Mapping Soil Available Nitrogen Using Crop-Specific Growth Information and Remote Sensing

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Authors

I have reviewed the manuscript entitled "A study on soil available nitrogen mapping with the introduction of growth information of different crop types". This is an interesting study as selecting covariates is of great interest in digital soil mapping communities. The study employed the standard process of digital soil mapping; however, the utilization of covariates derived from Sentinel-2 and satellite indices is relatively new, especially for N mapping. Moreover, I have several points that need improvement.

General comment:

State the objective of the study

Specific comments

 

Line 67: Correct the citation that only has a number at the beginning of the sentence in Line 67, 78

example: Wu et al. [11] used NDVI time-series data
example: Lobell et al. [16] used..

Line 148: verify annual cumulative temperature
Line 150: verify the precipitation. Is it the cumulative rainfall of summer or the monthly rainfall in summer?

Table 2: delete column soil depth and add depth information in the table title
Table 2: delete "%" in cells

Line 311: delete "and analysis
Line 312: delete "Analysis of" 
Line 313: change "characterization" to "character"
Line 316-317: delete introductory phrase "By analyzing...and October)"
Line 331: delete "analysis of"
Line 334-335: delete introductory phrase " By analyzing...growing season"
Line 347: delete introductory phrase "In studying...crop growth"
Line 352-353: delete introductory phrase "In studying...growth dynamics"
Line 365: delete word "analysis"
Line 367-368:delete introductory phrase "By analyzing...and October)"
Line 385: delete word "analysis"
Line 438-465: paragraph too long. divide into 3 para for readability
Line 502-523: paragraph too long. divide into 2 to 3 para for readability
Line 545: what is AI?
Line 502-523: paragraph too long. divide into 2 to 3 para for readability

 

Author Response

Dear reviewer:

Sincerely thank you for your careful review and valuable feedback on this article. We have carefully studied every suggestion you have put forward and made careful revisions and improvements to address the shortcomings in the article. This revision aims to improve the academic quality and innovative expression of the paper, fully absorbing your professional guidance. We have systematically revised the research methods, innovative points, and literature comparison of the article, striving to make it more rigorous, clear, and persuasive. Please refer to the attachment for details.

Thank you very much for providing professional guidance on the academic quality of this article. Each of your suggestions is a valuable opportunity for us to improve our research. We sincerely hope that this revision can fully respond to your professional opinions and look forward to receiving further guidance from you.

Sincerely, Yihan Ma

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

1. The abstract does not clearly explain how the Optuna-RF model was implemented, which predictors were used, or how accuracy was validated. Adding brief but specific methodological details would improve transparency and reproducibility.
2. The abstract notes crop-stage-specific differences in mapping accuracy but lacks explanation of the physiological basis. Clarifying why certain growth stages improve AN prediction would strengthen the biological relevance and generalisability.
3. The introduction repeats ideas (e.g., AN importance, DSM potential) and should be made more concise.
4. The novelty of using crop-specific EVI and Optuna-RF is not clearly framed against existing literature.
5. The rationale for focusing on maize and soybean is underexplained; agronomic differences need more clarity.
6. The introduction part lacks a well-defined hypothesis or innovation statement, limiting its scientific framing.
7. L 54: add the following relevant reference: https://doi.org/10.1016/j.heliyon.2024.e32774
8. The methodology part is well written. I have no comments. 
9. L 311: Results (no need to write analysis)
10. L 331-361: The claim that EVI is more sensitive than NDVI lacks statistical backing. No correlation analysis or significance testing is provided, making the conclusion appear speculative rather than data-driven.
11. Conclusion must be as per the objectives.

Author Response

Dear reviewer:

Sincerely thank you for your careful review and valuable feedback on this article. We have carefully studied every suggestion you have put forward and made careful revisions and improvements to address the shortcomings in the article. This revision aims to improve the academic quality and innovative expression of the paper, fully absorbing your professional guidance. We have systematically revised the research methods, innovative points, and literature comparison of the article, striving to make it more rigorous, clear, and persuasive. Please refer to the attachment for details.

Thank you very much for providing professional guidance on the academic quality of this article. Each of your suggestions is a valuable opportunity for us to improve our research. We sincerely hope that this revision can fully respond to your professional opinions and look forward to receiving further guidance from you.

Sincerely, Yihan Ma

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This article explains how crop-specific growth stage data with remote sensing improves the accuracy of soil available nitrogen mapping for precision agriculture. The article is interesting. However, it can be improved.

1. Check Title….Revise it….“Mapping……Using Crop-Specific Growth Information and Remote Sensing”.
2. Abstract…..Many times you have mentioned “different crop types”….Avoid that…..What are those??…..Can you list? You have specified soybean and maize….Whether you are talking about cereals (agronomic crops), horticultural crops, etc.
3. Can you provide any range of soil available nitrogen?
4. What are the results of crop growth stages?
5. Keywords: It should be at least 5. Try to avoid terms that are already used in title.
6. Introduction…..The importance of soil nitrogen, its forms, stocks can be detailed with regards to plant nutrition. What is the status of soil nitrogen in the study location? Provide literature.
7. Introduction…..Briefly describe the technology of digital soil mapping.
8. Introduction…..What type of crops and crop growth stages you are referring in this study? Discuss.
9. Introduction…..Check the term “different crop types”. I think you are mostly talking of soybean and maize.
10. Section…..2.2.2. Soil sample data collection…..Please mention the soil depth in the text also.
11. Elaborate data processing, geometric correction, software tools used in Methodology.
12. How the data was used for model prediction? Was any data transformation, such as log(n), required during preprocessing?
13. Line 311…..Results and analysis…..Delete “and analysis”.
14. Check the quality of Figures in the Results. Figure 5….Check spacing (a)April (b)May…units 65-125mg kg^-1…Give space between the words.
15. The Results section should be presented in a more structured scientific format to enhance clarity and comprehensibility.
16. The Discussion section is relatively brief. It should be expanded to include a thorough interpretation of the results in the context of relevant literature. Key factors such as crop types, soil sampling depth, geographic location, and environmental variables should be considered to provide a more comprehensive analysis.
17. Check whether Figure 9 should be presented in Discussion section or Results section.
18. Line 548….optimal time window period of remote sensing data…..justify properly.
19. Conclusive line for crop growth stages?

Comments on the Quality of English Language

Moderate editing is required.

Author Response

Dear reviewer:

Sincerely thank you for your careful review and valuable feedback on this article. We have carefully studied every suggestion you have put forward and made careful revisions and improvements to address the shortcomings in the article. This revision aims to improve the academic quality and innovative expression of the paper, fully absorbing your professional guidance. We have systematically revised the research methods, innovative points, and literature comparison of the article, striving to make it more rigorous, clear, and persuasive. Please refer to the attachment for details.

Thank you very much for providing professional guidance on the academic quality of this article. Each of your suggestions is a valuable opportunity for us to improve our research. We sincerely hope that this revision can fully respond to your professional opinions and look forward to receiving further guidance from you.

Sincerely,

Yihan Ma

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

No comments. Satisfied with the revision made by the authors.