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Peer-Review Record

Effect of Different Thresholds of Drip Irrigation Using Saline Water on Soil Salt Transportation and Maize Yield

Water 2018, 10(12), 1855; https://doi.org/10.3390/w10121855
by 1, 2,3,*, 1,4,*, 5 and 6
Reviewer 1: Anonymous
Reviewer 2: Anonymous
Water 2018, 10(12), 1855; https://doi.org/10.3390/w10121855
Received: 11 November 2018 / Revised: 4 December 2018 / Accepted: 5 December 2018 / Published: 14 December 2018
(This article belongs to the Section Water Use and Scarcity)

Round  1

Reviewer 1 Report

See attached file

Comments for author File: Comments.pdf

Author Response

Dear Editors and Reviewers:

Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Effect of Different Thresholds of Drip Irrigation Using Saline Water on Soil Salt transportation and Maize Yield”, (Water-396466). 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 comments carefully and have made correction which we hope this revision can make our paper more acceptable. Revised portion are marked in green in the paper. The main corrections in the manuscript are as flowing:

Title and abstract.

Page 1. As reviewer suggested that we have remove the numbering in the “Abstract” and rewrite it as follow:

       Sustainable development of saline water irrigation was restricted in HID (Hetao Irrigation District) by serious yield reduction and severe salt accumulation without effective irrigation schedule. Field experiments were carried out to study the effects of drip irrigation thresholds on soil salt transportation and maize yield with shallow saline ground water in 2015 and 2016 in HID. The irrigation was triggered by four SMP (Soil Matric Potential) treatments which measured 20 cm beneath the drip emitter. Results indicated that the shape of wetting body approximated to one-fourth ellipse on the vertical profile perpendicular to the drip line, while the horizontal radius increased with the increase of SMP, moreover, salt accumulation decreased with the increasing thresholds in 0-1000px layer, while the soil salt in 40-100 cm was hardly affected by SMP thresholds under drip irrigation quota of 22.5mm. Maize yield showed a quadratic relationship with SMP threshold, and the IWUE (Irrigation Water Use Efficiency) showed a linear increase in response to the decrease in SMP threshold. Taking into account the salt accumulation, yield and IWUE, SMP threshold higher than -30kPa is suggested as the appropriate indicator for maize mulched drip irrigation with shallow saline groundwater in HID.

Page 1. As reviewer suggested that we have written the text “Irrigation water use efficiency”, after the IWUE acronym according to another reviewer comments.

Page 1. As reviewer suggested that we have added “ (Hetao Irrigation District)” after the acronyms of “HID”;

Introduction.

Page 1. As reviewer suggested that we have added “ (Hetao Irrigation District)” after the acronyms of “HID”;

Page 3. As reviewer suggested that we have added “(Soil Matric Potential)” after the acronyms of “SMP”;

Page 3. As reviewer suggested that we have replaced the expression “irrigation water use efficiency (IWUE)” by “IWUE (Irrigation Water Use Efficiency)”;

Material and methods.

Page 7. In section 2.3.4 Maize Yield, the equation “” is added to estimate maize yield. Where  is the estimated maize yield (kg/ha), while  is the measured maize yield (kg/12 m2).

Discussion.

Page 17. We have re-written the Discussion according to the reviewer’s suggestion: “According to the 2 years field experiment conducted in HID, soil moisture and soil salt revealed a short-term fluctuation during the maize growth period, a low-salt zone in the plough layer and a high-salt region in the topsoil out of the mulch emerged, the isoline distribution of soil salt was similar to that of soil moisture, moreover, as a result of point source infiltration, a wetting body similar to one-fourth ellipse in the vertical profile perpendicular to the drip line emerged, and the horizontal radius of the wetting body increased with the increase of SMPs, while the vertical radius remained 40 cm despite the SMP varied from -40 kPa to -10 kPa, which illustrate that the wetted depth in loam hold 40 cm under drip irrigation quota of 22.5mm. The result of the present study is consistent with the research of Zheng et al. (2011), who indicated that, an inverted cone of soil wetted zone and a salt shell outside the wetting body formed after drip irrigation.

With the influence of saline water irrigation, rainfall, strong evaporation and groundwater recharge, salt accumulation decreased with the increasing thresholds in the 0-1000px layer, which is similar to the research of Feng et al., (2017) and Liu et al. (2011); however the SMPs had no significant effect on soil salinity in the 40-100 cm layer, which is different from the research of Qiao et al. (2007), who investigated that salt accumulation does not appear in 0-100 cm soil layer during the whole growth stage of summer maize, when water salinity level is lower than 4.0 g/L and groundwater depth is higher than 3m.

With shallow saline groundwater drip irrigation, the ear length, 100-kernel weight and fresh ear weight of maize decreased with the decrease of target SMPs. Moreover, the IWUE increase lineally in response to the decrease of SMP threshold, while maize yield showed a quadratic relationship with SMP threshold and maximum production was reached with SMP of -20 kPa, these findings are concordant with those of Wan et al., (2011). Considering the considerable yield, litter salt accumulation and high IWUE, the irrigation system of S3 (-30kPa) is recommended for maize production in the study area.”

Bibliography/References.

We have made a broader and more recent literature review according to the reviewer’s suggestion:

Page 18.  Add new references as follow:

    [7] Min, W.; Guo, H.J.; Zhou, G.W.; Zhang, W; Ma, L.J.; Ye, J.; Hou, Z.A. Root distribution and growth of cotton as affected by drip irrigation with saline water. Field Crops Research 2014, 169, 1-10, 10.1016/j.fcr.2014.09.002.

[11] Li, X.B.; Kang, Y.H.; Wan, S.Q.; Chen, X.L.; Chu, L.L. Reclamation of very heavy coastal saline soil using drip-irrigation with saline water on salt sensitive plants. Soil and Tillage Research 2015a, 146, 159–173. 10.1016/j.still.2014.10.005.

[18] Sun, J.X.; Kang, Y.H.; Wan, SQ; Hu, W; Jiang, SF; Zhang, TB. Soil salinity management with drip irrigation and its effects on soil hydraulic properties in north China coastal saline soils, Agricultural Water Management 2012, 115 ,10-19, 10.1016/j.agwat.2012.08.006.

[19] Li, X.B. Salt leaching and Iris germanica L. growth in two coastal saline soils under drip irrigation with saline water. Scientia Horticulturae 2018, 237, 164-168, 10.1016/j.scienta.2018.04.002.

[20] Wang, R. S.; Wan, S.Q.; Sun, J.X.; Xiao, H.J. Soil salinity, sodicity and cotton yield parameters under different drip irrigation regimes during saline wasteland reclamation. Agricultural Water Management 2018, 209, 20-31, 10.1016/j.agwat.2018.07.004.

[23] Feng, D.; Wan, S.; Kang, Y.; Xue, Z.; Zhang, T. Drip irrigation scheduling for annual crops in an impermeable saline-sodic soil with an improved method. Journal of Soil and Water Conservation 2017,72(4), 351-360, 10.2489/jswc.72.4.351.

[24] Liu, S.H.; Kang, Y.H.; Wan, S.Q.; Wang, Z.C.; Liang, Z.W.; Sun, X.J. Water and salt regulation and its effects on Leymus chinensis growth under drip irrigation in saline-sodic soils of the Songnen Plain. Agricultural Water Management 2011, 98(9), 1469-1476, 10.1016/j.agwat.2011.04.016.

Delate original references as follow:

[6] D. C. Elfving. Crop response to trickle irrigation. Horticultural Reviews 1982, 4, 1-48.

[12] C.R. Wilson; B.M. Pemberton; L.M. Ransom. The effect of irrigation strategies during tuber initiation on marketable yield and development of common scab disease of potato in Russet Burbank in Tasmania. Potato Research 2001, 44(3), 243-251, 10.1007/BF02357902.

[13] Kang, Y.H.; Wang, F.X.; Liu, H.J.; Yuan, B.Z. Potato evapotranspiration and yield under different drip irrigation regimes. Irrigation Science 2004, 23(3), 133-143, 10.1007/s00271-004-0101-2.

[19] Kang, Y.H.; Wan, S.Q. Effect of soil water potential on radish (Raphanus sativus L.) growth and water use under drip irrigation. Scientia Horticulturae 2005, 106(3), 275-292, 10.1016/j.scienta.2005.03.012.

[23] J. E. Ayars; R. B. Hutmacher; R. A. Schoneman; D. R. Dettinger. Influence of cotton canopy on sprinkler irrigation uniformity. Transactions of the ASABE 1991, 34(3), 890-896.

 

The other changes are as follow:

Page 1. Add a correspondence information;

Page 1. The misspelled word “Abstruct”was corrected by “Abstract”;

Page 2. The misquotation “ Yao et al., 1996” was corrected by “ Yao et al., 1995”;

Page 2. The misquotation “D.C. Elfving, 1982” was replaced by “Min W, 2016”;

Page 4. Re-number the numbering of the Table 2.

Page 5. Replace the length of each plot “35.0m” by “45.0m

Page 5. Change operating pressure “0.01 MPa” to “0.1 MPa

Page 6. Delate the superfluous “et al.” in the sentence of “Meteorological data, containing daily rainfall, wind speed, maximum temperature et al., were obtained from an automatic weather station (YM-03A) located 50 m from the field experiment site.”

Page 6. Add the word “away” between “50 m” and “from” in the sentence of “Meteorological data, containing daily rainfall, wind speed, maximum temperature, were obtained from an automatic weather station (YM-03A) located 50 m away from the field experiment site.”

Page 8.  Change “SPASS 20.0” to “SPSS 20.0”;

Page 9. Change the sentenceand the mean humidity at 0-40 cm distance from the drip emitter in 0-40 cm depth” in the third paragraph to “…and the mean soil moisture content in the interval 0-40 cm from the drip emitter in 0-40 cm depth…”

Page 9. Modify the sentencesSpecially, the soil moisture at 40-60 cm distance from the drip emitter in treatments arrived the minimum value and in the order of -10 kPa>-20 kPa> -30 kPa>-40 kPa for different treatments, meanwhile, the value of soil water content in 80-100 cm was stable for all treatments. Obviously, water content of 40-1500px is lower than that of the upper (0-1000px) and the lower (60-2500px), that may due to the soil texture of 40-1500px is loamy sand, the moisture holding capacity is lower than the other two layers.” to “In particular, at the interval of 40-60 cm from the emitter, soil moisture in all treatments reaches the minimum value and in the order of -10 kPa>-20 kPa> -30 kPa>-40 kPa. Soil water content at depth 80-100 cm remains unchanged for all treatments. It is obvious that the soil moisture in the 40-1500px layer is less than that of the upper (0-1000px) and the lower layer (60-2500px). This can be attributed to the texture of the 40-1500px soil layer, which is loamy sand and has lower field capacity than the other two layers.”

Page 9. Remove the last two paragraphs to page 12.

Page 10. Change the graph titleFigure 6. The spatial distribution of soil moisture along the vertical transect that perpendicular to the drip line before spring irrigation, before sowing, before and after the irrigation in jointing stage, and after harvest for treatments in 2015” to “Figure 6. Spatial distribution of soil moisture along the vertical transect that is perpendicular to the drip line A. before spring irrigation, B. before sowing, C. before the irrigation in jointing stage, D. after the irrigation in jointing stage, and E. after harvest, for all treatments in 2015”;

Page 11. Change the graph titleFigure 7. The spatial distribution of soil moisture along the vertical transect that perpendicular to the drip line before spring irrigation, before sowing, before and after the irrigation in jointing stage, and after harvest for treatments in 2016” to “Figure 7. Spatial distribution of soil moisture along the vertical transect that is perpendicular to the drip line A. before spring irrigation, B. before sowing, C. before the irrigation in jointing stage, D. after the irrigation in jointing stage, and E. after harvest, for all treatments in 2016”;

Page 12. Remove the last three paragraphs to page 15.

Page 13. Change the graph titleFigure 8. The spatial distribution of soil salt (g·kg-1) along the vertical transect that perpendicular to the drip line before spring irrigation, before sowing, before and after the irrigation in jointing stage, and after harvest for treatments in 2015” to “Figure 8. Spatial distribution of soil salt (g·kg-1) along the vertical transect that is perpendicular to the drip line A. before spring irrigation, B. before sowing, C. before the irrigation in jointing stage, D. after the irrigation in jointing stage, and E. after harvest, for all treatments in 2015”

Page 14. Change the graph titleFigure 9. The spatial distribution of soil salt (g·kg-1) along the vertical transect that perpendicular to the drip line before spring irrigation, before sowing, before and after the irrigation in jointing stage, and after harvest for treatments in 2016” to “Figure 9. Spatial distribution of soil salt (g·kg-1) along the vertical transect that is perpendicular to the drip line A. before spring irrigation, B. before sowing, C. before the irrigation in jointing stage, C. after the irrigation in jointing stage, and E. after harvest, for all treatments in 2016”

Page 16. Rewrite the section 3.5.2: “IWUE was calculated by equation (2), maize yield and IWUE increased with the increasing of SMPs, while the corresponding IWUE decreased with the increasing of SMPs (Table 8). As shown in Table 8, the yield of S1 treatment was higher than other treatments, while the IWUE was the lowest, instead, the IWUE of S4 treatment was the highest, but the yield was lower than other treatments. The yield of S3 treatment was just 0.36% and 0.84% lower than that of S2 treatment in 2015 and 2016, respectively, while the IWUE of S3 treatment was 18.46% and 21.57% higher than that of S2 treatment in 2015 and 2016, respectively. The detailed relationship between maize yield, IWUE and SMPs are illustrated in Figure 11, both in 2015 and 2016, the IWUE increased lineally with the decrease of SMPs, while maize yield increased slowly with the decrease of SMPs at first, and reached the maximum value when SMP amounted to around -20kPa, and then decreased rapidly as the SMP decreased, which in accordance with the research of Wang et al. (2011).”

        The present study was aimed at making reasonable irrigation regime for maize production, based on comprehensive consideration of high yield, little salt accumulation and high IWUE, the irrigation schedule using local shallow saline groundwater with SMP of -30kPa is recommended in the study area.

We have tried our best to improve the manuscript and made some changes in our manuscript. These changes will not influence the content and framework of the paper. We appreciate for editors/ reviewers’ warm work earnestly and hope that the correction will meet with approval.

Once again, thank you very much for your comments and suggestions.


Author Response File: Author Response.pdf

Reviewer 2 Report

General comments. The paper focuses on a field experiments carried out to study the effects of drip irrigation thresholds with saline water. This study proposes to assess the effect of different soil matric potentials (SMPs) on spatial distribution of volumetric soil moisture and soil salt; measure the impact of different SMPs on salt accumulation, maize yield and irrigation water use efficiency; and finally optimize proper irrigation schedule for maize shallow saline groundwater irrigation in the irrigation district under the study.

The Authors highlight positive results. The topic is very relevant, especially for the increase of droughts that became a worldwide concern and its consequences directly affect agriculture.

The proposed methodology is of good technical quality and research depth. Overall the paper is well structured. Specific comments are provided in what follows.

 

Title and abstract.

(i)             The paper’s title is suitable, concise and appealing.

(ii)           The abstract conveys the purpose of the study, methods, results and conclusions in a readable way, but I suggest to remove the numbering and render it more readable.

Introduction

·       The introduction informs the reader about the objectives of the paper that are well-focused. But when acronyms are included in the text should be explained [for example, Hetao Irrigation District (here in after HID)], not only in abstract, but especially in the introduction it is necessary to explain the experiment in the best possible way.

 

Material and methods.

·     The analysis is appropriate, but in section 2.3.4 Maize Yield: it is not very clear which methodology is used to estimate the yield

 

Results.

·       The discussion of results is clear,

·       The study proposes a very interesting methodology.

·       Captions of Figures and Table are adequate.

 

Discussion.

·      This section should be enriched The conclusions are appropriate and focused results.

 

Bibliography/References: are appropriate. But it is recommended to make a broader and more recent literature review to reinforce the theoretical framework.


Author Response

Dear Editors and Reviewers:

Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Effect of Different Thresholds of Drip Irrigation Using Saline Water on Soil Salt transportation and Maize Yield”, (ID: Water-396466). 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 comments carefully and have made correction which we hope this revision can make our paper more acceptable. Revised portion are marked in green in the paper. The main corrections in the manuscript are as flowing:

Page 1. We are very sorry for our incorrect writing, the misspelled word “Abstruct”was corrected by “Abstract”;

Page 1. The text “Irrigation water use efficiency” was added after the IWUE acronym according to another reviewer comments;

Page 2. We are very sorry for our negligence of the year, the misquotation “ Yao et al., 1996” was corrected by “ Yao et al., 1995”;

Page 2. The misquotation “D.C. Elfving, 1982” was replaced by “Min W, 2016”;

Page 4. As reviewer suggested that we have re-numbered the numbering of the table.

Page 5. We are very sorry for our incorrect writing, the length of each plot “35.0m” was replaced by “45.0m”;

Page 5. We are very sorry for our incorrect writing, the operating pressure “0.01 MPa” was replaced by “0.1 MPa”;

Page 6. As reviewer suggested that we have delated the superfluous “et al.” in the sentence of “Meteorological data, containing daily rainfall, wind speed, maximum temperature et al., were obtained from an automatic weather station (YM-03A) located 50 m from the field experiment site.”

Page 6. As reviewer suggested that we have added the word “away” between “50 m” and “from” in the sentence of “Meteorological data, containing daily rainfall, wind speed, maximum temperature, were obtained from an automatic weather station (YM-03A) located 50 m away from the field experiment site.”

Page 8.  As reviewer suggested that we change “SPASS 20.0” to “SPSS 20.0”;

Page 9. As reviewer suggested that we change the sentenceand the mean humidity at 0-40 cm distance from the drip emitter in 0-40 cm depth” in the third paragraph to “…and the mean soil moisture content in the interval 0-40 cm from the drip emitter in 0-40 cm depth…”

Page 9. As reviewer suggested that we modify the sentencesSpecially, the soil moisture at 40-60 cm distance from the drip emitter in treatments arrived the minimum value and in the order of -10 kPa>-20 kPa> -30 kPa>-40 kPa for different treatments, meanwhile, the value of soil water content in 80-100 cm was stable for all treatments. Obviously, water content of 40-1500px is lower than that of the upper (0-1000px) and the lower (60-2500px), that may due to the soil texture of 40-1500px is loamy sand, the moisture holding capacity is lower than the other two layers.” to “In particular, at the interval of 40-60 cm from the emitter, soil moisture in all treatments reaches the minimum value and in the order of -10 kPa>-20 kPa> -30 kPa>-40 kPa. Soil water content at depth 80-100 cm remains unchanged for all treatments. It is obvious that the soil moisture in the 40-1500px layer is less than that of the upper (0-1000px) and the lower layer (60-2500px). This can be attributed to the texture of the 40-1500px soil layer, which is loamy sand and has lower field capacity than the other two layers.”

Page 10. As reviewer suggested that we change the graph titleFigure 6. The spatial distribution of soil moisture along the vertical transect that perpendicular to the drip line before spring irrigation, before sowing, before and after the irrigation in jointing stage, and after harvest for treatments in 2015” to “Figure 6. Spatial distribution of soil moisture along the vertical transect that is perpendicular to the drip line A. before spring irrigation, B. before sowing, C. before the irrigation in jointing stage, D. after the irrigation in jointing stage, and E. after harvest, for all treatments in 2015”;

Page 11. As reviewer suggested that we change the graph titleFigure 7. The spatial distribution of soil moisture along the vertical transect that perpendicular to the drip line before spring irrigation, before sowing, before and after the irrigation in jointing stage, and after harvest for treatments in 2016” to “Figure 7. Spatial distribution of soil moisture along the vertical transect that is perpendicular to the drip line A. before spring irrigation, B. before sowing, C. before the irrigation in jointing stage, D. after the irrigation in jointing stage, and E. after harvest, for all treatments in 2016”;

Page 13. As reviewer suggested that we change the graph titleFigure 8. The spatial distribution of soil salt (g·kg-1) along the vertical transect that perpendicular to the drip line before spring irrigation, before sowing, before and after the irrigation in jointing stage, and after harvest for treatments in 2015” to “Figure 8. Spatial distribution of soil salt (g·kg-1) along the vertical transect that is perpendicular to the drip line A. before spring irrigation, B. before sowing, C. before the irrigation in jointing stage, D. after the irrigation in jointing stage, and E. after harvest, for all treatments in 2015”

Page 14. As reviewer suggested that we change the graph titleFigure 9. The spatial distribution of soil salt (g·kg-1) along the vertical transect that perpendicular to the drip line before spring irrigation, before sowing, before and after the irrigation in jointing stage, and after harvest for treatments in 2016” to “Figure 9. Spatial distribution of soil salt (g·kg-1) along the vertical transect that is perpendicular to the drip line A. before spring irrigation, B. before sowing, C. before the irrigation in jointing stage, C. after the irrigation in jointing stage, and E. after harvest, for all treatments in 2016”

Page 16. We have re-written the section 3.5.2 according to the reviewer’s suggestion: “IWUE was calculated by equation (2), maize yield and IWUE increased with the increasing of SMPs, while the corresponding IWUE decreased with the increasing of SMPs (Table 8). As shown in Table 8, the yield of S1 treatment was higher than other treatments, while the IWUE was the lowest, instead, the IWUE of S4 treatment was the highest, but the yield was lower than other treatments. The yield of S3 treatment was just 0.36% and 0.84% lower than that of S2 treatment in 2015 and 2016, respectively, while the IWUE of S3 treatment was 18.46% and 21.57% higher than that of S2 treatment in 2015 and 2016, respectively. The detailed relationship between maize yield, IWUE and SMPs are illustrated in Figure 11, both in 2015 and 2016, the IWUE increased lineally with the decrease of SMPs, while maize yield increased slowly with the decrease of SMPs at first, and reached the maximum value when SMP amounted to around -20kPa, and then decreased rapidly as the SMP decreased, which in accordance with the research of Wang et al. (2011).”

        The present study was aimed at making reasonable irrigation regime for maize production, based on comprehensive consideration of high yield, little salt accumulation and high IWUE, the irrigation schedule using local shallow saline groundwater with SMP of -30kPa is recommended in the study area.

Page 17. We have re-written the Discussion according to the reviewer’s suggestion: “According to the 2 years field experiment conducted in HID, soil moisture and soil salt revealed a short-term fluctuation during the maize growth period, a low-salt zone in the plough layer and a high-salt region in the topsoil out of the mulch emerged, the isoline distribution of soil salt was similar to that of soil moisture, moreover, as a result of point source infiltration, a wetting body similar to one-fourth ellipse in the vertical profile perpendicular to the drip line emerged, and the horizontal radius of the wetting body increased with the increase of SMPs, while the vertical radius remained 40 cm despite the SMP varied from -40 kPa to -10 kPa, which illustrate that the wetted depth in loam hold 40 cm under drip irrigation quota of 22.5mm. The result of the present study is consistent with the research of Zheng et al. (2011), who indicated that, an inverted cone of soil wetted zone and a salt shell outside the wetting body formed after drip irrigation.

With the influence of saline water irrigation, rainfall, strong evaporation and groundwater recharge, salt accumulation decreased with the increasing thresholds in the 0-1000px layer, which is similar to the research of Feng et al., (2017) and Liu et al. (2011); however the SMPs had no significant effect on soil salinity in the 40-100 cm layer, which is different from the research of Qiao et al. (2007), who investigated that salt accumulation does not appear in 0-100 cm soil layer during the whole growth stage of summer maize, when water salinity level is lower than 4.0 g/L and groundwater depth is higher than 3m.

With shallow saline groundwater drip irrigation, the ear length, 100-kernel weight and fresh ear weight of maize decreased with the decrease of target SMPs. Moreover, the IWUE increase lineally in response to the decrease of SMP threshold, while maize yield showed a quadratic relationship with SMP threshold and maximum production was reached with SMP of -20 kPa, these findings are concordant with those of Wan et al., (2011). Considering the considerable yield, litter salt accumulation and high IWUE, the irrigation system of S3 (-30kPa) is recommended for maize production in the study area.”

 

The other changes are as follow:

Page 1. We have added a correspondence information;

Page 1. We have modified the Abstract to “Sustainable development of saline water irrigation was restricted in HID (Hetao Irrigation District) by serious yield reduction and severe salt accumulation without effective irrigation schedule. Field experiments were carried out to study the effects of drip irrigation thresholds on soil salt transportation and maize yield with shallow saline ground water in 2015 and 2016 in HID. The irrigation was triggered by four SMP (Soil Matric Potential) treatments which measured 20 cm beneath the drip emitter. Results indicated that the shape of wetting body approximated to one-fourth ellipse on the vertical profile perpendicular to the drip line, while the horizontal radius increased with the increase of SMP, moreover, salt accumulation decreased with the increasing thresholds in 0-1000px layer, while the soil salt in 40-100 cm was hardly affected by SMP thresholds under drip irrigation quota of 22.5mm. Maize yield showed a quadratic relationship with SMP threshold, and the IWUE (Irrigation Water Use Efficiency) showed a linear increase in response to the decrease in SMP threshold. Taking into account the salt accumulation, yield and IWUE, SMP threshold higher than -30kPa is suggested as the appropriate indicator for maize mulched drip irrigation with shallow saline groundwater in HID.”

Page 1. We have added “ (Hetao Irrigation District)” after the acronyms of “HID”;

Page 3. We have added “(Soil Matric Potential)” after the acronyms of “SMP”;

Page 3. We have replaced the expression “irrigation water use efficiency (IWUE)” by “IWUE (Irrigation Water Use Efficiency)”;

Page 7. We have added the equation “” to estimate maize yield.

        Where  is the estimated maize yield (kg/ha), while  is the measured maize yield (kg/12 m2).

Page 9. We have removed the last two paragraphs to page 12.

Page 12. We have removed the last three paragraphs to page 15.

Page 18.  Add new references as follow:

    [7] Min, W.; Guo, H.J.; Zhou, G.W.; Zhang, W; Ma, L.J.; Ye, J.; Hou, Z.A. Root distribution and growth of cotton as affected by drip irrigation with saline water. Field Crops Research 2014, 169, 1-10, 10.1016/j.fcr.2014.09.002.

[11] Li, X.B.; Kang, Y.H.; Wan, S.Q.; Chen, X.L.; Chu, L.L. Reclamation of very heavy coastal saline soil using drip-irrigation with saline water on salt sensitive plants. Soil and Tillage Research 2015a, 146, 159–173. 10.1016/j.still.2014.10.005.

[18] Sun, J.X.; Kang, Y.H.; Wan, SQ; Hu, W; Jiang, SF; Zhang, TB. Soil salinity management with drip irrigation and its effects on soil hydraulic properties in north China coastal saline soils, Agricultural Water Management 2012, 115 ,10-19, 10.1016/j.agwat.2012.08.006.

[19] Li, X.B. Salt leaching and Iris germanica L. growth in two coastal saline soils under drip irrigation with saline water. Scientia Horticulturae 2018, 237, 164-168, 10.1016/j.scienta.2018.04.002.

[20] Wang, R. S.; Wan, S.Q.; Sun, J.X.; Xiao, H.J. Soil salinity, sodicity and cotton yield parameters under different drip irrigation regimes during saline wasteland reclamation. Agricultural Water Management 2018, 209, 20-31, 10.1016/j.agwat.2018.07.004.

[23] Feng, D.; Wan, S.; Kang, Y.; Xue, Z.; Zhang, T. Drip irrigation scheduling for annual crops in an impermeable saline-sodic soil with an improved method. Journal of Soil and Water Conservation 2017,72(4), 351-360, 10.2489/jswc.72.4.351.

[24] Liu, S.H.; Kang, Y.H.; Wan, S.Q.; Wang, Z.C.; Liang, Z.W.; Sun, X.J. Water and salt regulation and its effects on Leymus chinensis growth under drip irrigation in saline-sodic soils of the Songnen Plain. Agricultural Water Management 2011, 98(9), 1469-1476, 10.1016/j.agwat.2011.04.016.

Delate original references as follow:

[6] D. C. Elfving. Crop response to trickle irrigation. Horticultural Reviews 1982, 4, 1-48.

[12] C.R. Wilson; B.M. Pemberton; L.M. Ransom. The effect of irrigation strategies during tuber initiation on marketable yield and development of common scab disease of potato in Russet Burbank in Tasmania. Potato Research 2001, 44(3), 243-251, 10.1007/BF02357902.

[13] Kang, Y.H.; Wang, F.X.; Liu, H.J.; Yuan, B.Z. Potato evapotranspiration and yield under different drip irrigation regimes. Irrigation Science 2004, 23(3), 133-143, 10.1007/s00271-004-0101-2.

[19] Kang, Y.H.; Wan, S.Q. Effect of soil water potential on radish (Raphanus sativus L.) growth and water use under drip irrigation. Scientia Horticulturae 2005, 106(3), 275-292, 10.1016/j.scienta.2005.03.012.

[23] J. E. Ayars; R. B. Hutmacher; R. A. Schoneman; D. R. Dettinger. Influence of cotton canopy on sprinkler irrigation uniformity. Transactions of the ASABE 1991, 34(3), 890-896.

 

We have tried our best to improve the manuscript and made some changes in our manuscript. These changes will not influence the content and framework of the paper. We appreciate for editors/ reviewers’ warm work earnestly and hope that the correction will meet with approval.

Once again, thank you very much for your comments and suggestions.


Author Response File: Author Response.pdf

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