Azolla Biofertilizer Is an Effective Replacement for Urea Fertilizer in Vegetable Crops

Round 1

Reviewer 1 Report

This manuscript will be interesting for scientists, who study the effectiveness of using biofertilizers in different conditions. Also, these scientific results will have practical application. In order to improve the manuscript, I suggest the following corrections:

1. Conclusions do not contain a generalization of the study results, which are presented in the main part of the manuscript (determining the effectiveness of the use of different fertilizers in different conditions). Instead, it once again focuses attention on the increased prices of traditional fertilizers, their impact on soil and crop yields, and analyzes the economic factors of growing Azolla on farms, which was not the subject of the study. All this had to be analyzed in the Introduction section of the manuscript.

2. In Fig. 2-3, columns of the diagrams must be marked, since the scale of the legend does not allow readers to identify which column represents a particular fertilizer variant.

3. In my opinion, one year of field-testing is not enough to draw conclusions about the merits or demerits of different fertilizers.

4. The list of keywords is not completely correlated with the content of the manuscript.

Author Response

Thank you for taking the time to review our paper. Below we respond to each of your comments in italics.

This manuscript will be interesting for scientists, who study the effectiveness of using biofertilizers in different conditions. Also, these scientific results will have practical application. In order to improve the manuscript, I suggest the following corrections:

1. Conclusions do not contain a generalization of the study results, which are presented in the main part of the manuscript (determining the effectiveness of the use of different fertilizers in different conditions). Instead, it once again focuses attention on the increased prices of traditional fertilizers, their impact on soil and crop yields, and analyzes the economic factors of growing Azolla on farms, which was not the subject of the study. All this had to be analyzed in the Introduction section of the manuscript.—We have written a new paragraph to summarize our conclusions and changed the heading to “Conclusions and Future Recommendations.” The discussion of the need for an economic analysis is now stated as a recommendation for future research which builds off of the conclusions of our research.
2. 2. In Fig. 2-3, columns of the diagrams must be marked, since the scale of the legend does not allow readers to identify which column represents a particular fertilizer variant.—We have reformatted Figures 2 and 3 based on your suggestion.
3. In my opinion, one year of field-testing is not enough to draw conclusions about the merits or demerits of different fertilizers.—We agree that one year of field testing is inadequate to draw conclusions. By using 2 crops grown on each of 2 sites, we effectively collected 4 site-years of data, increasing confidence in our conclusions.
4. The list of keywords is not completely correlated with the content of the manuscript.—We have added fertilizer, urea, and vegetable crops as additional keywords.

 

Reviewer 2 Report

1.Title: The title introduces Azolla Biofertilizer has two characteristics. One is efficiency and the other is sustainability. However, sustainability is not evident in the article. The title needs to be revised according to the content of the article.

2. Abstract: Lines 1 --7need to be rewritten to highlight the source and significance of Azolla Biofertilizer. The part about the three experimental sites needs to add some data support to show the conclusion and significance of the paper. 

3.Introduction: The third line of the first paragraph explains too little about carbon footprint, and its significance in agricultural production and fertilizer application is not clearly explained. 

4.Introduction: The role of heterocystous cyanobacterium in the first line of the third paragraph is not fully explained, and its influence in the experiment needs to be supplemented. 

5. Introduction: The country mentioned in the last sentence of the third paragraph is wrong. Taiwan should be changed to Taiwan, China, or deleted.

6. 2.1. Laboratory Incubation: In the fourth paragraph of the fifth line of the article, how the use of Moringa oleifera seeds as a coagulant affects the number of cyanobacterial cells in the water. Why the cyanobacterial cells were reduced in the experiment? This part is not clearly explained and needs to be further supplemented by reading literature.

7. 2.3. Field Testing: In the third paragraph, the basis for choosing red spinach and daikon radish as experimental materials is not clearly written.

8. 3. Results: It is written that “all fertilizer treatments increased yield and root mass and plant height (data not shown) as compared to the control.” According to the data results of different processing groups, some effective numerical results can be added to the article as support.

9. REFERENCES:3/4/6/8/10 The format is incorrect. The number is in the same format.

10. Fig. 5 The first image is missing border lines.

Author Response

Thank you for taking time to review our paper. We have responded to each of your comments in italics below.

1.Title: The title introduces Azolla Biofertilizer has two characteristics. One is efficiency and the other is sustainability. However, sustainability is not evident in the article. The title needs to be revised according to the content of the article.—We edited the title as suggested.

2. Abstract: Lines 1–7 need to be rewritten to highlight the source and significance of Azolla Biofertilizer. The part about the three experimental sites needs to add some data support to show the conclusion and significance of the paper. –We have modified the beginning of the Abstract to better clarify where Azolla comes from and why it is important. We also added some data into the Abstract to support the conclusions.

3.Introduction: The third line of the first paragraph explains too little about carbon footprint, and its significance in agricultural production and fertilizer application is not clearly explained.—We have replaced the term “carbon footprint” with “greenhouse gas emissions” and added additional text to the sentence to improve clarity.

4.Introduction: The role of heterocystous cyanobacterium in the first line of the third paragraph is not fully explained, and its influence in the experiment needs to be supplemented.—We have added text here and in the Materials and Methods where the Cyano fertilizer treatment is described to clarify this. The Cyano treatment is a free-living cyanobacterium, whereas the Azolla-Anabaena complex is a symbiosis.

5. Introduction: The country mentioned in the last sentence of the third paragraph is wrong. Taiwan should be changed to Taiwan, China, or deleted.—We have removed the mention of specific countries and referred to “many countries in Asia” instead.
6. Laboratory Incubation: In the fourth paragraph of the fifth line of the article, how the use of Moringa oleifera seeds as a coagulant affects the number of cyanobacterial cells in the water. Why the cyanobacterial cells were reduced in the experiment? This part is not clearly explained and needs to be further supplemented by reading literature.—I apologize for the confusion. We added text to clarify this. The literature cited was about use of Moringa in wastewater treatment, thus their goal was to reduce the number of cyanobacteria in the liquid. In our work, our goal was to separate the cyanobacteria from the liquid so that we could use the cyanobacteria as a solid fertilizer.
7. Field Testing: In the third paragraph, the basis for choosing red spinach and daikon radish as experimental materials is not clearly written.—Text and citations were added in lines 248-251 explaining our choice of crops.
8. Results: It is written that “all fertilizer treatments increased yield and root mass and plant height (data not shown) as compared to the control.” According to the data results of different processing groups, some effective numerical results can be added to the article as support.—We merged the first two sentences of this section to clarify that data is shown in figures for yield and root mass, but it is not shown for height. We also added numerical results into the paragraph.
9. REFERENCES:3/4/6/8/10 The format is incorrect. The number is in the same format.—We have carefully read the Instructions for Authors and attempted to comply with the proper format for Sustainability. If any inconsistencies remain, please tell us exactly what is wrong, and we will correct them immediately.
10. Fig. 5 The first image is missing border lines.—We have added the border lines as requested. Thanks for catching this.

Reviewer 3 Report

Thank you for the opportunity to review the manuscript (sustainability-2287156) “Azolla Biofertilizer is an Effective and Sustainable Replacement for Urea Fertilizer in Vegetable Crops”.

 

This paper evaluates the potential of Azolla for use as a fertilizer for vegetable crops, where three hypotheses were investigated: laboratory incubation, greenhouse evaluation, and field testing. The subject of this paper is very interesting. Moreover, the paper has been very organized and well-written. For these reasons, I recommend to accept this manuscript for publication.

 

Yours faithfully,

The Reviewer

Author Response

Thank you for taking the time to review our paper.

Reviewer 4 Report

El trabajo es de importancia para la reducción de fertilizantes inorgánicos, y como alternativa al uso de otros métodos de aporte de nutrientes en plantas de interés económico y hortícola. Veo un trabajo que está adecuadamente analizado y su estructura de investigación es buena, ya que han realizado la experimentación a escala de laboratorio y a escala comercial.

Sin embargo, a pesar de tener una metodología y unos resultados excelentes, veo que las conclusiones no representan el gran trabajo realizado. Por ello, he hecho un par de comentarios, que espero ayuden a mejorar el gran trabajo realizado por los autores:

L83-86. ¿Alguna justificación/beneficio de por qué se usa de esta manera?

¿Por qué en las pruebas de campo no se realizaron las estadísticas como en los 2 experimentos anteriores? ¿Qué criterios se utilizaron para elegir la diferencia en la metodología del software?

Especifique las cifras, por ejemplo, Figura 1. Suelo NH4+-N (A) y NO3-N (B). Y en la figura especificarlo, así con ambas figuras.

Unificar las leyendas de las figuras, especialmente las estadísticas.

Unificar el formato de las figuras.

Cuidar el orden de las tablas y figuras, poniendo siempre las mencionadas después de su primera mención, o en orden.

L513-515 No veo reflejada esta parte en la introducción, y no creo que sea apropiada como conclusión.

L515-519 no es una conclusión de la obra, esta parte puede reestructurarse en la introducción o en otra parte de la obra.

L519-520 Precisar las ventajas que se han encontrado en este trabajo.

L521-523 En este trabajo no se realizó ningún análisis económico, no pueden ser conclusiones.

Reestructurar las conclusiones para reestructurar y separar incluso las hipótesis descritas.

Author Response

Thank you for taking the time to review our paper. We translated your comments using Google Translate, so I hope we understood your concerns correctly. After each comment below, we have responded in italics.

The work is important for the reduction of inorganic fertilizers, and as an alternative to the use of other methods of nutrient supply in plants of economic and horticultural interest. I see a work that is adequately analyzed and its research structure is good, since they have carried out experimentation on a laboratory scale and on a commercial scale.

However, despite having an excellent methodology and results, I see that the conclusions do not represent the great work done. Therefore, I have made a couple of comments, which I hope will help improve the great work done by the authors:

L83-86. Any justification/benefit for why it's used this way?—Agronomic practices have evolved differently around the world and in different cropping systems. In perennial systems, such as orchards, tillage could damage roots, so mulching is another way to gain benefit from Azolla without risking root damage. In annual crops, such as vegetables, soils are commonly tilled, and Azolla can be incorporated into soils more easily.

Why were the statistics not carried out in the field tests as in the 2 previous experiments? What criteria were used to choose the difference in software methodology?—The 2 statistical software packages used (R and SAS) both utilize the same calculations and methodology. Essentially, two different graduate students worked on this project, and they had different backgrounds and training in statistics. Since the calculations and methodology are the same, and both software packages are respected and reliable, I see no benefit to forcing them to use the same software.

Specify the figures, for example, Figure 1. Soil NH4+-N (A) and NO3-N (B). And in the figure specify it, like this with both figures.—We have followed this suggestion in Figures 1, 2, 5, and 6.

Unify the legends of the figures, especially the statistics.—We have modified Figures 2 and 3 to match with the other similar figures (5 and 6).

Unify the format of the figures.—We have unified the formatting of the figures as suggested.

Take care of the order of the tables and figures, always putting those mentioned after their first mention, or in order.—We checked this carefully, and the tables and figures are all mentioned in order in the text. We would like them to be placed in the proofs following those first mentions. Please let us know if this is something that we, as the authors, are supposed to facilitate.

L513-515 I don't see this part reflected in the introduction, and I don't think it's appropriate as a conclusion.-- We have written a new paragraph to summarize our conclusions and changed the heading to “Conclusions and Future Recommendations.” The discussion of the need for an economic analysis is now stated as a recommendation for future research which builds off of the conclusions of our research.

L515-519 is not a conclusion to the work, this part can be restructured in the introduction or in another part of the work.—By inserting a new paragraph which summarizes our results on the agronomic feasibility of the use of Azolla as fertilizer before this section, this is now considered as an area needing future research before our results can be implemented under real-world conditions.

L519-520 Specify the advantages found in this work.—This is now clearly stated in the first paragraph of the “Conclusions and Future Recommendations” section.

L521-523 In this work no economic analysis was carried out, they cannot be conclusions.-- The discussion of the need for an economic analysis is now stated as a recommendation for future research which builds off of the conclusions of our research.

Restructure the conclusions to restructure and separate even the hypotheses described.—Thank you for these comments. We have added a new paragraph to this section, and the hypotheses are now addressed in order in the first paragraph of the “Conclusions and Future Recommendations” section.

Round 2

Reviewer 2 Report

The responses are satisfying. I recommend it be published.