Economic Viability of Ultrasonic Sensor Actuated Nozzle Height Control in Center Pivot Irrigation Systems

Round 1

Reviewer 1 Report

ABSTRACT:

• L14-15: it is necessary to clarify these declarations. It is not always the case. Potential is higher than in other systems.
• 24: In the same way, "could have".

KEYWORDS: I think you should not repeat words in the title (center pivot).

INTRODUCTION:

-        The data provided in the introduction are interesting and not redundant. Part of the introduction should be moved to material and methods. In my opinion, it should be complemented with some data, for example, the impact on the total cost (as a percentage) of certain advances, or on uniformity. Improving uniformity does not necessarily improve profitability. water redistribution in the soil is a key factor.

-        You may wish to consult: https://doi.org/10.1016/S0378-3774(99)00006-2 https://doi.org/10.1016/j.agwat.2009.06.015

-        L. 42. Reference [6] in bibliography, is correct?

-        L. 51. In my opinion, more justified in terms of energy savings

-        L. 56-69. It is not “introduction”. It is methodology.

-        L. 67-69. Not to make such categorical statements.

Methodology:

2.1. Cost Estimates:

• L.77. should not begin a sentence such as: "Table 10.” Is it a typo?
• L.81. 33 hours and gross and net depth? % speed?
• Table 1: use “,” always for separation of thousands (3,158.88)
• L.98. (81 acres) is not necessary. It was previously indicated.

2.2. DESA components….:

• A picture of the system or at least a schematic would facilitate its understanding

2.3. Calculation of water losses in the center pivot irrigation system

• L.121-122. 400 mm per irrigation even? 400000 m3/ha and year? that is illogical. The logical value is 100 times lower
• Table 2. Reference?
• Table 2. 30000 to 42000 m3/ha and year of water loses? I don’t understand it.
• L.140-143. This is essential. If this is not clearly justified by references, the results cannot be considered valid.
• Table 3. How were these values obtained? References.
• Tables 4-5. The analysis is too simplistic for a journal of this impact factor. The origin of the data is not justified. Are these not results?

Results:

The results are based on an assumption of water losses due to wind that is neither justified nor referenced. The water savings values are unrealistic (13500 to 27300 m3/ha, Table 3) and therefore the monetary savings are not supported (Tables 4-5).

• L.173. Typo in the header
• L.231 Typo “,” at the end.

In my opinion the AED system is a good idea and is potentially applicable.

If the work is only simulation (no experimentation) the data used should be clearly justified, and it is not.

The water savings achieved should be better justified and some more scenarios should be presented.

Author Response

Reviewer comments are listed in plain type, our responses are in italics Reviewer: thank you for your comments. We believe that your efforts have improved the manuscript and have endeavored to address all of your concerns. Reviewer 1 ABSTRACT: • L14-15: it is necessary to clarify these declarations. It is not always the case. Potential is higher than in other systems. • We recast this statement to reflect potential as one of the factors. • 24: In the same way, "could have". • Agreed and changed. KEYWORDS: I think you should not repeat words in the title (center pivot). We delete it. INTRODUCTION: - The data provided in the introduction are interesting and not redundant. Part of the introduction should be moved to material and methods. In my opinion, it should be complemented with some data, for example, the impact on the total cost (as a percentage) of certain advances, or on uniformity. Improving uniformity does not necessarily improve profitability. water redistribution in the soil is a key factor. - You may wish to consult: https://doi.org/10.1016/S0378-3774(99)00006-2 https://doi.org/10.1016/j.agwat.2009.06.015 Thank you for these two references, we add them to the introduction. - L. 42. Reference [6] in bibliography, is correct? No, fixed - L. 51. In my opinion, more justified in terms of energy savings Good point we added it, and a reference. - L. 56-69. It is not “introduction”. It is methodology. We have rearranged this section to clarify and establish the objectives and outcomes of the manuscript. - L. 67-69. Not to make such categorical statements. Entire set of statements deleted. Methodology: 2.1. Cost Estimates: • L.77. should not begin a sentence such as: "Table 10.” Is it a typo? Thank you for your notice. No, we deleted it. • L.81. 33 hours and gross and net depth? % speed? • Water depth added • Table 1: use “,” always for separation of thousands (3,158.88) Thank you for your notice. We fixed it. • L.98. (81 acres) is not necessary. It was previously indicated. Thank you for your notice. We deleted it. 2.2. DESA components….: • A picture of the system or at least a schematic would facilitate its understanding Thank you for your notice. We add the DESA schematic. 2.3. Calculation of water losses in the center pivot irrigation system • L.121-122. 400 mm per irrigation even? 400000 m3/ha and year? that is illogical. The logical value is 100 times lower • Great insight and you are correct, the 400mm is for the season not an irrigation event. This then propagated through the tables and calculations which are all now Fixed • Table 2. Reference? Table 2 is our calculation depending on the literature data we maintained in the section 2.3. • Table 2. 30000 to 42000 m3/ha and year of water loses? I don’t understand it. • These numbers are much more in line with expectations with the fix from your prior comment propagating through the tables. • L.140-143. This is essential. If this is not clearly justified by references, the results cannot be considered valid. We already have a reference for that above [22,23], but we add it below again. “The total irrigation water loss per area was calculated as the water loses percentage from wind draft times application efficiency loses in center pivot irrigation times total water applied per area [22,23].” • Table 3. How were these values obtained? References. We used this equation below Total water saving per area = water-saving percentage* total water loss by wind draft per area It was maintained in the methodology. We don’t have a reference because this is our calculation. • Tables 4-5. The analysis is too simplistic for a journal of this impact factor. The origin of the data is not justified. Are these not results? • Moved to results. Results: The results are based on an assumption of water losses due to wind that is neither justified nor referenced. The water savings values are unrealistic (13500 to 27300 m3/ha, Table 3) and therefore the monetary savings are not supported (Tables 4-5). Calculations are updated and in line with your expectations • L.173. Typo in the header • L.231 Typo “,” at the end. Typos fixed In my opinion the AED system is a good idea and is potentially applicable. If the work is only simulation (no experimentation) the data used should be clearly justified, and it is not. The data used are all literature values and cited. The scenario analysis explores the range of literature reported values. The water savings achieved should be better justified and some more scenarios should be presented. More scenarios added, per your suggestion

Reviewer 2 Report

Congratulations on your research reaching this level in the publishing process. I am addressing both the positive aspects and the issues to be addressed in my comments below. Please know that these comments are my opinion as a consulting editor, and I respectfully put those forth for you to consider in your revision. They are in no way meant to take anything away from the hard work and rigor you have already put into the research and manuscript development process.

Positive aspects of the manuscript:

1. The manuscript is generally well-written, logical to follow, easy to read, grammatically correct, and organized well. However, a few grammatical errors remain (as is the case with almost all articles).

2. This research addresses an existing gap in the literature and is relevant to the needs of the profitability of the irrigation industry today in multiple countries.

3. The introduction does a good job of referencing literature while telling the story of why this research is needed.

4. The objectives of the research are clearly stated and are a logical end to the needs of the irrigation industry that you identified in the introduction.

5. The literature reviewed and contained in the manuscript is appropriate for the topic, reinforces the need for this research, and up to date.

6. The methodology is appropriate for the type of research conducted and the statistics used are suitable for the analyses conducted.

7. The results are presented in an orderly and logical manner and adequately describe the analyses conducted regarding the costs of using the dynamic variable height irrigation systems. You also do a good job of weaving in literature that compares to your findings.

Suggestions to consider in your revision: 

It is mainly the assumptions that I am concerned with. You use several ranges in percentages that are not substantiated with literature as to why you chose these ranges.

For example:

Line 92 -- Why did you use a discount rate of 12.5%?

Line 142 -- Why did you assume wind drift losses of 50%, 60% and 70%?

Line 145-146 -- Similarly, why did you assume wind drift of 45%, 55%, and 65%?

Line 159 -- You used water values ranging from $0.005 to $0.10 per m3. Why did you not use a value higher than $0.10 from those you found in the literature?

Author Response

Hi 

Congratulations on your research reaching this level in the publishing process. I am addressing both the positive aspects and the issues to be addressed in my comments below. Please know that these comments are my opinion as a consulting editor, and I respectfully put those forth for you to consider in your revision. They are in no way meant to take anything away from the hard work and rigor you have already put into the research and manuscript development process.

Positive aspects of the manuscript:

1. The manuscript is generally well-written, logical to follow, easy to read, grammatically correct, and organized well. However, a few grammatical errors remain (as is the case with almost all articles).

2. This research addresses an existing gap in the literature and is relevant to the needs of the profitability of the irrigation industry today in multiple countries.

3. The introduction does a good job of referencing literature while telling the story of why this research is needed.

4. The objectives of the research are clearly stated and are a logical end to the needs of the irrigation industry that you identified in the introduction.

5. The literature reviewed and contained in the manuscript is appropriate for the topic, reinforces the need for this research, and up to date.

6. The methodology is appropriate for the type of research conducted and the statistics used are suitable for the analyses conducted.

7. The results are presented in an orderly and logical manner and adequately describe the analyses conducted regarding the costs of using the dynamic variable height irrigation systems. You also do a good job of weaving in literature that compares to your findings.

Suggestions to consider in your revision: 

It is mainly the assumptions that I am concerned with. You use several ranges in percentages that are not substantiated with literature as to why you chose these ranges.

For example:

Line 92 -- Why did you use a discount rate of 12.5%?

The discount rate refers to the interest rate used in discounted cash flow (DCF) analysis to determine the present value of future cash flows. Normally in Agri systems, the discount rate for utilities varies from 12.5% to 20%. In this case, although the discount rate lies in the higher range, we selected the lowest among it ~12.5%, which shows that the buyer is willing to pay less today for the future cash. As in terms of the major seller and market conditions, the discount values are less ~10 % for public enterprises and relatively high i.e. 20% for startups that have been recently developed. A higher discount rate is a high risk for fresh startups. The US-based Agri instruments would lie between 10-15%.

Line 142 -- Why did you assume wind drift losses of 50%, 60% and 70%?

Because water loss by wind drift comprises the majority of losses and accounts for 50-70% depending on the reference below.

“B. Molle, S. Tomas, M. Hendawi, and J. Granier, “Evaporation and wind drift losses during sprinkler irrigation influenced by droplet size distribution,” Irrig. Drain., vol. 61, no. 2, pp. 240–250, 2012.”

Line 145-146 -- Similarly, why did you assume wind drift of 45%, 55%, and 65%?

You are correct to note that these are assumptions in the analysis.  As such we expanded the range to cover the vst majority of physical possibilities.  Leaving out very high savings % as those are unlikely and leaving out 0% as that is the trivial solution. 

Line 159 -- You used water values ranging from $0.005 to $0.10 per m3. Why did you not use a value higher than $0.10 from those you found in the literature?

Thank you, We added higher price scenarios per your suggestion.

Author Response File: Author Response.docx