Effect of Reduced Nitrogen Fertilization on the Chemical and Biological Traits of Soils under Maize Crops

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Editor and authors, the article is interesting and has some data that deserve to be published, however the structure and writing of the article need to be improved a lot so that it can be approved. Below are some suggestions:

-The introduction is extensive, and could be more concise, in addition there are papers that talk about the management of N fertilization, about the main focuses of the work and these should be used, exemplifying how the management of N fertilization affects them.

-The material and methods section is well written and detailed

-The results section can be summarized, highlighting only the most relevant results to the study, as many of the results presented do not help much in the discussion of the data.

-The qualities of the figures can be improved, and many can be grouped, for example the ammonium and nitrate contents, grouping them and dividing them into sections, a and b, as the number of total figures (18) is high.

-Correlation analyzes are shown twice in different approaches, that is, the same data is repeated, so authors must enter the data only once, duplication of data is irrelevant and inappropriate.

-The discussion section could be more concise, as could the results section.

-The conclusion must be rewritten, as written it is a summary of the results section, the conclusion should preferably be a single paragraph, which is highly related to the objectives proposed at the end of the introduction.

Author Response

Response to Reviewer 1 comments:

1. The introduction is extensive, and could be more concise, in addition there are papers that talk about the management of N fertilization, about the main focuses of the work and these should be used, exemplifying how the management of N fertilization affects them

Ad. 1 Thank you for this suggestion. Introduction was shortened with previously included information and the aspects of  the management of N fertilization was added, supported by quotes from recent publications.

2. The material and methods section is well written and detailed

Ad. 2 Thank you for this comment.

3. The results section can be summarized, highlighting only the most relevant results to the study, as many of the results presented do not help much in the discussion of the data.

Ad. 3 Thank you for this suggestion. In the current version results description was shortened.

4. The qualities of the figures can be improved, and many can be grouped, for example the ammonium and nitrate contents, grouping them and dividing them into sections, a and b, as the number of total figures (18) is high.

Ad. 4 According to your insightful suggestion we grouped presented figures into 8 instead of 18 figures contained in the previous ms version. Moreover some figures are now presented as Appendix 1.

5. Correlation analyzes are shown twice in different approaches, that is, the same data is repeated, so authors must enter the data only once, duplication of data is irrelevant and inappropriate

Ad. 5 Thank you for the suggestion, we have moved these repeated data into Appendix 1 section.

6. The discussion section could be more concise, as could the results section.

Ad. 6 Thank you. We have concised the discussion section.

7. The conclusion must be rewritten, as written it is a summary of the results section, the conclusion should preferably be a single paragraph, which is highly related to the objectives proposed at the end of the introduction.

Ad. 7 Thank you for this comment. According to your insightful suggestion, conclusions were rewritten and now are presented as a single paragraph related to the objectives of the study.

Reviewer 2 Report

Comments and Suggestions for Authors

I have reviewed the paper entitled "Effect of Reduced Nitrogen Fertilization on The Chemical and Biological Traits of Soils under Maize Crops". The objective of their study was to check whether the 20% lower N fertilization (in agreement with the EU “Farm to Folk” directive) may ensure good yields on the one hand and, on the other hand, may contribute to the maintenance of soil fertility in monoculture maize cultivation in the NT system versus the traditional PL system. the manuscript is good fit for the journal and the analysis of the study are reasonable however, I have some questions which should be addressed.   

1. The abstract directly starts from the aim of the study, which should be corrected as follows the order, such as what the problem is, then objective, M&M, results, suggestions for future research, etc. 

2. The introduction is length and the start of introduction should start with the statement of the problem and then flow it to the solution. The introduction might benefit from being condensed. Additionally, there are articles discussing the management of nitrogen fertilization and the primary objectives of the study, which could be cited to illustrate the ways in which these objectives are impacted by N fertilization management.

3. what was thee experimental design? The material and techniques part is thorough and written nicely. 

4. Since many of the results offered are not very helpful in the discussion of the data, the results section might be condensed to just the most significant findings for the research.

5.As there are a lot of figures (18 in all), many of the qualities of the figures may be enhanced and grouped, such as the ammonium and nitrate contents, which can then be divided into portions, a and b.
6. Authors only need to submit the data once since correlation analyses are displayed twice using separate methodologies, meaning that duplicate data entry is improper and useless.

7. Both the findings and the comments sections may need some tightening up.

8. The conclusion has to be revised; as it is, it summarizes the findings section. Ideally, the conclusion should consist of only one paragraph and should be closely tied to the goals that were stated at the end of the introduction.

Comments for author File: Comments.pdf

Author Response

Response to Reviewer 2 comments:

1. The abstract directly starts from the aim of the study, which should be corrected as follows the order, such as what the problem is, then objective, M&M, results, suggestions for future research, etc. 

Ad. 1 Abstract section was rewritten according to your helpful suggestion. However, please remember that in fact this section has limited words, consequently in the former ms version we tried to avoid going over the word limit and did not include an introductory sentence (what the problem is). In the current version the problem and suggestions for the future were added.

2. The introduction is length and the start of introduction should start with the statement of the problem and then flow it to the solution. The introduction might benefit from being condensed. Additionally, there are articles discussing the management of nitrogen fertilization and the primary objectives of the study, which could be cited to illustrate the ways in which these objectives are impacted by N fertilization management.

Ad. 2 Thank you for this suggestion. Introduction was shortened with previously included information and the knowledge of  the management of N fertilization was added, supported by quotes from recent publications.

3. what was thee experimental design? The material and techniques part is thorough and written nicely. 

Ad. 3 Thank you for such a nice opinion. To more illustrate our experimental design a new Figure with the experimental design was added to Appendix 1.

4. Since many of the results offered are not very helpful in the discussion of the data, the results section might be condensed to just the most significant findings for the research.

Ad. 4 Thank you for this suggestion, according to your recommendation the results section was condensed.

5. As there are a lot of figures (18 in all), many of the qualities of the figures may be enhanced and grouped, such as the ammonium and nitrate contents, which can then be divided into portions, a and b.

Ad. 5 We grouped presented figures into 8 instead of 18 figures contained in the previous ms version. Moreover some figures are now presented as Appendix 1.

6. Authors only need to submit the data once since correlation analyses are displayed twice using separate methodologies, meaning that duplicate data entry is improper and useless.

Ad. 6 Thank you for the suggestion, we have moved these repeated data into Appendix 1 section.

7. Both the findings and the comments sections may need some tightening up.

Ad. 7 Thank you. We have concised the results section.

8. The conclusion has to be revised; as it is, it summarizes the findings section. Ideally, the conclusion should consist of only one paragraph and should be closely tied to the goals that were stated at the end of the introduction.

Ad. 8 Thank you for this comment. According to your insightful suggestion, conclusions were shortened and now are presented as one paragraph related to the goals of the study.

Reviewer 3 Report

Comments and Suggestions for Authors

Dear authors of the manuscript

I have read your work with great interest. How much fertilizer is used for growing crops is an important economic and environmental issue. To get the right answer to it requires the accumulation of a voluminous pool of data from many independent studies. From this point of view, a large area of experimental fields and well-thought-out methods of data collection are an undoubted advantage of the study. However, I wish you to take a closer look at the interpretation of the results obtained. It seems to me that the manuscript can be improved. Comments and suggestions are presented below.

1)      I do not fully agree with the conclusions of the study written in the conclusion.  Some of these differences are not statistically significant. This concerns NO3-N (NT), Mg pool (PL), NH4-N (NT) in spring, Ca (NT), NO3-N (NT) in autumn.

2)      Line 22 «maize yield was mainly the result of both … N rate» On the contrary, it seems to me that the results indicate a weak correlation between the yield of maize and N rate.

3)      Line 488. «The compilation of the entire dataset showed numerous statistically significant correlations between the variables under study, as presented in Figure 18. It was evidenced that all the studied factors are important for maintaining good soil quality and interdependent, as confirmed by these correlations». This interpretation of the calculated correlations does not seem reasonable to me. All these soil properties strongly depended on one external factor - the season of the year.  It is seasonality that generates a correlation, not a strong connection between the properties of the soil. This is clearly visible in Figures 16 and 17.

4)      In the results, much attention is paid to the correlation between soil properties. Correlations are practically not discussed in the discussion. Between which of the correlating properties is there a known cause-and-effect relationship?

5)      Have the maize yield data been statistically processed? The significance of the differences is not shown in table 2.

6)      Short remarks on the description of the study

-Was a study of the chemical properties of soils in these two fields conducted in 2019 in order to identify abnormal plots? This may be important because the distribution of plots in the figure 1 is ordered, not random.

-Information about the duration of the use of reduced doses of fertilizers is important for understanding the value of the article. As I understand it, it was four years. I think it's worth emphasizing in the abstract and conclusion.

-The question of when the spring samples were taken requires clarification. Did it happen before fertilization or after? Have you started practicing no-till since 2019 or 2022?

-In the captions of figures you can write how many repetitions each analysis had so that the drawings could be easily analyzed regardless of the text.

Author Response

Response to Reviewer 3 comments:

1. I do not fully agree with the conclusions of the study written in the conclusion. Some of these differences are not statistically significant. This concerns NO3-N (NT), Mg pool (PL), NH4-N (NT) in spring, Ca (NT), NO3-N (NT) in autumn.

Ad. 1 We agree and we have re-written the conclusion section.

2. Line 22 «maize yield was mainly the result of both … N rate» On the contrary, it seems to me that the results indicate a weak correlation between the yield of maize and N rate.

Ad. 2 We agree but this study was conducted only one year and the effects may not be clearly visible yet. For that reason we have suggested in the Conclusions that further studies are required.

3. Line 488. «The compilation of the entire dataset showed numerous statistically significant correlations between the variables under study, as presented in Figure 18. It was evidenced that all the studied factors are important for maintaining good soil quality and interdependent, as confirmed by these correlations». This interpretation of the calculated correlations does not seem reasonable to me. All these soil properties strongly depended on one external factor - the season of the year. It is seasonality that generates a correlation, not a strong connection between the properties of the soil. This is clearly visible in Figures 16 and 17.

Ad. 3 Thank you for such an important comment. We agreed with your statement that in fact seasonality was the main reason for determined correlations in respect to soil properties. This was corrected in ms text according to your recommendation. 

4. In the results, much attention is paid to the correlation between soil properties. Correlations are practically not discussed in the discussion. Between which of the correlating properties is there a known cause-and-effect relationship?

Ad. 4 The description of the result section was shortened (also as a suggestion for other reviewers). We also added a short fragment regarding the most important factors correlating each other to the discussion section.

5. Have the maize yield data been statistically processed? The significance of the differences is not shown in table 2.

Ad. 5 We have added the results of statistical analysis in lines: 396 and 406-407.

6. Short remarks on the description of the study

-Was a study of the chemical properties of soils in these two fields conducted in 2019 in order to identify abnormal plots? This may be important because the distribution of plots in the figure 1 is ordered, not random.

Baseline studies in all fields of the  Potulicka Foundation Group, including:  P, K, Mg, pH are done regularly every 3 years since 2014, that is 2017, 2020, 2023. Fertilization with these components and liming is always adjusted to the results. We reduced nitrogen fertilization because there were droughts in recent years in Poland, and we made the yield potential realistic, which is the starting point for calculating fertilizer needs, and thus the need for nitrogen.

-Information about the duration of the use of reduced doses of fertilizers is important for understanding the value of the article. As I understand it, it was four years. I think it's worth emphasizing in the abstract and conclusion.

Yes, the duration of the use of reduced doses of fertilizers on the studied fields runs from 2019, this fact are pointed both in the abstract as in the conclusions

-The question of when the spring samples were taken requires clarification. Did it happen before fertilization or after? Have you started practicing no-till since 2019 or 2022?

The spring samples were taken before fertilization, so we treat this treatment as control values. We started practicing NT in 2019.

-In the captions of figures you can write how many repetitions each analysis had so that the drawings could be easily analyzed regardless of the text.

We have added this information (n=5) to the first full caption (Figure 2) and for Figures 8 (n=240), A3 and A3 (both n=120).

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript can be accepted in the current version.

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have significantly improved the manuscript by incorporating all of my suggestions, addressing my comments, and answering my questions. Therefore, I have no further comments, and I recommend the paper for publication in its current form.

Reviewer 3 Report

Comments and Suggestions for Authors

Dear authors of the manuscript, I have read your work after the revision and agree that the changes made to it are appropriate.