Effect of Tillage Systems on Physical Properties of a Clay Loam Soil under Oats
Round 1
Reviewer 1 Report
The manuscript "Effect of Tillage Systems on Physical Properties of a Clay Loam Soil Under Oats" have been improved significantly through the hard-work of the authors. However, it still need serious improvements. The introduction still needs to be improved as it does not convey the information appropriately. For example, lines 40-42 should be a single sentence (not two). Furthermore, the points discussed in the introduction are not well discussed, i.e., the points are not connected and does not transition smoothly.
The use of the units of measurement is not consistent throughout the manuscript. For example, depth was reported in two different units (mm and cm). Please be consistent throughout.
Equation 2 is not for calculating total porosity, it is for calculating percent pore spaces! Furthermore, it is not written correctly. The ratio of bulk density to particle density is subtracted from 1 and not bulk density subtracted from 1 and then divided by particle density. Please be careful.
There are two table 1s!! Please correct this.
In figure 1, please reformat these figures. Delete the major and minor lines and insert the x and y axis. Furthermore, please label the y-axis correctly (don't just use the units).
Author Response
Response to Reviewer 1 Comments
Point 1: The manuscript "Effect of Tillage Systems on Physical Properties of a Clay Loam Soil Under Oats" have been improved significantly through the hard-work of the authors. However, it still need serious improvements. The introduction still needs to be improved as it does not convey the information appropriately. For example, lines 40-42 should be a single sentence (not two). Furthermore, the points discussed in the introduction are not well discussed, i.e., the points are not connected and does not transition smoothly. ..
Response 1: The manuscript has been improved as indicated by all the reviewers. The introduction has been enhanced trying to connect better the paragraphs in a clear line of thought. we received the help of a native English speaker colleague. All the editing in the introduction is in red. The specific correction of the example mentioned is in Line 44
Point 2: The use of the units of measurement is not consistent throughout the manuscript. For example, depth was reported in two different units (mm and cm). Please be consistent throughout.
Response 2: Throughout the manuscript, specifically in table 1 and 2 and in the chapter 2 methodology it has been corrected the units of measurements to be consistent, al correction are in red specially for the units of cm.
Point 3: Equation 2 is not for calculating total porosity, it is for calculating percent pore spaces! Furthermore, it is not written correctly. The ratio of bulk density to particle density is subtracted from 1 and not bulk density subtracted from 1 and then divided by particle density. Please be careful.
Response 3: Equation 2 has been corrected and we use the term pore space throughout the manuscript.
Point 4: There are two table 1s!! Please correct this
Response 4: We are sorry, the numbers of the tables has been corrected.
Point 5: In figure 1, please reformat these figures. Delete the major and minor lines and insert the x and y axis. Furthermore, please label the y-axis correctly (don't just use the units).
Response 5: We corrected the figures as indicated
Reviewer 2 Report
The revision significantly improved the qualty of the paper. Longer term investigation is recommended, as considerable changes in the physical properties of soils due to the change of the management practice can be recorded after several years only.
Author Response
Response to Reviewer 2 Comments
Point 1: The revision significantly improved the quality of the paper. Longer term investigation is recommended, as considerable changes in the physical properties of soils due to the change of the management practice can be recorded after several years only ..
Response 1: Thank you very much for your revision, it is very helpful to have your comments and suggestions to improve the manuscript, we appreciate very much your time invested in the revision. We plan to continue with the measurements as you recommend.
Reviewer 3 Report
The study presented by Karen Denisse Ordonez-Morales deals with the impact of different tillage practices on the physical properties of a cultivated clay loam soil. This is a very important topic for sustainable cultivation and improvement of agricultural systems. The experimental design seems reasonable and the fact that the authors took samples over a period of four years provides a very valuable dataset for process understanding and modeling. However, the parameters obtained do not really allow a clear conclusion and some of the explanations given by the authors relate to other studies and parameters that have not been investigated in the respective study itself. Furthermore, the statistical analysis seems to be a bit too simple and no clear differences between the years and treatments could be found. I suggest to re-do the statistics using a more complex analysis and, for example, repeated measures ANOVA.
The Introduction section needs a re-writing. Some information are given about the parameters that were studied in this experiment, but the different paragraphs are not well connected and a clear line of thought is missing. The hypothesis should be derived based on the information provided in the Introduction. Though the general problem is mentioned by the authors in ll. 68 – 71, a clearer description of the “basic knowledge” and the problems associated with tillage practices in that specific region (climate) should be provided in the Introduction.
The description of the study site given in the Materials and Methods section could be made in a separate subchapter, e.g. 2.1. Study site. Information about the statistical analysis should be moved towards the end of the Materials and Methods section and could be presented in an own subchapter (“Statistical analyses”). Be more precise here: which R version and R packages were used to handle the data and perform the statistical analyses (and don’t forget to cite both R and the individual packages)? Which functions were used? R has different possible functions for almost any test and it should be stated which one was used in this study. How were the figures made? If they were made in R, please provide and cite the package(s) used. Generally, I think that the Tukey test is not the best choice for analyses of such a dataset. Since the experiment was performed in randomized blocks and with three repetitions and over time, I would think that a repeated measures ANOVA would be more appropriate. This might give more power to the results of the analysis and the final conclusions.
The results should be presented by first mentioning the actual numbers in the respective subchapters of bulk density, total porosity, Ks and crop yield under the different treatments. The information about significant differences should be provided afterwards. Since the authors are relating the missing significance to drying and wetting of the soil, as well as intensity of rainfall, it would be helpful for the reader to get some information about the weather and site conditions during the 4 years of experiment. This should be presented first, e.g. “3.1. Site conditions”. I do not expect the air temperature to fluctuate a lot between the years, but the rainfall intensity most likely would. Since soil moisture has not been measured in this experiment, conclusions based on wetting and drying of the soil are hard to make.
The Conclusions are basically a repetition of the results presented in the Results and Discussion section rather than a real conclusion. The study does not cover any sampling of soil biology or soil moisture. Those issues and limitations should be mentioned here and (if possible) recommendations or a future outlook should be given.
Please find some minor comments on the individual sections below:
Abstract
l. 14: local information of what?
ll. 19 – 20: results should be a bit more informative. Which treatment had the highest bd, TP and Ks? Please provide numbers here! Were crop yields different between the years? A short conclusion is needed, i.e. what are the recommendations and lessons learned from this experiment?
Introduction
l. 26: what are “inadequate practices”? Be specific at this point.
l. 27: I suggest to re-write the first part of the sentence and make clear where the increase in bulk density derives from, that it leads to compaction and that compaction in turn leads to further degradation of the soil.
l.38: why does intensive tillage lead to soil degradation? More explanation is needed here.
ll. 40 – 41: This sentence seems to be incomplete
l. 41: what is vertical tillage? Please explain the different tillage practices you focused on already in the Introduction.
ll. 57 – 58: root growth in a clay loam with 1.5 – 1.6 g cm-3 was bigger than what? The comparable information is missing here.
l. 64: what do the authors mean by “the technique of taking the data”? The sampling technique?
Materials and Methods
Table 1: which implement was used during CT and VT? This could be an additional information provided in the table.
ll. 133 – 135: This is a lot of information given in one sentence – please split the information into two sentences.
Results and Discussion
Table 1: this should be Table 2. I assume that the table shows the average values for bulk density – what about the standard deviations? They should be provided in this table as well.
l. 151 + l. 153: I am not really sure, but I would replace “normal” by “typical”
l. 161: I suggest to cite study [41] here already (maybe after (29 years)) – otherwise, the note “In the same story” in l. 163 is confusing.
ll. 172 – 174: This is a difficult comparison. The eight-week study certainly compared the bulk density conditions before and closely after the tillage event. At that point, the soil is still impacted by the tillage event and the desired loosening is still visible. However, the soil usually collapses after some time and the differences between the treatments become smaller. So it does not surprise me that the differences found in an experiment where soil was sampled three months after the tillage event are lower than in the cited study. I would think that this comparison does not hold.
ll. 189 – 192: This short conclusion should be wider – what could be the reasons for the decrease in bulk density in 2016? Drying and wetting have not been measured, but the rainfall intensity and patterns could give a hint. Were changes in soil biology observed? The number of earthworms could influence the density of the soil and change the structure and porosity. These possibilities should be discussed in more detail at this point.
Figures 5, 6 and 7: These values (together with the standard deviations) might be better presented in a table.
l. 209: I suggest to replace “while” by “and”
l. 212: which studies? Please mention them here.
ll. 226 – 230: Clay loam soils? What soil texture are those studies referring to?
ll. 243 – 244: What is meant by “differing trends”? Be more specific here.
l. 248: remove “under”. The authors want to state that the yield under NT was lower compared to CT and VT, I suppose.
ll. 255 – 256: I would challenge this statement – there a quite some studies that have shown lower yields under NT compared to CT even in the long-term, e.g. Wright and Hons (2005) (Soil Science Society of America Journal, 69, 141 - 147, Fernandez et al. (2007) (Soil & Tillage Research, 94, 47 – 54, doi: 10.1016/j.still.2006.07.003), Boddey et al. (2010) (Global Change Biology, 16, 784 – 795, doi: 10.1111/j.1365-2486.2009.02020.x), Jacobs et al. (2015) (Archives of Agronomy and Soil Science, 61:8, 1079 – 1087, doi: 10.1080/03650340.2014.981669).
l. 258: Do the results correspond to just one other study? This last sentence is very weak and should be discussed further.
Author Response
Response to Reviewer 3 Comments
Point 1: The study presented by Karen Denisse Ordonez-Morales deals with the impact of different tillage practices on the physical properties of a cultivated clay loam soil. This is a very important topic for sustainable cultivation and improvement of agricultural systems. The experimental design seems reasonable and the fact that the authors took samples over a period of four years provides a very valuable dataset for process understanding and modelling. However, the parameters obtained do not really allow a clear conclusion and some of the explanations given by the authors relate to other studies and parameters that have not been investigated in the respective study itself. Furthermore, the statistical analysis seems to be a bit too simple and no clear differences between the years and treatments could be found. I suggest to re-do the statistics using a more complex analysis and, for example, repeated measures ANOVA.
Response 1: Thank you for your comments, observations and suggestions. We enhance the discussion and explanation in the section of Results and Discussion, improvements are in red. We have discussed your suggestion about the use of repeated measures ANOVA and we think that according to our data and objective it is not the best way to do the analysis. We were looking if there is any significant effect on the soil physical variables comparing the results of the treatments at the end of each season. In this four years the results for example bulk density are in parallel for all the tillage systems so no significant changes due to the treatments. In our conditions, it is necessary more time to see the effects.
Point 2: The Introduction section needs a re-writing. Some information are given about the parameters that were studied in this experiment, but the different paragraphs are not well connected and a clear line of thought is missing. The hypothesis should be derived based on the information provided in the Introduction. Though the general problem is mentioned by the authors in ll. 68 – 71, a clearer description of the “basic knowledge” and the problems associated with tillage practices in that specific region (climate) should be provided in the Introduction.
Response 2: In the introduction we have improved the writing according to suggestions of reviewers. The changes and editing of the introduction are in red throughout this chapter. The hypothesis has been enhanced based in the information added in the introduction. Information about problems associated with tillage practices in the country and region were added to the introduction in lines 31-32 and 76 -78.
Point 3: The description of the study site given in the Materials and Methods section could be made in a separate subchapter, e.g. 2.1. Study site. Information about the statistical analysis should be moved towards the end of the Materials and Methods section and could be presented in an own subchapter (“Statistical analyses”). Be more precise here: which R version and R packages were used to handle the data and perform the statistical analyses (and don’t forget to cite both R and the individual packages)? Which functions were used? R has different possible functions for almost any test and it should be stated which one was used in this study. How were the figures made? If they were made in R, please provide and cite the package(s) used. Generally, I think that the Tukey test is not the best choice for analyses of such a dataset. Since the experiment was performed in randomized blocks and with three repetitions and over time, I would think that a repeated measures ANOVA would be more appropriate. This might give more power to the results of the analysis and the final conclusions. ..
Response 3: We name a subchapter “2.1 study site” as can be seen in line 91. We also moved at the end of the chapter 2 the information about the statistical analysis as subchapter “2.7. Statistical analysis” in line 145. In this subchapters we are giving the information on the version of the R packages in line 149 -150. We have discussed and we think that the repeated measures ANOVA is not the most appropriate for the analysis of our data. We are looking for significant differences due to the effect of the tillage treatments on the soil physical variables comparing the results at each year.
Point 4: The results should be presented by first mentioning the actual numbers in the respective subchapters of bulk density, total porosity, Ks and crop yield under the different treatments. The information about significant differences should be provided afterwards. Since the authors are relating the missing significance to drying and wetting of the soil, as well as intensity of rainfall, it would be helpful for the reader to get some information about the weather and site conditions during the 4 years of experiment. This should be presented first, e.g. “3.1. Site conditions”. I do not expect the air temperature to fluctuate a lot between the years, but the rainfall intensity most likely would. Since soil moisture has not been measured in this experiment, conclusions based on wetting and drying of the soil are hard to make ..
Response 4: In the subchapters of the Results we change to mention first the data obtained and put the information about significant differences afterwards where appropriate.
In the discussion we put a reference about the temporal changes in density due to drying and wetting, discussing that not only tillage affects the bulk density but our aim is to look only to the effect of tillage we explain that in lines 160-163. We were not intending to make conclusions based on drying and wetting, rainfall intensity. So we rewrite this part.
Point 5: The Conclusions are basically a repetition of the results presented in the Results and Discussion section rather than a real conclusion. The study does not cover any sampling of soil biology or soil moisture. Those issues and limitations should be mentioned here and (if possible) recommendations or a future outlook should be given. ..
Response 5: We are deriving the conclusions based in the objective and the results obtained. Soil biology and soil moisture are by now out of the scope of this study, but we think that we should include in the future this important points.
Point 6: Abstract
l. 14: local information of what?
Response 6: we attend this in line 15
Point 7: l l. 19 – 20: results should be a bit more informative. Which treatment had the highest bd, TP and Ks? Please provide numbers here! Were crop yields different between the years? A short conclusion is needed, i.e. what are the recommendations and lessons learned from this experiment? ..
Response 7: Results have a lot of variation this is why we write in line 20-21 tillage systems ranged…… line 22 no significant differences in yield.
We write the recommendation in line 24
Point 8 Introduction and Response 8
l. 26: what are “inadequate practices”? Be specific at this point.
l. 27: I suggest to re-write the first part of the sentence and make clear where the increase in bulk density derives from, that it leads to compaction and that compaction in turn leads to further degradation of the soil.
this is arranged in lines 32-33
l.38: why does intensive tillage lead to soil degradation? More explanation is needed here.
Attended in line 41-42
ll. 40 – 41: This sentence seems to be incomplete
Attended in Line 44
l. 41: what is vertical tillage? Please explain the different tillage practices you focused on already in the Introduction.
Explained in lines 45-48
ll. 57 – 58: root growth in a clay loam with 1.5 – 1.6 g cm-3 was bigger than what? The comparable information is missing here.
Arranged in line 66
l. 64: what do the authors mean by “the technique of taking the data”? The sampling technique?
Arranged in line 72
Point 9 : Materials and Methods and Response 9
Table 1: which implement was used during CT and VT? This could be an additional information provided in the table.
Attended in line 100-104
ll. 133 – 135: This is a lot of information given in one sentence – please split the information into two sentences. ..
Arranged in Line 141-144
Point 10: Results and Discussion Response 10:
Table 1: this should be Table 2. I assume that the table shows the average values for bulk density – what about the standard deviations? They should be provided in this table as well.
Line 158 table 2 numbered and with the information of the standard error
l. 151 + l. 153: I am not really sure, but I would replace “normal” by “typical”
We replace for typical in line 169 and 171
l. 161: I suggest to cite study [41] here already (maybe after (29 years)) – otherwise, the note “In the same story” in l. 163 is confusing.
Was changed the place of the cite to line 185
ll. 172 – 174: This is a difficult comparison. The eight-week study certainly compared the bulk density conditions before and closely after the tillage event. At that point, the soil is still impacted by the tillage event and the desired loosening is still visible. However, the soil usually collapses after some time and the differences between the treatments become smaller. So it does not surprise me that the differences found in an experiment where soil was sampled three months after the tillage event are lower than in the cited study. I would think that this comparison does not hold.
This is no good comparison, we change the writing and used other cite in line 211-214
ll. 189 – 192: This short conclusion should be wider – what could be the reasons for the decrease in bulk density in 2016? Drying and wetting have not been measured, but the rainfall intensity and patterns could give a hint. Were changes in soil biology observed? The number of earthworms could influence the density of the soil and change the structure and porosity. These possibilities should be discussed in more detail at this point.
As already stated in respond 4, we were not measuring rainfall, soil biology, soil moisture we were not intending to make conclusions based on drying and wetting, rainfall intensity. So we rewrite this part. lines 211-214
Figures 5, 6 and 7: These values (together with the standard deviations) might be better presented in a table.
We presented the standard errors in the figures 5, 6 and 7. lines 221, 226 and 245
l. 209: I suggest to replace “while” by “and”
replaced in line 233
l. 212: which studies? Please mention them here.
We arranged the writing in lines 235 and 237
ll. 226 – 230: Clay loam soils? What soil texture are those studies referring to?
Arranged the writing in lines 251 and 253
ll. 243 – 244: What is meant by “differing trends”? Be more specific here.
Attended in line 268
l. 248: remove “under”. The authors want to state that the yield under NT was lower compared to CT and VT, I suppose.
Attended in line 271
ll. 255 – 256: I would challenge this statement – there a quite some studies that have shown lower yields under NT compared to CT even in the long-term, e.g. Wright and Hons (2005) (Soil Science Society of America Journal, 69, 141 - 147, Fernandez et al. (2007) (Soil & Tillage Research, 94, 47 – 54, doi: 10.1016/j.still.2006.07.003), Boddey et al. (2010) (Global Change Biology, 16, 784 – 795, doi: 10.1111/j.1365-2486.2009.02020.x), Jacobs et al. (2015) (Archives of Agronomy and Soil Science, 61:8, 1079 – 1087, doi: 10.1080/03650340.2014.981669).
Rewritten in lines 279 to 284
l. 258: Do the results correspond to just one other study? This last sentence is very weak and should be discussed further. ..
Rewritten in lines 286- 288
Round 2
Reviewer 1 Report
Thanks for making the suggested corrections. The manuscript has been greatly improved and I recommend publication.
Author Response
Thank you very much for your suggestions, comments and observations it was very helpful to improve the manuscript. We are very grateful for the time deserved to review our manuscript
Author Response File: 
Author Response.pdf
Reviewer 3 Report
The authors incorporated most of the minor changes given in the last review. However, in total, they have been a bit too superficial with the revision and most of the main comments have been ignored or have not been implemented thoroughly.
Among others, the authors often compare their results with “other studies”, but eventually only mention one study that either agrees or disagrees with their own results. In some cases, studies are cited, but the authors leave a clearer comparison open and do not give the exact results, the cited studies included (e.g. ll. 287 – 288).
Still, a reasoning for the missing differences between treatments is missing and the reader is often left alone with the interpretation of the results.
Regarding the statistical analysis, I am not really convinced by the authors´ reply, in which they state that they were looking at the results of the treatments at the end of each season. However, the authors very often mention the differences between the years, which certainly should be included in the analysis. Furthermore, the parameters were were measured in a random block design, which could be taken as a random effect. Using, for example, the repeated measures ANOVA would allow the authors to make a statement about the changes of the parameters over time, which makes the comparison with other long term studies more reasonable.
I further suggest to present the manuscript to a native speaker, in order to improve the language and style – this will help to make the manuscript better understandable.
Please see more detailed comments below.
Abstract
The last sentence of the Abstract is still a bit vague. I absolutely agree with the authors that long term investigation is necessary. Though, soil physical parameters change rather fast compared to, for example, soil carbon. Still, the presentation of the results in the Abstract is not very informative and the reader will want to know which treatment changed the parameters the most. Please invest one or two more sentences to really present the results observed for each treatment.
Introduction
The Introduction is still difficult to read, mainly due to the structure of the sentence and the authors´ choice of setting paragraphs. For example, the part covered by ll. 49 – 76 lists some studies that report different results about changes in soil physical parameters after different tillage practices and over different time spans. However, the way, these studies are listed in the manuscript is not very informative, since information about the locations and soil conditions of the studies are missing. Furthermore, the sentences should be restructured so that it becomes clear that the authors are talking about a different study compared to the previous sentence. The last sentence of this part (ll. 75 – 76) is very important and should be moved to the beginning of this part and before the list of studies (e.g. l. 50). I can see that the authors made an effort to improve the derivation of the hypothesis. Still, the hypothesis itself is very unspecific: what do the authors mean by “avoid degradation”? Which direction do they expect the soil hydraulic parameters to change to?
ll. 52 – 54: What was the reason for the decrease in bulk density?
l. 55: Why “other studies” when only one study is mentioned?
l. 64: You mean “In a different study”?
l. 77: “based on”
l. 77: What kind of tillage systems are that? Conventional or conservational?
l. 87: “our region” is very unspecific. I suggest to change it to “… of a cultivated clay loam soil under semiarid climate conditions in Northern Mexico.”
Materials and Methods
Having added the subsections “2.1 Study site” and “2.7 Statistical analysis” made the M&M section much clearer. However, some parts of the “Statistical analysis” should be moved to the “Study site”, i.e. ll. 147 – 149, as they describe rather the experimental setup than the analysis of the observations.
ll. 100 – 103: This should be written as a text, just as the no tillage specification in l. 104
l. 149 – 151: please cite the R software and the agricolae package. The commands in R are as follows: for the R software (R Core Team) you type “citation()” and for the agricolae package you type “citation(package = “agricolae”)”
Results and Discussion
The authors improved Table 2 by adding the standard errors and an introducing sentence to the subchapters. Still, after that, a description of the observations should follow and the observed values should be mentioned, rather than a comparison with other studies. For “3.1 Effects on bulk density”, the description provided in ll. 165 – 167 and ll. 169 – 172 should be moved to the beginning of the subchapter, e.g. after “… years observed.” In l. 156.
Although the authors mention the temporal behavior of most of the parameters, a clear presentation of the different treatments is not given. In how far do the conservational treatments behave differently (over time) compared to the conventional treatment? This is what was stated in the hypothesis, but it is not mentioned in the Results and Discussions. It is only in l. 257 (Saturated hydraulic conductivity) that the authors directly compare (and rank) the tillage treatments for some years.
Furthermore, some more explanation is missing regarding the different results and so far, the Results and Discussions section if more of a data presentation and comparison with other studies, but reasons for the changes of the parameters and differences between the treatments are still lacking.
ll. 163 – 164: I am not sure what the authors mean with this sentence. They obviously did not focus on the changes within the season and I suppose that this it was they are referring to. I would think that this sentence is unnecessary and could be removed. Otherwise, it should be shortened to “However, changes of the observed parameters within the cropping season were not in the scope of the study presented.”
l. 179: please change “not significant, in comparing the tillage systems” to “were not significant between the three applied tillage treatments.”
l. 180: “environments” = soil + climate? Or region? Or cultivation? I suggest to remove it and leave it with “similar research in Mexico”, as the details of that study are mentioned in the next sentence
l. 184: what does “working in profile up to 20 cm” mean?
l. 185: In how far do the results agree? Be more specific here!
ll. 282 – 284: “other studies”? Only one study is mentioned here. Use the literature suggested previously to find more studies that agree or disagree with the presented results. The sentence in ll. 287 – 288 is not a sufficient comparison. Which values do they present? Which crops were studied? Do they compare to the oat used in the presented study?
Conclusions
ll. 291 – 292: total porosity or pore space? Stay consistent!
Author Response
Response to Reviewer 3 Comments
Thank you very much for your comments, observations and suggestions. We are very grateful for the time you deserve for the review in order to improve our manuscript. We find your comments very useful and are doing our best to incorporate your observations. Incorporated improvements are in red and highlighted in yellow in the manuscript.
Point 1:
The authors incorporated most of the minor changes given in the last review. However, in total, they have been a bit too superficial with the revision and most of the main comments have been ignored or have not been implemented thoroughly.
Among others, the authors often compare their results with “other studies”, but eventually only mention one study that either agrees or disagrees with their own results. In some cases, studies are cited, but the authors leave a clearer comparison open and do not give the exact results, the cited studies included (e.g. ll. 287 – 288).
Response 1:
In the section of Results, we revised where it is mentioned the comparison with other studies and we gave more information about similarities or differences. Specifically, the case you mentioned that is now in lines 328 -337, other cases are in lines 197-201, 212-216 and 273-276
Point 2: Still, a reasoning for the missing differences between treatments is missing and the reader is often left alone with the interpretation of the results.
Response 2:
In the section of Results, we complete interpretation of results in the lines 191-196, 236-239, 265-268, 296-298, 315-316
Point 3:
Regarding the statistical analysis, I am not really convinced by the authors´ reply, in which they state that they were looking at the results of the treatments at the end of each season. However, the authors very often mention the differences between the years, which certainly should be included in the analysis. Furthermore, the parameters were were measured in a random block design, which could be taken as a random effect. Using, for example, the repeated measures ANOVA would allow the authors to make a statement about the changes of the parameters over time, which makes the comparison with other long term studies more reasonable.
Response 3:
We tried to analyse the data with a Repeated Measures ANOVA, the point is that for example bulk density from 0 to 5 cm depth, for year one we have the values of the variable very similar for the three tillage systems and for the second year again the values of the variable are very close for the tillage treatments but are higher compared to those of the first year, in the third year again the values of treatments are very close for each tillage treatment and similar to those of the second year, then at each year there is no significant differences of the variable among the treatments. With the results of repeated measures ANOVA values of bulk density for all the tillage treatments in year one are significantly different to those in the second year and to those in the third year, values of bulk density for the tillage treatments in year two are no significant different to those of year three. Of course this are changes of variables over time but in this case when there were changes from year one to year two and year one to year three, the changes were no due to the effect of the tillage treatments. Those can be due to other causes that we did not measure. For significant effects of tillage methods, we should continue with the experiment for a longer period.
Point 4:
I further suggest to present the manuscript to a native speaker, in order to improve the language and style – this will help to make the manuscript better understandable.
Response 4:
The manuscript has been now edited and improved by a colleague English native speaker
Point 5:
Abstract
The last sentence of the Abstract is still a bit vague. I absolutely agree with the authors that long term investigation is necessary. Though, soil physical parameters change rather fast compared to, for example, soil carbon. Still, the presentation of the results in the Abstract is not very informative and the reader will want to know which treatment changed the parameters the most. Please invest one or two more sentences to really present the results observed for each treatment.
Response 5:
We rewrite the part of results in the abstract (lines 22 – 24) although not significant different the results, we put the values of small changes in the variables observed for each tillage system.
Point 6:
Introduction
The Introduction is still difficult to read, mainly due to the structure of the sentence and the authors´ choice of setting paragraphs. For example, the part covered by ll. 49 – 76 lists some studies that report different results about changes in soil physical parameters after different tillage practices and over different time spans. However, the way, these studies are listed in the manuscript is not very informative, since information about the locations and soil conditions of the studies are missing. Furthermore, the sentences should be restructured so that it becomes clear that the authors are talking about a different study compared to the previous sentence
The correction have been made in lines 51 to 84 information about soil types and locations were added. The sentences have been restructured to make clear that are different studies.
The last sentence of this part (ll. 75 – 76) is very important and should be moved to the beginning of this part and before the list of studies (e.g. l. 50).
The sentence has been moved before the list of studies in lines 51-52
I can see that the authors made an effort to improve the derivation of the hypothesis. Still, the hypothesis itself is very unspecific: what do the authors mean by “avoid degradation”? Which direction do they expect the soil hydraulic parameters to change to?
It has been corrected in lines 97-98
ll. 52 – 54: What was the reason for the decrease in bulk density?
Corrected in line 57-59
l. 55: Why “other studies” when only one study is mentioned?
Corrected in line 61 and 65
l. 64: You mean “In a different study”?
Corrected in line 72
. 77: “based on”
Corrected in line 85
l. 77: What kind of tillage systems are that? Conventional or conservational?
Corrected in line 85
l. 87: “our region” is very unspecific. I suggest to change it to “… of a cultivated clay loam soil under semiarid climate conditions in Northern Mexico.”
Corrected in line 95
Point 7:
Materials and Methods
Having added the subsections “2.1 Study site” and “2.7 Statistical analysis” made the M&M section much clearer. However, some parts of the “Statistical analysis” should be moved to the “Study site”, i.e. ll. 147 – 149, as they describe rather the experimental setup than the analysis of the observations.
Corrected in line 107-109
ll. 100 – 103: This should be written as a text, just as the no tillage specification in l. 104
Corrected in line 111-114
l. 149 – 151: please cite the R software and the agricolae package. The commands in R are as follows: for the R software (R Core Team) you type “citation()” and for the agricolae package you type “citation(package = “agricolae”)”
in lines 159 and 160 Cites [38] and [39] have been made and added to the list of references
Point 8
Results and Discussion
The authors improved Table 2 by adding the standard errors and an introducing sentence to the subchapters. Still, after that, a description of the observations should follow and the observed values should be mentioned, rather than a comparison with other studies. For “3.1 Effects on bulk density”, the description provided in ll. 165 – 167 and ll. 169 – 172 should be moved to the beginning of the subchapter, e.g. after “… years observed.” In l. 156.
The paragraphs with the description mentioned were moved at the beginning of the subchapter (after years observed…..) in line 166
Although the authors mention the temporal behavior of most of the parameters, a clear presentation of the different treatments is not given. In how far do the conservational treatments behave differently (over time) compared to the conventional treatment? This is what was stated in the hypothesis, but it is not mentioned in the Results and Discussions. It is only in l. 257 (Saturated hydraulic conductivity) that the authors directly compare (and rank) the tillage treatments for some years.
Furthermore, some more explanation is missing regarding the different results and so far, the Results and Discussions section if more of a data presentation and comparison with other studies, but reasons for the changes of the parameters and differences between the treatments are still lacking.
We added information in the discussion to compare where possible, the differences and changes of the variables (although no significant) among the treatments. This information is in lines 191-196,
lines 236-239,
lines 265-268,
lines 296-298
lines 315-316
ll. 163 – 164: I am not sure what the authors mean with this sentence. They obviously did not focus on the changes within the season and I suppose that this it was they are referring to. I would think that this sentence is unnecessary and could be removed. Otherwise, it should be shortened to “However, changes of the observed parameters within the cropping season were not in the scope of the study presented.”
This is now corrected in lines 186-187
l. 179: please change “not significant, in comparing the tillage systems” to “were not significant between the three applied tillage treatments.”
It is now corrected in line 190
l. 180: “environments” = soil + climate? Or region? Or cultivation? I suggest to remove it and leave it with “similar research in Mexico”, as the details of that study are mentioned in the next sentence
It is now corrected in line 202
l. 184: what does “working in profile up to 20 cm” mean?
It is now corrected in line 207
l. 185: In how far do the results agree? Be more specific here!
It is now corrected in line 212 - 213
ll. 282 – 284: “other studies”? Only one study is mentioned here. Use the literature suggested previously to find more studies that agree or disagree with the presented results. The sentence in ll. 287 – 288 is not a sufficient comparison. Which values do they present? Which crops were studied? Do they compare to the oat used in the presented study?
Information was added in this point in lines 328 -337. We use at least two cites of the literature previously suggested and other studies. The information is about studies with small grain cereal crops such as wheat, barley and oat to compare with the crop we use.
Point 9 :
Conclusions
ll. 291 – 292: total porosity or pore space? Stay consistent!
Corrected in line 341
Author Response File: Author Response.pdf
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
Round 1
Reviewer 1 Report
The manuscript entitled "Effect of Tillage Systems in Physical Properties of a Clay Loam Soil Under Oats" examines important issues affecting crop production in semiarid regions. However, the manuscript is poorly written and the results not well discussed. The authors did not really explain the method of analysis. The manuscript needs to be re-written to correct for the grammatical errors (probably by a native English speaker). Below are some specific comments;
Introduction: Needs to be re-written to enhance reader comprehension.
Line 89: This particle size distribution and organic matter percent is at what depth?
Lines 96-100: What kind of equipment was used and to what depth was tillage done?
Lines 121-123: Very little information about this procedure. Readers will want to know how it's done (it is ok to cite other authors but you should also explain some of the procedure).
Figure 1: Averaging over all depths is not a good idea especially since we do not even know the tillage depth.
Reviewer 2 Report
I put sticky notes to the relevant sentences in the pdf file with my suggestions and remarks in order to improve the paper.
Comments for author File: Comments.pdf
