Evaluation of Metal(loids) Concentrations in Soils of Selected Rice Paddy Fields in Malawi
Round 1
Reviewer 1 Report
The paper reports a study on the evaluation of concentrations in soils of selected rice paddy fields in Malawi.
The paper is overall good, and it represents a good case study on soil contamination evaluation.
Anyway, some minor changes are required.
In particular, the authors report the use of a two-way ANOVA analysis of variance, to evaluate the level of significance of the impact of the metalloids on the sites. Firstly it is not clear (or clearly reported) the number of samples analyzed in the statistical analysis (is it 56 as reported in line 72? How many samples for each of the 22 sites? Are they numerical comparable?), then, p-value was analyzed by Fisher test, but the significance is not reported adequately in the figures. Figures 1, 2, and 3 must be changed: the meaning and the p-value are not clear and key-legends are required.
Conclusions should be also improved and expanded, also explain better WHY Malawi paddy fields are safe for the production of high-quality rice: concentration of metalloids are not the only parameters to evaluate to consider a soil safe for food production.
Author Response
Dear Reviewer 1,
I would like to thank you for giving us the opportunity to revise our manuscript. We have taken into consideration all comments and suggestions and alterations to the manuscript are provided in the submitted reviewers’ response and attached copy of manuscript with tracked changes.
If further clarification is required, we will be happy to supply this.
Regards
Angstone Thembachako Mlangeni, PhD
FOR All co-authors
Author Response File: 
Author Response.docx
Reviewer 2 Report
Evaluation of heavy metal(loids) concentrations in soils of selected rice paddy fields in Malawi
Mlangeni et al.
In this study, the concentrations of several metalloids (As, Cd, Co, Cr, Mn, U, and Ga) in paddy soils were determined using the soil samples collected from 22 sites across Malawi. The results were compared with UK CLEA guidelines and Chinese Environmental Quality standards for agricultural soils. This is a case study and lacks novelty. Also, the authors failed to highlight the importance of this study other than saying the soils are safe to produce high quality rice. The manuscript has critical issues as mentioned in point form below. The manuscript lacks scientific writing and contains a lot of typos and grammatical errors.
· The research problem is not clear, What is the purpose of doing this study?
· Materials and Methods- no map showing sampling location let alone the location of Malawi in Africa,
· How were the soil samples collected? by hand and what was the depth soils were collected? Surface or sub-surface? how the samples were preserved and transported? How soil samples were dried?
· In the Results and Discussion section, the names of various sampling locations are mentioned but no map showing these locations is presented. The x-axis of the graph contains abbreviations of the sampling 13-14 locations however, it says soils from 22 sites were collected. Also, no definition for each abbreviation.
· Table 1 is not in the manuscript
· The data of different sampling locations were discussed against each other with corresponding soil characteristics however, no such soil characteristics data are presented. compares and discusses.
· Not all elements were compared with all types of standards.
Comments for author File: 
Comments.pdf
Author Response
7th August 20212
The Editor
Agronomy, MDPI
Dear Reviewer,
I would like to thank you for giving us the opportunity to revise our manuscript. We have taken into consideration all the reviewer’s suggestions and all alterations are provided in the submitted reviewers’ response. For reference to changes made, a copy of manuscript with tracked changes have attached.
If further clarification is required, we will be happy to supply this.
Regards
Angstone Thembachako Mlangeni, PhD
FOR All co-authors
Author Response File: Author Response.docx
Reviewer 3 Report
The publication analyzed the content of selected elements in the soils of the paddy fields in Malawi. The concept of this work is interesting, however needs some work.
What was soil pH? The pH is decisive for the preservation of the trace elements in the soil. With an alkaline reaction, even high concentrations of elements are not a threat, because these elements are immobilized.
There is no information on soil composition and sorption.
The methodology requires a map with the location of research points. At what level were the samples taken? Were they surface samples? It was indicated that there were 56 samples in total, at the same time 22 locations were indicated with 4 samples in each (making 88 samples).
Line 119-121 to be removed. Charts should be described. What do the individual abbreviations mean? The methodology does not include any of them.
What are a, b, c, d, bc, abc (fig. 1-3)?
Table 3 - What do each * mean? Chapter 3.3 - one cannot draw conclusions of this type based only on the content of the general form of elements without a more comprehensive analysis.
The conclusions are quite general and need to be redrafted.
Author Response
17th August 20212
The Editor
Agronomy, MDPI
Dear Reviewer 3,
I would like to thank you for giving us the opportunity to revise our manuscript. We have taken into consideration all the reviewer’s suggestions and all alterations are provided in the submitted reviewers’ response. For reference to changes made, a copy of manuscript with tracked changes have attached.
If further clarification is required, we will be happy to supply this.
Regards
Angstone Thembachako Mlangeni, PhD
FOR All co-authors
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
The authors have addressed the comments however, there are still some issues.
1.) Inclusion of the map is good. The sampling sites in the map are numbered as Site1 to 22 and when discussing the results sample sites are identified by their names. Although site numbers are grouped and labeled according to their names while reading the Results and Discussion it is difficult to figure out which location represents which site. For example, Sites nos. 7 to 9 belong to the Nkhotakota region and you need to go and check Figure 1 to locate which region of Malawi it belongs to (here in the middle region). Therefore,
2.) it would be good to put a Table including Sites grouped in different locations and regions (northern, middle, and southern Malawi) of Malawi.
3.) Figure 1 has unnecessary labels which are not mentioned in the Results or Discussion section.
4.) Figure 1 needs to show the location of the Rumphi River which is mentioned in the Results section.
Author Response
The Editor
Heliyon
Dear Editor,
Submission of Revision
Thank you for the opportunity to revise our manuscript “Evaluation of heavy metal(loids) concentrations in soils of selected rice paddy fields in Malawi ”. We have taken on board the reviewer’s comments and suggestions. Below we have highlighted the alterations we have done under each of the reviewer’s comments.
For references to changes, we have attached a copy of the MANUSCRIPT with the track changes.
If there is any further clarification required, we will be happy to supply this.
Regards
- Mlangeni, PhD
For All authors
Comments and Suggestions for Authors
The authors have addressed the comments however, there are still some issues.
Comments and Suggestions 1: Inclusion of the map is good. The sampling sites in the map are numbered as Site1 to 22 and when discussing the results sample sites are identified by their names. Although site numbers are grouped and labelled according to their names while reading the Results and Discussion it is difficult to figure out which location represents which site. For example, Sites nos. 7 to 9 belong to the Nkhotakota region and you need to go and check Figure 1 to locate which region of Malawi it belongs to (here in the middle region).
Response to comments and suggestions 1: Numbers have been used in results and discussion section the first time the site is mentioned thereafter names only are mentioned in to assist readers to refer to sites easily. Regions have been shown in the map.
Comments and Suggestions 2: it would be good to put a Table including Sites grouped in different locations and regions (northern, middle, and southern Malawi) of Malawi.
Response to comments and suggestions 2: Geographical regional locations have been indicated in the new map. However, considering that sites from the same region have varying soil types and soil pH and mining activities, grouping for analyses sake were mainly based on these on these parameters other than geographical regions group. (as shown in the map above)
Comments and Suggestions 3: Figure 1 has unnecessary labels which are not mentioned in the Results or Discussion section.
Response to comments and suggestions 3: Unnecessary labels have been removed in the current figure 1 (as shown in the map above)
Comments and Suggestions 4: Figure 1 needs to show the location of the Rumphi River which is mentioned in the Results section.
Response to comments and suggestions 4: Location of Rumphi river has been shown and other rivers have been shown considering all most all sites were in rivers basin.
Author Response File: Author Response.docx
