of our MS.

 

  1. e) The use of "positive effect" should be mandatorily reviewed, as it sometimes suggests that positive refers to an increase and, at other times, that positive refers to a benefit, meaning the effect would be a decrease in salinity.

Response: Thank you for your suggestion. We changed them with promotive in line 227-230 in the new no-marked version of our MS.

 

  1. f) Authors should use t ha-1 throughout the manuscript as a unit of measurement for area.

Response: Thank you for your suggestion. We changed them.

 

  1. g) The presentation of the pyrolysis temperature ranges should be less confusing, as the current presentation makes them difficult for the reader to interpret. When these ranges are presented sequentially, it is impossible to distinguish one from the other.

Response: Thank you for your suggestion. We changed them in Table 1 and Fifure 3 in the new no-marked version of our MS.

 

  1. h) The keywords contain several terms that are already part of the title, so we suggest using terms such as: salt-affected soils; charcoal; meta-analysis; dry environments.

Response: Thank you for your suggestion. We ffixed them to “Charcoal; Salt-affected soil; Meta-analysis; Dry environments” in  line 34 in the new no-marked version of our MS.

 

  1. i) Lines 87 and 88: The sentence beginning with "Finally" should be rewritten.

Response: Thank you for your suggestion. We rewrote this sentence in llines 94-97 in the new no-marked version of our MS.

 

  1. j) Table 1: This table is huge and challenging to interpret, and can safely be presented in bulleted text.

Response: Thank you for your comments. We made it simpler in Line109 in the new no-marked version of our MS.

 

  1. k) Figure 1: This isn't easy to understand and interpret because of the indistinguishable information on the vertical axis, so it should be improved for better visualization. There are alignment and font proportion issues in the titles on the vertical axis. Additionally, the horizontal axis title has an exaggerated font.

Response: Thank you for your suggestion. We used colors to differentiate them.

 

  1. l) Line 237: Check whether it is correct to use 1 year or one year.

Response: Thank you for your comment. We changed this sentence.

 

  1. m) Lines 244 to 246: This sentence appears to be unfinished.

Response: Thank you for your suggestion. We corrected it.

 

  1. n) Lines 272 to 274: The opening sentence of the paragraph should be rewritten for better comprehension.

Response: Thank you for your suggestion. We rewrote this sentence.

 

  1. o) Line 275: The term "modicum" is not scientifically appropriate.

Response: Thank you for your suggestion. We rewrote this sentence.

 

  1. p) Line 308: It is incorrect to state that the effects were observed only in arid regions.

Response: Thank you for your suggestion. We fixed it to drylands.

 

  1. q) Line 345: The expression "in conclusion" should be replaced.

Response: Thank you for your suggestion. We deleted it.

 

  1. r) Line 240: The reference presented was not found.

Response: Thank you for your comment. We added this reference.

 

  1. s) Line 323: When referring to emerging evidence, references should be included.

Response: Thank you for your suggestion. We added the reference.

 

  1. t) Line 333: When referring to customized biochar, references should be included.

Response: Thank you for your suggestion. We added some references.

 

 

Final recommendation

Given the various inconsistencies and deficiencies identified, it is recommended that the manuscript undergo extensive modifications – Major Revision. In the case of new references, please note that this will require reformulation of the reference list numbering. We request that, in a future version of the manuscript, the authors identify the modifications made in compliance with this report.

Response: Thank you for your comments and suggestions. We have completed all the revisions of the opinions and suggestions, and have retained the modification marks in the marked version.

 

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors
  1. Table 1 must be presented as bulleted text.
  2. Figure 2 must be completely redesigned. It is incomprehensible as it is presented.

Recommendation

The manuscript still requires MAJOR REVISION before publication, because some items were not addressed as commented above. They may not seem important, but they are crucial to enhance the scientific soundness of the article.

Comments on the Quality of English Language
  1. Table 1 must be presented as bulleted text.
  2. Figure 2 must be completely redesigned. It is incomprehensible as it is presented.

Recommendation

The manuscript still requires MAJOR REVISION before publication, because some items were not addressed as commented above. They may not seem important, but they are crucial to enhance the scientific soundness of the article.

Author Response

1. Table 1 must be presented as bulleted text.

Response: Thank you for your suggestion. The revised format complies with the requirements of the journal, and we believe it is clear now.

2. Figure 2 must be completely redesigned. It is incomprehensible as it is presented.

Response: Thank you for your suggestion. We have made another revision. The relevant contents that needed to be aligned have all been aligned.