Analysis of Biophysical Variables in an Onion Crop (Allium cepa L.) with Nitrogen Fertilization by Sentinel-2 Observations

Round 1

Reviewer 1 Report

The article contributes to the Agronomy journal, however is important to add some comments that I already did to the manuscript body.

In Table 1, please change phenological stage instead of phenological cycle.

In line 230 please add, the readings (LAI) were taken on clear days.

In Figure 3a (LAI), please review dates 24/10/19 and 18/11/19. I think the values should be increase or explain what happened.

In Figure 4a what happened in november (18/11/19), explain.

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

 

The manuscript agronomy-1853883, entitled “Analysis of biophysical variables in an onion crop (Allium cepa L.) with nitrogen fertilization by Sentinel-2 observations” submitted by Casella et al. reported and discussed the results of a one-year field experiment set up in Argentina where the reliability of satellite Sentinel-2 observations was assessed on onion cultivated with four different N doses.

Considering the importance of remote sensing strategies in order to implement precision farming, and taking into account the relevance and the N consumption of onion, I believe that the manuscript is of potential interest to readers of “Agronomy” and falls within its scope.

In general, the experimental activity was carried out following a strict scientific logic and according to widely used methods which have made it possible to obtain reliable results. However, the experimental activity was carried out only during one cropping season and the experimental design implemented does not appear to be as described; in fact, it lacks randomisation. Another important aspect is the selection of the areas in which to choose the pixels, which steered the experiment towards obtaining good results that, although motivated, would perhaps not have been obtained under field conditions. These represent the main limitation of this experiment. However, it must be kept in mind that this is a useful experiment to increase the information related to remote sensing on a little-studied species. Therefore, in my opinion, the manuscript needs several revisions.

Abstract: Small changes are needed. On lines 31-32 did you specify “with different doses of granulated urea and granulated urea with urease inhibitor”. This last aspect (i.e.: granulated urea with urease inhibitor) did not emerge in the manuscript and in my opinion, could be deleted. I suggest also implementing the last sentence by adding some other results regarding N fertilization treatments (also percentage differences).

Keyword: Revised according to my specific suggestion in the enclosed pdf file.

Introduction: Small changes are needed in order to improve content and style. Some sentences must be rewritten because are difficult to understand. Moreover, I suggest to the authors to consider for the introduction and the discussion the manuscript doi:10.3390/drones5030061 that could help them to implement the part related to the precision farming for the onion cultivation.

Materials and Methods: Condense lines 204-207. Please, justify and revised the experimental design description: the experimental design not is a strip-plot and was not randomized, according with you figure. Therefore, in order to publish the article, I suggest to the author to do not mention this experimental design. Limit only to describe the plots that were arranged for the experiment. Between experimental plots there is an uncultivated area, why?

Results: in general, are clear and well written. In the figure 4 why the letters are only above one line?

Discussion: is quite simple and easy to read. However, I suggest to the authors to add some other sentence related to the effect of N on onion’s yield.

Conclusions are clear, well written and summarize the main results observed in the experiment.

My specific comments, which I hope will help the authors to improve their manuscript, are enclosed in the attached pdf file.

Comments for author File: Comments.pdf

Author Response

Please see the attachment

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The authors applied all suggested changes improving manuscript quality