Combining Controlled-Release Urea and Normal Urea to Improve the Yield, Nitrogen Use Efficiency, and Grain Quality of Single Season Late japonica Rice

Round 1

Reviewer 1 Report

The study reports the evaluation of different mixtures of controlled-release urea and normal urea on rice yield, nitrogen use efficiency and some grain qualitative traits. The field experiments were carried out in 2 growing seasons and in 1 site.

The manuscript gives some new insights in the role of controlled-release urea in rice cultivation.

Furthermore, although the structure of the article is linear, the general context and operational repercussions could be better discussed. Furthermore, I the statistical approach need to be reconsidered, above all because several result statements are not supported by data.  

General comments

My main criticism to the manuscript are related to the following aspects:

-          The presentation of data and the statistical analysis need to be reconsidered. The use of DUNCAN in not a correct approach in ANOVA (please see for example the Manuscript Acutis et al, 2012. Perfunctory analysis of variance in agronomy, and its consequences in experimental results interpretation. Eur.J. Agron. 43: 129-135 where clear information is reported on this subject). Please use other tests for multiple comparison.

Moreover, in my opinion the combined comparison of N fertilization and year is not the best option to present the results. In fact, for almost all the parameters, the interaction between year and treatment was never significant. It could be much clear present the separate effect of each single factor (year, treatment). In this way the comparison of treatment is just within the different N mixture (and not N mixture X year). Furthermore, using this approach the power of treatment in the ANOVA will increase, giving to opportunity to better consider the effect related to the fertilization treatment. If for some traits a significant interaction between N fertilization and year will be reported. is it interesting to present, it could be further introduced in figure such as Figure 1.

-          The result comment is often incorrect and not related to the data in the tables. I report just an example, but it could be verified for different parameters.

Pag. 8 L 1-3. “The visibility and balance of cooked rice increased first and then decreased with the decrease of the proportion of CUR, and there was no significant difference compared with LFP (Table 6)”. In table 6 the balance is significant and is “ab” for some N treatment with CRU, while is “de” for LFP.

Pag 8 L4-5. “The taste value of most one-time fertilization treatments was better than that of LFP”. In table 6 the taste value did not report in any of the 2 years a significant difference between CUR treatment compared to LFP. The only difference is between the unfertilized control and fertilized one.

According to the previous request, the statistical analysis and presentation of data need to be reconsidered, but I invite the authors to discuss correctly the data reported, in order to give a correct interpretation to the readers.

This because, the discussion is based on strong state such as “Our results show that the taste value of most SFMs was better than that of LFP” (Pag 11) that are not based on the result obtained.

-          The discussion need to consider more aspects. Authors need to be clear that the best combination of CRU and Urea depend on the type of soil, on the meteorological trend, on overall crop practices of the rice cropping system, with particular attention to the rice cultivar (since it is well known how different rice genotype have a different growth behavior, and capacity to respond to N input).  

Thus it is difficult to state that the right mixture of CRU and urea “synchronize the N reseal to the plant uptake”. It could limit the nutrient losses, resulting in a better uptake, but the dynamics of Nitrogen into the soil and the rice uptake are phenomenon much more complex and which did not necessary follow the same rules.

Moreover, although it is right that CRU could simplify the fertilization practice, to evaluate their profitability for farmers it is necessary to discuss adequately also the overall cost of this practices, considering the price of CRU fertilizer.

-          I not agree with the name of the N treatments. LFP is not a good name. All the farmers in the growing areas apply exactly this fertilization management (same rate, same fertilizer, same timing of application?). I think it is correct to use Fractionated urea, which highlight the difference respect to the use of CRU in mixture. I think that also SFM could be modified, above all to change the numbers (1, 2, 3,….) with a code that can easily make readers understand the technique adopted.

-          It is confusing the release period of N fertilizer. In the introduction and in the tables is always reported 80 d and 120 d, while in pag 12 in Material and Methods is reported 60 d and 100 d. Please insert the specific information of applied fertilized, giving clear detail of the method of slow release of N and the brand of the fertilizer. Moreover, it is not stated if LFP was fertilized with conventional urea.

-          The manuscript format is not well managed. First it is very difficult to revise without the number of lines. Furthermore, the right order of manuscript structure for Agronomy consider Material and Methods before the Result section and not at the end (that format is applied for other journal such as Plant, but when you resubmit you have to change according to the new journal rules). Moreover, there are some typing errors (a large number of words with dashes such as “ammonia volatiliza-tion” in pag. 1. last line). Moreover, the use of acronyms is applied randomly (an example, you could certainly use N for nitrogen, but consistently troughs the paper).  

I recommended the publication only if authors could correctly present and discuss the data reported.

Specific comments

Abstract

-           there are some abbreviations used only once (for example DMA), while other (LFP) are not presented but used.

Introduction

-           Slow or controlled release N fertilizer (S/CRF) contain N L65…….. It would be better do report only acronym used consistently in the paper. After the authors refers only to CRU, thus I suggest to delete SRF o CRF.

Table 1 (and other tables)

In table 1 in the Analysis of variance is reported only the p-value. In the other tables there are numbers (F??) and p-value. Please uniform, but also clearly state what are the numbers reported.

Discussion

“Compared with the application of CRU alone, the mixed………..”. It seems that in the present paper the use of CRU alone was considered. It is not true.  But it could be discussed why this control treatment was not introduced in the experiment design.

-          3.3. “We found a similar result, in our study, we found that Combining…” Rephrase.

Material and Methods

-          What is the rice cultivar? The amylose content is low for a japonica genotype. It is really important this and other qualitative traits for this cultivars? Report also more information on the yield aptitude and precocity of the genotype considered.

-          Reported the date of harvesting and of all the main growth stages for both years.

-          “The values in the figures and tables are presented as mean ± stand-ard error (SE).”. It is not true. Sem is reported only in figure, while are not reported in the tables. Since the homogeneity of variance has been verified, it is incorrect to repot a different sem for each treatment.

Author Response

Dear Editor and Reviewers:

Thank you for your comments and suggestions concerning our manuscript entitled “Combining controlled-release urea and normal urea to improve the yield, nitrogen use efficiency and grain quality of single season late japonica rice” (agronomy-2037091). We have taken all of them into account and modified the paper accordingly. We hope you will find them satisfactory. The font of the modified content was marked red. The main corrections and the responses to the reviewers’ comments are the flowing:

Reviewer(s)' Comments to Author:

General comments

My main criticism to the manuscript are related to the following aspects:

1. The presentation of data and the statistical analysis need to be reconsidered. The use of DUNCAN in not a correct approach in ANOVA (please see for example the Manuscript Acutis et al, 2012. Perfunctory analysis of variance in agronomy, and its consequences in experimental results interpretation. Eur.J. Agron. 43: 129-135 where clear information is reported on this subject). Please use other tests for multiple comparison. Moreover, in my opinion the combined comparison of N fertilization and year is not the best option to present the results. In fact, for almost all the parameters, the interaction between year and treatment was never significant. It could be much clear present the separate effect of each single factor (year, treatment). In this way the comparison of treatment is just within the different N mixture (and not N mixture X year). Furthermore, using this approach the power of treatment in the ANOVA will increase, giving to opportunity to better consider the effect related to the fertilization treatment. If for some traits a significant interaction between N fertilization and year will be reported. is it interesting to present, it could be further introduced in figure such as Figure 1.

Response：Thank you for your valuable suggestion. We reanalyzed the data and conducted ANOVA again. When comparing the twelve treatments, LSD test (p < 0.05) was used. We agree with the reviewer. We found that the parameter we measured had no interactive effect in the year and fertilizer treatment (Y×T). Some parameters had significant differences between different years, while some parameters had significant differences between twelve treatments. Based on this, we modified the results to better match the data in our whole text.

Please see the modified manuscript. We have add relevant content to the manuscript.  

2.The result comment is often incorrect and not related to the data in the tables. I report just an example, but it could be verified for different parameters. Pag. 8 L 1-3. “The visibility and balance of cooked rice increased first and then decreased with the decrease of the proportion of CUR, and there was no significant difference compared with LFP (Table 6)”. In table 6 the balance is significant and is “ab” for some N treatment with CRU, while is “de” for LFP.

Response：Thank you for your valuable suggestion. We have corrected it in results. Please see lines 284-293.

3.Pag 8 L4-5. “The taste value of most one-time fertilization treatments was better than that of LFP”. In table 6 the taste value did not report in any of the 2 years a significant difference between CUR treatment compared to LFP. The only difference is between the unfertilized control and fertilized one.

Response：Thank you very much. We have modified the text as you requested.

4.According to the previous request, the statistical analysis and presentation of data need to be reconsidered, but I invite the authors to discuss correctly the data reported, in order to give a correct interpretation to the readers. This because, the discussion is based on strong state such as “Our results show that the taste value of most SFMs was better than that of LFP” (Pag 11) that are not based on the result obtained.

Response：We have modified it according to your comments.

5.The discussion need to consider more aspects. Authors need to be clear that the best combination of CRU and Urea depend on the type of soil, on the meteorological trend, on overall crop practices of the rice cropping system, with particular attention to the rice cultivar (since it is well known how different rice genotype have a different growth behavior, and capacity to respond to N input). Thus it is difficult to state that the right mixture of CRU and urea “synchronize the N reseal to the plant uptake”. It could limit the nutrient losses, resulting in a better uptake, but the dynamics of Nitrogen into the soil and the rice uptake are phenomenon much more complex and which did not necessary follow the same rules.

Response：Thank you very much. We have modified the text as you requested.

6.Moreover, although it is right that CRU could simplify the fertilization practice, to evaluate their profitability for farmers it is necessary to discuss adequately also the overall cost of this practices, considering the price of CRU fertilizer. I not agree with the name of the N treatments. LFP is not a good name. All the farmers in the growing areas apply exactly this fertilization management (same rate, same fertilizer, same timing of application?). I think it is correct to use Fractionated urea, which highlight the difference respect to the use of CRU in mixture. I think that also SFM could be modified, above all to change the numbers (1, 2, 3,….) with a code that can easily make readers understand the technique adopted.

Response：Thank you very much. We have modified the text as you requested.

7.It is confusing the release period of N fertilizer. In the introduction and in the tables is always reported 80 d and 120 d, while in pag 12 in Material and Methods is reported 60 d and 100 d. Please insert the specific information of applied fertilized, giving clear detail of the method of slow release of N and the brand of the fertilizer. Moreover, it is not stated if LFP was fertilized with conventional urea.

Response：Thank you very much. The release period of N fertilizer is 80d and 120d. We have modified the text according to your valuable suggestions.

8.The manuscript format is not well managed. First it is very difficult to revise without the number of lines. Furthermore, the right order of manuscript structure for Agronomy consider Material and Methods before the Result section and not at the end (that format is applied for other journal such as Plant, but when you resubmit you have to change according to the new journal rules). Moreover, there are some typing errors (a large number of words with dashes such as “ammonia volatiliza-tion” in pag. 1. last line). Moreover, the use of acronyms is applied randomly (an example, you could certainly use N for nitrogen, but consistently troughs the paper). 

Response：Thank you very much. We have modified the text according to your valuable suggestions and marked red.

I recommended the publication only if authors could correctly present and discuss the data reported.

Specific comments

Abstract

9.there are some abbreviations used only once (for example DMA), while other (LFP) are not presented but used.

Response：Thanks for the careful work. We have corrected it in our manuscript.

Introduction

10.Slow or controlled release N fertilizer (S/CRF) contain N L65…….. It would be better do report only acronym used consistently in the paper. After the authors refers only to CRU, thus I suggest to delete SRF o CRF.

Response：Thanks for the careful work. We have corrected it in our manuscript. Please see lines 40-41.

11.Table 1 (and other tables)

In table 1 in the Analysis of variance is reported only the p-value. In the other tables there are numbers (F??) and p-value. Please uniform, but also clearly state what are the numbers reported.

Response：Thanks for the careful work. We have corrected it in our manuscript.

Discussion

12.“Compared with the application of CRU alone, the mixed………..”. It seems that in the present paper the use of CRU alone was considered. It is not true.  But it could be discussed why this control treatment was not introduced in the experiment design.

Response：Thanks for the careful work. We checked the reference and have corrected the text in our manuscript. Please see lines 316-318.

13.3.3. “We found a similar result, in our study, we found that Combining…” Rephrase.

Response：Thank you very much. We have modified the text as you requested.

Material and Methods

14.What is the rice cultivar? The amylose content is low for a japonica genotype. It is really important this and other qualitative traits for this cultivars? Report also more information on the yield aptitude and precocity of the genotype considered.

Response：Thank you very much. We have modified the text as you requested. Please see line 92.

15.Reported the date of harvesting and of all the main growth stages for both years.

Response：Thank you very much. We have modified the text as you requested. Relevant information is shown in the table S1. Please see supplementary information.

Table S1 the main growth stages of Nangeng 9108

16.“The values in the figures and tables are presented as mean ± stand-ard error (SE).”. It is not true. Sem is reported only in figure, while are not reported in the tables. Since the homogeneity of variance has been verified, it is incorrect to repot a different sem for each treatment.

Response：Considering the simplicity and beauty of tables, we only use the average value to show the results. We have modified it in this part.

Reviewer 2 Report

Abstract:

Must be improved. It is unclear what SFM2 SFMx are.

80 and 120? Later in the paper, you say 60 and 100 days (section 4.2).

Introduction:

Briefly describe how CRU works and what the CRU fertilizers are made of. Here, in the introduction describe it briefly but, in the methodology, explain clearly about these fertilizers and their differences.

At the end of the Introduction, you say: “However, there are few studies on the effect..” Provide citations of those studies.

Why (expand on the processes) could slow-release fertilizer increase yield? Earlier you say the opposite (2^nd paragraph).

And then, what is your hypothesis? After explaining the processes involved in these fertilizers you should be able to state a hypothesis before your objectives.

Results:

It is difficult to follow the treatment names. I would suggest renaming the treatments to SFM_80_7/3 or SFM_80_70% or something like that.

The final sentence of the first paragraph should say was, not is.

Since you have a lot of treatments, I strongly suggest exploring some broad comparisons. For example, you can make comparisons between treatments with 80 vs 120 release periods (contrasts) or 80 vs traditional urea and 120 vs traditional urea. This suggestion could help answer the following questions: can we maintain or improve yield with CRU fertilizers? Are better 80- or 120-days CRU fertilizers? and then you can explore which are the best combinations/ratios of CRU and urea.

Discussion:

This is the weakest section of the manuscript and should be rewritten. Authors should focus on the implication and significance of their results.

Conclusion:

I do not understand the message of the first sentence.

Change SFM2 and SFM8 with a full description of the treatment. As I said It is difficult to remember the treatments. Change it as suggested.

You have not proved an economic or environmental benefit of CRU. Please conclude what your results showed.

Author Response

Dear Editor and Reviewers:

Thank you for your comments and suggestions concerning our manuscript entitled “Combining controlled-release urea and normal urea to improve the yield, nitrogen use efficiency and grain quality of single season late japonica rice” (agronomy-2037091). We have taken all of them into account and modified the paper accordingly. We hope you will find them satisfactory. The font of the modified content was marked red. The main corrections and the responses to the reviewers’ comments are the flowing:

Abstract:

1.Must be improved. It is unclear what SFM2 SFMx are.

Response：Thank you for your valuable suggestion. We have modified it according to your comments.

2.80 and 120? Later in the paper, you say 60 and 100 days (section 4.2).

Response：Thank you for your valuable suggestion. We have corrected it in our manuscript.

Introduction:

3.Briefly describe how CRU works and what the CRU fertilizers are made of. Here, in the introduction describe it briefly but, in the methodology, explain clearly about these fertilizers and their differences.

Response：OK. We added relevant content in our manuscript. Please see lines 42-47

4.At the end of the Introduction, you say: “However, there are few studies on the effect..” Provide citations of those studies.

Response：Thank you for your valuable suggestion. We have corrected it in our manuscript.

5.Why (expand on the processes) could slow-release fertilizer increase yield? Earlier you say the opposite (2nd paragraph).

Response：Thanks for the careful work. In 2nd paragraph, we said that“one-time basal application of slow-release fertilizer alone will lead to insufficient nutrients in the early stage of rice growth, thus affecting yield”. In order to deal with the shortcomings of slow-release fertilizer, people often mix CRU with normal urea as basal fertilizer. We found that mix application of CRU and normal urea could increase yield.

6.And then, what is your hypothesis? After explaining the processes involved in these fertilizers you should be able to state a hypothesis before your objectives.

Response：Thank you for your valuable suggestion. We have corrected it in our manuscript. We have set a series of ratios of slow-release fertilizer and urea, and there must be an optimal ratio to make rice yield, nitrogen efficiency and rice quality better. Please see lines 66-67.

Results:

7.It is difficult to follow the treatment names. I would suggest renaming the treatments to SFM_80_7/3 or SFM_80_70% or something like that.

Response：Thank you for your valuable suggestion. We have corrected it in our manuscript.

8.The final sentence of the first paragraph should say was, not is.

Response：Thanks for the careful work. We have corrected it in our manuscript.

9.Since you have a lot of treatments, I strongly suggest exploring some broad comparisons. For example, you can make comparisons between treatments with 80 vs 120 release periods (contrasts) or 80 vs traditional urea and 120 vs traditional urea. This suggestion could help answer the following questions: can we maintain or improve yield with CRU fertilizers? Are better 80- or 120-days CRU fertilizers? and then you can explore which are the best combinations/ratios of CRU and urea.

Response：Thanks for the careful work. We reanalyzed the data and conducted ANOVA again. When comparing the twelve treatments, LSD test (p < 0.05) was used. We agree with the reviewer.

Discussion:

10.This is the weakest section of the manuscript and should be rewritten. Authors should focus on the implication and significance of their results.

Response：Thanks for the careful work. We have corrected it in our manuscript.

Conclusion:

11.I do not understand the message of the first sentence.

Response：Sorry for that. Thanks for the careful work. We have corrected it in our manuscript.

12.Change SFM2 and SFM8 with a full description of the treatment. As I said It is difficult to remember the treatments. Change it as suggested.

Response：OK, we have corrected it in our manuscript.

13.You have not proved an economic or environmental benefit of CRU. Please conclude what your results showed.

Response：Thank you for your valuable suggestion. We have corrected it in our manuscript. Please see the supplementary information.

Round 2

Reviewer 1 Report

Tha authors have provided several changes according to my previous request.

Furthermore I still consider that the combined comparison of N fertilization and year is not the best option to present the results. In fact, for almost all the parameters, the interaction between year and treatment was never significant. These presentation require that each N fertilization treatment need to be verified separately for eahc year.

It could be much clear present the average effect of each single factor (year, treatment). In this way the comparison of treatment is just within the different N mixture (and not N mixture X year, that for certain parameters is hard to follow since the difference are between N treatments of one year in comparison to other treatments in the other year).

Furthermore, using this approach the power of treatment in the ANOVA will increase, giving to opportunity to better consider the effect related to the fertilization treatment. If for some traits a significant interaction between N fertilization and year will be reported. is it interesting to present, it could be further introduced in figure such as Figure 1.

I encourage the authors to resubmit the paper with this different presentation of the results.

For some parameters (Table 6, Table 8) the measurement unit is not clear. Moreover, for qualitative parameters it is important to provide some information (in the text or as footnotes) that help to understand the meaning in terms to desired traits. 

Related to the previous point, as far as the qualitative traits is concerned, it seems that the different parameters did not lead to a so marked differences in the cooking quality of rice. Only a few treatment showed differences compared to FU, and only for 1 or 2 parameters,each time, and the treatments with effect changes for the differents traits. Maybe the analysis carried out on the average of the 2 years, and more information on parameters meaning, could better adress the impact of the practices on rice quality.

Rephrase in line 335-336.

Author Response

Dear Editor and Reviewers:

Thank you for your comments and suggestions concerning our manuscript entitled “Combining controlled-release urea and normal urea to improve the yield, nitrogen use efficiency and grain quality of single season late japonica rice” (agronomy-2037091). We have taken all of them into account and modified the paper accordingly. We hope you will find them satisfactory. The font of the modified content was marked red. The main corrections and the responses to the reviewers’ comments are the flowing:

Reviewer(s)' Comments to Author:

1. Furthermore, I still consider that the combined comparison of N fertilization and year is not the best option to present the results. In fact, for almost all the parameters, the interaction between year and treatment was never significant. These presentation require that each N fertilization treatment need to be verified separately for eahc year. It could be much clear present the average effect of each single factor (year, treatment). In this way the comparison of treatment is just within the different N mixture (and not N mixture X year, that for certain parameters is hard to follow since the difference are between N treatments of one year in comparison to other treatments in the other year).

Furthermore, using this approach the power of treatment in the ANOVA will increase, giving to opportunity to better consider the effect related to the fertilization treatment. If for some traits a significant interaction between N fertilization and year will be reported. is it interesting to present, it could be further introduced in figure such as Figure 1. I encourage the authors to resubmit the paper with this different presentation of the results.

Response：Thank you for your valuable suggestion. We think the comments made by the reviewers are very scientific, and we have made thorough modifications as required. Through this revision of the article, we learned a lot about data analysis, which may be the new knowledge brought by the review. Thank you again. We have corrected it in results. Please see our new manuscript.

2. For some parameters (Table 6, Table 8) the measurement unit is not clear. Moreover, for qualitative parameters it is important to provide some information (in the text or as footnotes) that help to understand the meaning in terms to desired traits. Related to the previous point, as far as the qualitative traits is concerned, it seems that the different parameters did not lead to a so marked differences in the cooking quality of rice. Only a few treatment showed differences compared to FU, and only for 1 or 2 parameters,each time, and the treatments with effect changes for the differents traits. Maybe the analysis carried out on the average of the 2 years, and more information on parameters meaning, could better adress the impact of the practices on rice quality.

Response：Thank you for your valuable suggestion. We have added the unit in the title of Table 6. For Table 8, some index related to eating quality had no unit. Eating quality score was measured in a Cooked Rice Taste Analyzer STA1A, the instrument is based on Yueguang rice as a reference, analysis of the value. We have added some information in the text according to your suggestion. The data was averaged over years, please see the results.

3.Rephrase in line 335-336

Response：Thank you very much. We have modified the text as you requested.

Reviewer 2 Report

Most of the comments were addressed.

Author Response

Dear Editor and Reviewers:

Thank you for your comments and suggestions concerning our manuscript entitled “Combining controlled-release urea and normal urea to improve the yield, nitrogen use efficiency and grain quality of single season late japonica rice” (agronomy-2037091). We have taken all of them into account and modified the paper accordingly. We hope you will find them satisfactory. The font of the modified content was marked red.