Droplet Deposition of Leaf Fertilizers Applied by an Unmanned Aerial Vehicle in Coffea Canephora Plants
, Francisco de Assis Ferreira 2, Yubin Lan 3 and Pengchao Chen 3Round 1
Reviewer 1 Report
Leaf fertilizers have to be use more intensively in plant nutrition. The main methods recommended for application of leaf fertilizers in coffee crop are based on manual and electric knapsack sprayers as well as air-assisted tractor sprayers. They require a lot of manual work, and their precision of application is unsatisfactory. Although UAV are one of the promising techniques, the scale of their application is still small. One of the reasons is the lack of research results on the effectiveness of the treatment, including the uptake of nutrients. Therefore, the Authors proposed to evaluate the effect of configurations of UAV and its parameters when sprayed Conilon coffee plants. This kind of experiments will allow the wider use of UAVs in agricultural practice, especially for performing treatments in hard-to-reach areas. Overall, the article is written correctly, but requires some minor corrections before it is published.
The reader of the article would like to receive an explanation on the following questions:
1) Is it possible to determine volumetric mean diameter based on the measurements of droplets spot with the use of WSP?
2) How can you explain the decreasing of spray coverage and spray deposition with increasing spray height ? (Fig. 5).
The paper can be published after corrections as below.
1) Figures and tables should be self-explanatory without the need to use the text of the article. 2) Fig. 4 is illegible and incomprehensible.
3) There are no a, b, c symbols in the diagrams (fig. 5).
4) What is the difference between regulation and calibration (line 116) ?
5) What method has been used for droplet size measurements (table 2) ?
6) Whether it concerns one or two atomizers (table 2; Flow) ?
7) What are the units used in equation 1 (line 135) ?
8) Coverage, density, and deposition of spray droplets are not the measure of spraying efficacy. (line 236).
9) Data on the place of production (town, country) should be completed for: Type of spray nozzle, food dye, DropScope® system, spectrophotometer (Genesys), adjuvant, meteo station.
Author Response
The answers to the questions were commented on and sent inthe attachament.
thank you
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Evaluating the application efficacy with UAV should be compared with the classical methods of application of spraying solutions.
With the classic methods, the parameters of the solution application can be changed by using different types of nozzles, and when applying by UAV, only the centrifugal nozzle is used, where only the rotation is changed (7,500 and 10,000 rpm respectively). Based on which specifications were the rotations of 7,500 and 10,000 rpm was chosen?
In table 2, it is not specified how the VMD was estimated.
Figure 3 does not clearly show the heights at which the sensitive paper was placed.
Author Response
The Answers to the questions were commented on the send in the attachment.
thank you
Author Response File: Author Response.pdf
Reviewer 3 Report
The article has plenty of clues on ethical issues. The introduction is similar to the one in https://doi.org/10.3390/agronomy13020340. Although it is believed to be a different experiment, Figure 4 in the article proposed for publication is the same as Figure 5 in https://doi.org/10.3390/agronomy13020340, and Figure 3 is a photograph of the same area in Figure 4 of https://doi.org/10.3390/agronomy13020340, but from a different angle.
Author Response
Dear,
First we thank you for the detailed analysis of the manuscript and the comments regarding the images. We affirm that it is not the intention of the authors to act in an unethical way, much less to benefit us through illicit attitudes. It is worth mentioning that the authors of the articles mentioned are the same and figures were used in part for the purpose of schematic presentattion on how the dara was collected, because the methodology of data collections beteween the cited studies was similar.
However, if this fact does not interfere in the quality of the text, in methodology, in discussion and the conclusion of the results.
Finally, in these image similarities are enough to disqualify or invalidate the publication of the manuscript, we are at your diposial to remake it in such a way that it may meet the expectations of Agronomy.
Round 2
Reviewer 3 Report
In the light of the issues I have mentioned and the differences of opinions between the reviewers, the editor will reach a final decision.
Author Response
Dear,
Thank you for you analysis, understanding and sincerety. I reiterate that the fact cited in your reviews doesn't invalidate the quality of the submitted manuscript and doesn't characterize act in bad faith of the authors. We respect your observation and opinion, but will keep the manuscript according to the latest update and await the Editor's final decision.
Thank you very much.
