Evaluation of Alkaline Hydrolyzable Organic Nitrogen as an Index of Nitrogen Mineralization Potential of Some Coastal Savannah Soils of Ghana
, Mohamed S. Kamara 1,2, Abena Asamoah-Bediako 1, Samuel G. K. Adiku 1, Dilys S. MacCarthy 3, Samuel K. Kumahor 1 and Dora Neina 1Round 1
Reviewer 1 Report
Dear Authors and Editors,
Estimating the amount of nitrogen available to plants in the soil is indeed an old problem of agricultural chemistry. To evaluate the hydrolyzable N content, the authors investigated a recent method. The article presenting the new method was published earlier by the first author, together with Prof. M.A. Tabatabai, referred to in the manuscript: [18] Dodor, D.E., and M.A. Tabatabai. A simple alkaline hydrolysis method for estimating nitrogen mineralization potential of soils. West African J. Applied Ecol. 2019, 27(2): 16-31. https://www.ajol.info/index.php/wajae/article/view/192375.
The subject of the manuscript is certainly interesting. However, its title is quite similar to the title of the above-mentioned paper, so I would recommend specifying it, e.g. Evaluation of an alkaline hydrolysis method for estimating nitrogen mineralization potential of tropical soils.
Abstract is appropriate. The Introduction is sufficiently detailed and appropriate to the topic of the manuscript. Materials and Methods discusses the conditions of the experiment in proper detail.
In Results, in Line 173, the text says "The fCO2 varied significantly (p<0.05) among the soils" and there is a reference to Table 1. Please indicate in the table in which case the fCO2 values differ significantly from each other.
In the title of Figure 1 and 2, instead of “vertical bar”, the term “error bar” is more accurate (see e.g. John H. McDonald (2014): Handbook of Biological Statistics. 3rd ed. or Field et al. (2012): Discovering Statistics Using R)
The title of Figure 2 indicates, that plot a) refers to 1 M NaOH and plot b) refers to 1 M KOH. Instead, probably due to subsequent modifications, plot a) and b) refers to 1 M NaOH, and plot c) and d) refers to 1 M KOH. Please make the corrections.
The last row of Table 2 shows LSD values, which probably refers to Fisher’s least significant difference, as a post-hoc test for ANOVA, however Line 168 mentions Tukey range test (also known as HSD). Please clarify which method was used. It is recommended to use letters to distinguish significantly different values.
The Discussion is well written and adequately interprets the results of the experiment. Conclusion is also appropriate and based on the results.
Overall, it is a well-written, high-quality manuscript that I recommend for publication after the correction of the minor errors.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
General note.
The introduction is presented correctly, in accordance with the subject. The methodology of the study was clearly presented, and appropriate to the proposed objectives.
However, there are some changes I am suggesting in the detailed comments below.
Detailed comments
All figures need improvement.
Authors should review the discussion section and try to explain which are the main reasons affecting the results achieved and make some comparisons with more actual research. I recommend that authors should introduce some references from latest years/ more actual.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and suggestions for Authors
Evaluation of an alkaline hydrolysis method for estimating nitrogen mineralization potential of soils
Subject is very interesting and fall within the scope of the journal. The experimental dataset undoubtedly are useful and constitutes scientific values.
The study was to assess the suitability of alkaline hydrolyzable ON as a chemical index of mineralizable N pool in soils, using the long-term incubation and the 3-day fCO2 as benchmarks.
The manuscript requires minor additions and corrections.
General remarks
In order to increase the usefulness of the article, Authors must refer to the following points.
Materials and Methods: In subsection 2.1. Soils and characterization description should be completed with soil types according to World Reference Base for Soil Resources.
Results: Table 1. The content of sand, silt and clay should be given in%. The data in Table 1 should be verified. E.g., ID 1: Nt (1.9 g.kg-1) - [NH4+-N + NO3--N + Norg] = 1.6632 g.kg-1.
1.6632 g.kg-1 - What kind of nitrogen is it?
The title of Figure 2 should be corrected. Explain 2a, 2b, 2c and 2d correctly.
The font should be corrected when describing all figures.
Specific comments
References: Save correctly in accordance with editorial requirements. DOI needs to be completed.
Lines 417-418 – Wang et al. 2001 not referenced in the manuscript.
Manuscript contains interesting results, but requires improvement before publication.
Best regards
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Accept in present form.
