Soil Hydraulic Properties of Plinthosol in the Middle Yangtze River Basin, Southern China

Round 1

Reviewer 1 Report

Dear authors, see the attached file with my comments. 

Comments for author File: Comments.pdf

Author Response

Dear Editor and Reviewers:

  Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Soil Hydraulic Properties of Plinthosol in the Middle Yangtze River Basin, southern China” (Manuscript ID: water-821202). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied the comments carefully and have made correction which we hope meet with 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 flowing:

 

Responds to reviewers’ comments:

 

Reviewer 1

 

MAJOR COMMENTS:

 

1. Comments to methodology: i) No in situ infiltration experiments were carried out to determine saturated/unsaturated hydraulic conductivity, which in my opinion should be present in a study dealing with the soil hydraulic properties; ii) No description and comments to porous system of the tested soil except of total porosity is present (distribution and quantification of macropores, mesopores and micropores can substantially contribute to water infiltration description); iii) possible seasonal changes are not involved, but the sampling was conducted from March to October 2018; iv) only three replicates per layer and site were evaluated.

  Response:

Thanks for your comments to the methodology section in our paper. We have made some emendation in the paper according to your comments, and some not clear and detailed statements also been re-described in the revised version.

i), The in situ infiltration experiment is a practical technique for obtaining accurate and precise data on soil hydraulic conductivity, and we are sure that this method will improve the accuracy of our study. However, there is no doubt that the measurement in the laboratory is still a widely accepted method, and the data are also credible in studying the soil hydraulic properties [a-b]. According to our experimental schedule, the in situ experiments and monitoring will be held in September 2020, some experimental items, such as the variation of soil temperature and moisture, soil erosion process and infiltration process will be carried out in the field, which belongs to another research project, and it will be described in the following paragraph, too.

References:

[a] Çerçioğlu, M.; Anderson, S.H.; Udawatta, R.P.; Alagele, S. Effect of cover crop management on soil hydraulic properties. Geoderma 2019, 343, 247-253.

[b] Kool, D.; Tong, B.; Tian, Z.; Heitman, J.L.; Sauer, T.J.; Horton, R. Soil water retention and hydraulic conductivity dynamics following tillage. Soil Till. Res. 2019, 193, 95-100.

 

ii), Thanks very much for your advice about the porous system of the tested soil. This is a wonderful question. The size, gradation and distribution of soil pores have vital effects on soil hydraulic properties, and this is one of the key scientific issues in the study of plinthosol, which requires a series of detailed experiments, for example, the 3-D scanning and in situ experiments. Therefore, another study program is in the process of preparing, which concentrates on the soil porous system, including the size and distribution of porosity, infiltration process, preferential flow and erosion process of plinthosol.

 

iii), Thanks for your suggestion about the seasonal change of soil. We totally agree with you on this issue. We added the climate of the sampling sites in line 117-126, in this paragraph, the climatic conditions and seasonal changes are involved. We know that the hydraulic properties of the plinthosol may change with seasons. Therefore, although the time interval of sampling is relatively long, the sampling time we chose avoid rainy seasons. Some other factors that may have an impact on the results are also avoided as far as possible, such as the conditions of temperature, vegetation coverage and human activities, which minimized the sampling error.

 line 118-126: All three study sites are located in the middle reaches of the Yangtze River, where subtropical monsoon climate is the main climate type. In Jiujiang city, the annual average temperature is 16 ℃ to 17 ℃; the annual rainfall is 1300 mm to 1600 mm, and more than 40 % is concentrated in the second quarter. Heavy rains are relatively frequent during the rainy season. In Wuhan city, the annual average temperature is 15.8 ℃ to 17.5 ℃, the annual precipitation is 1150 mm to 1450 mm. The rainfall is concentrated in June to August every year. The precipitation of these three months account for 40 % of the annual rainfall. In Yueyang city, the annual average temperature is 16.5 ℃ to 17.2 ℃. The annual rainfall is 1290 mm to 1560 mm, and 70 % of the precipitation are concentrated in the spring and summer, the annual distribution of rainfall is uneven at YE site.

iv), Thanks for your advice about the replicated measurements. This comment is very helpful for our study. There is no doubt that the more repeated measurements, the more accuracy of the experiments, and we will increase the number of replicated measurements in the following studies. In practice, three replicated measurements with good repeatability could provide sufficient support for a study [28,33,34]. So, the data in this study is credible.

References:

[28] Çerçioğlu, M.; Anderson, S.H.; Udawatta, R.P.; Alagele, S. Effect of cover crop management on soil hydraulic properties. Geoderma 2019, 343, 247-253.

[33] Bagarello, V.; Baiamonte, G.; Caia, C. Variability of near-surface saturated hydraulic conductivity for the clay soils of a small Sicilian basin. Geoderma 2019, 340, 133-145.

[34] Tian, Z.; Kool, D.; Ren, T.; Horton, R.; Heitman, J.L. Approaches for estimating unsaturated soil hydraulic conductivities at various bulk densities with the extended Mualem-van Genuchten model. J. Hydrol. 2019, 572, 719-731.

 

2. Climatic conditions of the experimental sites are completely missing. Especially those showing precipitation data, averages, sums and also intensity are of relevance, since this study is intended to investigate factors causing soil erosion. More detailed description of the soil cover, type of clay minerals (possible shrinking and swelling extents), and porous system description is needed in order to describe water infiltration and movement through the soil profile (and possible surface and subsurface runoff formation). In my opinion, all this information should be given to the readers in the Materials and Methods section.

  Response:

  Thanks for your comments to the details about experimental sites, we have added the climatic conditions, soil cover, type of clay minerals of sampling sites according to your suggestion. Please see: line 112-126.

  Line 112-126: The red and brown color of plinthosol was caused by Fe oxide. Generally, the red matrix contains more Fe oxide and leads to brown color, the white vines contain less Fe oxide and shows white and light-yellow color. Clay minerals are fairly stable and are an important component of soil, and clay minerals in the plinthosol are mainly illite, kaolinite, illite–smectite mixed-layer clays, and minor chlorite [10]. Mineral types in different places are slightly different, which caused by difference of weathering and origin [15].

All three study sites are located in the middle reaches of the Yangtze River, where subtropical monsoon climate is the main climate type. In Jiujiang city, the annual average temperature is 16 ℃ to 17 ℃; the annual rainfall is 1300 mm to 1600 mm, and more than 40 % is concentrated in the second quarter. Heavy rains are relatively frequent during the rainy season. In Wuhan city, the annual average temperature is 15.8 ℃ to 17.5 ℃, the annual precipitation is 1150 mm to 1450 mm. The rainfall is concentrated in June to August every year. The precipitation of these three months account for 40 % of the annual rainfall. In Yueyang city, the annual average temperature is 16.5 ℃ to 17.2 ℃. The annual rainfall is 1290 mm to 1560 mm, and 70 % of the precipitation are concentrated in the spring and summer. Furthermore, compared with the other two sampling sites, the annual distribution of rainfall is uneven at YE site.

  We are very sorry that the description about the soil porous system is missed. As the statements in response 1-ii), the study of porous system is listed in our next program, which will be carried out in this September.

 

3. I miss the new insights in the presented manuscript, I see a nice summary of measured data, but the discussion only comments the results and does not address the environmental problems of the area being investigated.

  Response:

  Thanks for your advice. Portions of the Discussion this manuscript was modified according to your advice. Please see:

  Line 417-423：As an important parameter in predicting soil erodibility factor and hence inter-rill erosion [38], the fractal dimension of soil aggregates also reflects the soil disintegration resistance. Generally, lower value of fractal dimension implies a better disintegration resistance. In this study, the value of fractal dimension in JU is lower than that in WH and YE, which indicates that the stability of JU plinthosol is better than that of WH and YE plinthosol. Since the study area suffers from severe soil erosion, our result is helpful for calculating the resistance of soil erodibility, and taking the corresponding soil conservation measurements in different regions.

 

  MINOR COMMENTS:

 

1. Keywords selection – I would recommend some minor changes since practically all keywords are within the title which limits the visibility of the paper.

Response:

Line 34, thanks for your advice, the key words were re-selected. The “Discriminant analysis; Fractal dimension” were added

 

2. Line 133: “Particle size distribution” is a term usually used instead of “Grain-size composition”.

Response:

Thanks for the tip, in line 149, the “grain-size composition” was replaced as “Particle size distribution”

 

3. Lines 144: “∆h is the pressure head” … I would use the term “inflow and outflow difference” instead of pressure head.

  Response:

Thanks for your advice, line 161, the “pressure head (cm)” was corrected as ““inflow and outflow difference (cm)”

 

4. Line 147: Why the temperature of 10°C was used? Usually the laboratory temperature is kept at 20°C.

Response:

Thanks for your suggestion about the temperature. The measurement of the soil saturated hydraulic conductivity was carried out in November and no air conditioning at work, the indoor temperature was at around 10°C and varied with time. In order to make the results comparable to each other, we converted the value of K_s into the same temperature (10℃).

 

5. Missing reference to the wet sieving method.

  Response:

Thanks for the tip. Line 168, the reference has been added. (35. Yoder, R.E. A direct method of aggregate analysis of soils and a study of the physical nature of erosion losses. J. Am. Soc. Agron. 1936, 28, 165-169.)

 

6. Type of the device should be mentioned together with the method description on line 150.

  Response:

Thanks for your advice, Line 166-168, the type of the device was added. (The type of device is TTF-100, produced by Shangyu Shunlong Laboratory Instruments Factory, Zhejiang Province, China)

 

7. Was drying of the samples for 12 hours enough to reach the constant mass?

  Response:

Thanks for your suggestion. We are very sorry that we made a mistake, actually, all the soil samples have been dried more than 24 hours, we have rectified this mistake in our manuscript.

Original statement: The aggregates retained on each sieve were collected and weighed after drying at 105°C to dry for 12 hours.

Revision: Line 172, The aggregates retained on each sieve were collected and weighed after drying at 105°C to dry completely (24 hours).

 

8. The equation used for the fitting by RETC should be specified (RETC offers eight different models for retention data fitting). Also the settings of the fitting code should be specified; in some cases the code fitted saturated water content θs higher than calculated porosity (see the results presented in Table 1 and Table 3). The code enables to set minimum and maximum values for each of the fitting parameter.

  Response:

Thanks for your advice, we added the equation in our paper. (line 198-199).

The maximum number of iterations is set to 50. The type of the retention curve model is ven Genuchten, m=1-1/n (type 3), equation used for the fitting by RETC is formula (7).

 

9. The “Porosity” data are probably in cm3/cm3 (for % expression, they should be multiplied by 100)

    Response:

Thanks for your advice, we have modified the mistake. Line 238, we have corrected the “%” as “cm³·cm^-3”.

 

10. Correlations between Ks and other characteristics; correlation coefficients reaching 0.3 or 0.35 are referring to a weak relationship. It can also be interesting to see the correlations between Ks and OM contents.

  Response:

Correlations between K_s and OM contents have been showed in Table 2, the explanation about the Table 3 was added (line 327-329).

The result shows a strong positive correlation between the K_s values and OM contents in Table 2. Which confirmed that the K_s values of soil is indeed affected by the OM contents.

 

11. Line 296- Figure 10: Soil water retention curve – In my opinion, the SWRC should be displayed as pF curve (water suction in cm in log scale). The points at the lower suctions would be nicely distinguished. Moreover, the title should be changed accordingly to the data displayed (it appears to me that measured data are displayed as points and fitted data as lines). This fact should also be added to the legend of the graphs.

  Response:

Thanks for your advice, we have modified figure 10 and its caption according to your suggestion. Please see line 335-338.

Line 335-338: Caption of Figure 11, Soil water retention curves (SWRCs) of YE, WH and JU profile. (In this figure, the dots represent the measured data and the fitted data were exhibited by lines. In the legend, the ten numbers 01 to 10 are marked with points in different colors, which represent the ten soil layers from 0-10 cm to 90-100 cm.)

 

12. Line 312: Table 3 – The fitting accuracy of the SWRC can also be expressed as RMSD (root mean square difference). This value quantifies the differences between the data pairs “measured – fitted” and thus evaluate the quality of the fit in a nice and comparable way.

  Response:

Thanks for your advice. In Line 360, Table 3 was modified according to your suggestion. The RMSD was added in Table 3. Most of the values of RMSD were less than 0.01.

 

13. Line 344: “Effect of source on …” It appears to me that “Effect of soil origin…” should be used.

  Response:

Thanks for your advice, line 396, the “source” was corrected as “soil origin”. We also replaced every “source” with “soil origin” in this manuscript.

 

14. Line 381: “spatial variability” instead of “special variability”

  Response:

Thanks for your advice, line 441, the “special variability” was corrected as “spatial variability”.

 

15. Lines 428-445 – Conclusions: should be reformulated to meet the purpose of the study described on Lines 88-91 and not to repeat the results.

Response:

Thanks for your suggestion, in line 496-512, we have modified the Conclusion. In the revised version, we highlighted our insights and the interrelation between the indices mentioned in the paper.

This study focused on the soil water hydraulic properties of the plinthosol in the middle Yangtze River basin, three typical profiles were sampled and studied. The main conclusions are summarized as follows:

(1) Discriminant analysis showed, in JU profile, the range of Y value is -12.37 to 6.94, and most samples are lower than -2.7411; while in WH and YE profile, all the Y values are higher than -2.7411. This result indicates that the origin of JU plinthosol is aeolian sediments, while in WH profile and YE profile, the origin might be alluvial deposition.

(2) The difference of soil origin affects soil hydraulic properties. The macro-aggregates content of JU profile is relatively higher than that of YE and WH profile, while the D_i, D_r are lower in JU plinthosol. Fractal dimension analysis shows, the D value of JU plinthosol is lower than that of WH and YE plinthosol, which confirmed that the stability of JU plinthosol is superior to that of the other two sites.

(3) Soil origin plays a basic role in soil particle size distribution, which affects the water holding capacity, soil stability, hydraulic conductivity and soil-water holding capacity. Meanwhile, soil hydraulic conductivity has a strong correlation with the organic matter contents.

(4) The water stability of white vein and red matrix showed great difference. The particle size composition and the proportion of white vein and red matrix played an important role in the difference of soil hydraulic properties.

This study confirmed the multiple origin of plinthosol in the middle Yangtze River basin, and different origins could result in the difference in soil hydraulic properties. These findings about plinthosol in hydraulic conductivity, water-holding capacity and disintegration resistance could provide implications in vegetation construction and soil and water conservation in the middle Yangtze River basin.

 

16. Line 446 – Patents: it looks there are no patents involved, so the heading should be removed.

  Response:

    Thanks for your advice, line 514-Patents, have been removed.

 

  Special thanks to you for your comments and suggestions! Your comments are especially important for our future studies!

 

Author Response File: Author Response.docx

Reviewer 2 Report

In this manuscript, the authors address soil hydraulic properties and their variations from three places in Southern China. For this purpose, soil aggregate sizes, water retention curve, saturated hydraulic conductivity along other soil properties were measured. The authors discuss that variation in soil hydraulic properties could be due to the origin of Plinthosol. Overall, the manuscript is well written and justified. However, as several places, the English quality of the manuscript should be improved. Reference list should be updated somehow. Detailed comments can be found in the manuscript body. After major revisions, the manuscript can be published.

Comments for author File: Comments.pdf

Author Response

Dear Editor and Reviewers:

  Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Soil Hydraulic Properties of Plinthosol in the Middle Yangtze River Basin, southern China” (Manuscript ID: water-821202). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied the comments carefully and have made correction which we hope meet with 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 flowing:

 

Reviewer 2

 

MAJOR COMMENTS:

 

1. In this manuscript, the authors address soil hydraulic properties and their variations from three places in Southern China. For this purpose, soil aggregate sizes, water retention curve, saturated hydraulic conductivity along other soil properties were measured. The authors discuss that variation in soil hydraulic properties could be due to the origin of Plinthosol. Overall, the manuscript is well written and justified. However, as several places, the English quality of the manuscript should be improved. Reference list should be updated somehow. Detailed comments can be found in the manuscript body. After major revisions, the manuscript can be published.

Response:

Thanks very much for your comments about our manuscript. We have studied comments carefully and have made correction which we hope meet with approval. In the revised manuscript, some new references have been added, and the writing mistakes have been modified.

   

2. Another index or parameter that the authors might have calculated from aggregate size distribution is mass fractal dimension.

Response:

Thank you very much for your suggestion. Mass fractal dimension is a very useful parameter for the study of soil aggregates. We studied the recommended paper carefully. Unfortunately, during the measurement of WSA, we did not test the volume of aggregates at different water content. So, it is very hard for us to calculate the mass fractal dimension by the equation in paper you listed. However, the fractal dimension of soil aggregates could take the place, it be calculated by the Formula (5), so we applied this index in Line 177.

Line 177: Furthermore, the fractal dimension based on the soil aggregates were calculated [37-38].

(5)

Where the d_i is the aggregates size class, d_max is the mean diameter of the largest aggregates class, the D is fractal dimension, m_i is cumulative mass of aggregates of size less than i-th size fraction and the m_max is the total mass of all size fraction aggregates.

Reference:

[37] Ahmadi, A.; Neyshabouri, M.R.; Rouhipour, H.; Asadi; H. Fractal dimension of soil aggregates as an index of soil erodibility. J. Hydrol. 2011, 400, 305-311.

[38] Tagar, A.A.; Adamowski, J.; Memon, M.S.; Do, M.C.; Mashori, A.S.; Soomro, A.S.; Bhayo, W.A. Soil fragmentation and aggregate stability as affected by conventional tillage implements and relations with fractal dimensions. Soil Till. Res. 2020, 197, 104494.

 

Line 292-299: The fractal dimension of WSA was shown in Figure 8. Generally, the lower D value indicates a stronger stability [37-38]. In WH and YE profile, the D value of the upper layer is higher than that in the middle and bottom layers, which indicates the strong stability in the upper layer. In JU profile, the D value is lower than that in WH and YE profile, the lowest D value appeared at the depth of 60 cm, demonstrates that the stability of plinthosol in JU profile is the highest among the sampled profiles. The results of fractal dimension strongly support the result of the WSA content.

Figure 8. Fractal dimension (D) of WSA in JU, WH and YE profile.

 

 

3. Response to comment in line 199: “What is the midpoint? Please clarify”.

  Response:

Thanks for your advice, we have added the description of the midpoint. “the median value of maximum and minimum of i-th size fraction, such as the midpoint particle diameter of 0-2 μm is 1 μm.” (line 225-226)

 

4. Response to comment in line 294: “The figure’s caption should be self-content. What is the line really representing in Fig. 10? Please clarify in the caption and context”.

  Response:

  Thanks for your advice, we have added the details of the figure 10, and the number has been changed to 11.

Line 335-338: Figure 11. Soil water retention curves (SWRCs) of YE, WH and JU profile. In this figure, the color dots represent the measured data and the lines represent the fitted curve using van Genuchten (m=1-1/n) model. In the bottom of this figure, a series of colored points numbered from 01 to 10, represent the sampled soil layers from 1-10 cm to 90-100 cm (only 9 layers in YE profile.

 

5. The table caption is not informative! The authors have to clearly mention which parameter is which (define parameters), and also state that these are van Genuchten model parameters. Neither the caption nor the context explains that! In addition, if lines in Fig. 10 represent the van Genuchten model, those have to be continuous in form starting from saturated water content to high matric potentials. Currently, they look like denoting the Brooks and Corey (1964) model, which is discontinuous in form and breaks at the air entry pressure.

  Response:

  Thanks for your advice, we have modified the caption and contents of Figure 10 (in the revised version, this figure was re-arranged as figure 11) and added the equation in this manuscript. The parameters of the equation have been explained at the methodology (line 360-362). Actually, the other reviewer’s comments are similar to yours, but not exactly the same. We have made many modifications in the manuscript to meet the requirements as much as possible.

Line 360-362: The R² and root mean square difference (RMSD) were calculated in this Table. The θ_r, θ_s are the residual water content and the saturated water content, respectively. The α (kPa^-1), n and m (m=1−1/n) are empirical parameters.

 

6. Response to comment in line 320-321: “The authors could be more specific about the relationship between parameter alpha and the air entry pressure. For example, Ghanbarian et al. (2010) showed that alpha is a power-law function of air entry pressure with a negative exponent. Please see Eqs. (13) and (18) in their paper”.

  Response:

  Thanks for your advice. We have read the paper carefully that you recommended for us. And some description about the parameters have been added. (Line363-364 and line 367-368)

  Line 364-365: The α (cm^-1) and n are model parameters; m=1-1/n.

Line 368-369: In this study, the values of fitting parameter α vary at different layers, and decrease with depth. However, the variation of α is different among the study sites.

 

7. Response to comment in line 408-430 (section 4.3): “The authors mention weathering at several places but do not provide detail about it. What kind of weathering? Silicate, chemical, or what? Please clarify in the context”.

  Response:

Thanks for your advice, we have modified the Section 4.3 of this manuscript and added the details about the weathering. Line 464-470:

Clay minerals are layer silicates that formed as products of progressive chemical weathering [60]. Chronological studies indicated that plinthosol was formed under humid and warm climatic conditions during the mid-Pleistocene [10]. Generally, this type climate is accompanied by strong weathering. Plinthosol is thought to have been produced by strong pedogenesis with intense oxidation and leaching, which resulted from enhanced East Asian summer monsoon activity [11]. In the studies of plinthosol, the particle size distribution was frequently used as a parameter to characterize the weathering intensity [12,49].

References：

[10] Liu, C.; Deng, C.; Liu, Q. Mineral magnetic studies of the vermiculated red soils in southeast China and their paleoclimatic significance. Palaeogeogr. Palaeocl. 2012, 329-330, 173-183.

[11] Hong, H.; Gu, Y.; Yin, K.; Zhang, K.; Li, Z. Red soils with white net-like veins and their climate significance in south China. Geoderma 2010, 160, 197-207.

[12] Hu, X.; Cheng, T.; Wu, H. Do multiple cycles of aeolian deposit-pedogenesis exist in the reticulate red clay sections in southern China. Chinese Sci. Bull. 2003, 48, 1251-1258.

[49] Zhang, Z.; Pendin, V.; Nikolaeva, S.; Zhang, Z.; Wu, J. Disintegration characteristics of a cryolithogenic clay loam with different water content: Moscow covering loam (prQIII), case study. Eng. Geol. 2019, 258, 105159.

[60] Gabriel, R.P.A.; Antonio, C.A.; Jacqueline, K.L.; Thais C.A. Weathering of Permian sedimentary rocks and soil clay minerals transformations under subtropical climate, southern Brazil (Paraná State). Geoderma 2019, 336, 31-48.

 

  MINOR COMMENTS:

 

1. Line 17, focused

Response:

Thanks for the tip, the “focused” was corrected as “focuses”. (Line17)

2. Line 20-24, The results showed: (1)...(2)...(3)

Response:

Thanks for your advice, the “The results showed” and the serial number “(1), (2), (3)” were deleted. (Line 20-27)

3. Line 154, How many sieves and which sizes? Please clarify.

Response:

Thanks for your advice, the number and size of sieves were added in paper. The revised statement: “The mesh sizes for sieves were 5 mm, 2 mm, 1 mm, 0.5 mm and 0.25 mm, respectively”. (Line 172-173)

 

4. Line 186, that,

Response:

Thanks for the tip, the “that,” was corrected as “that”. (Line 212)

 

5. Line 276, Not surprising! Typically bulk density increases and porosity decreases with depth. That might be why Ks decreased with depth.

Response:

Thanks for your advice, we have corrected the original statement as “With the increase of bulk density, the porosity decreases and the K_s of the three profile decreases with depth (Figure 10).” (Line 310-311)

 

 

6. Line 281, For the sake of consistency, please use saturated hydraulic conductivity.

Response:

Thanks for your suggestion. the “water permeability” was corrected as “saturated hydraulic conductivity”. (Line 315)

 

7. Line 293, This statement here is confusing! Please remove.

Response:

Thanks for your advice, the “K_s value (cm/d)” was removed. (Line 331)

 

8. Line 322, indexes

Response:

Thanks for the tip, the “indexes” was corrected as “indices”. (Line 374)

 

 Thank you very much for your valuable comments!

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Dear Authors,

Thank you for your point-by-point response to my comments and suggestions. I have only one additional point, which needs to be sorted out before I can recommend it to Editors for publication. That point deals with the “Minor change of Figure 10 (now figure 11)” dealing with the Soil water retention curve graphs.

My new comment:

Please check carefully the fitting of your measured data. Van Genuchten’s model is a special shaped curve fitting the measured points of the SWRC quite nicely. Please see the attached file with the figure and an example of the  shape of the fitted curves by employing van Genuchten eq. The straight line shapes in your graphs do not look correct. Please clarify. 

Comments for author File: Comments.pdf

Author Response

Thank you very much for your new comments. These comments are especially valuable for improving this manuscript, we checked the measured data carefully and studied the recommended paper.

In our manuscript, the fitting data was obtained by the software named RETC, and the figure was made by another software named Origin. We checked the fitting data carefully and confirmed that the data in table 3 is correct. However, the formatting setting of figure 11 is defective. In order to solve the problem mentioned in your comments, we reset the parameters before running the software, and a new figure has been obtained.

Author Response File: Author Response.docx

Reviewer 2 Report

The authors have addressed most of my comments satisfactorily, and now the manuscript can be accepted for publication.

Author Response

Thank you very much for your affirmation and encouragement. Our deepest gratitude goes to you for your careful work and useful suggestions that have helped improve this paper substantially.

Author Response File: Author Response.docx