Optical-Sensor-Based Nitrogen Management in Oat for Yield Enhancement
, Sami Ullah Khan 1, Sajjad Khan 3, Zulfiqar Ali Gurmani 3, Sajid Fiaz 4 and Abdul Qayyum 1,*Round 1
Reviewer 1 Report
In this manuscript, empirical results associated with the use of an optical sensor (GreenSeeker [GS]) to control the application of a N-fertilizer to fodder oat are presented. It was also considered the impact of a proper seed rate which is shown to have an "interaction" with the N-application process. It has been concluded that the application of an initial dose of 25% of the typical recommended value, followed by two other applications managed by GS, provide the best results both in terms of fodder yield and also in relation to a smaller amount of applied N that can mitigate pollution risks.
The paper is easy to read and many of the discussions are sound and in agreement with existing works. Nonetheless, the concerns of this reviewer are mainly concentrated with these 3 aspects:1) As a commercial device, GS was already used for similar purposes as indicated in the literature. However, physico-chemical principles behind the operation of instruments such as GS and also the reasons why NDVI values can serve as a good indicator of the plant stress are omitted in this manuscript. A picture of the instrument and the typical way that GS readings are collected are missing details in this paper. Moreover, there is no discussion a) if the natural illumination conditions impact (or not) the GS and b) if the weather conditions interfere with the GS readings.
2) A typical "Literature Review" section was substituted by 2 paragraphs at the Introduction section (lines 58-79). Part of this review is provided at the end of each sub-section 3.x which is a very good provision. Nonetheless, before starting Section 2, it is important to indicate why technology X (in this case, the one behind GS) is better than other technologies/methods Y, Z, etc. for the research challenge under consideration. In this case, there is no need to have citations of papers that are specifically related to oat. It can be other plants; the important aspect is simply to have an idea of the level of yield improvements that have been reported when NDVI method is used compared to other approaches.
3) The expression "managed with GS" (or similar) is used extensively in this manuscript without a proper definition of what kind of management is obtained. One can understand that it may be associated with the best moment "in time" to have an additional N application. One can interpret that the NDVI readings from the GS instrument may indicate "where" in the site more N must be applied compared to an adjacent area (i.e., non-uniform N application). The GS management can even be a combination of both but a proper discussion is not provided in Section 2. Moreover, related to the treatments N3 and N4, how much N was applied when GS readings are taken? At Table 1, rather than "+GS", it would be better to add a column with "Treatment #" and at the column "N (kgha-1)" to refer to the actual numbers. If these numbers for N3 and N4, changed, it is necessary to state this fact and to provide associated tables/figures.
Minor aspects to be considered:a) The use of the GreenSeeker term is not consistent in this paper - it has different forms, such as green seeker, Green seeker, etc.
b) The Abstract must highlight the main results associated with the 2 main goals: yield and less pollution. Other aspects can be omitted in the abstract - it is more important to have a highlight similar to this one: "With N1, a total of xxx kg of fertilizer is necessary to achieve an estimated net profitability of $yy. With N4, a total of vv kg of fertilizer is employed to achieve a net profitability of $zzz".
c) Section 3.3 is not mentioning Fig. 1.
d) Section 3.4 is not mentioning Table 4.
e) Section 3.5 is not mentioning Fig. 3.
f) Line 322: typo at "reduce".
g) Line 34: grammar improvement at "Moreover, N is less in the cultivated soils..".
h) Line 340: grammar improvement at "were the good among other".
Author Response
Dated: 10th June 2021
Dear Editor,
Greetings,
Thank you very much for your time and comments regarding our manuscript (sustainability-1236426). Our manuscript “Optical Sensor Based Nitrogen Management in Oat for Yield Enhancement” has been revised carefully and here we are giving our response to the reviewers’ comments. We have improved the manuscript according to the reviewers’ comments and suggestions. All the revisions can be easily identified from manuscript highlighted with yellow color.
Once again thanks for your co-operation and valuable comments and suggestion. Moreover, the efforts of the reviewer are highly appreciated. We are hoping for pleasant response and further good comments (if any) from your side.
Dr. Abdul Qayyum
Department of Agronomy,
The University of Haripur 22620 Pakistan
*********************************************************************
We are thankful to editor and reviewers for timely completion of review process and providing us with valuable feedback.
Response to reviewer # 1:
Dear reviewer, we are grateful to you for your comments and suggestions for the improvement of our research manuscript. We have tried our best to revise the manuscript in light of your comments.
Comment: In this manuscript, empirical results associated with the use of an optical sensor (GreenSeeker [GS]) to control the application of an N-fertilizer to fodder oat are presented. It was also considered the impact of a proper seed rate which is shown to have an "interaction" with the N-application process. It has been concluded that the application of an initial dose of 25% of the typical recommended value, followed by two other applications managed by GS, provide the best results both in terms of fodder yield and also in relation to a smaller amount of applied N that can mitigate pollution risks.
The paper is easy to read and many of the discussions are sound and in agreement with existing works. Nonetheless, the concerns of this reviewer are mainly concentrated with these 3 aspects:
- As a commercial device, GS was already used for similar purposes as indicated in the literature. However, physico-chemical principles behind the operation of instruments such as GS and also the reasons why NDVI values can serve as a good indicator of the plant stress are omitted in this manuscript. A picture of the instrument and the typical way that GS readings are collected are missing details in this paper. Moreover, there is no discussion a) if the natural illumination conditions impact (or not) the GS and b) if the weather conditions interfere with the GS readings.
Response: The physico-chemical principles behind the operation of instruments such as Green seeker and also the reasons why NDV values can serve as a good indicator of the plant stress has been included in the introduction section of the revised manuscript. Adequate explanation about natural illumination conditions on GS reading and other weather conditions which can interfere with the GS readings has also been included.
Comment: A typical "Literature Review" section was substituted by 2 paragraphs at the Introduction section (lines 58-79). Part of this review is provided at the end of each sub-section 3.x which is a very good provision. Nonetheless, before starting Section 2, it is important to indicate why technology X (in this case, the one behind GS) is better than other technologies/methods Y, Z, etc. for the research challenge under consideration. In this case, there is no need to have citations of papers that are specifically related to oat. It can be other plants; the important aspect is simply to have an idea of the level of yield improvements that have been reported when NDVI method is used compared to other approaches.
Response: Adequate explanation regarding Green seeker as an optical sensor used for Nitrogen management and its comparison with other similar precision agriculture instruments has been provided in the introduction section of the revised manuscript. Similarly as per your valued comment to include similar type of work NDVI used for other crops has been included with exact references in the revised manuscript.
Comment: 3. The expression "managed with GS" (or similar) is used extensively in this manuscript without a proper definition of what kind of management is obtained. One can understand that it may be associated with the best moment "in time" to have an additional N application. One can interpret that the NDVI readings from the GS instrument may indicate "where" in the site more N must be applied compared to an adjacent area (i.e., non-uniform N application). The GS management can even be a combination of both but a proper discussion is not provided in Section 2. Moreover, related to the treatments N3 and N4, how much N was applied when GS readings are taken? At Table 1, rather than "+GS", it would be better to add a column with "Treatment #" and at the column "N (kgha-1)" to refer to the actual numbers. If these numbers for N3 and N4, changed, it is necessary to state this fact and to provide associated tables/figures.
Response: The exact detail of how many times Green seeker was used to obtain reading at what growth stage and at how much distance of crop canopy has been provided in the Material and methods section of the revised manuscript. The adequate discussion about GS induced Nitrogen management has been included in the revised manuscript in the methodology section of the revised manuscript. For N3: treatment, 40 kg ha-1 Nitrogen was used by conventional application (Broad cast) and remaining nitrogen (28 kg) was applied on the basis of NDVI reading of Green seeker. Similarly with regard to N4 Treatment, 40 kg Nitrogen was used by conventional application in two equal split doses of 20 kg each (Broad cast), while remaining amount of N was calculated with the help of Green seekerTM reading (18 kg was applied based on green seeker calculation).
Comment: Minor aspects to be considered:
- The use of the Green Seeker term is not consistent in this paper - it has different forms, such as green seeker, Green seeker, etc.
Response: The term Green seekerTM has been used throughout in the revised text.
Comment: The Abstract must highlight the main results associated with the 2 main goals: yield and less pollution. Other aspects can be omitted in the abstract - it is more important to have a highlight similar to this one: "With N1, a total of xxx kg of fertilizer is necessary to achieve an estimated net profitability of $yy. With N4, a total of vv kg of fertilizer is employed to achieve a net profitability of $zzz".
Response: The abstract has been revised in light of your valued comments and yield maximization and reduction in environmental pollution associated with indiscriminate use of Nitrogen by conventional methods has been added for more clarity. Similarly, from economic analysis table, exact amount of fertilizer and corresponding net profit in US dollars has been provided in the revised manuscript. It has been performed for N1, N2, N3 and so on treatments.
The table format has been revised and column with N amount has been provided in all the tables (Revised manuscript) i.e. In Crux, with N1, a total of 80 kg ha-1 of Nitrogen was applied to achieve an estimated net profitability of $582.13. In N3, a total 68 kg ha-1 nitrogen was used to achieve net profit of $758.71. With N4, a total 58 kg ha-1 Nitrogen was used to achieve a net profitability of $ 838.16", therefore this treatment was found as environmentally safe as compared to N1(80kg ha-1).
Comment: c) Section 3.3 is not mentioning Fig. 1.
Response: Reference for the Figure.1 has been included in the section 3.3 of the revised manuscript.
Comment: d) Section 3.4 is not mentioning Table 4.
Response: Table 4 has been mentioned in section 3.4 of the revised manuscript.
Comment: Section 3.5 is not mentioning Fig. 3.
Response: Figure.3 has been mentioned in section 3.5 of the revised manuscript.
Comment: Line 322: typo at "reduce".
Response: Typographical mistake has been corrected at Line#322 in the revised manuscript.
Comment: Line 34: grammar improvement at "Moreover, N is less in the cultivated soils.".
Response: At line 34 the sentence has been restructured for more clarity as per your valuable feedback.
Comment: Line 340: grammar improvement at "were the good among other".
Response: At line#340, the sentence has been rephrased as per your valuable suggestion.
Reviewer 2 Report
The work is very interesting and fits into the subject of the Sustainability magazine.
However, there are some shortcomings.
The methodology describes that the tests were performed during a slow walk.
What is slow walk - how many km / h or how many m / s?
In figure 2, only two nitrogen doses are shown in the legend, while the graph shows 4 curves. I recommend completing the legend.
The summary is too poor. I recommend adding the direction for further research.
Author Response
Dated: 10th June 2021
Dear Editor,
Greetings,
Thank you very much for your time and comments regarding our manuscript (sustainability-1236426). Our manuscript “Optical Sensor Based Nitrogen Management in Oat for Yield Enhancement” has been revised carefully and here we are giving our response to the reviewers’ comments. We have improved the manuscript according to the reviewers’ comments and suggestions. All the revisions can be easily identified from manuscript highlighted with yellow color.
Once again thanks for your co-operation and valuable comments and suggestion. Moreover, the efforts of the reviewer are highly appreciated. We are hoping for pleasant response and further good comments (if any) from your side.
Dr. Abdul Qayyum
Department of Agronomy,
The University of Haripur 22620 Pakistan
*********************************************************************
We are thankful to editor and reviewers for timely completion of review process and providing us with valuable feedback.
Response to reviewer # 2:
Dear reviewer, we are grateful to you for your comments and suggestions for the improvement of our research manuscript. We have tried our best to revise the manuscript in light of your comments.
Comment: The work is very interesting and fits into the subject of the Sustainability magazine.
However, there are some shortcomings.
The methodology describes that the tests were performed during a slow walk.
What is slow walk - how many km / h or how many m / s?
Response: The methodology section has been updated and improved for more clarity in line with your valuable comments.
Comment: In figure 2, only two nitrogen doses are shown in the legend, while the graph shows 4 curves. I recommend completing the legend.
Response: The Figur.2 has been revised and other Nitrogen dose legend has been inserted in the revised Figure.2.
Comment: The summary is too poor. I recommend adding the direction for further research.
Response: The summary of the revised manuscript has been modified in line with your valuable feedback.
Author Response File: 
Author Response.docx
Reviewer 3 Report
Manuscript review: “Optical Sensor Based Nitrogen Management in Oat for Yield Enhancement” by Shah et al.
The written English is awkward in places and the entire manuscript would benefit greatly from a careful editing to improve clarity, style and grammar.
In the Abstract there is no description of what the “Hand-held Green seeker” is. It appears to be the following instrument: GreenSeeker TM (Trimble Inc., Sunnyvale, California, USA). Is so, it should be spelled as such so the reader can locate more information before reading the rest of the paper. A sentence explaining what the instrument is would also be helpful and appropriate and a reference with a link to a source for more information is needed.
As the instructions to authors indicate, within the text “reference numbers should be placed in square brackets [ ], and placed before the punctuation; for example [1], [1–3] or [1,3].” This draft does not use the correct referencing system.
Line 44 – This paragraph is a single sentence. Can it be combined with other appropriate text?
Line 111 – The abbreviation “DAT” was not defined. And since it is used just twice in the manuscript there really isn’t a need for an abbreviation.
Line 128 – There is no reference provided for the citation: (CIMMYT Economics Program, 1988). More information is needed for the methodology used for the economic analysis. Is this actually capturing the costs and returns of using the instrument or just for the various rates of N fertilizer that were pre-planned for the experiment and the various yield outcomes? Further, the authors report using US$ in the methods but present their results in Pakistani Rupees. Are the total costs or variable costs used for this analysis?
Line 154 – It seems usual to have the superscript “-1” after the word "plant" throughout section 3.2? It is also found once in the Abstract. Perhaps tillers per plant works better for the text?
Figure 1 – Is a line graph the most appropriate choice for showing the differences among the distinct treatments. Since the x axis is not a continuous variable, would a bar graph be more appropriate? Perhaps the authors have already considered this.
Table 4 – A space is needed between “kg” and “ha-1” in the first column.
Figure 4 – Add the units to the y axis for fresh weight.
Line 325 – A space is needed between “kg” and “ha” after 80.
Table 10 – The column titled “Money” should be “Income.”
Line 340 – A space is needed between “kg” and “ha” for the seed rate.
The references are not formatted correctly according to the journal's guidelines. These need to be corrected throughout.
Author Response
Dated: 10th June 2021
Dear Editor,
Greetings,
Thank you very much for your time and comments regarding our manuscript (sustainability-1236426). Our manuscript “Optical Sensor Based Nitrogen Management in Oat for Yield Enhancement” has been revised carefully and here we are giving our response to the reviewers’ comments. We have improved the manuscript according to the reviewers’ comments and suggestions. All the revisions can be easily identified from manuscript highlighted with yellow color.
Once again thanks for your co-operation and valuable comments and suggestion. Moreover, the efforts of the reviewer are highly appreciated. We are hoping for pleasant response and further good comments (if any) from your side.
Dr. Abdul Qayyum
Department of Agronomy,
The University of Haripur 22620 Pakistan
*********************************************************************
We are thankful to editor and reviewers for timely completion of review process and providing us with valuable feedback.
Response to reviewer # 3:
Dear reviewer, we are grateful to you for your comments and suggestions for the improvement of our research manuscript. We have tried our best to revise the manuscript in light of your comments.
Comment: Manuscript review: “Optical Sensor Based Nitrogen Management in Oat for Yield Enhancement” by Shah et al.
The written English is awkward in places and the entire manuscript would benefit greatly from a careful editing to improve clarity, style and grammar.
Response: The entire manuscript has been revised for clarity with regard to style and grammer aspects.
Comment: In the Abstract there is no description of what the “Hand-held Green seeker” is. It appears to be the following instrument: GreenSeeker TM (Trimble Inc., Sunnyvale, California, USA). Is so, it should be spelled as such so the reader can locate more information before reading the rest of the paper. A sentence explaining what the instrument is would also be helpful and appropriate and a reference with a link to a source for more information is needed.
Response: Description about Green seeker has been provided in the abstract of the revised manuscript as per your valuable feedback. Moreover link for the originator of the technology has been provide in the methodology section of the revised manuscript. An adequate description about the instrument, purpose of its use (working principle) and its advantage over other similar instruments used in Precision Agriculture has been provided in detail in the revised manuscript.
Comment: As the instructions to authors indicate, within the text “reference numbers should be placed in square brackets [ ], and placed before the punctuation; for example [1], [1–3] or [1,3].” This draft does not use the correct referencing system.
Response: The correct referencing style (Journal’s recommended style) has been used in the revised manuscript.
Comment: Line 44 – This paragraph is a single sentence. Can it be combined with other appropriate text?
Response: At line 44, the subject paragraph has been revised as per your valuable suggestion.
Comment: Line 111 – The abbreviation “DAT” was not defined. And since it is used just twice in the manuscript there really isn’t a need for an abbreviation.
Response: At line# 111, the subject abbreviation has been deleted in the revision version of the research manuscript.
Comment: Line 128 – There is no reference provided for the citation: (CIMMYT Economics Program, 1988). More information is needed for the methodology used for the economic analysis.
Response: The reference for citation CIMMYT Economics Program, 1988 has been provide both in the text as well cited section of the revised manuscript.
Comment: Is this actually capturing the costs and returns of using the instrument or just for the various rates of N fertilizer that were pre-planned for the experiment and the various yield outcomes? Further, the authors report using US$ in the methods but present their results in Pakistani Rupees. Are the total costs or variable costs used for this analysis?
Response: The economic analysis was performed taking in to account all the expenditure incurred on research experimentation including nitrogen doses, seed and labor etc. (Total expenditure) and other and profitability of Fodder yield obtained (Total Income earned).
Comment: Line 154 – It seems usual to have the superscript “-1” after the word "plant" throughout section 3.2? It is also found once in the Abstract. Perhaps tillers per plant works better for the text?
Response: At line #154 and other places in the text tillers per plant has been used.
Comment: Figure 1 – Is a line graph the most appropriate choice for showing the differences among the distinct treatments. Since the x axis is not a continuous variable, would a bar graph be more appropriate? Perhaps the authors have already considered this.
Response: Your valuable feedback is highly appreciated and the matter was discussed in detail and majority contributors agreed to keep that figure as such.
Comment: Table 4 – A space is needed between “kg” and “ha-1” in the first column.
Response: The space has been added between Kg and ha-1 in the column.
Comment: Figure 4 – Add the units to the y axis for fresh weight.
Response: The units for fresh weight has been provided in Figure. 4.
Comment: Line 325 – A space is needed between “kg” and “ha” after 80.
Response: At line 325 space has been added between Kg and ha after 80.
Comment: Table 10 – The column titled “Money” should be “Income.”
Response: In Table 10, the needed correction has been done.
Comment: Line 340 – A space is needed between “kg” and “ha” for the seed rate.
Response: At line#340, space has been inserted between kg and ha for the seed rate.
Comment: The references are not formatted correctly according to the journal's guidelines. These need to be corrected throughout.
Response: The correct reference style has been used/adopted as per Journal’s guidelines in the revised manuscript.
Author Response File: 
Author Response.pdf
Round 2
Reviewer 1 Report
My concerns were addressed in this updated version of the manuscript. Nonetheless, I still recommend the addition of pictures showing the way the instrument was used for the data collection.
Reviewer 3 Report
It is difficult to read the PDF with the editing shown fully with track changes, but based on my reading of the manuscript and the responses of the authors, I think that my concerns about the previous draft have been addressed.
