Soil Water Infiltration Model for Sprinkler Irrigation Control Strategy: A Case for Tea Plantation in Yangtze River Region
Round 1
Reviewer 1 Report
Review of the manuscript agriculture-567812 entitled “soil water infiltration model for sprinkler irrigation control strategy: A case for tea plantation in Yangtze River region”. This manuscript focuses on modeling and measurements of infiltration rate and water redistribution within the soil profile under multiple slope gradients. The subject is worthy of investigation and is within the scope of the journal. The manuscript is relatively easy to follow. However, the writing needs substantial improvement as it suffers from both grammatical and phrasing errors.
Following are more comments to improve the manuscript:
~ A final round of proofreading, preferably by a native English speaker, is required as I found quite a few grammatical and phrasing errors.
~ Line 25: the increment of volumetric water content (VWC) at 10 cm depth changed, you mean the VWC increased at 10 cm depth as the water application rate increased?
~ Lines 28-29: Are you saying that the infiltration increased as the slope gradient increased? The common belief is that higher slops increase the runoff which in turn reduce the relative infiltration.
~ Lines 30-31: How come there are two values for the relative error between the measured and expected infiltration values?
~ Line 40: photosynthetic and respiration rates of tea leaves decrease
Figure 1. Please add a photo of the irrigation setup here.
~ Line 124: needs citation
~ Lines 126-130: Was the initial soil water content similar each time the infiltration test conducted?
~ Lines 126-130: How did you measure deep percolation and runoff?
~ Line 192: How did you calculate the required irrigation time? 144 minutes runtime is likely to cause significant runoff.
Author Response
Dear reviewer,
Thank you for your letter and the reviewers’ comments concerning our manuscript entitled” “Soil water infiltration model for sprinkler irrigation control strategy: A case for tea plantation in Yangtze River region”. (ID: agriculture-567812). Thank you for giving our opportunity to revise our manuscript. Those comments are all valuable and very helpful for improving our manuscript. We have studied the comments carefully and have made correction which we hope will meet your request and for approval.
Revised portion are marked in green in the revised version.
Best,
Yongzong Lu and Yongguang Hu.
Review of the manuscript agriculture-567812 entitled “soil water infiltration model for sprinkler irrigation control strategy: A case for tea plantation in Yangtze River region”. This manuscript focuses on modeling and measurements of infiltration rate and water redistribution within the soil profile under multiple slope gradients. The subject is worthy of investigation and is within the scope of the journal. The manuscript is relatively easy to follow. However, the writing needs substantial improvement as it suffers from both grammatical and phrasing errors.
Following are more comments to improve the manuscript:
(1) A final round of proofreading, preferably by a native English speaker, is required as I found quite a few grammatical and phrasing errors.
R: Thanks for your kind comments for revising and improving our manuscript. I have asked help from my hosting supervisor on improving the language quality who are from the University of California, Davis. I have carefully checked all the citations and sentences and found some obvious errors. Especially, I have revised the results and conclusions sections to make it more fluent and clarified. I have already revised them in the new manuscript. If the reviewer evaluates my revised manuscript and thinks that it still needs to be improved by the professional editing, I would like to ask help from the MDPI author service to improve it.
The relevant corrections have been made in the revised version in the manuscript.
(2) Line 25: the increment of volumetric water content (VWC) at 10 cm depth changed, you mean the VWC increased at 10 cm depth as the water application rate increased?
R: Thanks for your revision. We accept your revision.
The relevant corrections have been made in revised version in the manuscript.
(3) Lines 28-29: Are you saying that the infiltration increased as the slope gradient increased? The common belief is that higher slops increase the runoff which in turn reduce the relative infiltration.
R: From our experiments, we found that soil water infiltration rate increased with the application rate when the slope gradient remained constant. Meanwhile, it decreased with the increase of slope gradient at a constant water application rate. However, at a constant water application rate, the infiltration depth increased with the increasing of slope gradient. The runoff is related to a certain critical slope gradient. Based on the slopes we selected in the research, the testing results showed that the infiltration depth increased as the slope gradient increased. The relationship between slope and infiltration depth is basically a trend of convex curve which has been validated in several research papers.
(4) Lines 30-31: How come there are two values for the relative error between the measured and expected infiltration values?
R: In the infiltration model validation experiments, two cases were selected to based on the most common terrains of tea farms in the Yangtze River region: (1) gradient 0° and 8.0mm/h for water application rate; (2) gradient 8° and 4.0mm/h for water application rate. So, there are two values for the relative error between the measured and expected infiltration values, respectively.
The relevant corrections have been made in revised version in the manuscript.
(5) Line 40: photosynthetic and respiration rates of tea leaves decrease
R: Thanks for your kind comments. Here is the grammar mistake and I accept your revision.
The relevant corrections have been made in revised version in the manuscript.
(6) Figure 1. Please add a photo of the irrigation setup here.
R: Thanks for your comments. I added a photo of the irrigation setup.
The relevant corrections have been made in revised version in the manuscript.
(7) Line 124: needs citation
R: Thanks for your kind comments. We added the citation for the line 124.
The relevant corrections have been made in revised version in the manuscript.
(8) Lines 126-130: Was the initial soil water content similar each time the infiltration test conducted?
R: The initial soil water content was shown in the figure 4 (a), there were almost similar but not the same. So we compared the increment of the VWC under nine treatments.
(9) Lines 126-130: How did you measure deep percolation and runoff?
R: For the deep percolation, the depth of the soil in the frame box is much deeper than the ultimate infiltration depth. Under the three kinds of water application rates, there was no deep percolation in this research. In this research, a plastic shade was set up on the top of the experiment area in the rainy days to avoid the influence of rainfall. As we all know, sprinkler irrigation basically does not cause so much deep leakage and surface runoff. So, in the nine treatments, we did not measure the runoff. We did not take the runoff into consideration before we conducted the experiment. We think the runoff is pretty small in the box frame with the slope gradient changed from 0~15 °. We will take the runoff into consideration in our future research to find out the relationship between runoff, VWC and slope rates.
(10) Line 192: How did you calculate the required irrigation time? 144 minutes runtime is likely to cause significant runoff.
R: As shown in the line175 to 187, we provided the calculation procedure of the required irrigation time. The irrigation required time is calculated by the infiltration rate, the required infiltration depth and the root depth of the tested tea plant. The infiltration rate and required infiltration depth is calculated by the the linear regression equation between infiltration rate, slope gradient, and water application rate. We ignore the influence of the runoff in all the nine treatments. We will take the runoff into consideration in our future research to find out the relationship between runoff, VWC and slope rates.
line175 to 187: “through the multivariate regression analysis, it can be concluded that the relationship between slope gradient, water application rate and the ratio of stopping irrigation depth to infiltration depth.
By multivariate regression analysis, the linear regression equation between infiltration rate, slope gradient, and water application rate were obtained. The coefficient of equation determination (R2) is 0.92. The linear regression equation is as follows.
Author Response File: 
Author Response.docx
Reviewer 2 Report
General
The paper shows a nice example of combined field experiments and modelling work. It shows that models can be applied to explain variations in measured soil moisture with Sprinkler irrigation method. The paper is well-structured and the english is good. Some of the figures can be improved. I'll come to that later.. However, I could not find any new things/state of the art in this paper.
Some general remarks
Minor revision
Page 1 - line 37 – please, enter the evapotranspiration information to complete the climatological description
Page 3 - line 104 – The acronym is cited for the first time, and therefore, should be entered its full meaning
Page 5 - line 126- The first sentence may be more accurate
Page 7, line 172, what is the meaning of the term “surface epidermis”?
Page 7, lines 177, 183,184, and 185 - It is important to discuss the application limits of the developed model.
Page 9, line 214 - Discussion - In general, this part is not sufficiently discussed with the scientific literature.
Page 7. Line 179- The root mean square error (RMSE) can be used to evaluate the fitting effect of the model
Figure:
Page 3 -Figure 1 - The Figure resolution should be improved, because it is not possible to see the numbers corresponding to the position of the sensor.
Page 4 - Figure 3 - The caption of Figure 3 may be more detailed.
Page 5, Table 3 - Table 3 caption may be more detailed
Page 5, line 139 - 2.2.3. Infiltration model validate experiments - this part is poorly detailed, please develop further the paragraph by providing more details on the experiments’ validation.
The information concerning the used multivariate regression appears in the results but is not well detailed in the methodology.
Page 6 - Figure 4. The shape and color of the T7 marker hamper the identification on the chart.
References
I recommend standardizing the references’ formatting. For example, references 36 and 42 are missing a point at the end of the authors’ list.
Author Response
Dear reviewer,
Thank you for your letter and the reviewers’ comments concerning our manuscript entitled” “Soil water infiltration model for sprinkler irrigation control strategy: A case for tea plantation in Yangtze River region”. (ID: agriculture-567812). Thank you for giving our opportunity to revise our manuscript. Those comments are all valuable and very helpful for improving our manuscript. We have studied the comments carefully and have made correction which we hope will meet your request and for approval.
The revised portion is marked in green in the revised version.
Best,
Yongzong Lu and Yongguang Hu.
The paper shows a nice example of combined field experiments and modelling work. It shows that models can be applied to explain variations in measured soil moisture with Sprinkler irrigation method. The paper is well-structured and the english is good. Some of the figures can be improved. I'll come to that later.. However, I could not find any new things/state of the art in this paper.
Some general remarks
Minor revision
(1) Page 1 - line 37 – please, enter the evapotranspiration information to complete the climatological description
R: Thanks for your kind comments. We added the evapotranspiration information in the description.
“The annual reference evapotranspiration (ET0) was 892.24 mm which was observed in the last 55 years (1961-2015) [37]”
The relevant corrections have been made in revised version in the manuscript.
(2) Page 3 - line 104 – The acronym is cited for the first time, and therefore, should be entered its full meaning
R: Sorry for making you confused. We revised sentence as follows:
“The classification of soil texture is based on the World Reference Base (WRB) soil classification system[38]”.
The relevant corrections have been made in revised version in the manuscript.
(3) Page 5 - line 126- The first sentence may be more accurate
R: Sorry for making you confused. We revised sentence as follows:
“Soil type in the experimental site the was homogeneous sandy loam soil.”
The relevant corrections have been made in revised version in the manuscript.
(4) Page 7, line 172, what is the meaning of the term “surface epidermis”?
R: Sorry for making you confused. We found here was a description error and we deleted this sentence.
The relevant corrections have been made in revised version in the manuscript.
(5) Page 7, lines 177, 183,184, and 185 - It is important to discuss the application limits of the developed model.
R: Thanks for your kind comments for revising and improving our manuscript. We added some discussion for limitation of the developed model.
(6) Page 9, line 214 - Discussion - In general, this part is not sufficiently discussed with the scientific literature.
R: Thanks for your kind comments for revising and improving our manuscript. We added some discussion for the research on the infiltration characteristic.
The relevant corrections have been made in revised version in the manuscript.T
(7) Page 7. Line 179- The root mean square error (RMSE) can be used to evaluate the fitting effect of the model
R: Thanks for your kind comments. We added the RMSE information in the manuscript.
Figure:
(8) Page 3 -Figure 1 - The Figure resolution should be improved, because it is not possible to see the numbers corresponding to the position of the sensor.
R: Thanks for your kind comments. I think you are talking about the figure 3. Only figure 3 showed the position of the sensor. we improved the quality of the figure 3 to make the number more clearly.
(9) Page 4 - Figure 3 - The caption of Figure 3 may be more detailed.
R: Thanks for your kind comments, we added more information in the figure 3.
(10) Page 5, Table 3 - Table 3 caption may be more detailed
R: Thanks for your kind comments, we added more information in the table 3
(11) Page 5, line 139 - 2.2.3. Infiltration model validate experiments - this part is poorly detailed, please develop further the paragraph by providing more details on the experiments’ validation. The information concerning the used multivariate regression appears in the results but is not well detailed in the methodology.
R: Thanks for your kind comments. We revised the section 2.2.3 as following:
“Soil water infiltration model was established based on tea root depth, water application rate, and slope gradient. The reliability of the model was evaluated in the box frame experiments based on two cases which were the most common terrains of tea farms in the Yangtze River region: (1) gradient 0° and 8.0mm/h for water application rate; (2) gradient 8° and 4.0mm/h for water application rate. The required irrigation time and expected infiltration depth were calculated. VWC at the depth of 10.0cm, 20.0cm, 30.0cm and 40.0cm was measured, respectively. The ultimate infiltration depth was compared with the expected value to obtain the relative error between measured and expected value.”
Page 6 - Figure 4. The shape and color of the T7 marker hamper the identification on the chart.
R: Thanks for your kind comments. We changed the color and shape of the T7 to make it more clearly.
References
I recommend standardizing the references’ formatting. For example, references 36 and 42 are missing a point at the end of the authors’ list.
R: Thanks for your kind comments. We checked all the references and revised the format to meet the requirement of the journal.
Author Response File: Author Response.docx
