Review Reports

Round 1

Reviewer 1 Report

The authors have made a great effort to determine the effects of charcoal and sago bark ash on retaining N and pH buffering capacity in acid soil. The attained results are of interest to readers and scientists who are working in agronomy and crop science. The authors can find some useful comments and suggestions for improving the quality of the current paper as follow:

1. Introduction part, some information needs to verify by adding references (see in pdf file). Line 90 to 93 should be moved to the discussion part.
2. Figure 1 should move in the supplementary material section
3. The "leaching study set up" part should be narrated in detail, for example, how conditions the authors set up the leaching experiments? even though in laboratory condition?
4. Why was the leaching study carried out for 30 days?, no discussion or mention was made
5. Line 158-162 should describe in detail
6. Results and discussion part, there are many Figs (total 15 figure), hence, it looks like the dissertation, not a scientific paper. In my opinion, some Figs should be moved in the supplementary materials. Fig 15 should be changed by the high quality and solution fig.
7. Discussion should be improved to discussed the significantly attained results and other related literature. One of the weakest points of this study was that all experiments were performed in bioassay (laboratory conditions). Further discussion needs to explain how and possibility N leaching in nature or any hypothesises
8. Conclusion is fine
9. References should be judiciously rechecked. Many of them have not formatted following the submitted journal (further see in the pdf file).

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

The authors presented the results of an interesting experiment. In my opinion, the work presents material suitable for publication but still requires significant corrections. First of all, the visual side of the work, i.e. charts, signatures under the axes and tables, must be carefully checked and corrected once again. I do not see the need to present the soil collection site in the figure, firstly, the picture is of poor quality, and secondly, it can be described in the text by giving geographic coordinates. I don't understand table number 1. Range * is it just literature data for a given place, region? Why are they introduced here? Does it concern Tab. 1, was there nitrogen in the form of (NK₄ ⁺ and NO₃^-) in these soils? Are these values ​​just traces of the detection threshold of the device? Some results are reported with too high accuracy (e.g. L. 155).
L 187 in fact, this method only checks a certain range of soil buffering, the authors only use it to check the buffer against acidification (you can read about it in this article DOI: 10.2489 / jswc.74.4.372)
please sort out the way of writing about cations e.g. sometimes you have K + sometimes just K
As I mentioned, the graphic side and the captions on the graphs are to be improved, e.g. fig 2 looks like the X axe is "Treatments" and yet there are days. For example, in Fig 2 variant C1 has a different symbol than in Fig 3. why Fig 4 black and white? the caption for Fig 7. Fig 9 may be enough in the text if the graph needs to be given what "nd" means. The next table does not match the citation number in the text. In figures, 11 pieces of information are duplicate with those from Table 2 (3).
Summing up, it seems to me that from this data you can "get" more information, for example, discuss the C: N value, which will also tell you a lot about nitrogen availability.

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

Please refer to my suggestions on the uploaded file.

i found the research project relevant and practical, and would likely lead to improvement of soil fertile in the region and other tropical areas around the world. 

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The authors have made significant changes according to the comments and suggestions. The paper is fine now. However, some minor edits such as errors in spelling, grammar, typing etc should be checked in the whole paper including the reference. (see in the pdf file)

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript is well prepared, authors take into account most of the reviewers' comments.

Author Response

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Author Response File: Author Response.docx