Optimisation of Anaerobic Digestate and Chemical Fertiliser Application to Enhance Rice Yield—A Machine-Learning Approach
, Suraj Panja 2,†, Richik GhoshThakur 1,†, Aman Basu 3, Apurba Koley 1, Anudeb Ghosh 1, Kalipada Pramanik 4, Shibani Chaudhury 1, Amit Kumar Hazra 5, Narottam Dey 2, Andrew B. Ross 6 and Srinivasan Balachandran 1,*
Round 1
Reviewer 1 Report
This study evaluates the application of different inoculum-to-substrate ratios from digestate of anaerobic digestion from water hyacinth and cow dung with combinations of NPK (16-22-22) fertilizer to increase rice yield. Machine learning models were applied to model the measured data. Principal component analysis revealed NPK content as the first component in fertilizer preparation.
Applied methods and results are correctly conferred, and could be significant, however, the presented PCA analysis is not clear enough. After corrections, I propose accepting this work for publication.
Minor editing of English language required
Author Response
Reviewer’s #1 Comment
Querry 1. The presented PCA analysis is not clear enough
Response: Thanks for your suggestion. We have modified the PCA analysis.
Modified in line no. 289-310.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The manuscript ID: sustainability-2540947 investigate the integrative organic and chemical fertilizer optimization to enhance rice yield. The aim of these study is to explore the best treatment ratio of biogas digestate and chemical fertilizer (NPK) to maximize the crop yield and substitute the amount of chemical fertilizer. Several agronomic traits were taken, predictive analysis and PCA were performed. Overall, this manuscript is well written and briefly arranged throughout all the sections.
However, I have some observation and suggestion that may improve this work:
In the introduction section, I suggest to clarify the idea of partial replacement of chemical fertilizers and organic fertilizers in previous researches.
In M&M section:
There is a question about whether it is better to put only the organic fertilizer in the mentioned proportions with the soil before rice transplanting for the possibility of benefiting the plant.
Sometimes the authors use water hyacinth and sometimes use Eichhornia bio-fertiliser, I suggest to be consistent throughout the manuscript, or may be need to identify this at first mentioned.
In table 1 ‘EBF’ abbreviation must be defined.
In result and discussion:
Many details in the figures (especially Figures 1,2, and 4) are not clear both in resolution and abbreviations. I suggest that the authors try to sharpen the graphs or increase their size to increase clarity.
I think the discussion part is week in this manuscript, further interpretation with deep discussion are needed.
Line 202 -205: Not clear, please rewrite again.
The authors used different abbreviation to the treatment making the distracted, like in line 207 (NPK0I3S1 and NPK0I6S1 42 UG/P), Line 209 (IS) and figure 1. It is suggested that the authors be consistent in defining treatments particularly in the text throughout the manuscript.
In conclusion; Line 317-319: Are this research found that water hyacinths can generate methane and fertilizers that can provide up to half of the total fertilizer requirements for rice plants?
No
Author Response
Reviewer’s #2 Comment
Querry 1. In the introduction section, I suggest to clarify the idea of partial replacement of chemical fertilisers and organic fertilisers in previous researches.
Response: Thanks for your suggestion. We have included a statement to clarify the concept of partially replacing chemical fertilisers and organic fertilisers.
Mentioned in line no 67-69.
Querry 2. In M&M section:
There is a question about whether it is better to put only the organic fertiliser in the mentioned proportions with the soil before rice transplanting for the possibility of benefiting the plant.
Response: Thank you for your very relevant point. We have not tried this option yet, but we can undoubtedly do so when we accelerate and further modify the overall process for advanced study.
Querry 3. Sometimes, the authors use water hyacinth and sometimes use Eichhornia bio-fertiliser, I suggest to be consistent throughout the manuscript, or may be need to identify this at first mentioned.
Response: Thanks for your suggestion. Now, in the manuscript, we have used only water hyacinth.
Querry 4. In table 1 'EBF' abbreviation must be defined.
Response: Thanks for your suggestion. We have changed the EBF to CW-BF (Cow dung water hyacinth bio-fertiliser)
It is modified and corrected the abbreviation in Table 1.
Querry 5. In result and discussion: Many details in the figures (especially Figures 1,2, and 4) are not clear both in resolution and abbreviations. I suggest that the authors try to sharpen the graphs or increase their size to increase clarity.
Response: Thanks to your suggestion, we have replaced the currently uploaded figures with the previously uploaded figures.
Querry 6. I think the discussion part is week in this manuscript, further interpretation with deep discussion are needed.
Response: Thanks for your suggestion. We have modified the discussion part.
It is modified in line no. 201-212, 217-219, 227-229, 249-250, 279-283, 289-310.
Querry 7. Line 202 -205: Not clear, please rewrite again.
Response: Thanks for your suggestion. We have rewritten the section.
Modified in line no. 208-212.
Querry 8. The authors used different abbreviation to the treatment making the distracted, like in line 207 (NPK0I3S1 and NPK0I6S1 42 UG/P), Line 209 (IS) and figure 1. It is suggested that the authors be consistent in defining treatments particularly in the text throughout the manuscript.
Response: Thanks for your suggestion. We have modified the sentence.
Querry 9. In conclusion; Line 317-319: Are this research found that water hyacinths can generate methane and fertilisers that can provide up to half of the total fertiliser requirements for rice plants?
Response: Thanks for your suggestion. We have modified the sentence.
Modified in line no. 328-329
Additionally, the study found that water hyacinths can generate fertilisers that meet up to half of the total fertiliser requirements for rice plants. Reviewer’s #2 Comment
Querry 1. In the introduction section, I suggest to clarify the idea of partial replacement of chemical fertilisers and organic fertilisers in previous researches.
Response: Thanks for your suggestion. We have included a statement to clarify the concept of partially replacing chemical fertilisers and organic fertilisers.
Mentioned in line no 67-69.
Querry 2. In M&M section:
There is a question about whether it is better to put only the organic fertiliser in the mentioned proportions with the soil before rice transplanting for the possibility of benefiting the plant.
Response: Thank you for your very relevant point. We have not tried this option yet, but we can undoubtedly do so when we accelerate and further modify the overall process for advanced study.
Querry 3. Sometimes, the authors use water hyacinth and sometimes use Eichhornia bio-fertiliser, I suggest to be consistent throughout the manuscript, or may be need to identify this at first mentioned.
Response: Thanks for your suggestion. Now, in the manuscript, we have used only water hyacinth.
Querry 4. In table 1 'EBF' abbreviation must be defined.
Response: Thanks for your suggestion. We have changed the EBF to CW-BF (Cow dung water hyacinth bio-fertiliser)
It is modified and corrected the abbreviation in Table 1.
Querry 5. In result and discussion: Many details in the figures (especially Figures 1,2, and 4) are not clear both in resolution and abbreviations. I suggest that the authors try to sharpen the graphs or increase their size to increase clarity.
Response: Thanks to your suggestion, we have replaced the currently uploaded figures with the previously uploaded figures.
Querry 6. I think the discussion part is week in this manuscript, further interpretation with deep discussion are needed.
Response: Thanks for your suggestion. We have modified the discussion part.
It is modified in line no. 201-212, 217-219, 227-229, 249-250, 279-283, 289-310.
Querry 7. Line 202 -205: Not clear, please rewrite again.
Response: Thanks for your suggestion. We have rewritten the section.
Modified in line no. 208-212.
Querry 8. The authors used different abbreviation to the treatment making the distracted, like in line 207 (NPK0I3S1 and NPK0I6S1 42 UG/P), Line 209 (IS) and figure 1. It is suggested that the authors be consistent in defining treatments particularly in the text throughout the manuscript.
Response: Thanks for your suggestion. We have modified the sentence.
Querry 9. In conclusion; Line 317-319: Are this research found that water hyacinths can generate methane and fertilisers that can provide up to half of the total fertiliser requirements for rice plants?
Response: Thanks for your suggestion. We have modified the sentence.
Modified in line no. 328-329
Additionally, the study found that water hyacinths can generate fertilisers that meet up to half of the total fertiliser requirements for rice plants.
Author Response File: Author Response.docx
Reviewer 3 Report
Comments for author File: 
Comments.pdf
Quality is not up to the marked level. Needs to improve the quality by moderate editing of English Language.
Author Response
Reviewer’s #3 Comment
Querry 1. L-48-49 "which are very important for the earth, and acidity and leaching [8,9]"- Not clear, rewrite this part.
Response: Thanks for your suggestion. We have deleted the line.
Modified line no. 48-49.
Querry 2. L-52: L. camara - For first time, write the full form of L.
Response: Thanks for your suggestion. We have corrected the expression.
Modified the expression in Line no. 52
Querry 3. Table 1: Table should be self-explanatory. Ratio/ Different combinations of ratios of?? (Inoculum: Substrate), What does it mean by EBF? Explain in the footnote. In the table there is a column for Biomass (gm). Is it substrate (water hyacinth)? If yes, then use either substrate or biomass throughout the whole manuscript. Otherwise, it may create confusion.
Response: Thanks for your suggestion. We modified the Biomass with Substrate and changed EBF into CW-BF to maintain uniformity, as suggested by the reviewer.
Querry 4. There is confusion about the ratios of inoculum and biomass. For example, in serial no. 3, the ratio is 1:1 EBF but 9.74 gm inoculum and 10.26 gm biomass were added for this treatment. Literally, for 1:1 ratio, the amount of inoculum and biomass should be same (for 20 gm preparation, it should be 10 gm inoculum and 10 gm biomass). Authors are requested to clarify it.
Response: Thanks for your query, if the digester was loaded according to weight basis, then the biomass and inoculum should be the same, but in this manuscript, the amount of inoculum and biomass is determined based on the volatile solid (VS) concentration, so the amount (g) varies accordingly to VS content of inoculum and substrate.
Querry 5. L-153: Replace "selected the as" with "selected as"
Response: Thanks for your suggestion, we have corrected the expression.
Modified and corrected the expression in Line no. 157.
Querry 6. L-184: ………. the yield rate has on input parameters- Not clear, Rewrite it.
Response: Thanks for your suggestion, we have rewritten the sentence.
To ascertain the extent of dependency of the yield rate on input parameters
Modified and mentioned in Line no 188.
Querry 7. L-200-201: "inoculum: substrate: NPK ratio (3:1:1)"- In this treatment combination, the amount added as inoculum, substrate and NPK does not represent 3:1:1 ratio (as shown in Table 1).
Response: Thanks for your query, we have modified the table 1.
Querry 8. L-204 and Figure1: Indication about the test weight of rice. But sometimes the authors used different terms like in L-25, 1000/100-grain weight, in L-139, 100-grain weight (GWt) etc. It is confusing. Same term should be used. It should be confirmed whether it is 1000 or 100 grain weight.
Response: Thanks for your suggestion. The grain weight is 1000, and the sentence is modified accordingly in lines 25 and 143.
Querry 9. L-207: "NPK0I3S1 and NPK0I6S1"- In the materials section, the treatments are not presented in this way.
Response: Thanks for your suggestion, we have modified the sentence. Now, we have modified CW-BF as suggested by the reviewer.
Modified and corrected the expression in Line no. 213.
Querry 10. L-207-210: "Moreover, Njogu et al., [47] and Bhui et al., [48] observed that inoculum to-substrate ratio of 3:1 (cow dung and water hyacinth) produced maximum biogas yield, indicating that IS ratio of 3:1 can be utilised for maximum biogas production and increase the rice productivity with NPK."- Is there any relationship between biogas production and rice productivity? But the statement in L-207-210 reveals that if there is higher biogas production, it will increase the rice productivity. Authors need to review more literature and then rewrite the discussion.
Response: Thanks for your suggestion, we agree with the reviewer's valuable comment that biogas production is irrelevant in this manuscript, so removed from the section.
Querry 11. L-221 and 226: Is it the number of test weights (g)? Or just the test weight of rice?
Response: Thanks for your suggestion, it is the grain weight of 1000 rice, and the unit is in g.
Querry 12. Figure 2: Not clear, Make it visible.
Response: Thanks to your suggestion, we have replaced the figure.
Querry 13. L-244, 246: "Table. 2"- It should be Table 2
Response: Thanks for your suggestion, we have corrected the expression.
Modified and corrected the expression in Line no. 255, 258.
Querry 14. L-292, 304: "Table. 3"- It should be Table 3
Response: Thanks for your suggestion, we have corrected the expression accordingly.
Modified in line no. 306.
Querry 15. L-317-319: "Additionally, the study found that water hyacinths can generate methane and fertilisers that can provide up to half of the total fertiliser requirements for rice plants." – In the present study, there is no data regarding methane production by water hyacinths.
Response: Thanks for your suggestion, we have deleted the sentence as it is irrelevant in the manuscript, as suggested by the reviewer.
Modified in line no. 328-329.
Additionally, the study found that water hyacinths can generate fertilisers that meet up to half of the total fertiliser requirements for rice plants.
Querry 16. 319-321: "Our findings add to the growing body of research showing that using digestate as a biofertiliser can decrease reliance on expensive imported fertilisers and increase agricultural output alternatives in the face of nutrient constraints."- Rewrite the sentence.
Response:Thanks to your suggestion, we modified the sentence.
Modified in line no. 330-333.
The results from the present study contribute to the expanding body of research demonstrating that utilising digestate as a biofertiliser can reduce dependency on expensive imported fertilisers and enhance agricultural production choices in the face of nutrient scarcity.
Querry 17. Reference style should be same for all references. Authors are requested to follow the authors guidelines. There are some problems in reference section, like- In L-349 & is used before the last author's name but in many cases & is not used.
Response: Thanks to your suggestion, we have modified the references.
Querry 18. Journal's name is mostly written in abbreviated form but in L-469-470 full name of the journal (International Journal of Scientific Research in Computer Science, Engineering and Information Technology) is written.
Response: Thanks to your suggestion, we have modified the references; however, it is difficult to find the abbreviation of some journals.
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
The authors made the suggested modifications and I think the manuscript could be published in this form.
Nothing
Author Response
Thanks for your suggestion, the English has been checked by one of the co-authors of the manuscript who is a native English speaker and highlighted in the manuscript.
Author Response File: Author Response.docx
Reviewer 3 Report
Thanks for improvement of the manuscript. However, regarding the ratios of inoculum and biomass used is determined based on the volatile solid (VS) concentration, so the amount (g) varies accordingly to VS content of inoculum and substrate. I agree with this argument. But there is no indication in the manuscript. So, it may create confusion.
Title of Table 1 is “Different components of mixed fertiliser applied to pot cultured rice plant (Inoculum: Substrate: cow dung)”. But in L-104-105, it is stated that cow dung is used as inoculum. So, the ratio Inoculum: Substrate: cow dung will make confusion.
Minor editing will improve the manuscript. in this manuscript, the amount of inoculum and biomass is determined based on the volatile solid (VS) concentration, but it is not mentioned in the manuscript. Otherwise, it will make confusion regarding the ratios of inoculum and biomass. I asked the authors to correct it.
Author Response
Comments: Thanks for improvement of the manuscript. However, regarding the ratios of inoculum and biomass used is determined based on the volatile solid (VS) concentration, so the amount (g) varies accordingly to VS content of inoculum and substrate. I agree with this argument. But there is no indication in the manuscript. So, it may create confusion. Title of Table 1 is “Different components of mixed fertiliser applied to pot cultured rice plant (Inoculum: Substrate: cow dung)”. But in L-104-105, it is stated that cow dung is used as inoculum. So, the ratio Inoculum: Substrate: cow dung will make confusion. Minor editing will improve the manuscript. in this manuscript, the amount of inoculum and biomass is determined based on the volatile solid (VS) concentration, but it is not mentioned in the manuscript. Otherwise, it will make confusion regarding the ratios of inoculum and biomass.
Response: Thanks for your suggestion, now it is incorporated in line no 106, “[according to volatile solid (VS) basis]”. Thanks for your suggestion, we have modified the Table 1. Now Title of Table 1 is “Different components of mixed fertiliser applied to pot cultured rice plant (Inoculum: Substrate: NPK)”. Thanks for your suggestion, now it is incorporated in line no 106.
Author Response File: Author Response.docx
