Parameter Calibration and Systematic Test of a Discrete Element Model (DEM) for Compound Fertilizer Particles in a Mechanized Variable-Rate Application
Round 1
Reviewer 1 Report
Manuscript ID: agronomy-2231205
Manuscript title: Parameter calibration and systematic test of discrete element model (DEM) for compound fertilizer particles in mechanized variable-rate application
The topic discussed in this manuscript is very interesting in the area of agricultural biosystems development, specifically for variable rate technology and in particular variable fertilizer spreaders. This work attempted to establish a simulation model to measure the contact parameters of the compound fertilizer particle. However, below are some notes that may help improve the manuscript
1. In the methods section (Page: 7, Lines: 213-215) you stated that “In the test, the fertilizer’s moisture content was 213 found to be 5.6% which is a low moisture content, so there was hardly any adhesion on 214 the compound fertilizer particles’ surfaces”. You need to justify this statement or simply provide a supporting scientific reference.
2. Regarding the equivalent diameter (D) of the compound fertilizer particles (Page: 7), you reported that (Page: 7, Lines: 230-231) “compound fertilizer particles are well-rounded”. So, how you specify L, W, and H? Also, Equation 8 (Page: 7), used to determine D, needs a supporting scientific reference.
3. In the results section (Page: 9), the ANOVA of Plackett-Burman test results (Table 4) indicates that Model B shows highly significant difference. However, Model B was not chosen for the scheme and results of the steepest ascent test, and this needs to be justified.
General Comment
This manuscript is acceptable for publication in the journal of Agronomy after minor revision.
Author Response
Response to reviewers
Dear editor and reviewers,
We would like to begin with our sincere appreciation for all the valuable comments, insightful suggestions and thoughtful corrections offered by the reviewers and editor to our manuscript (agronomy-2231205). The comments and suggestions definitely helped us to improve the quality of the manuscript. In the revision, we have addressed all of these comments. We hope the revised manuscript has now met the publication standard of your journal. We highlighted all the reversions in red. These changes are summarized below following a point-by-point response to reviewers’ comments.
Comment 1: In the methods section (Page: 7, Lines: 213-215) you stated that “In the test, the fertilizer’s moisture content was 213 found to be 5.6% which is a low moisture content, so there was hardly any adhesion on 214 the compound fertilizer particles’ surfaces”. You need to justify this statement or simply provide a supporting scientific reference.
Response: Thanks for your advice. References [30] and [31] are cited to demonstrate that the adhesive force can be ignored when the moisture content of cohesive soil does not cause plastic deformation. In order to be more scientific and rigorous, we made the assumption that the adhesion of fertilizer was ignored, and selected the Hertz-Mindlin no-slip model as the contact model of compound fertilizer particles. The accuracy and reliability of this model are also verified by the regression model analysis in the following paper.
Comment 2: Regarding the equivalent diameter (D) of the compound fertilizer particles (Page: 7), you reported that (Page: 7, Lines: 230-231) “compound fertilizer particles are well-rounded”. So, how you specify L, W, and H? Also, Equation 8 (Page: 7), used to determine D, needs a supporting scientific reference.
Response: The length, width and thickness of the actual model of compound fertilizer particles are defined as the size of particles on the X axis, Y axis and Z axis respectively. The relative description has been added in Page 8. Moreover, Figure 7 (a) is added to illustrate the definition of length, width and thickness. As for the Equation 8 used to determine D, we refer to literature [32] to confirm it.
Comment 3: In the results section (Page: 9), the ANOVA of Plackett-Burman test results (Table 4) indicates that Model B shows highly significant difference. However, Model B was not chosen for the scheme and results of the steepest ascent test, and this needs to be justified.
Response: Thanks for your suggestion. The p-value of parameter B in Table 4 is 0.063 greater than 0.05, which is not a significant parameter affecting the angle of repose. I think what you would like to say is that parameter D has significant influence, why not choose D for the steepest ascent test. Although D is a significant parameter, its p-value is 0.0461, very close to 0.05, while the p-values of other significant parameters are all less than 0.01. Compared with other significant parameters, D has less influence, so D was not selected for the steepest climb test. In addition, we also cite two papers to demonstrate the feasibility of this method.
Reviewer 2 Report
Review comments for improving the manuscript are provided in the attached reviewed manuscript. Authors are advised to respond to all comments appropriately.
Comments for author File: 
Comments.pdf
Author Response
Response to reviewers
Dear Editor and Reviewers,
We would like to thank the reviewers for carefully reading our manuscript (agronomy-2231205). We appreciate the comments and suggestions. In the following, we include a point-by-point response to the comments. In the revised manuscript, all the changes have been highlighted in red.
Comment 1: This sentence needs to be broken down to make it more understandable.
Response: Thanks for your advice. We have made this correction in the abstract as your suggestion.
Comment 2: This sentence sounds more like part of a set of instructions rather than a report. Revision is recommended.
Response: Thanks for pointing out the mistake. We have revised it.
Comment 3: Sentence needs revision for better clarity. Also, mean of what?
Response: Thanks. We have modified it.
Comment 4: Section 4 and its contents seem to all belong under Materials and Methods.
Response: Thanks. We've removed the method part.
Comment 5: Is the TMS-Pro really a mass spectrometer?
Response: Thanks for pointing out the mistake. We have modified it.
Comment 6: Variable appears to be hanging. Also, all variables need to be italicized.
Response: Thanks for pointing out the mistake. We've changed all the variables in italics in the paper.
Comment 7: Were each of these particles whole?
Response: Thanks for your advice. We have changed from "fertilizer particles" to "intact fertilizer particles."
Comment 8: This sentence sounds more like an instruction from a manual than a report. Revision is recommended.
Response: Thanks for pointing out the mistake. We have modified it.
Comment 9: This statement is implying that the oblique projectile motion is dependent on the conditions of Eqn.3.However, isn't Eqn.3 rather a resultant of the oblique projectile motion? Please verify and revise appropriately.
Response: Thanks for pointing out the mistake. We've changed the statement.
Comment 10: Should be in past tense.
Response: Thanks. We've changed it to the past tense.
Comment 11: These both range over 10 degrees. Are these for the same fertilizer or different fertilizers?
Response: Thanks for your advice. These two ranges are the ranges of static friction coefficient and rolling friction coefficient respectively, which come from the same compound fertilizer. This is the result of the actual test. In addition, the static friction coefficient must be greater than the rolling friction coefficient.
Comment 12: All of this sound more like from an instructional manual than it is a report. This should be written in past tense.
Response: Thanks for your advice. We have revised it.
Comment 13: Incomplete statement. Consider.
Response: We have modified it.
Comment 14: If you must use this table, it will belong under Materials and Methods. The table contents do not show any results. These are only a repeat of parameters displayed in Table 1. What is different here?
Response: Thanks for your advice. Table 1 and Table 2 are indeed similar. However, Table 1 shows all parameters related to discrete elements obtained through physical tests or references. The parameters in Table 2 are the variables used for emulation. Table 2 turns the parameters into variables and the scope of the parameters into code. References [18] and [36] also list these two tables.
Comment 15: Groups need to be defined.
Response: Thanks. We've changed the statement.
Comment 16: If software, provide company information.
Response: Thanks for your advice. We have provided the company information of all the software in this article.
Reviewer 3 Report
The comments and suggestions are given in the attached file
Comments for author File: Comments.pdf
Author Response
Response to reviewers
Dear editor and reviewers,
We would like to thanks the reviewer for carefully reading our manuscript (agronomy-2231205). We appreciate the comments and suggestions. In the following, we include a point-by-point response to the comments. In the revised manuscript, all the changes have been highlighted in red.
Comment 1: Too lengthy sentence try to split it with background and aim of study lines separately.
Response: Thanks for your advice. We have made this correction in the abstract as your suggestion.
Comment 2: Try to add one or two more specific keywords.
Response: Thanks. We added a specific model, Hertz-Mindlin no-slip model, to the keyword.
Comment 3: In last lines show the main aim or study gap?
Response: We have revised it as your suggestion.
Comment 4: Capital letters?
Response: Thanks for pointing out the mistake. We have modified it.
Comment 5: ?
Response: We have explained the JKR.
Comment 6: Add more literature and study gap is not present properly.
Response: Thanks for your advice. We have revised it as your suggestion.
Comment 7: Novelty and objectives or aims of the study should be present in points form.
Response: Thanks. We've listed the novelty and purpose points.
Comment 8: Reference?
Response: Thanks for your advice. Since there was no evidence that Huachang 15-15-15 compound fertilizer was a typical fertilizer in the middle and lower reaches of the Yangtze River, we modified the expression method.
Comment 9: Add some physical image of the materials.
Response: Thanks. We have added a picture of the test material as shown in Figure 1.
Comment 10: Reference?
Response: Thanks. We have cited the reference [25-27]
Comment 11: Equation formating?
Response: Thanks. We have modified how to obtain the regression equation. We refer to literature [17-20], etc., and the regression equations obtained are all ascending equations, so we did not modify the equations.
Comment 12: Not understands.
Response: We have changed the expression.
Comment 13: At the start of the conclusion section try to write what you done and which methods were used then write conclusion in points form.
Response: Thanks for your advice. We have revised the conclusion according to what you said.
Comment 14: Add some future perspectives of the study.
Response: Thanks. We have revised it as your suggestion.
