Mapping Maize Tillage Practices over the Songnen Plain in Northeast China Using GEE Cloud Platform

Round 1

Reviewer 1 Report

The novelty of the presented mapping method is not enough, and the readability of the entire manuscript is poor. Additionally, the process of mapping method is hard to follow, in particular for the estimations of MRC and CRC.

1.     The use of “corn” and “maize” in this study are mixed

 2.     Line 180-181: The maize residue coverage (MRC) appears after maize harvest. So, why did you choose satellite images after maize sowing?

 3.     Why not use the estimation model from section 3.1. to replace the equation 1 in the section 3.2?

 4.     How did you acquire the maize distribution map for 2019-2022? And, what is the source for the digital elevation data?

 5.     This study focus on maize, however, the field sample used for model development and validation was CRC (Fig.1).

6.    Line 203-204：This sentence refers to the relationships between NDTI and MRC. But the equations 1 shows the relationships between NDTI and CRC.

7.     Many abbreviations do not have full names, e.g., RT and CT in Table 7.

8.     You mentioned“Higher levels of accuracy, stability, and applicability can be derived by using time-series images instead of single-period images”, but Table 4 showed results for only images of 10 days.So, why didn’t you choose a longer time series? 

9.     The preprocessing steps of Sentinel-2 data are not clearly presented.

 

 

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

This study determined the best time series and streamlining functions based on the correlation coefficients of NDTI and MRC measured data. The MRC estimation and mapping of tillage practices in the Songnen Plain for 2019– 2022 were then conducted using the cloud computing platform and the model of Xiang et al. (2022). Geostatistical analysis using ArcGIS was applied to identify the spatial and temporal distribution characteristics of the MRC and conservation tillage in the Songnen Plain. This study generally is good, however, the language need to modify. 

Line 35:  in responding to should be "in responding to"

Section 2.2: suggest authors to list a table to display all datasets you used, including accessed website, resolution, etc. Then, brief introduction is needed. 

Line 204: in formula 1, whta is CRC, i guess it should be MRC.

Figure 3: based on figure 3, in 3(c) is the high correlation coefficient right? the upper three points, is it belonged to outliers? please give detailed explanation.

Line 276-Line 303: it seems more like discussion part. suggest authors to rearrange your content.

Line 363-392: this part also should be put in discussion part.

Section 4.1: is it propriate to introduce GEE platform in discussion part. Please change this section

Figure 8 is similar to figure 3, these samples, is it belonged to outliers?.

This manuscript had too many long sentences, authors should modify your manuscript to avoid long sentences, which were hard to understand. Meantime, this manuscript had several grammars, which needed careful check.

English language really need extensive modification. It seems more like directly translated by Chinese.

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

The manuscript depicts and interesting topic minor improvements are necessary before going ahead in the publication phase. The manuscript is generally well strutured and written but some parts like introduction and material need little adjustments. If authors well follow the suggestion given I will certainly recommend this manuscript to be published on Remote Sensing.

Firstly, I suggest to improve the introduction better describing GEE potentialities and limitis in mapping maize and other crops tillage practices as well as land cover in different area worldwide. To do this and help you I strongly advice and suggest to include the following references:

- https://doi.org/10.3390/rs15010178

- https://doi.org/10.1007/s12011-021-03074-6

- https://ieeexplore.ieee.org/document/8453842

Then I suggest you to better describe the processing workflow followed in GEE to do this it would be helpful considering to include a workflow to sum up each step performed. Then Please consider to include in appendix the code script or link in supplementary material your GEE profile sharing the code. This would be crucial to help scalability and chack the quality of the work as open access Journal.

Finally, consider to report EPSG or datum and reference system in the map.

Results and conclusion are fine.

 

Then I suggest to include in material the software adopte to processed the data and report a workflow describing each step in order to favor scalability.

Then please report the UAV flight parameters (altitude, spead, flight plan, camera angle, FOV, acqusition mode etc) they are necessary.

Consider also to add eventually in results the confusion matrix reporting errors and accuracy if you have a ground validation set to verify your approach and findings.

Moreover I suggest to include in appendix eventually the calibration tests the GCP.

Results and conclusion are fine! Consider to better explain the separability of the classes into the mathods it is not well explained. Did you have performed a F test and normality test at the beginning of your analysis? 

Then consider discussing the suitability and feasibility of the approach suggested.  Finally point out better your findings in the conclusion

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

1. The used satellite data has different spatial resolution, how did you address the spatial inconsistency between different data?

2. The spatial resolution of MRC and tillage method are not indicated.

3.  Line197-199：The application of sentient-2 data is not clear to readers. Authors should clarify the number of time series from May 1–10, May 10–20, May 20–30, and May 30–June 8 in 2019-200.

4. The section 3.1 and 3.2 are a little bit mixed up. The author claimed the equation 1 derived from Xiang et al. (2022) was close to the actual situation between NDTI and MRC, why not use the equation 1 to estimate optimal temporal images?

5. Figure 4: The spatial distribution of MRC only referred to 2022, I suggest authors display the spatial distribution of MRC for 2019-2022.

6. Line 301-306: “CRC” should be “MRC”.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

Authors have addressed all my concerns.

Author Response

Thanks for the comments.

Reviewer 3 Report

The manuscript has been very well improved. Authors has well follow each suggestion given therefore according to the present reviewer it can be considered suitable for pubblication on Remote Sensing. Anyway as a last point I just recomend you to include the Google earth engine code used to performed in the present work into an appendix or supplementary material in order to scale your analysis in other areas. After that the manuscript can be consider for pubblication by editorial office.

Author Response

Thanks for the comments. Google Earth engine code has been put into the supplementary material.