A Review on Nitrogen Flows and Obstacles to Sustainable Nitrogen Management within the Lake Victoria Basin, East Africa

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

I have read the manuscript with interest. The selected topic of this manuscript is of theoretical value and practical significance. As the author pointed out, the Nitrogen is crucial for agricultural production and environmental conservation especially for developing countries. This paper adopts the literature review to summary Nitrogen flows and Obstacles to Sustainable Nitrogen Management within the Lake Victoria Basin. It provides some insights, but the paper needs thorough changes before meeting the requirements for publication.
(1) This paper summarized nitrogen flows and options to overcome N management obstacles in the Lake Victoria Basin based on the previous studies. Although the paper provided some experiential insights, the summary of regularity was seriously insufficient.
(2) This paper did not propose future research direction and framework base on the previous studies, which let to a lack of academic value. 
(3) Another important aspect of this study is to propose specific policy implications based on the pervious research, which might help to increase the practical value of this paper. 
(4) The keywords are too much. Recommend delete those with weaker correlation.
(5) The manuscript needs more in-depth improvements in English. Some of the language expressions are not accurate enough, it should be more concise and accurate.

 

 

 

 

 

 

Comments on the Quality of English Language

The language expression is not concise and accurate enough. I suggest further modifying and polishing the language expression.  

Author Response

(1) This paper summarized nitrogen flows and options to overcome N management obstacles in the Lake Victoria Basin based on the previous studies. Although the paper provided some experiential insights, the summary of regularity was seriously insufficient

Reply : Although, this could be extended to more detailed summaries, we think that what is summarised here is enough to supporting the drawing of appropriate conclusions and recommendations and avoiding lengthening the manuscript.

(2) This paper did not propose future research direction and framework base on the previous studies, which let to a lack of academic value.

Reply : Although, this was announced in page 14 (subsection on Overcoming obstacles), we added …. should be explored by scientists.  see P14

(3) Another important aspect of this study is to propose specific policy implications based on the pervious research, which might help to increase the practical value of this paper.

Reply : In Page 14 (subsection on Overcoming obstacles), we added …… is also a good opportunity for scientists and extension services. This is also stated in the second and third  paragraphs of the conclusion. See P14.

(4) The keywords are too much. Recommend delete those with weaker correlation

Reply : The number of Keywords has been reduced from nine (9) to six (6). See P1

(5) The manuscript needs more in-depth improvements in English. Some of the language expressions are not accurate enough, it should be more concise and accurate.

Reply : Language editing has been made by the authors throughout the manuscript and highlighted in yellow in the revised version.

Reviewer 2 Report

Comments and Suggestions for Authors

The paper entitled “A Review on Nitrogen flows and Obstacles to Sustainable Nitrogen Management within the Lake Victoria Basin, East Africa” deals with the long term sustainable N management and obstacles in achieving it. The paper is well written and could be accepted after some minor revisions as follows:

 

Subsection 3.1. Please, give some numerical characteristics of Atmospheric N depositions, not only percentage.

 Subsection 3.1. It seems to be better to use identical units of N fluxes from different sources not only in the Table 1 but also in the text.

 Subsection 3.2. “Air quality”. It is known that PM2.5 and PM10 contain various impurities, including N. It would be good to provide data on the amount of N, not only PM concentrations. Alternatively, remove mention about PM2.5 and PM10 if there is no data on N content.

 Section “Challenges and obstacles to better N management within the food production and consumption system”. Is it probably section number 4? It is not quite clear how gender can affect Sustainable Nitrogen Management? As well as HIV/AIDS.

 Subsection 5.2., page 12. “The water quality of Lake Victoria has deteriorated over time to 33 t^.y^-1, 57 t^.y^-1 and 324 t^.y^-1 in Uganda, Kenya, and Tanzania, respectively of N discharge”. Compared to what period has there been a deterioration in water quality?

 Subsection 5.2., page 13. “Similarly, Kisat wastewater treatment plants in Kisumu have low N removal efficiency, and the analyzed nutrients ranged from 2.82 to 41.30 %”. “The wastewater treatment plant in Homa Bay reduced both total nitrogen (TN) and total phosphorus (TP) by 11 %, whereas the Kisat and Nyalenda wastewater treatment plants reduced TN and TP by 10 % and 31 %, respectively”. What are the correct numbers for Kisat? Or is it different data at all?

 Subsection 5.2., page 13, line 8. Misprint. Probably means “autotropHic”

 Instructions for Authors: Your references may be in any style, provided that you use the consistent formatting throughout.

In this manuscript references are given either in square brackets (for example [109] or in parentheses (for example “According to Zhang et al. (2010)…”). Probably, it is necessary to use the consistent formatting.

Author Response

Responses to Reviewer 2 comments

To Manuscript ID: sustainability-2985226 : A Review on Nitrogen flows and Obstacles to Sustainable Nitrogen Management within the Lake Victoria Basin, East Africa

The paper entitled “A Review on Nitrogen flows and Obstacles to Sustainable Nitrogen Management within the Lake Victoria Basin, East Africa” deals with the long term sustainable N management and obstacles in achieving it. The paper is well written and could be accepted after some minor revisions as follows:

Subsection 3.1. Please, give some numerical characteristics of Atmospheric N depositions, not only percentage.

Reply : This is done. See section 3.1, P4

 Subsection 3.1. It seems to be better to use identical units of N fluxes from different sources not only in the Table 1 but also in the text.

Reply : It has appeared difficult at this stage to use the same units for fertilizer and manure in farm here. However, wherever possible, Gg N.yr^-1 is used.

 Subsection 3.2. “Air quality”. It is known that PM2.5 and PM10 contain various impurities, including N. It would be good to provide data on the amount of N, not only PM concentrations. Alternatively, remove mention about PM2.5 and PM10 if there is no data on N content.

Reply : No data are available to decompose PM2.5 and PM10. Consequently, we removed the paragraph on Air quality as suggested by the reviewer. See p5.

 Section “Challenges and obstacles to better N management within the food production and consumption system”. Is it probably section number 4? It is not quite clear how gender can affect Sustainable Nitrogen Management? As well as HIV/AIDS.

Reply : The section number was missing and it is repaired. Thanks.

The role of gender issue was clarified in P8

The paragraph on HIV/AIDS was removed.  See P8

Subsection 5.2., page 12. “The water quality of Lake Victoria has deteriorated over time to 33 t^.y^-1,  57 t^.y^-1 and 324 t^.y^-1 in Uganda, Kenya, and Tanzania, respectively of N discharge”. Compared to what period has there been a deterioration in water quality?

Reply : The values reported here are actual annual N discharge into the lake starting from zero. The sentence has been reformulated for more clarity. See Section 5.2. P12

Subsection 5.2., page 13. “Similarly, Kisat wastewater treatment plants in Kisumu have low N removal efficiency, and the analyzed nutrients ranged from 2.82 to 41.30 %”. “The wastewater treatment plant in Homa Bay reduced both total nitrogen (TN) and total phosphorus (TP) by 11 %, whereas the Kisat and Nyalenda wastewater treatment plants reduced TN and TP by 10 % and 31 %, respectively”. What are the correct numbers for Kisat? Or is it different data at all?

Reply : The two concerned paragraphs have been reformulated for more clarity. See Section 5.2. P13.

 Subsection 5.2., page 13, line 8. Misprint. Probably means “autotropHic”

Reply : Yes. It is autotrophic. See P13

 

 Instructions for Authors: Your references may be in any style, provided that you use the consistent formatting throughout.

In this manuscript references are given either in square brackets (for example [109] or in parentheses (for example “According to Zhang et al. (2010)…”). Probably, it is necessary to use the consistent formatting.

Reply : Yes. Corrections were made to harmonize the formatting of citations throughout the manuscript using the citation style of MDPI Sustainability in Mendeley.

Reviewer 3 Report

Comments and Suggestions for Authors

This manuscript provides an in-depth analysis of the challenges, obstacles, and possible solutions to current nitrogen management in the Lake Victoria Basin (LVB), which is extremely valuable for agricultural and environmental policymakers in the region and even globally. 

The manuscript successfully elaborates on the background and importance of the research. It is well structured and its methods used are appropriate. It proposes a series of options to address nitrogen management barriers and some suggestions for policymakers. The conclusion section provides a good summary of the main findings of the study.

Overall, this paper has made significant contributions to research in this field.

The layout format of Table 5 may be adjusted accordingly.

Comments on the Quality of English Language

It is very good.

Author Response

Responses to Reviewer 3 comments

To Manuscript ID: sustainability-2985226 : A Review on Nitrogen flows and Obstacles to Sustainable Nitrogen Management within the Lake Victoria Basin, East Africa

This manuscript provides an in-depth analysis of the challenges, obstacles, and possible solutions to current nitrogen management in the Lake Victoria Basin (LVB), which is extremely valuable for agricultural and environmental policymakers in the region and even globally. 

The manuscript successfully elaborates on the background and importance of the research. It is well structured and its methods used are appropriate. It proposes a series of options to address nitrogen management barriers and some suggestions for policymakers. The conclusion section provides a good summary of the main findings of the study.

Overall, this paper has made significant contributions to research in this field.

The layout format of Table 5 may be adjusted accordingly.

Reply : We thank the reviewer for positive comments. A key explaining the Decision tools was added to table 5. See P11.

Acknowledgment was made to thank anonymous reviewers for their valuable comments and suggestions. See P15 Acknowledgements.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

I read the revised draft of this manuscript with great interest. However, I am very disappointed that the manuscript had not been made substantial modifications. I still suggest that the authors should make thorough revisions to the sixth section “Summary of Lessons learnt”. Future research direction and framework as well as specific policy implications should be systematically proposed, which are the core of a review article. Unfortunately, these are precisely the serious shortcoming of this manuscript. Meanwhile, it would be best to provide future research framework diagram based on the previous studies.

Comments on the Quality of English Language

The language expression is relatively accurate enough.

Author Response

Comments and Suggestions for Authors From Reviewer 1

I read the revised draft of this manuscript with great interest. However, I am very disappointed that the manuscript had not been made substantial modifications. I still suggest that the authors should make thorough revisions to the sixth section “Summary of Lessons learnt”. Future research direction and framework as well as specific policy implications should be systematically proposed, which are the core of a review article. Unfortunately, these are precisely the serious shortcoming of this manuscript. Meanwhile, it would be best to provide future research framework diagram based on the previous studies.

Reply: We agree with the reviewer and this has been taken into account. A paragraph named “Areas of future research and policy perspectives” and a related graph (Fig 4) were added in the 6^th section “Summary of Lessons learnt”. See p14 and p15

Comments on the Quality of English Language : The language expression is relatively accurate enough.

Reply : We appreciate positive comments from the reviewer.

Round 3

Reviewer 1 Report

Comments and Suggestions for Authors

The key problems had been revised by the authors, and the manuscript basically meets the requirements for publication.