Evaluation and Application of the AquaCrop Model in Simulating Soil Salinity and Winter Wheat Yield under Saline Water Irrigation
Round 1
Reviewer 1 Report
The paper presents an interesting approach of the evaluation and application of AquaCrop for simulating the impacts of saline water irrigation in winter wheat crop. The scenarios are relevant to irrigation management, because irrigation water is supplementary for rainfall, a important fact thinking about strategies for saline water use. However, I have some doubts, questions, or even concerns about the calibrating experiment and how the irrigation management was performed.
For the model validation experiment, as the irrigation management presented, it is not possible to say that, for the full irrigation treatments, there really was full irrigation. Precisely, it cannot be named as full irrigation. Moreover, if an overirrigation was performed, there was a great chance of ions leaching below the root zone, what is not expected when the irrigation water depth is just right, or less than it. So, some questions can be placed:
i) How can authors guarantee that there was not soil moisture above the field capacity, during the field essays?
ii) How was irrigation performed? Using which method and irrigation system?
iii) How was irrigation scheduling done in each growth stage? How was the irrigation partition? What were the irrigation intervals
iv) How a wrong irrigation management could influence the field results and the model calibration, mainly regarding the soil solute content?
Some suggestions:
i) It would be better for international readers if the information regarding greater than or less than would be written from left to right, e.g.: R² >= 0,70.
ii) Please check the use of “the” instead of “a” and vice versa
iii) When writing about liquid precipitation, is more interesting to use the word “rainfall”
iv) Introductory section, page 2, line 47: Using the mentioned marginal water COULD ONLY maintain agricultural production, compared to skipping irrigation IF accurate management of poor-quality water is achieved. And that is exactly where the problem and the rationale of the presented study lie. This should be highlighted in Introduction section, also mentioning the interdependence between natural rainfall and irrigation, in this case.
v) The paragraph “This study could be addressed more efficiently and conveniently by mathematical models.” should be deleted.
vi) Page 2, line 89: Richards equation
vii) The 3rd objective must let clear that the development of proper saline water irrigation strategies was studied by modelling and simulation.
viii) Table 2 is confusing. The T scenarios refer to irrigation strategies, but is not clear, in this part of the text, that for each of them, all the EC levels were simulated. Also, this table must show the total water amount for each stage, supplied by irrigation and rainfall.
ix) Discussion is needed on the dependence between irrigation management performed in the field experiment, its influence on model calibration and, therefore, possible improvement in model performance.
Author Response
We appreciate your valuable comments and suggestions. We have incorporated your suggested changes in the revised manuscript. Attached is our response document to your comments one by one.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Water scarcity results in the use of low to moderate-quality water in irrigation agriculture. This water contains varying levels of salt and other impurities. This would affect crop production, land sustainability and groundwater pollution. Therefore, identifying the most tolerable limits of salinity in the irrigation water and assessing tools are important. Therefore, the area discussed in this manuscript is more relevant and important. The authors have reasonably selected the techniques/parameters for evaluating the results relating to the objective of the study. However, I have the following comments and observations concerning this paper.
Comments
Abstract-
Line 20-27- Irrigation strategies listed here are not clear in the scenario analysis section. Please check.
In general, the abstract is well written with the required details.
Materials and Methods-
Line 117 – include units for each parameter, temperature, precipitation, etc.
Line 120-124 – It will be great if you use a table to include these data.
Figure 1(b) – Include the figure legend
Figure 1 caption – Please indicate the units. Also, you have mentioned cumulative precipitation. Please be consistent the same in other places as well, eg. in line 117 and in Figure 1(a) and (b) legends.
Line 132-135 – I would suggest reorganizing the sentence by directly stating the irrigation treatments and salinity levels.
Line 133-134 – check and change full irrigation with 10 dS/m saline water (F5) to (F10)
Line 136-137 – The basin irrigation was performed ….. – The basin irrigation is stated first time here. Please clarify/state the specific type of basin irrigation method used eg. furrow?
Line 140-141 – In this study, the experiment has been started in October. However, full and deficit irrigation treatments have been started in December and March. Is there any reason, please clarify.
Line 141 – 146 – Should move up closer to line 131 – before the irrigation treatments.
Line 151 - …oven –drying method’... – Please exactly indicate the method of experiment you’ve used. Eg. gravimetric or volumetric method.
Line 153-154 – Should indicate the oven-dried temperature and the oven drying process, eg. fan forced oven, etc.
Line 154 – Then in=season aboveground …. – insert a space between above and ground
Line 156-157 - see the comment for Line 153-154
Line 157 -158 – It is not clear how you’ve collected the final grain yield. Please state any sorting or grading method used, if any.
Line 182 – fHI and HI0 – should reorganize to match the format given in the equation. Also, prove definitions for other terms, eg. Tc
2.3 Observations – suggest to rewriting or reorganizing this section to make the data collection process more clear and meaningful. Include the methods and techniques used.
Results
Figure 2 and Figure 3 – it will be great if you separate the two seasons and use labels a), b), c), etc. to clearly express each figure. Then, organize figure captions accordingly.
Line 246 – 247 – please check the values. It seems they are not matched with the values shown in their respective figure/s.
Scenario analysis
The process or the base of selection of treatments T1 to T5 and dry, normal and wet years is not clear.
Conclusion
The recommendation on the use of full irrigation and deficit irrigation is not clear.
Author Response
We appreciate your valuable comments and suggestions. We have incorporated your suggested changes in the revised manuscript. Attached is our response document to your comments one by one.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The authors addessed the suggested corrections and explained in the text, the concerning points. Information on soil moisture was added during the experimental evaluations, however, it is necessary to make it clear whether the values are on a volumetric or gravimetric basis. If possible, I suggest that volumetric moisture be presented, as it is more appropriate for understanding irrigation management
Author Response
We are grateful for your insightful reviews and valuable comments that helped to improve the manuscript.
The soil moisture values of this study were the volumetric soil water content. Soil samples were collected from the 0-60 cm layer with an interval of 10 cm on the day before and after irrigation. The gravimetric soil water content was determined by drying samples at 105 ℃ in a fan-forced oven until obtaining a constant weight. The volumetric soil water content was determined by multiplying gravimetric soil water content with bulk density.
Soil water content was replaced by volumetric soil water content throughout the manuscript.
Author Response File: Author Response.docx
Reviewer 2 Report
Thanks for providing amended manuscript.
I find that the authors have satisfactorily update the document.
Thank you.
Author Response
We are grateful for your insightful reviews and valuable comments that helped to improve the manuscript.
