Simulation Analysis and Experiments for Blade-Soil-Straw Interaction under Deep Ploughing Based on the Discrete Element Method
Round 1
Reviewer 1 Report
1. The discrete element simulation test is described in detail in the abstract, but from the content of the article, the introduction of pre-theoretical analysis is missing.
2. In“2.1.2. Mechanisms of rotary blades”，Please check the format of subscripts letter in the paper, e.g. Vd, Vm.
3. "2.1.2. Mechanism of rotating blade" part of the kinematic analysis of the working process of the rotary tillage knife, to obtain the equations of motion of the rotary tillage blade, but lack of summary, it is recommended to add the discussion related to this part.
4. Line 143-147：Is the content relevant to the research content of this paper? It is suggested that it be removed.
5. The selection of test factors needs to consider their research value. In the results of Box-Behnken test, test factor C did not have a significant effect on the test, is it necessary to include the test? If test factor C interacts with other test factors, it is suggested to add a description.
6. Simulation tests have shown the mechanism of the movement of the rotating tillage blades. Can it be verified in field trials?
7. Views on the manuscript are fully discussed in Section 4. Necessary analysis should be carried out in combination with the previous research and the viewpoint of the manuscript in order to highlight the advantages and significance of the research work.
8. Please check the format of the article carefully. You need to insert Spaces in some places.
Author Response
1. (line 82-91,176-265) We have added the relevant theoretical analysis in revised manuscript.
2. The formatting has been modified, with subscripts and skewing.
3. (line 165-169) We have made the relevant lump sums for the rototilling process in revised manuscript.
4. This section has been removed.
5. (line 474-477) We chose the study of Factor C because it has been less studied and is taken into account in this paper, and its interaction is experimentally obtained as shown in Figure 10. (c), with the relevant explanation.
6. It has been proven that if the modeling simulation conditions are set up with little difference from the actual, the simulation results really do not differ much from the experimental results. The error between the field test and simulation in this study is within a reasonable range, so it can be verified. It is just that the real conditions cannot color the soil in different movement directions, and the observation cannot reach the conditions of simulation, but the modeling and simulation are completely consistent with the actual situation.
7. (line 540-546) We have made the appropriate changes in line 437.
8. The formatting issues have been carefully revised.
Reviewer 2 Report
The specific suggestions are listed in the attachment.
Comments for author File: 
Comments.pdf
Author Response
1.We changed the title to “Simulation Analysis and Experiments for Blade-soil-straw Interaction under Deep Ploughing Based on the Discrete Element Method”
2.（line13-21）We have made relevant modifications.
（line82-91）We have added a description of the discrete element method in the text.
We have condensed the content.
（line100-104）At the end of the introduction, we have highlighted the contribution of manuscript.
3.There are many benefits to deep tillage of the soil, which will be listed later. The power consumption mentioned in the text is exactly the problem addressed by this study.Deep tillage can bury organic fertilisers, crushed straw, weeds and pests, promote the activity of aerobic microorganisms and the release of nutrients, and create good conditions for the growth and development of wheat.Deep tillage can loosen the soil, deepen the tillage layer, improve the water and gas condition of the soil, effectively solve the contradiction between water and gas inside the deep tillage layer, enhance the water percolation and storage capacity of the soil, and thus improve the drought resistance of the soil and the ability to retain and supply fertiliser.
4.Figure 1 (a) is only intended to present a schematic diagram of the installation position of the rotary tiller blades in operation, the exact layout does not need to be listed.
5.We aim to find out the structural parameters of the rotary cutter that are suitable for deep rotation, to solve the problems of high-power consumption and poor straw burying in deep rotation, to find the best combination of parameters that affect power consumption and straw burying, and to guide the design of the rotary cutter. The single rotating knife is the basis for the study of the whole machine operation and is a key step, the results of the study can provide theoretical reference for the subsequent deep rotation operation.
6.We have done this study to use existing knowledge to explore the unknown. The selection of test parameters based on existing rototilling theory to guide the test is an important function of this section and we have added and deleted in the appropriate places.
7.We have removed the text.
8.（line175）We have updated the article with the relevant data from the soil straw model. The simulation methods for the main indicators are in section 2.2.2 and （line375-396）field test methods have been added.
9.（line278-280）As we explained in the previous text, since the value of B is influenced by the values of R and β, when the values of R and β are certain, the value of B is also certain, so only R and β are used as variables and no longer B is used as a variable.
10.The description of soil information in the field is indicated by moisture content and the pressure of penetration resistance. Straw is expressed as a percentage of cover.
We have added a description of the relevant installation methods. Removed Figure 7(a)
11.Figure 6 is a schematic diagram of the field test method, which aims to measure the straw coverage and tillage depth before tillage.
12.We have revised the discussion part and added other references for comparison.
13.We rearrange the conclusion according to the order of the article.
14.We have carefully screened and corrected the details you mentioned and other relevant details.
Reviewer 3 Report
In order to solve the problems of insufficient rotary tillage depth, high power dissipation, and poor straw burying effects during the deep rotary tillage operation. The study was conducted with rotary blade structure parameters as the test factors, and power, soil crushing rate and wheat straw burying rate as the test indicators to optimize the rotary blade structure. The mathematical model of blade - soil - straw based on the discrete element method was established and the accuracy of the model was verified by field trials. The optimized mathematical model can effectively and accurately predict the test indicators under different test conditions. Through the above methods, the operating power consumption was reduced and the indexes of rotary tillage blade were improved after operation. The research content has some value, but there are several problems.
1. (Line 157) The relevant theoretical approaches to the calculation of contact models can be introduced as appropriate.
2. (Line 163) The value "106" in” Shear modulus(Pa)”should be "106", Please check the same question in the manuscript.
3 (Line 172，Figure 4. )To ensure that the tillage depth is equal to 200mm, adjust the center of rotation to the appropriate position. According to the experimental design in Table 4 , when the rotary radius is 150~240mm, there are two situations where the roller partially or completely enters the soil, which will directly affect the operating power consumption and indexes of rotary tillage blade. The impact of this part is not analyzed in the results, please add the relevant analysis.
4.(Line 202, 2.3. Simulation) In this paper, the discrete element method is used to optimize the rotary blade structure, reduce the power consumption of deep rotary tillage operation, improve the indexes of rotary tillage blade. Furthermore, the movement of the blade on the soil and the blade on the straw were described. However, the interaction relationship between rotary blade, soil particle and straw in the process of deep rotary tillage was not analyzed in combination with the main purpose of the article, such as the mechanism of soil particle-straw collision and transport, is not analyzed in depth with the main idea of the article.
5.(Line 399) Conclusions needs more condense in it, as it's more of an afterthought. The authors are suggested to include afterthought of this work.
Author Response
1. (Line 194-265) We have added the relevant discrete elements to the theory related to computational contact models.
2. We have reformatted the text.
3. We have described in discussion (a) the phenomenon of increased power consumption when the knife stick is fully incorporated into the soil.
4.(Line 343-361) We have added relevant descriptive analyses.
5.(Line 557) We added an afterthought.
Round 2
Reviewer 2 Report
The author has made many modifications or supplements to the the manuscript. But the author still needs to fully consider the working principle of rotary tillage, the arrangement of rotary baldes, and the role of retaining plates(rear shield\above cover panel). Also, the structure of the simulation model should be consistent with the experimental apparatus for ensuring the reliability of simulation results.
Author Response
Dear Reviewer.
We would like to express our sincere thanks again for your patient and meticulous suggestions. We have always found your suggestions to be very helpful and we know that adding this part of the experiment would enhance the paper as a whole, but this paper is looking at the positive rotary tillage mode, where the role of the baffle is mainly secondary soil breaking and does not have a significant effect on the rotary cutter-straw-soil interaction, so it will not be used as a test factor for the single cutter structure for the time being. As shown in the paper, our test and simulation model are consistent, so their conclusions are consistent. This article has clarified the single blade - soil - straw interaction law for deep rotary tillage in the operating mode.
