Crop Monitoring Strategy Based on Remote Sensing Data (Sentinel-2 and Planet), Study Case in a Rice Field after Applying Glycinebetaine

Round 1

Reviewer 1 Report

The authors have proposed a new vegetation index for crop monitoring. Detailed suggestions are as follows:

1. The abstract should be a short and clear summary of the aims, key methods, important findings, and conclusions.
2. The abstract must clearly bring out the novelty in the study.
3. The introduction section should contain the current state of the topic and limitations of current knowledge in this field.
4. Why the study was necessary should be clearly explained.
5. The novelty of the study should be mentioned in the Introduction.
6. The authors should provide detailed information about the aim of the study.
7. Newly published references should be quoted in the paper.
8. The generated spectral indexes should be presented visually and compared.
9. A workflow chart should be added to better summarize the methods used in the study.
10. The study area should be specified with a location map.
11. Satellite image dates should be given.
12. 194-208: There is background information in the Methods section which should be in the Introduction.
13. To develop a spectral index, the success of the index must be demonstrated for different study areas and different dates.
14. If the purpose of the article is a construction of a new vegetation index, the article should be designed accordingly. However, in the current form of the manuscript, there are methods and results about correlations between visible and NIR regions and the effect of GB on spectral band reflectances. It is recommended that these sections in Methods and Results be reorganized, taking into account the main purpose and motivation of the study.
15. This paper has numerous grammar and language issues, which need to be addressed.

Author Response

Response to Reviewer 1:

We thank the Reviewer 1 for his/her comments and suggestions.

Reviewer 1 question 1:

“1.         The abstract should be a short and clear summary of the aims, key methods, important findings, and conclusions”

Following your indication, we have rewritten the abstract in order to fulfil your indications.

Reviewer 1 question 2:

“2.         The abstract must clearly bring out the novelty in the study”

The abstract has been rewritten to point out the novelty in the study

Reviewer 1 question 3:

“3.         The introduction section should contain the current state of the topic and limitations of current knowledge in this field”

According to your suggestions, the introduction has been improved and now it reviews the current state of the topic highlighting the limitations of different aspects that are mentioned in the introduction.

Reviewer 1 question 4 and 5:

“Why the study was necessary should be clearly explained” and “The novelty of the study should be mentioned in the Introduction”

Following your indication, the introduction was rewritten and we think now, the novelty is more clearly explained.

Reviewer 1 question 6:

“6.         The authors should provide detailed information about the aim of the study”

Last paragraph of the introduction has been modified to point out the aim of the study

Reviewer 1 question 7:

“7.         Newly published references should be quoted in the paper”

References from 19 to 22 and 40 to 41 have been added

Reviewer 1 question 8:

“8.         The generated spectral indexes should be presented visually and compared”

In order to fulfil your indications, next pictures have been added (Figures 9 and 11 in the new version)

Reviewer 1 question 9:

“9.         A workflow chart should be added to better summarize the methods used in the study”

Thanks for your suggestion. Next workflow chart has been added to summarize the methods used in the study (Figure 4 in the new version).

Reviewer 1 question 10:

“10.       The study area should be specified with a location map”

Thanks for your suggestion. The following map has been added (Figure 1 in the new version).

Reviewer 1 question 11:

“11.       Satellite image dates should be given”

Next table has been introduced showing the satellite imagen dates (Table 1 in the new version)

Reviewer 1 question 12:

“12.       194-208: There is background information in the Methods section which should be in the Introduction”

Thanks for your suggestion. The paragraph has been moved to the introduction section.

Reviewer 1 question 13:

“13.       To develop a spectral index, the success of the index must be demonstrated for different study areas and different dates”

Reviewer 1 question 14:

“14.       If the purpose of the article is a construction of a new vegetation index, the article should be designed accordingly. However, in the current form of the manuscript, there are methods and results about correlations between visible and NIR regions and the effect of GB on spectral band reflectance. It is recommended that these sections in Methods and Results be reorganized, taking into account the main purpose and motivation of the study”

We agree with the reviewer on questions 13 and 14. The index should be tested in more areas and years to demonstrate a clear evidence that it contributes to a better monitoring of rice crop, therefore, a preliminary study has been presented in this paper. The NCMI (Normalized Crop Management Index) has been constructed to verify the crop monitoring strategy. According to this comment and to avoid over expectation in the reader, we have reviewed the text to clearly explain that this index is proposed and tested in this particular context, while its successful applicability in a broader context should be demonstrated in a more extended study.

Reviewer 1 question 15:

“15.       This paper has numerous grammar and language issues, which need to be addressed”

The paper has been revised by a native English speaker.

Author Response File: Author Response.pdf

Reviewer 2 Report

The topic is well justified. However, some improvements are needed.

- Study area section: I recommended that adding some descriptions for study area: diagram, place name, topography...

- Section 2.4. needs to show the number of image, observation date of each type of satellite image was used.

- The results section presented only by tables, graphs and analysis without any result product from satellite image. So it's really hard to convince the reader. I suggest the authors should add image results calculated from satellite images to illustrate the research results. 

- The discussion section should be restructured more clearly and concisely.

- Line 589, page 15: "improving" should be changed to "monitoring"

- Correction of page numbers from the 7th page of manuscript.

Author Response

Response to Reviewer 2:

We thank Reviewer 2 for his/her comments and suggestions.

Reviewer 2 question 1:

“1.         Study area section: I recommended that adding some descriptions for study area: diagram, place name, topography...”

Following your recommendations, some descriptions of the study area as well as a location map have been added (Figure 1 in the new version).

Reviewer 2 question 2:

“Section 2.4. needs to show the number of images, observation date of each type of satellite image was used”

Thanks for your suggestion. Several images have been added and also next table has been introduced showing the satellite imagen dates (Table 1 in the new version)

Reviewer 2 question 3:

“The results section presented only by tables, graphs and analysis without any result product from satellite image. So, it's really hard to convince the reader. I suggest the authors should add image results calculated from satellite images to illustrate the research results”

Following your recommendations, we have added some image results calculated from satellite images to illustrate the research results. In this sense, figures 9 and 11 have been embedded to results section.

Reviewer 2 question 4:

“The discussion section should be restructured more clearly and concisely.”

Discussion section has been restructured and we believe that now is clearer and better structured.

Reviewer 2 question 5:

“Line 589, page 15: "improving" should be changed to "monitoring".”

We thank the reviewer for his/her comment. We have changed it.

Reviewer 2 question 6:

“6.         Correction of page numbers from the 7th page of manuscript”

We thank the reviewer for his/her comment. We have corrected it.

Author Response File: Author Response.pdf

Reviewer 3 Report

The authors study an important topic.

The introduction clearly explains the state of the art and the purpose of the work.

The topic examined is highly significant for the future developing in rice cultivation managing.

The work was carried out with in-depth bibliographic analysis and in a good scientific way.

I have some remarks:

This work does not evaluate different application techniques, so I would like to remove the word “drone“ from the title of the paper.

Line 154

Please add information about the distribution performed. Only the technical characteristics are mentioned.

Add: application volume (l/ha), forward speed (m/s), spray height (m), type of nozzle, pressure.

Line 170

Explain how the sampling points were identified to avoid edge effect on the sides of the plot.

Line 261 – table 1

Grain yield - Why use hg/ha? Usually is kg or t

If I correct understand your data 10767 hg/ha means 1076.7 kg/ha or 1.07 t/ha. Is it a standard yield in Valencia area? I have found mean rice yield of 6-8 t/ha.

Author Response

Response to Reviewer 3:

We thank the Reviewer 3 for his/her comments and suggestions.

Reviewer 3 question 1:

“1.         This work does not evaluate different application techniques, so I would like to remove the word “drone“ from the title of the paper.”

We thank the reviewer for his/her comment. We have removed the word drone from the title, also other modifications have been made and the new title is:

“Crop Monitoring Strategy Based on Remote Sensing Data (Sentinel-2 and Planet), Study Case in a Rice Field After Applying Glycinebetaine”

Reviewer 3 question 2 and 3:

“Line 154

Please add information about the distribution performed. Only the technical characteristics are mentioned. Add: application volume (l/ha), forward speed (m/s), spray height (m), type of nozzle, pressure”

We have modified the paragraph adding more information. The new paragraph is now:

The GB was applied by drone to avoid any additional machinery overpass: AGR model A6; tank volume: 6 L; flow rate: 0.57 L·min-1; pressure: 6 bar; forward speed: 6 m·s-1; spray height: 1.5 m; swath width: 2 m; 4 nozzles (Agroplast Ppij, model 6MS 01C anti-drift orange with ceramic tip, fan-shaped, 110°) [47] [40].

Reviewer 3 question 4:

“Line 170

Explain how the sampling points were identified to avoid edge effect on the sides of the plot”

We have modified the paragraph adding more information. The new paragraph is now:

Plant height, panicle length, panicles per m2, filled grain per panicle, weight of 1000 grains, grain length and width were obtained with field measurements at harvest time. These measurements were acquired in an area of 0.25 m2, randomly selected avoiding edge effect (10 meters inside) in 4 repetitions for each replication. In addition, we measured the days elapsed from sowing until the emergence of 50% of the panicles and the marketable yield (kg·ha-1) for each replication.

Reviewer 3 question 5:

“Line 261 – table 1

Grain yield - Why use hg/ha? Usually is kg or t.”

We thank the reviewer for his/her comment. It is a typo-error. We have corrected it; the units are: Grain yield (kg·ha-1)

Reviewer 3 question 6:

“If I correct understand your data 10767 hg/ha means 1076.7 kg/ha or 1.07 t/ha. Is it a standard yield in Valencia area? I have found mean rice yield of 6-8 t/ha”

As you comment, our data 10767 means kg/ha. Our measurements show that this is a value that can be found at within-field level, but when averaging at field level, the extreme yield values are minimized.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors made all the reviews. The study is can be published in the journal.

Yazarlar tüm değerlendirmeleri yaptı. Çalışma dergide yayınlanabilir.