Effect of Water Quality and Date Palm Biochar on Evaporation and Specific Hydrological Characteristics of Sandy Soil

Round 1

Reviewer 1 Report

This paper reports the changes in main hydraulic properties of soils  (e.g. hydraulic conductivity, evaporation rate) with the addition of biochar. While the setting of experiment could potentially provide interesting results regarding the effects of biochar amendment on these properties, the severe lacks in english writing and the clarity exposing the results make almost impossible to understand the main trends observed in this study. Therefore, a strong implementation of the writing of this paper is needed to consider it to publication.

Starting from the abstract, a first sentence focusing on the importance of this study is missing, then main results are reported with too much detail (lines 11-18) making difficult to focus on the main trends. Finally, the last sentence ("The biochar as soil conditioners could be under fresh and saline water to enhance the hydrological properties of sandy soils."), which should be a take home message, results hard to understand.

The introduction lacks of  a general discussion of the state of the art. The authors limit to report previous case studies, without finding the knowledge gap which this study could fill. Therefore, a suggest to rewrite this section, considering in a more critical manner the common recent findings and highlighting the novelties of the paper in this sector.

The methods should be revised, since different details are missing. For example, in line 64 the authors stated "The cations were estimated 64 by titration with (EDTA)."; differently, they should state which cations were estimated. Also, duration of pyrolysis experiment is not reported and the sentence regarding oxygen conditions (lines 74-75) should be clarified, indicating if these experiments were performed in air or using inert gases (e.g. nitrogen). 

Moreover, unclear sentences makes hard to read through this section. For example, in lines 84-85 ("Applied water was 25 mL of freshwater (EC 0.73 84 dS m-1) and saline water (3.6 dS m-1) were added at every cycle") should be rewritten as "25 ml of fresh water and saline water were added at every cycle" avoiding repetitions. Another example is in lines 91-93, where the sentence should be rewritten, such as "The disk infiltrometer was placed in water before measurements to verify saturation and avoiding interaction with air".

Moreover, I suggest to the authors to measure also salinity after the leaching experiments, to understand the effects of biochar even to this important parameter affecting pore water.

Moving to the results and discussion, authors should more critically and systematically report and discuss the obtained results, starting from the effects of biochar on soils with different texture and then highlighting which properties are more or less affected by biochar amendment. Then authors should critically analyze all aspects of the obtained results. For example, in lines 164-165, the clear advantages of water retention are reported, but other effects (such as the limited leaching of chemicals, as well as possible increase of runoff) are not considered. Moreover, different unclear sentences (such as line 144 and in lines 158-159) need to be rewritten.

I also suggest to highlight the changes induced by biochar addition in graphs to emphasize the results. Graphs in figures 1, 2 and 3 as they are clearly show the differences between the two types of water, but the evaluation of biochar at different concentrations is not observable. Therefore, I suggest to plot in the same graph the effects on hydraulic feature with different loads of biochar (using different panels for fresh and sea water).

Finally, in the conclusion section some main results are rightly presented, but a final take home message and main conclusions derived from the obtained results should be added.

Following these main issues, there are many misspellings and unclear sentences which should be addressed (please find the attached pdf version of the manuscript with the sentences which should be revised highlighted).

In light of these serious lacks, I suggest to reject this paper, which needs a complete revision before being considered for publication.

Comments for author File: Comments.pdf

Author Response

 (Reviewer 1)

Comment 1

This paper reports the changes in main hydraulic properties of soils (e.g. hydraulic conductivity, evaporation rate) with the addition of biochar. While the setting of experiment could potentially provide interesting results regarding the effects of biochar amendment on these properties, the severe lacks in English writing and the clarity exposing the results make almost impossible to understand the main trends observed in this study. Therefore, a strong implementation of the writing of this paper is needed to consider it to publication.

Response 1

The English writing through out the text has been corrected.

Comment 2

Starting from the abstract, a first sentence focusing on the importance of this study is missing, then main results are reported with too much detail (lines 11-18) making difficult to focus on the main trends. Finally, the last sentence ("The biochar as soil conditioners could be under fresh and saline water to enhance the hydrological properties of sandy soils."), which should be a take home message, results hard to understand.

Response 2

Thank for your comments but this is not what other reviewer view the manuscript. The authors will attach a certificate for proof of the manuscript from native English writer.

Comment 3

The introduction lacks of a general discussion of the state of the art. The authors limit to report previous case studies, without finding the knowledge gap which this study could fill. Therefore, a suggest to rewrite this section, considering in a more critical manner the common recent findings and highlighting the novelties of the paper in this sector.

Response 3

The authors have cited of many works on the using of biochar and its effect of soil physical properties. However, the of using biochar with saline water is very limited and this is the gap which this study could fill.

Comment 4

The methods should be revised, since different details are missing. For example, in line 64 the authors stated "The cations were estimated 64 by titration with (EDTA)."; differently, they should state which cations were estimated. Also, duration of pyrolysis experiment is not reported and the sentence regarding oxygen conditions (lines 74-75) should be clarified, indicating if these experiments were performed in air or using inert gases (e.g. nitrogen).

Response 4

This has been corrected and some sentences were rewritten and add words.

Comment 5:

Moreover, unclear sentences makes hard to read through this section. For example, in lines 84-85 ("Applied water was 25 mL of freshwater (EC 0.73 84 dS m-1) and saline water (3.6 dS m-1) were added at every cycle") should be rewritten as "25 ml of fresh water and saline water were added at every cycle" avoiding repetitions. Another example is in lines 91-93, where the sentence should be rewritten, such as "The disk infiltrometer was placed in water before measurements to verify saturation and avoiding interaction with air".

Moreover, I suggest to the authors to measure also salinity after the leaching experiments, to understand the effects of biochar even to this important parameter affecting pore water.

Response 5:

These sentences were modified as suggested by the reviewer. 

Comment 6

Moving to the results and discussion, authors should more critically and systematically report and discuss the obtained results, starting from the effects of biochar on soils with different texture and then highlighting which properties are more or less affected by biochar amendment. Then authors should critically analyze all aspects of the obtained results. For example, in lines 164-165, the clear advantages of water retention are reported, but other effects (such as the limited leaching of chemicals, as well as possible increase of runoff) are not considered. Moreover, different unclear sentences (such as line 144 and in lines 158-159) need to be rewritten.

Response 6

The authors have taken these suggestions in consideration and sentences were modified.

Comment 7

I also suggest to highlight the changes induced by biochar addition in graphs to emphasize the results. Graphs in figures 1, 2 and 3 as they are clearly show the differences between the two types of water, but the evaluation of biochar at different concentrations is not observable. Therefore, I suggest to plot in the same graph the effects on hydraulic feature with different loads of biochar (using different panels for fresh and sea water).

 Response 7

The effect of biochar rates using fresh water has been published by the same authors as we cited the work in text.

Comment 8

Finally, in the conclusion section some main results are rightly presented, but a final take home message and main conclusions derived from the obtained results should be added.

Following these main issues, there are many misspellings and unclear sentences which should be addressed (please find the attached pdf version of the manuscript with the sentences which should be revised highlighted).

Response 8

Thank you for offers to improve the manuscript.

Comment 9

Give importance of this study at the beginning and English of abstract should be improved to highlight and focus on the important results.

Response 9

Done and thank you.

Author Response File: Author Response.docx

Reviewer 2 Report

Manuscript provides interesting findings in a very important topic, how to decrease negative impact of saline waters on soil and biochar seems to be a good material mitigating this problem. My only doubt is about application is to answer the question if there is enough of biomass that can be transformed in to a biochar in arid climate zones if we would like to implement this solution. However this is the message to consider in future research and this manuscript can be recommended for publication in present form after minor changes in introduction. In my opinion introduction relays on citation of other authors work and not fully describe the need and the content of the paper. It would be good if Authors would add some own point of view on the topic to convince the reader that it is very important.     

Author Response

Comments of reviewer 2

Manuscript provides interesting findings in a very important topic, how to decrease negative impact of saline waters on soil and biochar seems to be a good material mitigating this problem. My only doubt is about application is to answer the question if there is enough of biomass that can be transformed in to a biochar in arid climate zones if we would like to implement this solution. However this is the message to consider in future research and this manuscript can be recommended for publication in present form after minor changes in introduction. In my opinion introduction relays on citation of other authors work and not fully describe the need and the content of the paper. It would be good if Authors would add some own point of view on the topic to convince the reader that it is very important.     

Response:

In Saudi Arabia there are more that 30 million date palm trees grown in different area of the kingdom. The waste coming of this is really huge and producing biochar from that is great beneficial environmentally.

Round 2

Reviewer 1 Report

The authors presented a revised version of this manuscript aiming to observe the main changes in physical properties of soil after the addition of biochar. While the quality is surely improved from the previous version of the manuscript, there are still some minor issues to be addressed. In fact, while the authors attached a report of language editing for this manuscript, I still find some sentences confusing and there are some misspellings.

I still think that the abstract in this form should be revised, at least for a first sentence outlining the main topic of the paper.

Line 33: remove "and"

The sentence in line 35-36 is hard to understand.

In line 51-52 the sentence should be rewritten (I suggest "Nonetheless, only few studies reported the effects of biochar on soil physical properties using brackish or saline water. Consequently, this study aims to evaluate...").

Line 62:remove "of"

Line 71: "pyrolysis was performed" instead of "done"

Lines 125-134: remove parenthesis for the acronym C.E. after its definition in line 123.

Please remove the sentence in line 133 "Figure (1) illustrates that...". The authors can instead write, in line 130 "The decrease of water is observable in figure 1..".

Line 167: remove "for"

Authors, moreover, should rewrite the sentences in lines 179-182 and in lines 189-190, which are not clear to understand.

Line 203: please use the dot instead of the comma, since this is the end of a sentence.

Author Response

response was provided in the attached file.

Author Response File: Author Response.docx