Effects of Land Use on Soil Physical-Hydric Attributes in Two Watersheds in the Southern Amazon, Brazil

Round 1

Reviewer 1 Report

Dear Authors.

The reviewed article is devoted to the evaluation of land use influence on the physical properties of soil in two watersheds in the southern part of the Amazon, Brazil. This is quite a relevant research topic. It is particularly noteworthy that there is a large factual material of field observations.

You have done a good job emphasizing the importance of studying changes in land use and their impact on the physico-hydraulic characteristics of soil in fragile ecosystems such as the Cerrado-Amazonian ecotone region. The specific research objectives are clear and well-defined. The article is well-structured, with an effective introduction that represents the relevant literature supporting your observations.

Overall, this article will be of great interest to researchers, policymakers, and stakeholders investigating the impact of land use changes on the physico-hydraulic properties of soil in the Cerrado-Amazonian ecotone region. The article is well-written and makes a valuable contribution to the scientific literature in this field.

The article can be assessed positively. However, it requires some revisions:

It is necessary to supplement the analysis of publications on the topic of land use influence on the physical properties of soil in other areas of the Amazon basin. It is unclear from the introduction whether other studies have been conducted in the river basin areas or not.

The colors in Table 12 (blue and green) are a bit pale and poorly distinguishable. Could you make them brighter?

Can you please provide more details about the results of the Pearson correlation analysis between the physical properties of soil for different depths?

The article can be accepted after the minor revisions.

Author Response

Dear Authors.

The reviewed article is devoted to the evaluation of land use influence on the physical properties of soil in two watersheds in the southern part of the Amazon, Brazil. This is quite a relevant research topic. It is particularly noteworthy that there is a large factual material of field observations. You have done a good job emphasizing the importance of studying changes in land use and their impact on the physico-hydraulic characteristics of soil in fragile ecosystems such as the Cerrado-Amazonian ecotone region. The specific research objectives are clear and well-defined. The article is well-structured, with an effective introduction that represents the relevant literature supporting your observations.

Overall, this article will be of great interest to researchers, policymakers, and stakeholders investigating the impact of land use changes on the physico-hydraulic properties of soil in the Cerrado-Amazonian ecotone region. The article is well-written and makes a valuable contribution to the scientific literature in this field.

The article can be assessed positively. However, it requires some revisions:

We appreciate the contributions and reviews of all reviewers. We inform you that the manuscript underwent some changes to meet all the suggestions. All data and statistical analyses were checked and revised, and, when necessary, changed.

It is necessary to supplement the analysis of publications on the topic of land use influence on the physical properties of soil in other areas of the Amazon basin. It is unclear from the introduction whether other studies have been conducted in the river basin areas or not.

References 43 to 45 were inserted to show that other works have already been developed in the Amazon.

The colors in Table 12 (blue and green) are a bit pale and poorly distinguishable. Could you make them brighter?

Thanks for the suggestion. The colors have been changed.

Can you please provide more details about the results of the Pearson correlation analysis between the physical properties of soil for different depths?

Other details observed in the Pearson correlation were inserted, focusing on the variables with greater significance.

The article can be accepted after the minor revisions.

Thank you for your review.

Reviewer 2 Report

1. in result section, some description of the results is inconsistent with the data in the tables and figures. in line 231-233, the description is inconsitstent with the table3.  in mouth regions of the Renato River, for both pasture and crops, there was an increase in bulk density when compared with native forest. but in middle regions of  the Renato River, for crops, there was an increase in bulk density comparing to native forest.

2. Line 309-310,  Please check the consistency between the expression of the results and the table data.

 English is easy to understand  and  be comprehensible

Author Response

We appreciate the contributions and reviews of all reviewers. We inform you that the manuscript underwent some changes to meet all the suggestions. All data and statistical analyses were checked and revised, and, when necessary, changed.

1. in result section, some description of the results is inconsistent with the data in the tables and figures. in line 231-233, the description is inconsitstent with the table3.  in mouth regions of the Renato River, for both pasture and crops, there was an increase in bulk density when compared with native forest. but in middle regions of  the Renato River, for crops, there was an increase in bulk density comparing to native forest.

Change made.

 Line 309-310,  Please check the consistency between the expression of the results and the table data.

Values and analysis statistics are corrected in the Table.

 Comments on the Quality of English Language

 English is easy to understand and  be comprehensible.

English was proofread by a native American (Dr. Aaron Hoshide), co-author of manuscript.

Reviewer 3 Report

Specific comments and questions: 

1- The Kruskal-Wallis nonparametric test, Pearson correlation analysis and multivariate principal component analysis mentioned by the authors are not inserted in this paper with the relevant formulas; references describing the method can also be cited.

2- In line 98 of the study area section, the area's climate is Aw (savanna climate) according to Köppen's classification; please confirm the full name and abbreviation!

3- The soil sampling and laboratory analysis sections are written vaguely; could the authors please organize, for each study area, how many samples were obtained by land use type? Were they received based on the site? For example, were more samples obtained for more extensive areas? How many pieces were obtained from the upper and lower reaches of the two watersheds? What is the basis?

4- In the footnote of Table 2, please indicate what is meant by Aa, ABa, Ab, ABb and Aab mentioned in the table.

5- Table 3, 4, and 5 also do not account for relevant information.

6- For line 273 in this paper, Classified Ksat of Freire et al. (2003) [34], please insert it as a list in this paper.

7- Table 6 ，7，8，9 and Figure 3,4 which also need to be docketed with relevant and essential information;

8- In the discussion section, please add a table of the comparative analysis results and the similarities and differences in the conclusions drawn by the two watersheds.

9- The conclusion is written macroscopically; please organize the results of each basin sample analysis separately.

Author Response

We appreciate the contributions and reviews of all reviewers. We inform you that the manuscript has been changed to meet all the suggestions. All data and statistical analyses were checked, revised, and changed when necessary.

1- The Kruskal-Wallis nonparametric test, Pearson correlation analysis and multivariate principal component analysis mentioned by the authors are not inserted in this paper with the relevant formulas; references describing the method can also be cited.

The authors understand that these statistical analyses are traditionally used in the area and the presentation of their generic equations would contribute little to the article. We added one more reference to address PCA.

2- In line 98 of the study area section, the area's climate is Aw (savanna climate) according to Köppen's classification; please confirm the full name and abbreviation!

Confirmed classification code and changed weather type description (line 109). 

3- The soil sampling and laboratory analysis sections are written vaguely; could the authors please organize, for each study area, how many samples were obtained by land use type? Were they received based on the site? For example, were more samples obtained for more extensive areas? How many pieces were obtained from the upper and lower reaches of the two watersheds? What is the basis?

We made significant changes in item 2.2 to meet this reviewer's consideration (lines 173 to 203). 

4- In the footnote of Table 2, please indicate what is meant by Aa, ABa, Ab, ABb and Aab mentioned in the table.

The notes in the tables are self-explanatory as to what uppercase and lowercase letters indicate when interpreting the statistical analysis. 

5- Table 3, 4, and 5 also do not account for relevant information.

The authors understand that the average values presented in these tables reference the other statistical analyses.

6- For line 273 in this paper, Classified Ksat of Freire et al. (2003) [34], please insert it as a list in this paper.

The list of classes and their respective values are presented right after the citation. 

7- Table 6 ，7，8，9 and Figure 3,4 which also need to be docketed with relevant and essential information;

The authors understand that the average values presented in These tables and Figures are references for the other statistical analyses. In addition, numerical observations of mean values will allow comparisons and citations with studies carried out in other regions of the Amazon.

8- In the discussion section, please add a table of the comparative analysis results and the similarities and differences in the conclusions drawn by the two watersheds.

Due to the particularities of land use and occupation between the two watersheds and the distinct geomorphological formations, these analyses were not presented. We performed cluster analyses for the specific variables BD, PT and Ksat in the surface layer (0.0-0.10m) to group the regions of the watersheds and the two basins; however, the Euclidean Distances between Clusters were not significant, not generating clusters between regions and watersheds.  

Reviewer 4 Report

Dear authors,

1.

In our common sense, the distribution of soil components, including sandy and clayey soils, in the upstream, midstream, and downstream regions of a watershed is influenced by various factors such as climate, geology, and vegetation cover.

In the upstream region, typically located in mountainous or hilly areas, the terrain is steep. Due to the fast water flow, sedimentation is relatively weak, resulting in a predominance of sandy soils. The soil in the upstream region may be rich in minerals such as quartz and feldspar, which are eroded and transported downstream by long-term hydraulic action.

The midstream region lies between the upstream and downstream areas, characterized by relatively gentle terrain. The soil composition in this region usually falls between the upstream and downstream, containing varying proportions of sand, clay, and silt. The slower water flow in the midstream region leads to sedimentation, resulting in higher amounts of silt and clay in the soil.

In the downstream region, typically found in plains or estuarine areas, the terrain is relatively flat. The slower water flow in this region enhances sedimentation, leading to a prevalence of clayey soils. The soil in the downstream area contains a higher concentration of clay particles due to the slower water flow, making suspended particles settle more easily.

Furthermore, the presence of river mouth deposits may occur in the downstream area. As the river water slows down and enters the ocean, sediment accumulates. The soils in these estuarine areas may be enriched with organic matter and fine-grained soil components.

However, the conclusion of this article differs significantly. The description in lines 473-484 and in lines 487-488 of the discussion section is inconsistent with common knowledge. This may confuse readers as to who is correct. Can further reasons or explanations be provided?

2.

In this scholarly paper, the authors investigate the influence of land use changes on soil properties, based on a soil sample analysis spanning from November 2019 to May 2020. The study raises two important considerations regarding the temporal limitations and the potential impact of seasonal variations on the conclusions drawn.

Firstly, the relatively short time span of the study period warrants cautious interpretation of the results. Land use changes and their impact on soil properties are often complex processes that require a longer observation period to capture more comprehensive trends and variations. While the authors have provided valuable insights within the given timeframe, it is essential to acknowledge the limitations associated with the chosen duration.

Secondly, the authors correctly acknowledge the potential influence of seasonal variations on soil properties. Seasonal changes, such as fluctuations in temperature and precipitation, can significantly affect soil characteristics and processes. It would be beneficial for the authors to elaborate on how these seasonal effects were considered or mitigated during the analysis. Providing a clear discussion on how the results might have been influenced by seasonal variations would enhance the credibility and robustness of their findings.

Considering the aforementioned points, the authors are encouraged to discuss the feasibility and reliability of their conclusions in a more nuanced manner. They could address the limitations arising from the short-term nature of the study, emphasize the need for long-term investigations, and highlight the potential influence of seasonal variations on their results. By doing so, the authors would provide a more comprehensive understanding of the complexities involved in the relationship between land use changes and soil properties.

In conclusion, this study contributes valuable insights into the impact of land use changes on soil properties. However, given the relatively short study period and the potential influence of seasonal variations, the authors should exercise caution when drawing conclusions. Expanding on the limitations and discussing the feasibility and reliability of their findings would strengthen the overall impact and scientific rigor of this research.

Author Response

We appreciate the contributions and reviews of all reviewers. We inform you that the manuscript underwent some changes to meet all the suggestions. All data and statistical analyses were checked and revised, and, when necessary, changed.

Dear authors,

1.

In our common sense, the distribution of soil components, including sandy and clayey soils, in the upstream, midstream, and downstream regions of a watershed is influenced by various factors such as climate, geology, and vegetation cover.

In the upstream region, typically located in mountainous or hilly areas, the terrain is steep. Due to the fast water flow, sedimentation is relatively weak, resulting in a predominance of sandy soils. The soil in the upstream region may be rich in minerals such as quartz and feldspar, which are eroded and transported downstream by long-term hydraulic action.

The midstream region lies between the upstream and downstream areas, characterized by relatively gentle terrain. The soil composition in this region usually falls between the upstream and downstream, containing varying proportions of sand, clay, and silt. The slower water flow in the midstream region leads to sedimentation, resulting in higher amounts of silt and clay in the soil.

In the downstream region, typically found in plains or estuarine areas, the terrain is relatively flat. The slower water flow in this region enhances sedimentation, leading to a prevalence of clayey soils. The soil in the downstream area contains a higher concentration of clay particles due to the slower water flow, making suspended particles settle more easily.

Furthermore, the presence of river mouth deposits may occur in the downstream area. As the river water slows down and enters the ocean, sediment accumulates. The soils in these estuarine areas may be enriched with organic matter and fine-grained soil components.

However, the conclusion of this article differs significantly. The description in lines 473-484 and in lines 487-488 of the discussion section is inconsistent with common knowledge. This may confuse readers as to who is correct. Can further reasons or explanations be provided?

We agree with the reviewer. This highlight was included in the discussion, together with its justification (lines 715 to 738). 

2.

In this scholarly paper, the authors investigate the influence of land use changes on soil properties, based on a soil sample analysis spanning from November 2019 to May 2020. The study raises two important considerations regarding the temporal limitations and the potential impact of seasonal variations on the conclusions drawn.

Firstly, the relatively short time span of the study period warrants cautious interpretation of the results. Land use changes and their impact on soil properties are often complex processes that require a longer observation period to capture more comprehensive trends and variations. While the authors have provided valuable insights within the given timeframe, it is essential to acknowledge the limitations associated with the chosen duration.

Secondly, the authors correctly acknowledge the potential influence of seasonal variations on soil properties. Seasonal changes, such as fluctuations in temperature and precipitation, can significantly affect soil characteristics and processes. It would be beneficial for the authors to elaborate on how these seasonal effects were considered or mitigated during the analysis. Providing a clear discussion on how the results might have been influenced by seasonal variations would enhance the credibility and robustness of their findings.

Considering the aforementioned points, the authors are encouraged to discuss the feasibility and reliability of their conclusions in a more nuanced manner. They could address the limitations arising from the short-term nature of the study, emphasize the need for long-term investigations, and highlight the potential influence of seasonal variations on their results. By doing so, the authors would provide a more comprehensive understanding of the complexities involved in the relationship between land use changes and soil properties.

In conclusion, this study contributes valuable insights into the impact of land use changes on soil properties. However, given the relatively short study period and the potential influence of seasonal variations, the authors should exercise caution when drawing conclusions. Expanding on the limitations and discussing the feasibility and reliability of their findings would strengthen the overall impact and scientific rigor of this research.

We agree with the reviewer. This highlight was included in the discussion (lines 752 to 762). 

Thanks for your review.

Reviewer 5 Report

This manuscript aims at studying the effects of three types of land use (crop, pasture and native forest) on several soil physics attributes in two watersheds in the Southern Amazon, in Brazil. Although the impact of different types of land use on soil attributes is an important issue and contributions to its increased understanding would interest a broader public, in my opinion the pertinence of the manuscript is limited. The manuscript reports a local study that could have mainly local interest: the work adds to the existing soil data in the area, but the manuscript provides incomplete information on the conditions found in the study areas, which limits the possibility to compare this study with studies conducted for other areas. In addition, methodology used is not innovative and the outcomes are not sound, in my opinion. My main objection to this manuscript is finding that the work presents multiple flaws, which I would not expect to see in an academic journal article, hinting unreliability of the study.      

General comments

1) In my opinion there are main weaknesses in the manuscript, namely:

1.1 The literature review on similar studies does not provide an overview of the state-of-the-art on this topic, as one would expect in an academic paper. Many references include national works (likely of local significance), ignoring reference works of international relevance.

1.2 The scientific soundness of the manuscript and the appropriateness of the experimental design to test the hypothesis; it is acknowledged, however, the field and laboratory work related to data acquisition.

1.3 The testability of hypothesis in view of the soil sampling scheme used, which is nevertheless not justified by the authors and not adequately explained;

1.4 The reproducibility of the manuscript’s results based on the details given in the methods section.

1.5 Methodological inaccuracies and poor description. Although the manuscript presents a formal organization as one would expect, some contents of the sections are misplaced (e.g., methodology description found in the section “results”).

1.6 Soil attributes’ data presentation: data is provided in tables. Their representation in figures could better illustrate them and facilitate their interpretation and understanding. In my opinion, data is not interpreted appropriately/critically and there are inconsistent references to data in tables throughout the manuscript.

1.7 The data reporting in tables is not informative on the variability of results obtained for the different sampling sites, which limits the appraisal of the significance of the data reported and, thus, the interpretation of results provided by the authors. In this respect, there are many incoherencies and disparities between the data interpretation and analysis described in the text and the data provided in the tables.

1.8 Analysis and conclusions miss the support of controls, thus, some conclusions can only be seen as speculative.

1.9 Overall, the manuscript lacks sound evidence to support conclusions.

Specific comments

2. The manuscript presents a report on different attributes of the soil found at different locations in two drainage basins “headwater”, middle section and “mouth” (upper, middle and lower sections of the drainage basins). The criteria for identifying the limits of these three sections is not described and their dominant hydro-morphological conditions also not provided (hydrologic regime, relief, etc). This potentially limits the capacity to interpret results. Moreover, it is stated in the manuscript that “soil collections were performed under land use conditions that best represented the forms of land use in both watersheds” (line 134/135), but no details are given. Thus, references are not established for comparison purposes.

3. The study is based on a sampling scheme that is not clearly explained in the text and which could, potentially, bias the results, namely those regarding the attempt of the authors to establish the effect of different types of land use (crop, pasture and native forest) on several attributes of the soil. The location maps included in Figure 2 are not clear, and information cannot be readily extracted from those figures; namely a legend is not provided for those maps regarding land use. Thus, for example, the size of the representative classes’ samples for each of the watershed sections (headwater, middle, mouth, and land use type) is unknown. Results could be biased by the uneven representativeness of the soil samples collected in these three sections of the watersheds and for the different types of land use; consequently, conclusions cannot be appraised positively because they are not found to be supported by evidence in the text.

4. Conclusions are not supported by evidence in the text:

a) Soil samples were apparently collected during a seven-month period (line 147), whereas it is not known which crop and/or phase of the crop cultural cycle was found when samples were collected. This is important since the study focusses on the study of 3 soil layers: 0-10 cm, 10-20 cm and 20-40 cm, which could be highly affected by circumstantial factors, namely for “crop” land use.

b) The authors claim that soil attributes have been affected by the “conversion” of native forest into crop or pasture. However, i) the base line (i.e. control) characteristics of the soil (i.e. related to native forest) are not established, thus, comparisons and conclusions are likely invalid; ii) it is never discussed the “conversion”: was it recent or not? iii)  the distribution of the soil samples per land use type within given sections of the basins is not known, thus, sample sizes for a given class are unknown (disparity could bias results and conclusions); iv) although the authors claim that they have collected 5 soil samples at a given location and soil depth, the variability in the results is not presented or discussed. Nevertheless, the authors claim the significance of the difference in attributes found for several conditions, without providing sound evidence of that significance.

c) Most importantly, the undisturbed soil sampling scheme is not clear with respect to the size of the sampler rings used. Two sizes are mentioned, but it is not known when one or the other rings were used. Disturbingly, there is a major (and one could believe fatal) flaw in the manuscript when identifying, for both ring sizes, the volume of the undisturbed soil samples that were analysed (lines 159 and 162). The values calculated by the authors do not correspond to the volume associated to the ring sizes described. A ring of 0.05 m diameter and 0.05 m height involves a soil volume of approximately 0.0000982 m³ (not 0.0025 m³, as claimed by the authors) and a ring of 0.07 m diameter and 0.07 m height involves a soil volume of approximately 0.000269 m³ (not 0.0049 m³, as identified in the manuscript). This huge mistake is expected to affect all volumetric calculations and therefore the corresponding data and results presented in the manuscript, which one is led to believe that are thus not trustworthy.

d) Although it is not possible to confirm all values reported for soil attributes, since their variability depend on in situ conditions, some soil parameters reported are suspicious, in the sense that they differ from values usually reported in the literature for the textural classes identified in the manuscript. One such case is the soils’ hydraulic conductivity (Ks) reported in the manuscript. The calculation of Ks is supported by the Darcy Law (eq. 2), which definition provided in the manuscript is not correct. In particular, parameters L and t are incorrectly defined. In addition, the equation presented is not homogeneous in term of the units used. Implications of both these issues regarding the calculation of Ks are unknown. Moreover, the results reported in Tables 5 and 10 for the soils’ saturated hydraulic conductivity are very unlikely. For example, it is very doubtful that the mean value found from tests on 5 undisturbed samples classified as loamy sand reaches 631 cm/h (no information on standard deviation is given), which corresponds to more than 150 m/day. This value is reported for the 0-10m top layer (Table 5), but other rather high, non-typical values are also reported for deeper layers and both watersheds (Tables 5 and 10). I believe that there are problems in understanding the methods (namely the constant head permeameter used to determine Ks and the application of the Darcy Law) and in the calculations. Thus, the statistical analysis results included in the manuscript are likely deprived of value, i.e. meaningless.

5. Other comments:

5.1 Soil particle-size distributions are usually given in percentage, not as presented in Table 2. The form of representation should be given in Table 7 (indicating that the values are in percentage)

5.2 Identification of variables in equations 1 and 2 are incorrect (see above), although it is clearly a typo for equation 1. In equation 2, symbol “Q” is usually used to designate discharge, not volume.

5.3 Lines 291-293: the authors cite the work of others and describe values of soil moisture content at field capacity that are smaller than those at permanent wilting point. There must be a mistake.

5.4 Several statements in the body of the text do not correspond to the data and information in Tables. For example:

Lines 284 and 285: Table 6 does not show any relation of volumetric moisture contents and “sand and clay contents along the basin”;

Lines 306-309: the information therein is not consistent with the data in Table 7.

Line 312 refers the reader to Table 3 (Renato watershed), whereas it should concern Caiabi watershed.

Lines 316/317: not in accordance to Table 9.

Lines 320/323: not in accordance to Table 9.

Lines 340/341: not in accordance to Table 10.

Lines 358/359: not in accordance to Table 11.

Lines 540-543: not in accordance to data in Table 8.

Lines 545/546, PWP: not in accordance to data in Table 6.

Line 550: data not in accordance to Table 11.

The quality of English language shows disparity between different sections of the text, with some parts requiring a close editing. Some sentences, due to lack of grammatical rigour are difficult to follow or make no sense. There is also the need to eliminate the multiple repetitions found in some parts of the text.

Author Response

We appreciate the contributions and reviews of all reviewers. We inform you that the manuscript underwent some changes to meet all the suggestions. All data and statistical analyses were checked and revised, and, when necessary, adjusted.

This manuscript aims at studying the effects of three types of land use (crop, pasture and native forest) on several soil physics attributes in two watersheds in the Southern Amazon, in Brazil. Although the impact of different types of land use on soil attributes is an important issue and contributions to its increased understanding would interest a broader public, in my opinion the pertinence of the manuscript is limited. The manuscript reports a local study that could have mainly local interest: the work adds to the existing soil data in the area, but the manuscript provides incomplete information on the conditions found in the study areas, which limits the possibility to compare this study with studies conducted for other areas. In addition, methodology used is not innovative and the outcomes are not sound, in my opinion. My main objection to this manuscript is finding that the work presents multiple flaws, which I would not expect to see in an academic journal article, hinting unreliability of the study.      

We appreciate the contributions and reviews of all reviewers. We inform you that the manuscript underwent some changes to meet all the suggestions, especially for the comments made by reviewer 5. We did a full check of the databases and analyses carried out, and we found some corrected errors. We are very grateful for the reviewer's question regarding some values, since it provoked us in the general verification of the data. All data and statistical analyses were checked and revised, and, when necessary, changed.

General comments

1) In my opinion there are main weaknesses in the manuscript, namely:

1.1 The literature review on similar studies does not provide an overview of the state-of-the-art on this topic, as one would expect in an academic paper. Many references include national works (likely of local significance), ignoring reference works of international relevance.

New references and citations were inserted to improve the presentation and discussion of the article.

1.2 The scientific soundness of the manuscript and the appropriateness of the experimental design to test the hypothesis; it is acknowledged, however, the field and laboratory work related to data acquisition.

The hypothesis was inserted in the Introduction and Figure 1 was changed to improve understanding of the two river basins under study (lines 91 to 93).

1.3 The testability of hypothesis in view of the soil sampling scheme used, which is nevertheless not justified by the authors and not adequately explained;

Section 2.2 has been rewritten to address comments 1.3 and 1.4 (lines 173 to 203).

1.4 The reproducibility of the manuscript’s results based on the details given in the methods section.

Adjusted.

1.5 Methodological inaccuracies and poor description. Although the manuscript presents a formal organization as one would expect, some contents of the sections are misplaced (e.g., methodology description found in the section “results”).

???.

1.6 Soil attributes’ data presentation: data is provided in tables. Their representation in figures could better illustrate them and facilitate their interpretation and understanding. In my opinion, data is not interpreted appropriately/critically and there are inconsistent references to data in tables throughout the manuscript.

The authors understand that the presentation in the form of a table is more pertinent to show the statistical analyzes and their interpretations.

1.7 The data reporting in tables is not informative on the variability of results obtained for the different sampling sites, which limits the appraisal of the significance of the data reported and, thus, the interpretation of results provided by the authors. In this respect, there are many incoherencies and disparities between the data interpretation and analysis described in the text and the data provided in the tables.

Adjusted.

Specific comments

2. The manuscript presents a report on different attributes of the soil found at different locations in two drainage basins “headwater”, middle section and “mouth” (upper, middle and lower sections of the drainage basins). The criteria for identifying the limits of these three sections is not described and their dominant hydro-morphological conditions also not provided (hydrologic regime, relief, etc). This potentially limits the capacity to interpret results. Moreover, it is stated in the manuscript that “soil collections were performed under land use conditions that best represented the forms of land use in both watersheds” (line 134/135), but no details are given. Thus, references are not established for comparison purposes.

Information inserted in the text (lines 132 to 137)

3. The study is based on a sampling scheme that is not clearly explained in the text and which could, potentially, bias the results, namely those regarding the attempt of the authors to establish the effect of different types of land use (crop, pasture and native forest) on several attributes of the soil. The location maps included in Figure 2 are not clear, and information cannot be readily extracted from those figures; namely a legend is not provided for those maps regarding land use. Thus, for example, the size of the representative classes’ samples for each of the watershed sections (headwater, middle, mouth, and land use type) is unknown. Results could be biased by the uneven representativeness of the soil samples collected in these three sections of the watersheds and for the different types of land use; consequently, conclusions cannot be appraised positively because they are not found to be supported by evidence in the text.

Figures 1 and 2 changed and representation areas of the watershed regions were inserted in the characterization of the study areas

4. Conclusions are not supported by evidence in the text:
5. a) Soil samples were apparently collected during a seven-month period (line 147), whereas it is not known which crop and/or phase of the crop cultural cycle was found when samples were collected. This is important since the study focusses on the study of 3 soil layers: 0-10 cm, 10-20 cm and 20-40 cm, which could be highly affected by circumstantial factors, namely for “crop” land use.

Details about the phenophases of agricultural crops and other information were inserted to clarify this doubt (lines 175 to 179).

1. b) The authors claim that soil attributes have been affected by the “conversion” of native forest into crop or pasture. However, i) the base line (i.e. control) characteristics of the soil (i.e. related to native forest) are not established, thus, comparisons and conclusions are likely invalid; ii) it is never discussed the “conversion”: was it recent or not? iii)  the distribution of the soil samples per land use type within given sections of the basins is not known, thus, sample sizes for a given class are unknown (disparity could bias results and conclusions); iv) although the authors claim that they have collected 5 soil samples at a given location and soil depth, the variability in the results is not presented or discussed. Nevertheless, the authors claim the significance of the difference in attributes found for several conditions, without providing sound evidence of that significance.

Details about the samples and their representativeness and other information were inserted to clarify this doubt (lines 173 to 203).

1. c) Most importantly, the undisturbed soil sampling scheme is not clear with respect to the size of the sampler rings used. Two sizes are mentioned, but it is not known when one or the other rings were used. Disturbingly, there is a major (and one could believe fatal) flaw in the manuscript when identifying, for both ring sizes, the volume of the undisturbed soil samples that were analysed (lines 159 and 162). The values calculated by the authors do not correspond to the volume associated to the ring sizes described. A ring of 0.05 m diameter and 0.05 m height involves a soil volume of approximately 0.0000982 m³(not 0.0025 m³, as claimed by the authors) and a ring of 0.07 m diameter and 0.07 m height involves a soil volume of approximately 0.000269 m³(not 0.0049 m³, as identified in the manuscript). This huge mistake is expected to affect all volumetric calculations and therefore the corresponding data and results presented in the manuscript, which one is led to believe that are thus not trustworthy.

Dear Reviewer, Thank you for your comment. In fact, we made a mistake in the values mentioned in the text. Regardless of the size, the rings were numbered and the measurements of diameter and height of each ring were obtained (with a digital caliper with a resolution of 0.01). Subsequently, specific volumes were obtained for each ring. As an example, we present the table below, with the information of the smaller rings (0.05m). In the laboratory we had only 412 rings of each diameter available (totaling 824 rings)

In this way, we ensure that all results and analyzes are consistent and reliable. Lines 159 to 162 are corrected in the article

1. d) Although it is not possible to confirm all values reported for soil attributes, since their variability depend on in situ conditions, some soil parameters reported are suspicious, in the sense that they differ from values usually reported in the literature for the textural classes identified in the manuscript. One such case is the soils’ hydraulic conductivity (Ks) reported in the manuscript. The calculation of Ks is supported by the Darcy Law (eq. 2), which definition provided in the manuscript is not correct. In particular, parameters L and t are incorrectly defined. In addition, the equation presented is not homogeneous in term of the units used. Implications of both these issues regarding the calculation of Ks are unknown. Moreover, the results reported in Tables 5 and 10 for the soils’ saturated hydraulic conductivity are very unlikely. For example, it is very doubtful that the mean value found from tests on 5 undisturbed samples classified as loamy sand reaches 631 cm/h (no information on standard deviation is given), which corresponds to more than 150 m/day. This value is reported for the 0-10m top layer (Table 5), but other rather high, non-typical values are also reported for deeper layers and both watersheds (Tables 5 and 10). I believe that there are problems in understanding the methods (namely the constant head permeameter used to determine Ks and the application of the Darcy Law) and in the calculations. Thus, the statistical analysis results included in the manuscript are likely deprived of value, i.e. meaningless.

The values were checked and all analyzes linked to this variable were redone. In addition, references were inserted that indicate the high Ksat values for Amazonian soils. Thank you for this comment as it prompted a complete database review.

5. Other comments:

5.1 Soil particle-size distributions are usually given in percentage, not as presented in Table 2. The form of representation should be given in Table 7 (indicating that the values are in percentage)

The considered units of measurement allow the simplified obtaining of the percentages of each particle. It was based on the usual forms of presentation of this soil attribute observed in other articles published in MDPI.

5.2 Identification of variables in equations 1 and 2 are incorrect (see above), although it is clearly a typo for equation 1. In equation 2, symbol “Q” is usually used to designate discharge, not volume.

Thanks for the comment. The units were checked and this motivated us to review the values obtained.

5.3 Lines 291-293: the authors cite the work of others and describe values of soil moisture content at field capacity that are smaller than those at permanent wilting point. There must be a mistake.

Changed and new citations included.

5.4 Several statements in the body of the text do not correspond to the data and information in Tables. For example:

All examples of inconsistencies were checked and changed, when necessary.

Comments on the Quality of English Language

The quality of English language shows disparity between different sections of the text, with some parts requiring a close editing. Some sentences, due to lack of grammatical rigour are difficult to follow or make no sense. There is also the need to eliminate the multiple repetitions found in some parts of the text.

English was proofread by a native American (Dr. Aaron K. Hoshide), co-author of manuscript.

Thanks for your review.