Estimation of Actual Evapotranspiration and Crop Coefficient of Transplanted Puddled Rice Using a Modified Non-Weighing Paddy Lysimeter

Round 1

Reviewer 1 Report (Previous Reviewer 3)

The second comment to the modified version of the paper  „Estimation od  actual  Evapotranspiration and crop coefficient of transplated puddled rice using modified non/ weighing paddy lysimeter“.

 

Authors did some changes in the paper which improved undrstanding of the paper. They even formulated aim of this work. Methodology of this work is clear and simpler, but not new. But novelty of the method is not so important.Important is, if the paper is bringing somethink new.  And this is not the case. But, the critical is not appropriate  technics of rice in the lysimeters evapotranspiration measurement.

The main objection of mine is, that the basic data, which are actual evapotranspiration (and potential one as well in this case) measured by the lysimeter (see Fig.2) are not correct, due to „rim“ effect of the  walls of the  lysimeter marked as „A“. I have really a lot of experiences with such type of measurement and I guess that  te effect „rim“ about 35 cm above the soil surface  can significantly decrease evapotranspiration rate, usually more than 30% in comparison tot the field. In the volume of the air between water table in the lysimeter and the upper rim of the lysimeter is high air humidity and low coefficient of water vapour transport from water (and rice surfac) to the atmosphere just above. Therefore to use such data to calculate „real“ evapotranspiration and crop coefficient can lead to false results, and crop coefficiens estimated by this way will be lower, as well as irrigation doses, based on such results.

(This effect is very easy to verify. Take two glasses, one fill by water up to the top of it and the second water table will be  e.g. 10 cm below the upper  edge of the glass. After one day you can see significant differences, the water table deep below the upper edge of the glass will not change significantly, but the second one will lose much more.)

I am sorry, but publishing a such paper with elementary errors in data estimation, is not a good idea.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report (New Reviewer)

Dear Editor-in-Chief,

Thank you for the invitation to review this manuscript for your esteemed Journal.

The manuscript “Estimation of Actual Evapotranspiration and Crop Coefficient of Transplanted Puddled Rice using Modified Non-weighing paddy Lysimeter” has great scientific relevance, although it has several problems with variable acronyms and measurement units. I kindly ask that the authors take care with the writing, the agronomy is an important journal with readers from all over the world and it is necessary that the writing is adequate.

Line 21: Please remove the comma from the AETc acronym.

Line 23: The correct spelling should be: “stage-wise crop coefficient (Kc) values” ...

Line 27: The writing should be: “coefficient of determination (R2) of 0.63” ...

Line 28: Please add a space between “error (RMSE=0.80)”

Line 45: Please be careful with quotes. Add a space in: activities [1,2]

Note: This type of observation is repeated in the text, always add a space between the last word and quote.

Line 51: Note that you are using the % symbol sometimes next to the number and sometimes separate from the number, please standardize the writing!

Line 60: Please put: of the upland rice (Oryza sativa L.)

Line 117: AETc writing is different, letter c must be subscripted.

Line 136: Km should be written in km. The uppercase K unit is Kelvin in the international system of units.

Line 143: Please the word Soil in Table 2 should not be in bold.

Still in Table 2, what is the Field Capacity and Permanent wilting point measurement unit?

Line 149: Please put a ; after “within the root zone”

Line 165: Is Swarn Shreya rice a cultivar or variety?

Line 174: Please standardize the writing of the Reference evapotranspiration, would it be ETo or ET0? Are you writing it two ways, or is it different information?

Line 183-189: Please add a ; after the end of each element, and in line 190 at the end of deficit [kPa] add a period (.).

Line 197: Make the changes as above (Line 183-189).

Line 209: Make the modifications as reported on Line 183-189!

Still on Line 209, wouldn't it be AETc? Please be careful with these acronyms.

Line 234-235: The writing should be: (Eq. 10, 11, 12, 13 and 14), respectively. Daily...

Line 246: Please add a period after hours.

Line 249: Is this unit of measurement correct? In g/m2/º day, I believe it should be g/m2/ºCday. Please see this carefully.

Line 278: It would be nice if Figure 5 had the same design pattern as Figure 8.

Line 313: Please see that you use ;; after R²=0.79. Use only one; to separate.

The same error occurs on Line 317. Please be careful when writing!

Line 321: Figure 9 is very beautiful, follow the same pattern in Figure 5.

Line 340: Careful with the writing, is Kc subscripted or not?

Line 342: What is DAT? I think it's "days after transplanting", is that it? If so, identify what that acronym would be, please.

In Table 4 the word Correlation must not be bolded!

Also in Table 4, these spaces without values ​​please add a hyphen.

Line 363: An important note. What would be the asterisk on the graph, is it the significance? If so, how many percent is it? 5%, 1%? How much? This should be added in the description of the figure legend.

Line 373: Do these values ​​shown not have a unit of measurement? Please, add!

Same observation on Line 374. Which unit?

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 3 Report (New Reviewer)

General comment:

In this paper (Estimation of Actual Evapotranspiration and Crop Coefficient…) . the authors have evaluated three methodologies for estimating ETo. But the objective and methodology is not clear. ETo measurements are mixed with actual evapotranspiration (AETc). The values of kc obtained by lysimeters should be applied to the FAO methodology (AETc = ETo * Kc) and an improvement of the PAN coefficient should be considered. In my opinion the work is interesting and can provide important information for management decisions and can applied in similar areas.

In my opinion, the work contributes to provide information on kc values on a regional scale, but could be improved clarifying some aspects of the methodology and providing a solution to the Kp values used (PAN method). See all comments

 

Introduction:

ABSTRACT:

 

-       L.24-25. What is  “viz.”?.

Indirect methods “FAO Penman-Monteity equation and Pan Evaporation” estimate ETo, no actual evapotranspiration (AETc). Is the approach correct?

-       L. 26. FAO Penman-Monteity equation is referenced. Is it correct? It will not be FAO methodology by using FAO-PM?

-       L. 31-32. How were these estimates?

-       L 38. I think that “…can be applied to improve the irrigation scheduling”.

 

 

KEYWORDS: words in the title should not be repeated

 

INTRODUCTION:

-       The introduction describes the general problem and relates it to the trial country. It may be too long, but it is correct. -       L. 94. Statements such as " provides exact measurement " should not be made. They are repeated throughout the document. It is a method that can offer more precision than others, but “exact measurement” is not true -       L. 116-117. “…comparison of AETc and Kc values with indirect methods such as Penman-Monteith and Pan evaporation”. PM only estimate reference evapotranspiration.

 

 

Methodology:

 

2.1. Site description

- Table 2. “Methods employed for estimation”. A reference is needed.  

 

 

2.3.1.. FAO Penman-Monteith equation

 

-        It is widely known. one reference is enough, it is not necessary to express it.

 

 

2.3.2. Pan Evaporation approach

-       - The important thing is to know the Kp and justify it.

 

2.4. Estimation of stage-wise crop coefficient

-       How ETo was finally measured?

-       How ETc was finally measured?

-       Figure 3. I do not understand how “Kc” can be obtained from ETo (PM) and ETo (Pan evaporation). Where is ETc?

 

 

 

2.6. Water productivity and agro-meteorological indices

 

-       L. 235. “Base temperature of 10 ºC”, why?

-        

 

 

3. Results.

-       Named Epigraph 3 as “Results” not as “Results and discussion”.

 

3.1. Variation of reference evapotranspiration, water balance components and actual crop evapotranspiration

-       Fig. 5. If ETo is being determined in both cases, it is normal that there are such marked differences. Is any method “difficult” to apply under the test conditions?

-       273-276. Pan coefficient must been improved.

 

3.3. Comparation of actual evapotranspiration with FAO PM and Pan Evaporation-derived 293 evapotranpiration during crop period

 

- Kc Values used by FAO method must be shown and justified. This method seems adequate

 

3.5. Influence of weather variables on Reference and actual evapotranspiration

- the contribution is scientifically irrelevant. it is already known.

 

 

 

 

 

 

4. Discussion

4.1. Variation of reference evapotranspiration, water balance components, and actual 386 evapotranspiration

 

-       L. 388-397. In a scientific study, something must be contributed to solve it. For example, adjust the parameter. Is this possible?

 

4.2. Comparison of crop evapotranspiration and stage-wise crop coefficients

 

-       L. 454-456. it should be explained how to improve it

-        

 

4.3. Influence of weather variables on Reference and Actual evapotranspiration

-       This is a direct relationship with ETo, I don't think it contributes anything to a scientific study.

 

 

Conclusions:

-       Conclusions section must be improved.

-       L.484-490 are not conclusions. It is a general statement.

-       L.494-496. It is a good conclusion. They are different of FAO Kc values. Kc Values are “general”.

-       L. 496-499. The reference should be to local estimates. This method is not suitable. Is there anything proposed to improve it?

-       L. 502. why have they not been reviewed?

-       The conclusions are interesting but should be reduced. The first part are not conclusions. The possibility of improving the bread coefficient should be highlighted.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 4 Report (New Reviewer)

I suggest to do some corrections - e.g. (just a re-check by someone else inolved):

confirmmed (line 356); solar instead of Solar (line 358), plants' height (or plant heights) line 419, modified (425), postivite (465) ...

I saw different ways to write Pan (Pan Evaporation, Pan evaporation, pan coefficient) - pls re-check and adjust.

Decide whether you use 2 or 3 figures past the comma (line 366/367)

A cultivar is shown as 'xxx' OR cvar xxx ( see line 372 - Swarn Shreya)

beetwenweather (Figure 12)

To my mind - there is too much focus of the underestimation of the Pan method. It occurs relatively often. A discussion why Penman-Monteith works out better might be helpful.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report (New Reviewer)

Dear Editor-in-Chief,

Thank you for providing a revised version of this paper.

I am satisfied with the changes made.

Reviewer 3 Report (New Reviewer)

The authors have considered the recommendations of the reviewer and have justified the methodological procedure. In my opinion, the article can continue with the publication procedure.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

-         It is advised to take the help of professional English editors before it can be considered for publication.

-         The introduction can be improved, related to the amount of cited literature and the relevant studies. Much work has been reported regarding the actual evapotranspiration in puddled rice that can be incorporated into the introduction.

-         Only one season of data is used to develop crop coefficients. It is recommended to take at least two seasons before the developed coefficients can be used for irrigation application in given climatic conditions.

-         In Fig.2, the legend for two values is missing.

-         -         There is much confusion regarding the methods through which the conclusions are drawn, it needs a major revision on that.

-         References are also missing on line 66 and line 325. Kindly check all the references.

 

Author Response

Plese see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Dear Authors, please find my report in attachment. Thank you.

Comments for author File: Comments.pdf

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 3 Report

The basic and the most important shortcoming of this manuscript is „non- representativity“ of equipment used to measure  all the three water fluxes from modified (?) (Fig.3) lysimeters. The rim (the upper boundary) ro the lysimeters are located about 40 cm above the soil surface, which means, that microclimate in the 40 cm layer of air (in the area belowe rim ) is quite different, than it is in open field, therefore results of evapotranspiration measurements cannot be the same as it is in open field. Measured evapotranspiration should be significantly smaller than in the open field, and therefore it cannot be used for analysis.

Another important shortcoming is non declaring the aim of the study. It is usually located at the end of Introduction. Here it is written „an attempt was made to study actual evapotranspiration....using modified paddy lysimeter ans stage crop coefficient.“ And, even at conclusions, there are some general statements presented,  measured crop coefficients are given, which are probably quite different than real ones, because of different microclimate in upper part of lysimeters, different from reality. So, try to define the aim of the study clearly.

I was not able to find clear description of the  proposed  „modified paddy lysimeter“ and therefore it is difficult to find out (e.g. in Fig. 3) the sense of using it. Is „modified paddy lysimeter“  one of them, or all the three ?

So (in my opinion) important shortcoming is inadequacy of using such series of lysimeters to measure ( and assume) water fluxes in paddy field by such lysimeters. I agree, that it is really difficult problrm to do this, but this approach can lead to significant errors in evaluating evapotranspiration and  crop coefficients.  Using A/Pan equipment is risky too, because this (very old type) equipment can be used to compare relative values of evaporation from water surfaces, but measured data are far from real ones, because of the construction and exposition of this equipment. Therefore, it is not  surprise, that A Pan data are far from reality.

Finally, I do not know,what is new in this manuscript, the novelty of the papaer is not clearly described. Authors did really a lot of work and their  results deserves to be presented in literature. But they must clearly described what is the aim of this work and give  an ansver what was discovered.

Crop coeficients should not beeb „regionallY‘  dependent. „Regionality“ of the site is involved in reference evapotranspiration, and eventually the different sorts of plant (in this case different sorts of rice) can influence the crop coefficients and yields as well. So maybe  water balance of the system soil- rice (plant) – atmosphere using  your three different lysimeters can be calculated, but you must have in mind that evapotranspiration from lysimeters is different than in surrounding rice field, because (mentioned before) high rim of lysimeters modified transport coefficient between evaporating surfaces  and atmodphere (say at 2 m height).

I know, that you did a lot of work on this project, and results of measurement can be used to contribute to our knowledge of the problem. Having measured evapotranspiration, which is less than real (in the field), it can be used to calculate relative K_c  and relative ratio of E, D and O, which can be interesting information for readers. But it needs major revision of the paper.

Some other comment:

1.       Figures (or tables) captions should be selfexplaining, i.e. the text should be able to explain the content itself. But, in majority of figures it is not so (Figs, 2,3,6 and others). Not all the Figs. are necessary.

2.       Majority of equations (e.g. 1,3 and others) shoud be presented better. Indexes (as they are) in equations should be given even below equations as  indexed. To define terms (below equations) it should be used sign ( -)  instead of (=). The last one  can be used in equations only.

3.       Are equations 10 – 14 necessary? Their physical meaning is not clear and they are not used in the next analysis and I have not seen them incurrent  literature.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The revised manuscript still needs major improvements on the English front.  Words like ‘Haunted’ in the introduction section are suited for academic literature. The English writing skills are still at a subpar level to be considered for publication.

Generally, crop coefficients developed for one season are not recommended for adoption even on a regional scale because of the variability associated with the reference ETo values on a seasonal or yearly basis. I strongly suggest undertaking one more experiment to develop averaged Kc values.  

 

 

 

 

 

 

Reviewer 3 Report

I have read carefully the responses of the authors and the majority of my questions were involved in the paper or explained. Kc is higher than one, which is in harmony with reality. But some figures' captions deserve to be improved, to reach self explanation of the figures and tables.

Now I think, that this paper could be published, but... I would like to propose you to involve into the Abstract, Conclusions and in Discussion. a sentence like this: Because of technical difficulties to measure evapotranspiration of paddy rice by lysimeters` the rim (or border above the evaporating surface) must be  34 cm above the evaporating surface), it is expected, that especially during initial stages of rice development, measured evapotranspiration will be lower than in the field. Therefore even calculated Kc can be lower than calculated by the proposed method.

I assume, that differences will be minor, but in principle, they should be mentioned. The paper can be published. And try to improve especially figures and tables caption to make them self-explanatory.