Drop Size Measurement Techniques for Agricultural Sprays:A State-of-The-Art Review

Round 1

Reviewer 1 Report

Manuscript ID: agronomy-2189580

Title: Drop Size Measurement Techniques for Agricultural Sprays: A State-of-The-Art Review

Authors: Salvatore Privitera, Giuseppe Manetto, Simone Pascuzzi, Domenico Pessina, and Emanuele Cerruto

General comments

The article gives a brief and yet informative review of the statistical ways to express droplet size and its distribution as well as the non-intrusive and intrusive methods of drop size measurement.

What is missing and should be added in the section on droplet diameter expressions (lines 106-139) is the purpose and possible use of each expression. For the volumetric diameters information is missing on the practical use of VMD (e.g classification of spray quality for the nozzle/pressure used in the nozzle catalogues; … others?), Dv0.1 (e.g. drift reduction classification of nozzles in some countries like the Netherlands – see reports of Van de Zande et al. on SDRT classification; … others?), Dv0.9 (e.g. risk of reduced efficacy due to poor coverage in case of high value of Dv0.9; … others?), RSF (indicates variation among drop sizes; if low it should provide less drift potential and greater coverage; … others?). The other droplet diameters described by the equations from (2) to (6), next to the given definitions, also need information on their actual or potential use.

In genera lthe manuscript provides valuable information, is well structured and written with clear language. Some specific suggestions to improve the manuscript are given below.

I recommend publishing the article after additions as above.

Specific suggestions

18-22: The abstract should contain a minimum of essential information about the contents of the manuscript. Therefore, the last sentence should be followed by specification (naming) the presented droplet size measurement methods, separating the non-intrusive and intrusive ones

27-29: “Nowadays, Plant Protection Products (PPPs) are always used in the cultivation of major crops …”. The world “always” in this sentence sounds out of tune.  How about replacing the sentence by something like: “Despite the promotion of non-chemical methods of crop protection within the framework of integrated pest management, the plant protection products (PPP) are still used on a large scale. The environmental impact of the inappropriate use of the PPPs is a major public concern [1, 2]”

33: Suggest deleting “In general” and replacing “worker’s” by “occupational”.

36-37: Suggest replacing “the type of nozzles and their status” by “the type and quality of nozzles”.

40-43: In this sentence the phrase “in terms of”, repeated three times, seems inappropriate in the context. May be “”due to” would be more appropriate.

45: “higher quality application” or “higher application quality”?

46: Suggest replacing “in defining” by “for obtaining a desired”.

47: Suggest replacing “transfer” by “deposition”.

49: “… small droplets are more capable to reach the desired target …” – it is not true and not consistent with the rest the sentence. Due to the greater mass and therefore greater kinetic energy of the coarse droplets they often easier reach the target, especially in the circumstances conducive to drift (wind, high travel speed, high spray boom, lack of air assistance). This sentence needs  rewording.

51: Suggest replacing “mostly” by “especially”.

52-53: Suggest replacing “… are not usually deflected …” by “… are less prone to deflection …”.

84-87: Unnecessary repetition. This issue has already been raised in the Introduction.

182: Replace GAMMA(z) by GAMMA(ɑ)

208-209: Suggest replacing “… has a long been known …” by “… has for long been known …”

211-225: This part does not belong to the section on measuring techniques. It could be included in the Introduction where the effects of different droplet sizes are reported.

215-220: Herbicides kill weeds, not insects.

252: Suggest replacing “…several techniques laser-based …” by “…several laser-based techniques …”.

281: Please explain what is meant by “lens range” (sagittal depth?)

278: How about replacing “makers” by “manufacturers”?

300: How about replacing “a second drop” by “an other drop”?

423: Suggest replacing “… quickly response …” by “… quick response …”

519-524: Very long sentence losing the main idea. Consider splitting to get a clear message.

Author Response

Please, see the attached file.

Best Regards

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper summarizes the important significance of droplet size in agricultural spray, introduces the classification method of spray droplets, the expression method of droplet volume diameter and number diameter, and describes the measuring techniques for spray characterization, including non intrusive and invasive. The paper research has some reference for carrying out related research and measurement of pesticide droplets, and selecting appropriate droplet size using plant protection products

There are still some deficiencies in the paper, as follows:

 

1. The paper lacks the relevant research description of the specific application of droplet size in agricultural spray;

2. The paper lacks the analysis and comparison of practical application of droplet measurement methods;

3. The future research prospect of the paper on the droplet size is insufficient, and the droplet size is not the only factor affecting the spray effect. It is suggested that the droplet size and other factors should be considered comprehensively to improve the spray quality;

4. Like popular science, the author's description of droplet classification method, droplet diameter expression and droplet diameter measurement method are well-known conventional descriptions, lacking the author's thinking and innovative ideas.

Author Response

Please, see the attached file.

Best Regards

Author Response File: Author Response.pdf

Reviewer 3 Report

 

The article contains an overview of methods and means for spraying the solution when treating plants in the garden. The article is of practical interest.

I will note the comments that the authors need to eliminate for further publication in the journal.

1) In section 1, the purpose of the work is indicated - “to provide a literature review ... ..”.

Still, the goal needs to be formulated better - to conduct a critical analysis of known methods ...... by reviewing the literature .....

2) Please present the structure of your study by adding mind maps/graphs and additional explanations.

3) When referring to existing studies in the literature review, it is desirable to indicate the authors, year of publication and country, for example: “In the works of the Spanish scientists P.González-Tello, F.Camacho et al. (2008) [39] considered ....”. or "Portuguese explorers Panão, M.O.; Moita, A.S.; Moreira, A.L.. (2020) [42] proposed a method….”

4) Please add a section on the practical use of droplet measurement methods, for example, in robotic platforms, in hot mist treatment of plants, etc.

5) The analysis of the methods should be completed with a graphical visualization (where quantitative indicators can be compared). For example, you can compare the accuracy of a measurement in different ways and plot the accuracy versus method, plot the reduction in measurement error versus instrument class, and so on.

6) It would be good to systematize the processed literature and build a diagram - how many percent of the sources used relate to measurement methods, how many percent relate to devices, how many percent relate to mechanical devices, etc.

7) Figures 2-4 are well done, they are informative, show a set of technical means. . However, it is also desirable to show how the program works: the program interface, the algorithm.

8) Sections 5.1 and 5.2, where Intrusive methods are described, also lack the visualization of both hardware and software. This will increase the interest of the reader.

9) In the list of references there are works on this topic by the authors of the article, this is good. Perhaps you have links to videos of your installations (or your colleagues), it would be nice to add a link.

10) I also recommend adding photos of the actual work of installations in the garden or laboratory, this will significantly increase the level of the article and the interest of readers.

 

Author Response

Please, see the attached file.

Best Regards

Author Response File: Author Response.pdf

Reviewer 4 Report

This work presents a review paper illustrating several techniques for agricultural spray measurements (non-intrusive and intrusive) and highlighting the importance of droplet size in the PPP application.

However, the paper isn’t clear about its focus. It lacks some very important arguments for contextualizing the review (e.g., precision agriculture, innovative techniques, etc.).

I would propose a more detailed state of art and a more critical contextualization of the problem with a major review of the text before accepting publication.

 

Minor comments

Generally, not all the acronyms in the text were explicated.

 

Major comments

Introduction

Precision agriculture has become an increasingly important topic in recent years. The importance that an accurate and correct plant protection could have for a precise agronomic management is very high. Please insert a paragraph where the PA is contextualized from the point of view of Plant Protection Products (PPPs).

 

The aim is confused and not very explicit. Expand and define it better.

 

Paragraph 3

The paragraph "3. Measuring techniques for spray characterization" describes non-intrusive and intrusive techniques.

Generally, there are few applicative examples for these (report and cite them).

 

About DIA, many more examples of works referring to innovative techniques, such as artificial intelligence, machine learning, IoT, etc., should be reported.

Please include all these very important references to make the review as modern as possible

 

Conclusions

Insert a focus on new technologies and how they can help PPPs.

 

References

Modify the bibliography including more modern works.

Author Response

Please, see the attached file.

Best Regards

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The paper has made some additions and modifications on the basis of the original manuscript, but there are still some deficiencies, as follows:

1. Line 369 paper lists so many relevant references in Table 2, which is not appropriate.

2. 4.1, 4.2, 4.3 It is recommended to display the test images obtained from these three non-intrusive measurement methods, and make some image analysis to show the advantages of various methods.

3. Figure 5 The measurement results of water sensitive paper should be analyzed for the number of droplets, droplet deposition and droplet coverage

4. Fig. 6 The image collected by the silicone oil method is recommended to be analyzed, and compared with the water sensitive paper method to illustrate the difference and application characteristics of image processing

5. The paper introduces the measurement method of droplets, but how to control the droplet size is more important, and the factors that affect the droplet size are more important. For example, the hydraulic nozzle can increase the droplet size by increasing the spray pressure, nozzle diameter, etc; The centrifugal atomization nozzle can control the droplet size by controlling the rotating speed of the rotary table, etc.

6. The paper is slightly insufficient in promoting the future development of agriculture

Author Response

Please, see the attached file.

Author Response File: Author Response.pdf

Reviewer 3 Report

The authors finalized the article, took into account most of my wishes.

The formulation of the purpose and tasks of the work has been improved, the authors of the publications are indicated in the text of the review, photographs of the experimental setup and separate screens with the results of the software operation are given.

However, I think that at least one graph or diagram should be added to illustrate the analysis of information, where there are numerical results (paragraph 5 of my comments of the first round of reviews).

Author Response

Please, see the attached file.

Author Response File: Author Response.pdf

Reviewer 4 Report

The manuscript in the present form can be published in Agronomy as the authors have been improved it.

 

I don’t need to review another version because I accept the work in the present form.

 

 

Author Response

The authors would like to thank the Reviewer for his positive assessment of the new version of the manuscript.