Phosphorus Transformation in Soils Following Co-Application of Charcoal and Wood Ash
Round 1
Reviewer 1 Report
Throughout the text - units should be written in a format such as "mg kg-1", not "mg / kg"
Reference - this section should be prepared in accordance with the requirements set out in the Regulations for authors - we provide abbreviations of the names of journals and not their full names.
Author Response
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Author Response File: 
Author Response.docx
Reviewer 2 Report
Dear Authors,
Thank you for submitting the manuscript “Phosphorus Transformation in Soils and Management Practices Using Charcoal and Wood Ash.” It is indeed well written and easy to follow and understand and will be a great addition to research on increasing soil P availability using soil amendments. Please revise it based on the comments and suggestions stated below:
Major comments
- Reconsider re-writing the title. When writing a title, it is not proper to repeat words e.g. “and” in the title of this manuscript.
- Please organize the content of the abstract. In your abstract, start with the background of the study/review, the overall purpose, summary of review results and then a summary of your interpretations and conclusions or recommendations from your review based on the objectives.
- What are the future perspectives of using charcoal and ash on P transformation in soil? What questions or specific research topics are needed to be addressed by future research in regard to using charcoal to increase soil P availability? Please include them in this review.
- Please also visualize and include a graphical abstract or summary of all the “Mechanisms of Improving Phosphorus Availability Using Charcoal and Wood Ash as Organic and Inorganic Soil Amendments.”
- Activated carbon (AC) is also used as a soil amendment especially in mitigating continuous cropping problems in soil. Please, check and also discuss some articles which have studied AC and soil P availability.
- Please include some of the challenges that could be faced by farmers as they try to substitute commercial lime for charcoal, including economic considerations.
- Include the discussion of the different properties of charcoal/biochar that could affect its functioning on soil P transformation in soil.
- To maintain some level of uniformity for figures and equations, you do not need to snip these equations from their original sources. I think that where possible, just re-write them by yourself with precision and maintain the citations. This will also maintain the same font style as that written in the text.
Specific comments
- P3 line 92: Please add a brief explanation to why plant removal causes rapid soil acidification.
- P3 line 94: Please also read and include other causes of soil acidity including Organic acids, High amounts of organic matter, Plant uptake of cations, Nitrification, oxidation of sulphur during the decomposition of plant residues, acids (sulphuric and nitric acids) in precipitation.
- Equation 1 to 4. Aren’t Aluminum hydrolysis reactions reversible? Please confirm this and if so, use double arrows in each reaction to show this.
- Figure 3: Change Al3+ to Al3+.
- Figure 4: Change SI to Si.
Author Response
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Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
Dear Authors,
Thank you for revising the manuscript. All the comments and suggestions have been addressed.
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
Round 1
Reviewer 1 Report
The manuscript presented for evaluation is very extensive and interesting, but requires some corrections
1. I suggest that you consider modifying the title as "Mitigating Phosphorus Fixation in Acid Soils Using Charcoal and Wood Ash" only covers a small part of this manuscript. However, the introductory part of the article is very extensive.
2.Use SI units, e.g. to describe the mineral composition of wood ash (lines 769-778)
3.Adjust the entry of units to the journal requirements (e.g. lines 44-447; 466-469; 485-491; 647-648; 769-778
Author Response
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Author Response File: Author Response.docx
Reviewer 2 Report
This manuscript presents a picture of soil phosphate as might be read in any standard textbook. It is about time such textbooks were thrown away. Soil phosphate does not occur in discrete compounds as argued in this manuscript. See for example
Comparing the two theories about the nature of soil phosphate European Journal of Soil Science https://doi.org/10.1111/ejss.13027
and
The soil phosphate fractionation fallacy. Plant and Soil https://doi.org/10.1007/s11104-020-04476-6.
The manuscript also presents the simplistic, textbook, story about the effects of pH on phosphate uptake – which are also wrong. See:
The effects of pH on phosphate uptake from the soil Plant and Soil 410:401–410 DOI 10.1007/s11104-016-3008-9.
Measurement of the effects of pH on phosphate availability. Plant and Soil 454:217-224 https://doi.org/10.1007/s11104-020-04647-5.
The enumeration of different equations for describing the adsorption seems little different from that of The description of phosphate adsorption curves. Journal of Soil Science 29: 447-62 – which was published more than 40 years ago.
In the presentation of these equations it is forgotten that especially for fertilised soils one should expect that there will be some desorption. Sorption equation should therefore have an intercept.
The description of sorption curves. European Journal of Soil Science, 59, 900-919.
The material on lines 272 to 280 is nonsense. Adsorption reactions do not involve weak electrostatic bonds.
A similar fallacy occurs in the abstract in which it is written “fixation on positively charged surfaces”. This fallacy is widespread. Specific adsorption can and does occur on negatively charged surfaces. See for example this reference: Testing a mechanistic model 5 The points of zero salt effect for phosphate retention, for zinc retention and for acid/alkali titration. Journal of Soil Science. 37: 303-10. In this publication, note that reaction occurs at pH values above the point of zero salt effect – and therefore on negatively-charge surfaces.
Author Response
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Reviewer 3 Report
The review article titled “Mitigating Phosphorus Fixation in Acid Soils Using Charcoal
and Wood Ash” is a detailed review on Phosphorus fractions and the mechanisms of P release and retention in soil which is not indicated by the title at all! The article fails to deliver on its intent based on the given title. Several sections are not at all required instead authors should focus on detailing o the Mitigation Strategies with Charcoal and Wood Ash. IF the authors decide to keep the sections that this reviewer has suggested to be omitted then the title should be re-written according to that, however, then the review article will face the possibility of losing its novelty.
Section 11 and 12 in the current format of this manuscript should be more focused upon!
The strongest point of this manuscript is the current section 13. However, there need to be more sub-sections of the use of charcoal and wood ash in pastures, land reclamation, soil biodiversity propagation, etc. The mechanism section (13.1 and 13.2) is well written. Please, add details in sections 13.3 and 13.4.
Focus on the Mitigation Strategies with Charcoal and Wood Ash with mechanistic details and examples or case studies. There is ample work done on the P fractions, pools, etc.
The conclusion needs more focus on the use of charcoal and wood ash. Speculate possible strategies that might be useful and need to be ventured.
Specific comments and suggestions:
Line 17. Please write “crystalline and amorphous form”
Line 21. Rephrase. Very general statement.
Line 39 to 41. Cite.
Line 42. Use meq/100g instead of cmol/kg clay
Line 90 to 91. Citation needed.
Line 134 to 139. Unless the authors cite these sentences, they will be deemed speculative. Citation needed.
Line 143 to 146. This statement is a bit vague. Please, break down the sentence into how much P is available from organic sources and inorganic sources upon field application.
Line 214 to 225. Please, discuss the Phytate content in the soil in this section as they are a crucial part of Organic P mineralization.
Line 260. Section 4 is missing microbially mediated P release by phosphorous solubilizing bacteria and fungi. Microbial mediation of P release is extremely important. Authors might find this article useful. “Improving inorganic nitrogen in soil and nutrient density of edamame bean in three consecutive summers by utilizing a locally sourced bio-inocula”.
Line 419 to 516. What is the point of these two sections? Irrelevant. Please, revise and perhaps omit.
Line 367. Please discuss Phytates in the soil in section 5.2.
Line 518. This section needs to be more detailed. More examples and more mechanistic explanations.
Line 563. For this section also see this article that might strengthen the case for biochar use. “Phytostabilization of acidic mine tailings with biochar, biosolids, lime, and locally-sourced microbial inoculum: Do amendment mixtures influence plant growth, tailing chemistry, and microbial composition?”
Line 589. What is the point of this entire section 9 and 10? Revise and omit.
Author Response
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