Effects of Drip Tape Layout and Flow Rate on Water and Nitrogen Distributions within the Root Zone and Summer Maize Yield in Sandy Tidal Soil

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Authors

You conducted a study to assess the effects of drip tape layout and flow rate on water and nitrogen distributions within the root zone, as well as the performance of corn plants. This study aligns with the goal of enhancing production efficiency in the field of agriculture, making it an intriguing and relevant topic. However, there are certain fundamental concerns regarding the underlying philosophy of this study. Additionally, there are specific comments provided in various sections which are outlined below.

The main concerns

The primary concern of this study revolves around two drip tape layout patterns, namely 40+80 and 60 cm, which correspond to a total drip tape length of approximately 8333 m and 16666 m per hectare, respectively. The key question is: What are the objectives and intended outcomes of this work? A relevant point of comparison would be the control group consisting of maize grown under rainfed conditions. In terms of irrigation scheduling, the specific timing for each hectare is as follows:

Treatments		Growth stages	Irrigation amount (m3 ha-1)
Drip tape layout	Drip flow rate		2020	2021
NH one tape serving for two crop rows (40+80 cm)	2.0 L/h	V12	75 (55.3)	87 (55.3)
		VT	70 (55.3)	85 (55.3)
NL one tape serving for two crop rows (40+80 cm)	1.3 L/h	V12	75 (35.9)	87 (35.9)
		VT	70 (35.9)	85 (35.9)
EH one tape serving for each crop row (60 cm)	2.0 L/h	V12	75 (111)	87 (111)
		VT	70 (111)	85 (111)
EL one tape serving for each crop row (60 cm)	1.3 L/h	V12	75 (72.3)	87 (72.3)
		VT	70 (72.3)	85 (72.3)

The values enclosed in parentheses represent the flow rate of the entire dripper system per hectare. Designing an irrigation system that operates for just one or a maximum of four hours per hectare during the entire growth period seems impractical. A more practical and effective approach would be to include a control group that does not receive any irrigation treatment. This will provide a more comprehensive and informative summary of the study's findings.

 

The second issue pertains to the premature focus on recent and average rainfall years. To address this concern, it is crucial to incorporate long-term meteorological data for the region, including information about the typical rainfall levels. It is worth noting that during the study period, one year experienced abundant rainfall while another year had lower rainfall. If the objective of this study is to examine the impact of drought on the irrigation system and flow rate, it would be more appropriate to conduct the survey during multiple drought years or years with low rainfall, allowing for meaningful comparisons between different conditions.

 

 

 

 

 

Title

Line 1- please change the title to “Effects of drip tape layout and flow rate on water and nitrogen distributions within the root-zone and summer maize yield in sandy tidal soil”

 

Abstract

Line 14 - The first sentence, "Drip fertigation is one of the most efficient methods improving water- and nutrient-use efficiency and increasing crop yield," is not directly related to the focus of this study on drip tape layout and flow rate. Please replace it with a sentence that specifically addresses the impact of drip tape layout and flow rate.

Line 17- replace 2 with two

Line 17- If the study distinguishes between different years, such as wet and normal years, it is necessary to repeat the experiment in these specific years. Therefore, it suffices to state that there are two agricultural years, and when interpreting the results, it can be concluded that the amount of rainfall differs between these two years.

Line 33-35 – This summary carries a high risk of making recommendations without sufficient comparisons to a non-irrigation treatment and lacking economic analysis.

 

Introduction

In this study, supplementary irrigation was implemented using a drip tape system. However, the introduction lacks information regarding the average corn yield in non-irrigated conditions, as well as the rationale for implementing the relatively expensive supplementary irrigation system.

 

Furthermore, there is inconsistency in the terminology used, with both "irrigation" and "fertigation" being mentioned in the introduction.

 

To improve the introduction, it would be advisable to prioritize discussing previous research that investigates the distribution of water and fertilizer under various conditions, such as the distance between the drip tape tip and the plant, and the moisture content of the soil.

 

Lines 88-91- The climate has varied greatly in recent years with substantial variability in annual precipitation [23]. However, the effects of drip tape layout and flow rate on maize production under different precipitation conditions are poorly understood.

?- The objective of this study was to examine the impact of drip tape layout and flow rate on the water supply for corn. Randomly, in one of the study years, there was higher rainfall, while in the other year, rainfall was lower. Hence, the variation in rainfall cannot be considered a significant concern for the implementation of this study.

Line 99- two years instead of 2 years.

 

 

 

 

Materials and methods

This section needs to be completed with information regarding the planting and harvesting dates for each year, the quality of irrigation water, the potential for evapotranspiration, the methodology used to evaluate the water requirement of maize, and the criteria for selecting the specified irrigation water volumes.

Line 121- Table 1- Please add maximum and minimum temperature instead of average temperature in each maize growth stage

Line 121- Table 1. What is the accumulated temperature?! Please explain in more detail under the table or in the text. If your opinions are growth degree days, please indicate the T base and T threshold, too.

Line 122. Please show a list of the dates of sowing and harvesting in each figure section.

 Line 136. What are your reasons for using phosphorus fertilizer when available phosphorus of soil was 97.50 mg/kg?!

Line 140- Please clarify and add more details about measuring irrigation requirements in two years including the methods of measuring soil moisture and calculating water supply?

Line 141. This sentence “The amount of irrigation was based on the soil moisture” was repeated.

Line 177-178- Please add the references for PFP_N and WUE formulae.

Line 180- Please check the Definition of the term of Eta ??? irrigation water use+ effective rainfall + available section of soil water storge

 

Results

Line 191 - Can you please provide a clear explanation in advance regarding what constitutes normal and wet years? This will help prevent confusion for the reader by providing detailed information.

Line 257 - Please verify the scale of soil inorganic nitrogen content, specifically in (mg/ha).

Line 271 - In Figure 7, it is necessary to explain the letters used below the figure. Furthermore, it should be emphasized that the comparisons between each stage and the total, or between different totals, are separate.

Discussion

Line 400-403- In light of the accurate definition of water use efficiency, it is necessary to revise this paragraph and the results discussed within it.

 

Line 428 - It is necessary to clarify the meaning of A, B, and C in Figure 8 by providing relevant details.

Conclusions

 

Considering these results, it is essential to note that partly due to the absence of a non-irrigation treatment and the lack of economic analysis, it is not possible to draw a definitive conclusion. Therefore, this section requires revision.

Comments on the Quality of English Language

The aforementioned items of concern have been addressed in the preceding section.

Author Response

Dear Reviewer:

Thanks very much for your comments concerning our manuscript. The comments are all valuable and very helpful for improving our paper. We have thought the comments carefully over and have made corrections which we hope meet with your approval. Revised portion are marked in red in the paper. The main corrections in the paper and responds to the comments are as following:

You conducted a study to assess the effects of drip tape layout and flow rate on water and nitrogen distributions within the root zone, as well as the performance of corn plants. This study aligns with the goal of enhancing production efficiency in the field of agriculture, making it an intriguing and relevant topic. However, there are certain fundamental concerns regarding the underlying philosophy of this study. Additionally, there are specific comments provided in various sections which are outlined below.

The main concerns

The primary concern of this study revolves around two drip tape layout patterns, namely 40+80 and 60 cm, which correspond to a total drip tape length of approximately 8333 m and 16666 m per hectare, respectively. The key question is: What are the objectives and intended outcomes of this work? A relevant point of comparison would be the control group consisting of maize grown under rainfed conditions. In terms of irrigation scheduling, the specific timing for each hectare is as follows:

Treatments		Growth stages	Irrigation amount (m3 ha-1)
Drip tape layout	Drip flow rate		2020	2021
NH one tape serving for two crop rows (40+80 cm)	2.0 L/h	V12	75 (55.3)	87 (55.3)
		VT	70 (55.3)	85 (55.3)
NL one tape serving for two crop rows (40+80 cm)	1.3 L/h	V12	75 (35.9)	87 (35.9)
		VT	70 (35.9)	85 (35.9)
EH one tape serving for each crop row (60 cm)	2.0 L/h	V12	75 (111)	87 (111)
		VT	70 (111)	85 (111)
EL one tape serving for each crop row (60 cm)	1.3 L/h	V12	75 (72.3)	87 (72.3)
		VT	70 (72.3)	85 (72.3)

The values enclosed in parentheses represent the flow rate of the entire dripper system per hectare. Designing an irrigation system that operates for just one or a maximum of four hours per hectare during the entire growth period seems impractical. A more practical and effective approach would be to include a control group that does not receive any irrigation treatment. This will provide a more comprehensive and informative summary of the study's findings.

Reply: Considering present trends for the adoption of drip fertigation in field maize production, and insufficient knowledge on effects of drip-fertigation management on water and nitrogen distributions within the root-zone and summer maize yield in sandy tidal soil, objectives of present study were to find a best combination of drip tape layout and flow rate with the highest comprehensive benefit as a tradeoff of yield, and irrigation nitrogen and water use efficiency in the region.

For the irrigation amount, our drip fertigation area is based on the experimental plot area and every plot was 240 m². In both experiment years, the water content of each growth stage could basically meet the needs of maize growth without any drought stress. Therefore, drip fertigation is mainly used to apply fertilizers, and the irrigation amount is based on the soil moisture content, so the irrigation amount in each plot is relatively lower.

The second issue pertains to the premature focus on recent and average rainfall years. To address this concern, it is crucial to incorporate long-term meteorological data for the region, including information about the typical rainfall levels. It is worth noting that during the study period, one year experienced abundant rainfall while another year had lower rainfall. If the objective of this study is to examine the impact of drought on the irrigation system and flow rate, it would be more appropriate to conduct the survey during multiple drought years or years with low rainfall, allowing for meaningful comparisons between different conditions.

Reply: Thanks for your suggestions. As suggested, we would focus on the similarities rather than differences between wet and normal years. In fact, dry years are rare in this region. Further verification is indeed required to interpret the differences between different conditions.

Title

Line 1- please change the title to “Effects of drip tape layout and flow rate on water and nitrogen distributions within the root-zone and summer maize yield in sandy tidal soil”

Reply: As suggested, we have modified the title in the revised manuscript.

Abstract

Line 14 - The first sentence, "Drip fertigation is one of the most efficient methods improving water- and nutrient-use efficiency and increasing crop yield," is not directly related to the focus of this study on drip tape layout and flow rate. Please replace it with a sentence that specifically addresses the impact of drip tape layout and flow rate.

Reply: As suggested, we have modified the sentence to “Drip tape layout and flow rate are crucial variables that impact the effects of drip fertigation.”

Line 17- replace 2 with two

Reply: As suggested, we have replaced 2 with two in the revised manuscript.

Line 17- If the study distinguishes between different years, such as wet and normal years, it is necessary to repeat the experiment in these specific years. Therefore, it suffices to state that there are two agricultural years, and when interpreting the results, it can be concluded that the amount of rainfall differs between these two years.

Reply: Thanks for your suggestions. As suggested, we would focus on the similarities rather than differences between wet and normal years. Further verification is required to interpret the differences between these specific years.

Line 33-35 – This summary carries a high risk of making recommendations without sufficient comparisons to a non-irrigation treatment and lacking economic analysis.

Reply: Thanks for your attention. As suggested, we have rephrased this summary in our revised manuscript

Introduction

In this study, supplementary irrigation was implemented using a drip tape system. However, the introduction lacks information regarding the average corn yield in non-irrigated conditions, as well as the rationale for implementing the relatively expensive supplementary irrigation system.

Reply: Thanks for your suggestions. We have checked the recent literatures and added the information in Introduction.

Furthermore, there is inconsistency in the terminology used, with both "irrigation" and "fertigation" being mentioned in the introduction.

Reply: Sorry for the inconsistency in the terminology used. We have modified it in the introduction.

To improve the introduction, it would be advisable to prioritize discussing previous research that investigates the distribution of water and fertilizer under various conditions, such as the distance between the drip tape tip and the plant, and the moisture content of the soil.

Reply: As suggested, we have added the previous researches that investigates the distribution of water and fertilizer under various conditions in the revised manuscript.

Lines 88-91- The climate has varied greatly in recent years with substantial variability in annual precipitation [23]. However, the effects of drip tape layout and flow rate on maize production under different precipitation conditions are poorly understood.

?- The objective of this study was to examine the impact of drip tape layout and flow rate on the water supply for corn. Randomly, in one of the study years, there was higher rainfall, while in the other year, rainfall was lower. Hence, the variation in rainfall cannot be considered a significant concern for the implementation of this study.

Reply: Thanks for your suggestions. As suggested, we would focus on the similarities between the two years.

Line 99- two years instead of 2 years.

Reply: As suggested, we have replaced 2 with two in the revised manuscript.

Materials and methods

This section needs to be completed with information regarding the planting and harvesting dates for each year, the quality of irrigation water, the potential for evapotranspiration, the methodology used to evaluate the water requirement of maize, and the criteria for selecting the specified irrigation water volumes.

Line 121- Table 1- Please add maximum and minimum temperature instead of average temperature in each maize growth stage.

Reply: As suggested, we have added maximum and minimum temperature in each maize growth stage in the manuscript.

Line 121- Table 1. What is the accumulated temperature?! Please explain in more detail under the table or in the text. If your opinions are growth degree days, please indicate the T base and T threshold, too.

Reply: The accumulated temperature is the sum of the mean daily temperatures during the growing period in which the mean daily temperature is above 10 degrees Celsius (≥10 ◦C) each day. Therefore, the T base is 10 ℃. We have changed the accumulation to active accumulated temperature in the revised manuscript.

Line 122. Please show a list of the dates of sowing and harvesting in each figure section.

Reply: As suggested, we have added the dates of sowing and harvesting in each figure section.

Line 136. What are your reasons for using phosphorus fertilizer when available phosphorus of soil was 97.50 mg/kg?!

Reply: About the available phosphorus of soil, we feel very sorry for this mistake, we have double checked the result and revised the data in our revised manuscript.

Line 140- Please clarify and add more details about measuring irrigation requirements in two years including the methods of measuring soil moisture and calculating water supply?

Reply: As suggested, we have added more details about measuring irrigation requirements in the revised manuscript.

Line 141. This sentence “The amount of irrigation was based on the soil moisture” was repeated.

Reply: Sorry for this kind of mistake. We have deleted it in the manuscript.

Line 177-178- Please add the references for PFPN and WUE formulae.

Reply: Thanks for your suggestions. As suggested, we have added the references for PFP_N and WUE formulae.

Line 180- Please check the Definition of the term of Eta ??? irrigation water use+ effective rainfall + available section of soil water storge

Reply: As suggested, we have redefined the term of Eta in the revised manuscript.

Results

Line 191 - Can you please provide a clear explanation in advance regarding what constitutes normal and wet years? This will help prevent confusion for the reader by providing detailed information.

Reply: Thanks for your attention. The normal and wet years were assessed using the drought coefficient method which was described in section 2.1 above Table 1.

Line 257 - Please verify the scale of soil inorganic nitrogen content, specifically in (mg/ha).

Reply: Sorry for this kind of mistake. We have modified it in the revised manuscript.

Line 271 - In Figure 7, it is necessary to explain the letters used below the figure. Furthermore, it should be emphasized that the comparisons between each stage and the total, or between different totals, are separate.

Reply: As suggested, we have added explanations for the letters below the figure.

Discussion

Line 400-403- In light of the accurate definition of water use efficiency, it is necessary to revise this paragraph and the results discussed within it.

Reply: As suggested, we have revised this paragraph in the revised manuscript.

Line 428 - It is necessary to clarify the meaning of A, B, and C in Figure 8 by providing relevant details.

Reply: As suggested, we have redrawn Figure 8 and clarified the meaning of A and B.

Conclusions

Considering these results, it is essential to note that partly due to the absence of a non-irrigation treatment and the lack of economic analysis, it is not possible to draw a definitive conclusion. Therefore, this section requires revision.

Reply: Thanks for your suggestions. As suggested, we have rephrased this conclusion in our revised manuscript.

Thank again for your comments and suggestions.

Best wishes!

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

L-41: a large

L-44: The groundwater

L-48 : in promoting

L-49 : improving

L-76 : the irrigation

L-129: Since the root structure of the maize plant is large, a distance of 1 meter between plots is insufficient.

L-151: a drip

L-151: an auger

L-152: in a horizontal

L-174: At the maize

L-189-190:  was

L-194: an average

L-210: The Concentration

L-213: a wet

L-309: the irrigation

L-364: The growth

L-367: in the wet year

L-371: minimize

L-397: an increase

 

 

 

Author Response

Dear Reviewer:

Thanks very much for your comments concerning our manuscript. The comments are all valuable and very helpful for improving our paper. We have thought the comments carefully over and have made corrections which we hope meet with your approval. Revised portion are marked in red in the paper. The main corrections in the paper and responds to the comments are as following:

L-41: a large

L-44: The groundwater

L-48 : in promoting

L-49 : improving

L-76 : the irrigation

Reply: Thanks for your suggestions. As suggested, we have modified the mistakes in the revised manuscript.

L-129: Since the root structure of the maize plant is large, a distance of 1 meter between plots is insufficient.

Reply: Thanks for your questions. In our study, 1-m wide isolation area was used to isolate different plots. The sampling site was located in the relative middle of each plot.

L-151: a drip

L-151: an auger

L-152: in a horizontal

L-174: At the maize

L-189-190: was

L-194: an average

L-210: The Concentration

L-213: a wet

L-309: the irrigation

L-364: The growth

L-367: in the wet year

L-371: minimize

L-397: an increase

Reply: Thanks for your attentions. As suggested, we have modified the mistakes in the revised manuscript.

Thank again for your comments and suggestions.

Best wishes!

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Line 14: Please insert “of” between the words “efficient” and “methods”.

Line 20: Please remove the word “was” i.e. “the lower was the drip emitter….”

Line 60 – 61: “…. and increasingly severe water resource shortage”. Please change this statement to “…. “……. and severely increasing water resource shortage……”

Line 69: How does a low-volume irrigation system like drip irrigation reduce salinity? This seems to be contrary to what is already established in the literature, and more, the cited reference does not establish this claim nor was the referenced study conducted to evaluate soil salinity. Thus, the aim of the cited reference does not establish this claim. Please provide evidence for this claim with appropriate reference.

Line 70 to 72: Compared to what?

Lines 72 – 778: Several of the claims about drip irrigation in this section are confusing. Drip irrigation has been reported to cause leaching just like any other irrigation system, especially in sandy soil conditions. It all comes down to management, flow rate, application timing, frequency …….. What is water demand contradiction? If this is assumed to be in comparison to rainfed agriculture then is the alleviation of water demand contradiction only particular to drip or to other irrigation systems?  How does drip irrigation regulate air and heat sources required for crop growth? The authors are invited to provide explanations for these and many other claims in the manuscript.

Experimental design: The treatment layout in relation to drip tape location is not very clear as written in the current manuscript. This is critical information for the study and needs to be clearly described. In figure 2a, it seems like the drip tape is located between two plants at a distance of 40 cm from each plant and the distance between two maize rows is 80 cm apart. In figure 2b it seems like the drip tape is located 60 cm from the plant rows and each plant row is wider apart compared to Figure 2a. Is there any difference between the plant row distance between the layout in a and b? The authors are invited to include more details highlighting the treatment layout.

Irrigation scheduling: water is the most important factor of evaluation in this study and yet there is no information on the procedure used to determine the irrigation schedule described in the manuscript. A detailed description on how irrigation schedule was determined per crop growth stage is critical.

Soil sampling: Why was soil sampled taken up to 30 cm horizontal distance for N treatments and limited to 20 cm for the E treatment? A chart or figure similar to figure 2 describing how and where the soil samples were collected should be included in the manuscript.   

What is the total amount of water applied under each scenario? Is the amount of water the same or different? A table with the amount of water applied per time under each treatment condition should be included in the manuscript. This is because the results – nutrient, water flow is depend on this information.

Statistical analyses: Were the data analyzed using 2 different programs, Excel and SPSS?

As is, the materials and methods section needs to be improved as the picture on how the experiment was conducted is not clearly described.

Results:

Is the maximum vertical water transport reported an average of the three replications per treatment or just one maximum value of the three replicates? Please clarify in the manuscript.

Line 189. Please see the second comment above.

Figure 3, 4, and 5: What is the label on the E axis? In what unit are the legends?

 

The results section is difficult to review due to lack of clarity and important omission in the methods. The current state of the manuscript requires extensive work on the materials and methods. The materials and method section lacks clarity and thus difficult to connect the results described to the conditions of the experiment conducted. A detailed description of the methodology is essential to be able to appreciate the result and hence the discussion section.  

Comments on the Quality of English Language

Moderate revision is required.

Author Response

Dear Reviewer:

Thanks for the quick handling of our manuscript and we are pleased with the received comments. The comments are all valuable and very helpful for improving our paper. We have thought the comments carefully over and have made corrections which we hope meet with your approval. Revised portion are marked in red in the paper. The main corrections in the paper and the responds to the reviewer’s comments are as following:

Line 14: Please insert “of” between the words “efficient” and “methods”.

Reply: As suggested, we have modified the first sentence in the revised manuscript.

Line 20: Please remove the word “was” i.e. “the lower was the drip emitter….”

Reply: As suggested, we have modified it.

Line 60 – 61: “…. and increasingly severe water resource shortage”. Please change this statement to “…. “……. and severely increasing water resource shortage……”

Reply: As suggested, we have modified it in the revised manuscript.

Line 69: How does a low-volume irrigation system like drip irrigation reduce salinity? This seems to be contrary to what is already established in the literature, and more, the cited reference does not establish this claim nor was the referenced study conducted to evaluate soil salinity. Thus, the aim of the cited reference does not establish this claim. Please provide evidence for this claim with appropriate reference.

Reply: Sorry for this kind of mistake. The sentence that drip fertigation can reduce water scarcity have been deleted as suggested.

Line 70 to 72: Compared to what?

Reply: Drip fertigation systems efficiently and frequently deliver water and fertilizer to the root zone of crops, thus synchronizing water and fertilizer delivery compared to traditional irrigation and fertilization practices. As suggested, we have modified it in the revised manuscript.

Lines 72 – 78: Several of the claims about drip irrigation in this section are confusing. Drip irrigation has been reported to cause leaching just like any other irrigation system, especially in sandy soil conditions. It all comes down to management, flow rate, application timing, frequency …….. What is water demand contradiction? If this is assumed to be in comparison to rainfed agriculture then is the alleviation of water demand contradiction only particular to drip or to other irrigation systems? How does drip irrigation regulate air and heat sources required for crop growth? The authors are invited to provide explanations for these and many other claims in the manuscript.

Reply: Thanks for your attention and questions. As suggested, we have rewritten the introduction.

Experimental design: The treatment layout in relation to drip tape location is not very clear as written in the current manuscript. This is critical information for the study and needs to be clearly described. In figure 2a, it seems like the drip tape is located between two plants at a distance of 40 cm from each plant and the distance between two maize rows is 80 cm apart. In figure 2b it seems like the drip tape is located 60 cm from the plant rows and each plant row is wider apart compared to Figure 2a. Is there any difference between the plant row distance between the layout in a and b? The authors are invited to include more details highlighting the treatment layout.

Reply: Thanks for your attention and questions. We have redrawn the Figure 2. We also added a detailed description to the Materials and method section.

Irrigation scheduling: water is the most important factor of evaluation in this study and yet there is no information on the procedure used to determine the irrigation schedule described in the manuscript. A detailed description on how irrigation schedule was determined per crop growth stage is critical.

Reply: The big bell mouth stage and flowering stage are critical periods of water demand. As suggested, we have added the formula of field water consumption (Evaporate-transpiration, ET) in the revised manuscript.

Soil sampling: Why was soil sampled taken up to 30 cm horizontal distance for N treatments and limited to 20 cm for the E treatment? A chart or figure similar to figure 2 describing how and where the soil samples were collected should be included in the manuscript.  

Reply: In our study, drip emitter was as the center of the soil samples to study the effects of drip tape layout and flow rate on water and nitrogen distributions within the root-zone. In the horizontal direction, 0~20 cm around the maize root was the most active in absorbing nutrients. For the E treatment, 20 cm at horizontal distance was able to reach the absorption range of the root system (Figure 2). As suggested, we have modified Figure 2 to describe how and where the soil samples were collected.

What is the total amount of water applied under each scenario? Is the amount of water the same or different? A table with the amount of water applied per time under each treatment condition should be included in the manuscript. This is because the results – nutrient, water flow is depend on this information.

Reply: Thanks for your attention. The total amount of water applied under each scenario has been described in Section 2.2 above Table 2.

Statistical analyses: Were the data analyzed using 2 different programs, Excel and SPSS?

Reply: Excel was used to input raw data and SPSS was used to analyze data. We have modified it in the revised manuscript.

As is, the materials and methods section needs to be improved as the picture on how the experiment was conducted is not clearly described.

Reply: Thanks for your suggestions. As suggested, we have rephrased the corresponding section in the Material and methods to describe the used approach in more detail.

Results:

Is the maximum vertical water transport reported an average of the three replications per treatment or just one maximum value of the three replicates? Please clarify in the manuscript.

Reply: Thanks for your attention. The maximum vertical water transport was an average of the three replications per treatment. We have clarified it in the manuscript.

Figure 3, 4, and 5: What is the label on the E axis? In what unit are the legends?

Reply: As suggested, we have added the label and unit in Figure 3, 4, and 5.

The results section is difficult to review due to lack of clarity and important omission in the methods. The current state of the manuscript requires extensive work on the materials and methods. The materials and method section lacks clarity and thus difficult to connect the results described to the conditions of the experiment conducted. A detailed description of the methodology is essential to be able to appreciate the result and hence the discussion section.

Reply: Thanks for your suggestions. We have added detailed description in Materials and method section.

Thank again for your comments and suggestions.

Best wishes!

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Dear authors,

Thank you for taking the time to address the comments in the revised version of this manuscript. I appreciate your efforts and look forward to the presentation of your relevant research results.

Best regards,

Author Response

Dear Reviewer:

Thanks very much for your comments concerning our manuscript. We are very appreciated for your reply. As suggested, we have checked the references carefully and deleted the cited references which were not relevant to the research.

Thank again for your comments and suggestions.

Best regards!

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Lines 103 – 109: Information regarding the temperature and rainfall during the study period are results, not methods. Please move to the appropriate section in the results and discussion. Please do the same for irrigation water applications.

Figure 8. The figure indicates that both nitrate and ammonium move faster or deeper than water. This may seem confusing given the fact that these solutes move with a wet front or with water. Although the authors presented this as a conceptual paradigm and not the actual results obtained.  An adjustment of this sketch to the real possible scenarios is recommended.

Comments on the Quality of English Language

The authors made some major improvements to the current version of the manuscript. The manuscript reads well under the current conditions but very few sections of the manuscript with grammatical errors especially missing prepositions. I recommend that authors have a careful readthrough for necessary corrections.

Author Response

Dear Reviewer:

Thanks for your consideration and help again. The comments are all valuable and very helpful for improving our paper. We have tried our best to revise our manuscript according to the received comments and suggestions. The revisions in the manuscript have been highlighted in red color. We hope meet with your approval.

Comments and Suggestions for Authors

Lines 103 – 109: Information regarding the temperature and rainfall during the study period are results, not methods. Please move to the appropriate section in the results and discussion. Please do the same for irrigation water applications.

Reply: Thanks for your comments. As suggested, we have moved the information regarding the temperature and rainfall and irrigation water applications to section 3.1 in the results.

Figure 8. The figure indicates that both nitrate and ammonium move faster or deeper than water. This may seem confusing given the fact that these solutes move with a wet front or with water. Although the authors presented this as a conceptual paradigm and not the actual results obtained. An adjustment of this sketch to the real possible scenarios is recommended.

Reply: Thanks for your suggestions. As suggested, we have redrawn Figure 8 in the revised manuscript.

Comments on the Quality of English Language

The authors made some major improvements to the current version of the manuscript. The manuscript reads well under the current conditions but very few sections of the manuscript with grammatical errors especially missing prepositions. I recommend that authors have a careful readthrough for necessary corrections.

Reply: We are sorry for the mistakes. We have checked the full manuscript carefully and made some corrections.

Thank again for your comments and suggestions.

Best wishes!

Author Response File: Author Response.pdf