Development and Evaluation of an Emitter with a Low-Pressure Drip-Irrigation System for Sustainable Eggplant Production

Round 1

Reviewer 1 Report

The authors present a paper on the field evaluation of a new low pressure, pressure compensating drip emitter that was used to grow eggplant over one season and compared to traditional methods. They present critical standard performance characteristics such as manufacturer's coefficient of variation and emission uniformity. They also present crop yield and water productivity comparisons to traditional methods. The authors have conducted a sound study on an important topic. However, the paper unfortunately suffers from a number of major issues that lead me to recommend that they make major revisions, including collect additional data, and resubmit. Primarily, this paper claims to present a new pressure compensating (PC) dripper that operates at low pressure, but the authors have not reported their data on flow rate as a function of pressure in laboratory tests, which is a basic characterization that is fundamental to the characterization of a PC dripper. A PC dripper must show a characteristic leveling off of the flow rate at some activation pressure, which the authors are claiming is very low. The authors at various times report contradictory claims about how the flow rate behaves as a function of operating pressure, indicating that perhaps they have this data, but it is not presented. Reporting these results would validate their claims of low pressure operation and PC behavior, clear up their contradictory statements, and provide a fundamental characterization of a new dripper that they are reporting on. In addition, the authors fail to provide any dripper design context or analysis for most of their results. They do not describe the design process or basis of the dripper design. They state their results largely without hypothesizing why they are the way they are in terms of dripper design and without discussing the implications of their dripper results on the design or future design iterations of their dripper. If this is not intended to be a design paper, then the authors fail to provide analysis in the context of testing a low pressure dripper. They do not discuss their results in the context of operating their drippers at low pressure or on a slope (i.e. why these factors might result in the results they report). Finally, the paper suffers from a large number of methodological issues that need to be addressed. Specifically, in many instances, significant digits are not properly followed, uncertainties are not reported, methods are not properly stated, and citations are not properly used. I have addressed these issues with a large number of specific comments that I hope the authors will use to improve the paper and resubmit. I feel it is a good study that deserves to be published once it has been polished with all of its data included.    

Specific comments: 

L63 - typo (period)

L63 - define DIS

L72 - 73 - What is your basis for knowing DIS is limited in Bangladesh due to non-uniformity of water distribution and the small size and height of the water tank? This is unusual, as most of the literature points to cost as being the main barrier. I don't know of literature that specifically points to non-uniformity as being a barrier to DIS adoption in Bangladesh or elsewhere. Cite some sources, or state how you have come to this conclusion. 

L78 - salinity is, in fact, an accentuated problem in sub-surface drip irrigation. Be specific that you are talking about surface drip irrigation. 

L88 - this isn't necessarily true about the cost. The filters are quite expensive, as well as the pumps for a small system. For a larger system, the driplines because a larger cost, but it depends on the thickness of the tubing. If you have an off-grid system, the power system is the largest component of the cost. 

L101: You have not given any justification or reason for studying saline and non-saline water sources. Are these expected to behave differently given the type of emitter that you are testing or the conditions in which you are testing the emitter? 

L102: You have not given any justification or motivation for the testing of a low pressure emitter in particular. Why is it important that the emitter be low pressure? You should explicitly state the implication this has on the cost of the system and how it affects the cost (capital cost of the pump/gravity system and also recurring costs). 

L106 - 108: You have not said anything about how or why the new dripper was designed in the way it was. Why were the dimensions chosen? Was it trial and error? Did you start from a commercial emitter? Is there a patent you can refer to? Refer here to the table where you present the dimensions of your emitter. 

L110 - you cite this doctoral dissertation from 2011 when referring to the these emitters in particular. However, this implies that they are not new and have been tested previously. You should list the prior work on these emitters to give context. 

L141 - Table 1 - include a schematic or photo of the inside of the dripper with the dimensions labeled ('fin' etc) so that it is clear which features are associated with each reported dimension. 

L147 - spelling - installment, also "five emitters were placed on"

L145 - indicate the instrument you used to monitor the pressure (make and accuracy), including the uncertainty. Give also the uncertainty in your operating heads for the duration of the experiment (i.e. how well you were able to regulate each pressure) as +/- x m where 'x' is the uncertainty. 

L151 - pH and salinity measurements should have uncertainties with them according to the instruments used in their measurement. Give the make and model of the instrument used to measure salinity. 

L152 - give the uncertainty in the volume of the beaker (based on the size of the beaker and the precision of the tick marks)

L156 - give the uncertainty in the measured flow times. 

- As a rule of thumb, if it is a measurement, you must include an uncertainty estimate. Otherwise, we have no way to evaluate the accuracy of the measurement. 

L156-157 - do not just say the pressure remained constant, say it remained constant to within +/- X m. If you didn't see any movement on the instrument, then X will be the precision of the instrument.

L166 - L168 - you do not need to include the definition of average and standard deviation. These are common enough and well known. 

L169 - Table 2 should be cited. 

L179 - these columns should have numbered citations.  

L180 - Say why CU is different from EU and DU or what it might be used for that is different from the other two (same for DU). 

L194 - Table 4 columns should have numbered citations. 

L200 - give a range of salinity or approximate salinity of the non-saline zone versus the saline zone. 

L220 - You state that from Figure 2 as the slope increased the discharge rate increased, but from your data, it is ordered slope 1.5%, 0, 1%, not ascending.  

L222 - L223 - the precision on your flow rate measurement keeps changing (4 vs 3.77 l/hr). Choose the correct number of significant digits for your measurement and use them throughout.  

L231 - it isn't clear what data you are referring to here - you say the discharge rate increased linearly as the water pressure was raised - based on what data? It should at least be presented in the SI if you are going to say it was linear. 

The behavior of discharge rate with pressure is key behavior for a pressure compensating (PC) emitter and should be plotted and discussed. If the discharge rate really increases linearly with pressure then it is not a pressure compensating emitter, which should level off and have a constant flow rate with pressure after some activation pressure. This paragraph is very unclear. You say it increases linearly and then say that the discharge rate is nearly stable and then say it varied with the supply water pressure. These are all different statements. You should show this data and discuss it in the context of your assertion that this is a PC emitter. You say other studies showed emitter discharge variation, but what is key is how much variation (i.e. what percentage variation). Report that from your references and your data. 

L241 - you make a statement about your dataset and give two  citations (24, 25) - this implies that these citations support your assertions about your dataset, which I suspect is untrue (unless you have previously published this dataset in citations 24 and 25). Please correct your citations. If you intend to say that a publication found similar results, please state this properly and cite it accordingly. 

Figure 3: You use a vastly different Y-axis scale for the three rows of plots, which makes it difficult to compare the data. Use the same scale (even if it is offset). 

L242 - I disagree with your assertion that Figure 3 demonstrates "the variation in discharge rate was increased". Unless you mean the standard deviation of the discharge rate increased with slope? Be more clear what you mean by "the variation in discharge rate". Even for the standard deviation, this is not obvious from the plots. It seems to be about 0.7 - 1.0 in all of the plots. If you really want to draw this conclusion, you will need to show some summary statistics. Likewise for the comparison of variation in discharge rate between pressure heads - this is impossible to tell from your figure because of the difference in Y axis scales. Mostly, I think you simply see no trends in this data, and that is fine.  However, if you want to say the variation is increasing with slope or pressure head, you should show some statistics or more convincing data. Also, say why this might be the case and why it is important. 

L245 - "It showed that by increasing the slope, the variation in discharge rate increased at each lateral line." - you have not measured the variation in discharge rate for each lateral line individually. It is certainly not clear from your plot that the standard deviation of discharge rates for each individual lateral line increases as you go from low slope to high slope. Take L1 for example. The variation of that lateral line does not increase. If you want to draw this conclusion, back it up with statistics of the actual variations in discharge rates for the lateral lines and demonstrate that they increase generally with slope.   

L246 - "It was also exhibited the significant variation in increased discharge of emitter with respect to operating pressure and slope." - it is not clear what you mean by this statement. Do you mean variation in the the discharge rate increased with respect to increasing operating pressure and slope? 

L255 - refer to your data in Table 5. 

L255-257 -- Refer back to Table 2 for the ranges for CV

L257 - According to your statement, your citation 18 supports your statement "The results indicate that CVm for 2 m pressure head with 0 and 1% slope performed average while with 1.5% slope it performed as marginal" - however, this is a statement about your data, which is not supported by the ASAE citation. Your intention is for citation 18 to support the definition of marginal. The proper way to cite this is something more similar to: " The results indicate that CVm for 2 m pressure head with 0 and 1% slope performed average while with 1.5% slope it performed as marginal, as defined by the ASAE [18]". Please correct your citations throughout the paper. There are many that are incorrect in this same way. The sentence or clause preceding a citation should always be a summary of that citation and not a statement about your data. Check this for all of your citations. 

L258-259 - Be consistent and correct with your number of significant digits for CV and include uncertainty in this measurement. 

L262 --give the circumstances under which higher values are given. In addition, most conventional emitters on the market have CV in the range of 3 - 7%. 

L265 - it isn't clear what reference 29 is meant to refer to. It should be clear in the sentence what the reference refers to. 

L266 "The manufacturing and flow variation coefficients were considered excellent in all evaluations when the operating time did not influence the hydraulic performance of emitters [30]" - it is not clear what this means. What do you mean when the operating time did not influence the hydraulic performance of the emitters? What is reference 30 meant to refer to? 

L267 - "The emitter discharge rate was increased with increase of the pressure and the coefficient of variation was increased with decrease of the pressure [31]." -- again, this is a statement about your own data, yet you have a citation here. This citation has not published results about your own data, so you are incorrectly citing this work. If you mean that they saw similar results, then you must say so, and then cite that sentence. 

L273 - incorrect use of citation 

Also "The coefficient of determination (R2) was higher for 2 m head (Table 5), indicating that the system was efficient to get better yield."

- What is the basis of this statement? Better yield than what? Than 1.5m head? Is there any evidence that the size of the increase between 1.5 and 2m seen here would lead to a better yield? Include that data here. 

L286 - What is the basis of saying 2m head with 1% slope is excellent for better crop production? Better crop production than what? Than your other scenarios in this paper? Is there evidence that an increase in CU of the size seen in your data leads to better crop production? Provide some evidence of better crop production with higher CU (via a citation) and then you can say it will have better crop production than crops with whatever CU is indicated in that publication.  

L291 - Only give the acronym once and then use only the acronym from then on. Do this for all of your acronyms

L290 and L292 contradict each other. 

Section 3.3.4 - say what information the DU provides that is both valuable and distinct from the other metrics you measure or do not include it in this paper. Right now you simply report it to report it. You just report the value and say nothing about it that is different from the information you have gathered from the other metrics. If you cannot state one value that this metric brings above and beyond the other metrics, then there is no reason to include it in the paper and it should be removed entirely. Same with the Statistical Uniformity. You don't need them if they don't add value. 

Section 3.3.6 - You report results, but you do not discuss possible reasons for these results or their implications for your interests. Sometimes this can be done in a separate discussion section, but you don't have a separate discussion section. 

 L315 - you need to state how you measured the decrease in irrigation water and the yield in your methods section. In general, everything you measured and every measurement you report must be described in the methods section. 

L320 - Define SCWU, WP, M2. Define how you calculated WP 

L328 - 331 -- this is a conclusion of your paper, and so it should not be cited with an outside reference because the outside reference did not make the conclusion about your work. Properly cite the data from the reference and give that citation after that data. 

 Table 7 - Make sure you refer to all of your tables in the text where you discuss the data in them. Do this for all of your tables. Each table in your paper should be referred to in the text. Check all of the significant figures in this table and make sure they are correct. Do this for all of your tables. I suspect there are too many significant digits. Add errors to these measurements. This can be +/- added to each number or footnotes added to each column giving the percentage uncertainty.  All measured numbers must have an identifiable uncertainty somewhere in the paper. Do this for all tables. 

L344 - It still isn't clear what the locally available materials are - do you mean the plastic they are made of? Locally manufactured? 

L347 - You have not given any measure of the salinity of the water where you tested, so it not clear that you tested in saline and non-saline areas. You should include at least a salinity measurement from another publication to make this claim. 

Author Response

Date: 28 June 2019

To

Reviewer_1

Re: Resubmission of the revised version of the manuscript (Manuscript ID: agriengineering-532119) entitled: ‘Development and Evaluation of an Emitter with a Low-pressure Drip-Irrigation System for Sustainable Eggplant Production in Saline and Non-Saline Regions of Bangladesh’

Dear Reviewer_1

I am indebted to you for providing us with the opportunity to revise the paper. We have carefully considered your all of the comments and have attempted to address each with comment in the revised manuscript. We believe that due to constructive suggestions by the referees, these revisions have significantly improved the paper quality. We have provided point-by-point to your comments in below in red text.

We appreciate for giving us the opportunity to resubmit the paper. We stand ready to make additional changes if needed.

We look forward to hearing from you.

Sincerely yours,

Akbar Hossain, Ph.D

Senior Agronomist, Bangladesh Wheat and Maize Research Institute (BWMRI)

Dinajpur-5200, Bangladesh. Email: [email protected].

http://orcid.org/0000-0003-0264-2712

https://www.researchgate.net/profile/Akbar_Hossain2/publications

https://www.scopus.com/authid/detail.uri?authorId=55351853600

Response to Reviewer 1 comments

Review Report (Reviewer 1)

Comments and Suggestions for Authors p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Times} p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Times; min-height: 14.0px}

The authors present a paper on the field evaluation of a new low pressure, pressure compensating drip emitter that was used to grow eggplant over one season and compared to traditional methods. They present critical standard performance characteristics such as manufacturer's coefficient of variation and emission uniformity. They also present crop yield and water productivity comparisons to traditional methods. The authors have conducted a sound study on an important topic. However, the paper unfortunately suffers from a number of major issues that lead me to recommend that they make major revisions, including collect additional data, and resubmit. Primarily, this paper claims to present a new pressure compensating (PC) dripper that operates at low pressure, but the authors have not reported their data on flow rate as a function of pressure in laboratory tests, which is a basic characterization that is fundamental to the characterization of a PC dripper. A PC dripper must show a characteristic leveling off of the flow rate at some activation pressure, which the authors are claiming is very low. The authors at various times report contradictory claims about how the flow rate behaves as a function of operating pressure, indicating that perhaps they have this data, but it is not presented. Reporting these results would validate their claims of low pressure operation and PC behavior, clear up their contradictory statements, and provide a fundamental characterization of a new dripper that they are reporting on. In addition, the authors fail to provide any dripper design context or analysis for most of their results. They do not describe the design process or basis of the dripper design. They state their results largely without hypothesizing why they are the way they are in terms of dripper design and without discussing the implications of their dripper results on the design or future design iterations of their dripper. If this is not intended to be a design paper, then the authors fail to provide analysis in the context of testing a low pressure dripper. They do not discuss their results in the context of operating their drippers at low pressure or on a slope (i.e. why these factors might result in the results they report). Finally, the paper suffers from a large number of methodological issues that need to be addressed.

Specifically, in many instances, significant digits are not properly followed, uncertainties are not reported, methods are not properly stated, and citations are not properly used. I have addressed these issues with a large number of specific comments that I hope the authors will use to improve the paper and resubmit. I feel it is a good study that deserves to be published once it has been polished with all of its data included.   

Specific comments:

Point_1: L63 - typo (period):

Response_1: period included.

Point_2: L63 - define DIS:

Response: Has been defined (DIS; Deep Irrigation System) and inclided.

Point_3: L72 - 73 - What is your basis for knowing DIS is limited in Bangladesh due to non-uniformity of water distribution and the small size and height of the water tank? This is unusual, as most of the literature points to cost as being the main barrier. I don't know of literature that specifically points to non-uniformity as being a barrier to DIS adoption in Bangladesh or elsewhere. Cite some sources, or state how you have come to this conclusion.

Response: Yes, we agree. The cost is one of the barriers and constraints for small farmers. Citations for non-uniformity of water distribution and the small size and height of the water tank and high initial cost have been given in line 74.

Point_4: L78 - salinity is, in fact, an accentuated problem in sub-surface drip irrigation. Be specific that you are talking about surface drip irrigation.

Response: Has been revised. The DIS helps to reduce soil salinity due to wetting of the root zone.

Point_5: L88 - this isn't necessarily true about the cost. The filters are quite expensive, as well as the pumps for a small system. For a larger system, the driplines because a larger cost, but it depends on the thickness of the tubing. If you have an off-grid system, the power system is the largest component of the cost.

Response: Has been revised. It is true that all components of DIS are locally available with lower cost than in previous years.

Point_6: L101: You have not given any justification or reason for studying saline and non-saline water sources. Are these expected to behave differently given the type of emitter that you are testing or the conditions in which you are testing the emitter?

Response: You are absolutely right. In fact, we have tested the new emitter with DIS in just two locations (one non-saline and another saline zone) of Bangladesh. Hence, we have revised the title and abstract accordingly.

Point_7: L102: You have not given any justification or motivation for the testing of a low pressure emitter in particular. Why is it important that the emitter be low pressure? You should explicitly state the implication this has on the cost of the system and how it affects the cost (capital cost of the pump/gravity system and also recurring costs).

Response: Considering economic conditions of smallholders and small field size in Bangladesh, farmers are using traditional DIS which affects the non-uniformity distribution of water, unknown height of the water tank, and high import prices required from foreign countries. Therefore, the existing low cost DIS including emitter was developed and evaluated at lab and field conditions over two locations.

We have added these justifications at the last paragraph of the Introduction.

Point_8: L106 - 108: You have not said anything about how or why the new dripper was designed in the way it was. Why were the dimensions chosen? Was it trial and error? Did you start from a commercial emitter? Is there a patent you can refer to? Refer here to the table where you present the dimensions of your emitter.

Response: Based on existing locally available materials of drip fitting components and plastic materials in the market, we collected all information and tested. We followed the procedure of trial and errors method. First time, we developed and tested, the hydraulic performances were not satisfactory. Again, we developed and tested and we got desired performances and then evaluated for field performances over two locations.

Since, it was all hit and trial and ground work without any peer-review publication, we didn’t mention this in the Introduction. With all the hit and trial and ground work we however got a lot of experience on this.

Point_9: L110 - you cite this doctoral dissertation from 2011 when referring to these emitters in particular. However, this implies that they are not new and have been tested previously. You should list the prior work on these emitters to give context.

Response: The cited doctoral dissertation did not develop the new emitter. Instead, this developed a pvc type drip irrigation for maize variety. In this study, this type of drip irrigation can be operated by gravity pressure or pressured motor which is supported our works.

Point_10: L141 - Table 1 - include a schematic or photo of the inside of the dripper with the dimensions labeled ('fin' etc) so that it is clear which features are associated with each reported dimension.

Response: A schematic diagram of front, left and top view has been given using solidworks engineering drawings software.

Point_11: L147 - spelling - installment, also "five emitters were placed on"

Response: Has been revised.

Point_12: L145 - indicate the instrument you used to monitor the pressure (make and accuracy), including the uncertainty. Give also the uncertainty in your operating heads for the duration of the experiment (i.e. how well you were able to regulate each pressure) as +/- x m where 'x' is the uncertainty.

Response: For regulating each pressure (Head, m), the pressure gauge was mainly used and continuous inflow-outflow (remove excess water) was maintained to achieve the constant pressure.

Point_13: L151 - pH and salinity measurements should have uncertainties with them according to the instruments used in their measurement. Give the make and model of the instrument used to measure salinity.

Response: The model of the instrument for measuring pH, salinity and temperature instrument has been given in line 163.

Point_14: L152 - give the uncertainty in the volume of the beaker (based on the size of the beaker and the precision of the tick marks)

Response: The standard beakers were used and samples data were used for similar ways. Besides, for hydraulic performance, the sample volume and weights (both) were taken (Fig. 1) to get accuracy.

Point_15: L156 - give the uncertainty in the measured flow times.

- As a rule of thumb, if it is a measurement, you must include an uncertainty estimate. Otherwise, we have no way to evaluate the accuracy of the measurement.

Response: Stop watch and alarming bell (both) were used to maintain the flow times correctly.

Point_16: L156-157 - do not just say the pressure remained constant, say it remained constant to within +/- X m. If you didn't see any movement on the instrument, then X will be the precision of the instrument.

Response: We regulated the pressure properly……………

Point_17: L166 - L168 - you do not need to include the definition of average and standard deviation. These are common enough and well known.

Response: Sd & q have been deleted.

Point_18: L169 - Table 2 should be cited.

Response: Has been cited in Table 2

Point_19: L179 - these columns should have numbered citations. 

Response: Now, the columns have been numbered citations

Point_20: L180 - Say why CU is different from EU and DU or what it might be used for that is different from the other two (same for DU).

Response: These all are the indicators which have been established by ASAE for measuring hydraulic performances of micro-irrigation system. Therefore, we tested all indicators. We checked them thoroughly and revised as necessary.

Point_21: L194 - Table 4 columns should have numbered citations.

Response: Now he columns have numbered citations

Point_22: L200 - give a range of salinity or approximate salinity of the non-saline zone versus the saline zone.

Response: The variations and changes in soil salinity have been given.

Point_23: L220 - You state that from Figure 2 as the slope increased the discharge rate increased, but from your data, it is ordered slope 1.5%, 0, 1%, not ascending. 

Response: Fig. 2 (now Fig. 3 in revised version) is revised); Discharge (flow rates) vs. pressure heads under different slopes have been given.

Point_24: L222 - L223 - the precision on your flow rate measurement keeps changing (4 vs 3.77 l/hr). Choose the correct number of significant digits for your measurement and use them throughout.   

Response: Now the mean discharge value has been given.

Point_25: L231 - it isn't clear what data you are referring to here - you say the discharge rate increased linearly as the water pressure was raised - based on what data? It should at least be presented in the SI if you are going to say it was linear. The behavior of discharge rate with pressure is key behavior for a pressure compensating (PC) emitter and should be plotted and discussed. If the discharge rate really increases linearly with pressure then it is not a pressure compensating emitter, which should level off and have a constant flow rate with pressure after some activation pressure. This paragraph is very unclear.

You say it increases linearly and then say that the discharge rate is nearly stable and then say it varied with the supply water pressure. These are all different statements. You should show this data and discuss it in the context of your assertion that this is a PC emitter. You say other studies showed emitter discharge variation, but what is key is how much variation (i.e. what percentage variation). Report that from your references and your data.

Response: Line 231….. has been checked and revised. The new emitter is pc emitter but in this study, it was tested only for low pressure (gravity flow from water tank) for smallholders only 1.5, 2 and 2.5 m height for manually refilled water tank. When it will be tested for high pressure using motor pump, we may find out the optimization value. Therefore, the linkage of the study has been given in the conclusions section.

Point_26: L241 - you make a statement about your dataset and give two citations (24, 25) - this implies that these citations support your assertions about your dataset, which I suspect is untrue (unless you have previously published this dataset in citations 24 and 25). Please correct your citations. If you intend to say that a publication found similar results, please state this properly and cite it accordingly.

Response: Now the citations have been checked and revised.

Point_27: Figure 3: You use a vastly different Y-axis scale for the three rows of plots, which makes it difficult to compare the data. Use the same scale (even if it is offset).

Response: Scale of Fig. 3 (now Fig. 4 in revised version) has been checked and revised.

Point_28: L242 - I disagree with your assertion that Figure 3 demonstrates "the variation in discharge rate was increased". Unless you mean the standard deviation of the discharge rate increased with slope? Be clearer what you mean by "the variation in discharge rate". Even for the standard deviation, this is not obvious from the plots. It seems to be about 0.7 - 1.0 in all of the plots. If you really want to draw this conclusion, you will need to show some summary statistics. Likewise for the comparison of variation in discharge rate between pressure heads - this is impossible to tell from your figure because of the difference in Y axis scales. Mostly, I think you simply see no trends in this data, and that is fine.  However, if you want to say the variation is increasing with slope or pressure head, you should show some statistics or more convincing data. Also, say why this might be the case and why it is important.

Response: We thank a lot to the reviewer for giving us very good insights of our data. In fact, we had overlooked the trends in our data. We agree to the reviewer and rewrite the text as per the advice of the reviewer.

Point_29: L245 - "It showed that by increasing the slope, the variation in discharge rate increased at each lateral line." - you have not measured the variation in discharge rate for each lateral line individually. It is certainly not clear from your plot that the standard deviation of discharge rates for each individual lateral line increases as you go from low slope to high slope. Take L1 for example. The variation of that lateral line does not increase. If you want to draw this conclusion, back it up with statistics of the actual variations in discharge rates for the lateral lines and demonstrate that they increase generally with slope.   

Response: Please kindly see the response above for L242. That is applicable for this comment too.

Point_30: L246 - "It was also exhibited the significant variation in increased discharge of emitter with respect to operating pressure and slope." - it is not clear what you mean by this statement. Do you mean variation in the the discharge rate increased with respect to increasing operating pressure and slope?

Response: Lines 242-246 have been checked and revised.

Point_31: L255 - refer to your data in Table 5.

Response: Table 5 has been referred

Point_32: L255-257 -- Refer back to Table 2 for the ranges for CV

Response: Table 2 has been referred

Point_33: L257 - According to your statement, your citation 18 supports your statement

"The results indicate that CVm for 2 m pressure head with 0 and 1% slope performed average while with 1.5% slope it performed as marginal" however, this is a statement about your data, which is not supported by the ASAE citation. Your intention is for citation 18 to support the definition of marginal. The proper way to cite this is something more similar to: "The results indicate that CVm for 2m pressure head with 0 and 1% slope performed average while with 1.5% slope it performed as marginal, as defined by the ASAE [18]".

Please correct your citations throughout the paper. There are many that are incorrect in this same way. The sentence or clause preceding a citation should always be a summary of that citation and not a statement about your data. Check this for all of your citations.

Response: All citations have been checked and revised.

Point_34: L258-259 - Be consistent and correct with your number of significant digits for CV and include uncertainty in this measurement.

Response: Significant digit for CV is now written consistently.

Point_35: L262 --give the circumstances under which higher values are given. In addition, most conventional emitters on the market have CV in the range of 3- 7%.

Response: In this study, CVm was found in the range of 4-6%

Point_36: L265 - it isn't clear what reference 29 is meant to refer to. It should be clear in the sentence what the reference refers to.

Response:  Has been checked and revised.

Point_37: L266 "The manufacturing and flow variation coefficients were considered excellent in all evaluations when the operating time did not influence the hydraulic performance of emitters [30]" - it is not clear what this means. What do you mean when the operating time did not influence the hydraulic performance of the emitters? What is reference 30 meant to refer to?

Response: Has been checked and this is deleted.

Point_38: L267 - "The emitter discharge rate was increased with increase of the pressure and the coefficient of variation was increased with decrease of the pressure [31]." -- again, this is a statement about your own data, yet you have a citation here. This citation has not published results about your own data, so you are incorrectly citing this work. If you mean that they saw similar results, then you must say so, and then cite that sentence.

Response: Has been revised.

Point_39: L273 - incorrect use of citation

Response: Citation have been revised.

Also "The coefficient of determination (R2) was higher for 2 m head (Table

5), indicating that the system was efficient to get better yield."- What is the basis of this statement? Better yield than what? Than 1.5m head? Is there any evidence that the size of the increase between 1.5 and 2m seen here would lead to a better yield? Include that data here.

Response: Our results indicate that DIS at 2 m head could be an option for getting better yield through more efficient use of water.

Point_40: L286 - What is the basis of saying 2m head with 1% slope is excellent for better crop production? Better crop production than what? Than your other scenarios in this paper? Is there evidence that an increase in CU of the size seen in your data leads to better crop production? Provide some evidence of better crop production with higher CU (via a citation) and then you can say it will have better crop production than crops with whatever CU is indicated in that publication. 

Response: The DIS is excellent and could be considered for better crop production

Point_41: L291 - Only give the acronym once and then use only the acronym from then on. Do this for all of your acronyms

Response: Has been checked in whole document and revised

Point_42: L290 and L292 contradict each other.

Response: Has been checked and revised

Point_43: Section 3.3.4 - say what information the DU provides that is both valuable and distinct from the other metrics you measure or do not include it in this paper. Right now you simply report it to report it. You just report the value and say nothing about it that is different from the information you have gathered from the other metrics. If you cannot state one value that this metric brings above and beyond the other metrics, then there is no reason to include it in the paper and it should be removed entirely. Same with the Statistical Uniformity. You don't need them if they don't add value.

Response: We thank the reviewer for giving us insights about the presentation of our data. We carefully thought about DU and decided to remove it from the paper. This will not affect the interpretation and conclusion of the study.

Section 3.3.6 - You report results, but you do not discuss possible reasons for these results or their implications for your interests. Sometimes this can be done in a separate discussion section, but you don't have a separate discussion section.

Response: According to your suggestions, we are agreed to remove the DU and all related information about it but Us has been kept as we thought it would provide useful information and add value to our research.

Point_44: L315 - you need to state how you measured the decrease in irrigation water and the yield in your methods section. In general, everything you measured and every measurement you report must be described in the methods section.

Response: Details information on irrigation water (IW) and yield components have been given in methodology sections.

Point_45: L320 - Define SCWU, WP, M2. Define how you calculated WP

Response: All definitions are checked and revised.

Point_46: L328 - 331 -- this is a conclusion of your paper, and so it should not be cited with an outside reference because the outside reference did not make the conclusion about your work. Properly cite the data from the reference and give that citation after that data.

Response: This citation has been deleted

Point_47: Table 7 - Make sure you refer to all of your tables in the text where you discuss the data in them. Do this for all of your tables. Each table in your paper should be referred to in the text. Check all of the significant figures in this table and make sure they are correct. Do this for all of your tables. I suspect there are too many significant digits. Add errors to these measurements. This can be +/- added to each number or footnotes added to each column giving the percentage uncertainty.  All measured numbers must have an identifiable uncertainty somewhere in the paper. Do this for all tables.

Response: We have checked all tables and followed the reviewer’s suggestion.

L344 - It still isn't clear what the locally available materials are - do you mean the plastic they are made of? Locally manufactured?

Response: Yes

Point_48: L347 - You have not given any measure of the salinity of the water where you tested, so it not clear that you tested in saline and non-saline areas. You should include at least a salinity measurement from another publication to make this claim.

Response: We have salinity data measured at 15 days interval. According to the reviewer’s suggestion, we have now included the salinity data in Fig. 6

Author Response File: Author Response.docx

Reviewer 2 Report

18 June 2019

Manuscript: ‘Development and Evaluation of an Emitter with a Low-pressure Drip-Irrigation System for Sustainable Eggplant Production in Saline and Non-Saline Regions of Bangladesh’.

General comment to authors and editor:

I would recommend this manuscript for publication after a minor revision.

********************************

For this round:

Title: it fits perfectly the paper content. 

Abstract: it is quite adjusted to the paper content,

Authors should include the results of hydraulic performances obtained, and the characteristics of Saline and Non-Saline Regions.

Introduction: this section provides enough background and includes relevant references.

Line 75: ‘over-exploitation’ for ‘overexploitation’

Materials and Methods: data sets are clearly stated. The research shows a design appropriated and its methods have been adequately described.

Authors should include figure with the longitudinal cut of the tested emitter representing the characteristic dimensions.

Line 122: the sentence ‘For the system layout, when laterals are long a slope or are very long, the emitters are required to maintain uniformity [17]’ is unclear, what is the role of the emitter here? within which parameters of length of laterals is applicable?

Line 202: Author should indicate the soil-water extraction and chemical analysis, and if possible the electrical conductivity of saturated paste extract (ECe), salt cations and other soil properties related to salinity.

Author should indicate the source of irrigation water (with salinity ranging in dS m⁻¹).

Results and discussions: the results have been presented clearly.

Line 179: in the Table 3: ‘Merricum’ for ‘Merriam’

Line 276: ‘Here, manufacturer’s’ for ‘Manufacturer’s’

Line 334: Improve the quality of pictures (Figure 4)

Conclusions: they’re clear and concise and are supported by the results.

Author Response

Date: 28 June 2019

To

Reviewer_2

Re: Resubmission of the revised version of the manuscript (Manuscript ID: agriengineering-532119) entitled: ‘Development and Evaluation of an Emitter with a Low-pressure Drip-Irrigation System for Sustainable Eggplant Production in Saline and Non-Saline Regions of Bangladesh’

Dear Reviewer_2

I am indebted to you for providing us with the opportunity to revise the paper. We have carefully considered your all of the comments and have attempted to address each with comment in the revised manuscript. We believe that due to constructive suggestions by the referees, these revisions have significantly improved the paper quality. We have provided point-by-point to your comments in below in red text.

We appreciate for giving us the opportunity to resubmit the paper. We stand ready to make additional changes if needed.

We look forward to hearing from you.

Sincerely yours,

Akbar Hossain, Ph.D

Senior Agronomist, Bangladesh Wheat and Maize Research Institute (BWMRI)

Dinajpur-5200, Bangladesh. Email: [email protected].

http://orcid.org/0000-0003-0264-2712

https://www.researchgate.net/profile/Akbar_Hossain2/publications

https://www.scopus.com/authid/detail.uri?authorId=55351853600

Response to Review Report (Reviewer 2)

Review Report (Reviewer 2)

Comments and Suggestions for Authors 18 June 2019

Manuscript: ‘Development and Evaluation of an Emitter with a Low-pressure Drip-Irrigation System for Sustainable Eggplant Production in Saline and Non-Saline Regions of Bangladesh’.

General comment to authors and editor:

I would recommend this manuscript for publication after a minor revision.

********************************

For this round:

Point_1: Title: it fits perfectly the paper content.

Response: Thanks for the good comments.

Point_2: Abstract: it is quite adjusted to the paper content, authors should include the results of hydraulic performances obtained, and the characteristics of Saline and Non-Saline Regions.

Response: Thanks for the good words. Discharge rates for various pressure heads and sloes are given. As per the advice of reviewer 1, we deemphasized the saline and non-saline regions and hence removed from title. Our study was not to compare for saline and non-saline zones; rather the experiment was conducted in two locations – saline and non-saline. Hence, we believe there is no need to give characteristics of saline and non-saline regions. Moreover, these additions will increase the length of the paper.

Point_3: Introduction: this section provides enough background and includes relevant references.

Response: Thanks for the good words. We have again rechecked the section and revised as per suggestions of reviewer 1.

Point_4: Line 75: ‘over-exploitation’ for ‘overexploitation’

Response: Has been revised.

Point_5: Materials and Methods: data sets are clearly stated. The research shows a design appropriated and its methods have been adequately described.

Response: Happy to learn that M & M section is in good condition. However, again we also rechecked the whole section and revised where necessary.

Point_6: Authors should include figure with the longitudinal cut of the tested emitter representing the characteristic dimensions.

Response: Has been revised.

Point_7: Line 122: the sentence ‘For the system layout, when laterals are long a slope or are very long, the emitters are required to maintain uniformity [17]’ is unclear, what is the role of the emitter here? Within which parameters of length of laterals is applicable?

Response: Maintain water flows uniformly.

Point_8: Line 202: Author should indicate the soil-water extraction and chemical analysis, and if possible the electrical conductivity of saturated paste extract (ECe), salt cations and other soil properties related to salinity.

Response: We have revised all sections of M & M considering reviewers 1 and 2.

Point_9: Author should indicate the source of irrigation water (with salinity ranging in dS m⁻¹).

Response: We have already mentioned that the field validation was conducted in the research station in Gazipur (non-saline zone) and farmers’ field of Khulna (coastal saline zone) during the rabi (dry) seasons (Figure 6).

Results and discussions: the results have been presented clearly.

Point_10: Line 179: in the Table 3: ‘Merricum’ for ‘Merriam’

Response: These are references. Has been checked and referred as journal style.

Point_11: Line 276: ‘Here, manufacturer’s’ for ‘Manufacturer’s’

Response: Has been revised

Point_12: Line 334: Improve the quality of pictures (Figure 4)

Response: We have revised

Point_13: Conclusions: they’re clear and concise and are supported by the results.

Response: Thank you very much for valuable comments. We however checked again and revised as necessary.

Author Response File: Author Response.docx

Reviewer 3 Report

The authors indicate great knowledge about the advantages of drip irrigation systems  and the  evaluation of the statistical parameters  representing hydraulic assessment  of the system.  They evaluate a new pressure compensating emitter on the basis of the calculation of the following parameters: Manufacturer's coefficient of variation, Emission  uniformity, Christiansen's coefficient of uniformity,  Statistical uniformity of coefficient and Flow variation. They investigate these parameters with the variation of slope (0%, 1%, 1.5%) and the variation of head (1.5m, 2.0m, 2.5m). Linear regression models of hydraulic test parameters are derived for different operating pressures and slopes

Getting acquainted with the manuscript  I would like to recommend to The Editorial Board of Journal of AgriEngineering to publish it.

Author Response

Date: 28 June 2019

To

Reviewer_3

Re: Resubmission of the revised version of the manuscript (Manuscript ID: agriengineering-532119) entitled: ‘Development and Evaluation of an Emitter with a Low-pressure Drip-Irrigation System for Sustainable Eggplant Production in Saline and Non-Saline Regions of Bangladesh’

Dear Reviewer_3

I am indebted to you for providing us with the opportunity to revise the paper. We have carefully considered your all of the comments and have attempted to address each with comment in the revised manuscript. We believe that due to constructive suggestions by the referees, these revisions have significantly improved the paper quality. We have provided point-by-point to your comments in below in red text.

We appreciate for giving us the opportunity to resubmit the paper. We stand ready to make additional changes if needed.

We look forward to hearing from you.

Sincerely yours,

Akbar Hossain, Ph.D

Senior Agronomist, Bangladesh Wheat and Maize Research Institute (BWMRI)

Dinajpur-5200, Bangladesh. Email: [email protected].

http://orcid.org/0000-0003-0264-2712

https://www.researchgate.net/profile/Akbar_Hossain2/publications

https://www.scopus.com/authid/detail.uri?authorId=55351853600

Review Report (Reviewer 3)

Comments and Suggestions for Authors:

Point_1: The authors indicate great knowledge about the advantages of drip irrigation systems and the evaluation of the statistical parameters representing hydraulic assessment of the system. They evaluate a new pressure compensating emitter on the basis of the calculation of the following parameters: Manufacturer's coefficient of variation, Emission uniformity, Christiansen's coefficient of uniformity, Statistical uniformity of coefficient and Flow variation. They investigate these parameters with the variation of slope (0%, 1%, 1.5%) and the variation of head (1.5m, 2.0m, 2.5m). Linear regression models of hydraulic test parameters are derived for different operating pressures and slopes.

Getting acquainted with the manuscript I would like to recommend to The Editorial Board of Journal of AgriEngineering to publish it.

Response: Thanks for the nice comments. We are highly thankful and grateful to the reviewer for finding our paper very useful and novel.

Round 2

Reviewer 1 Report

I applaud the authors for an excellent revision. The manuscript is indeed very much improved and will make a solid contribution to the literature. I have only a few minor suggested revisions below, and I recommend publication. 

Suggested minor revisions: 

L158  - "For the system layout, when laterals are long a slope or are very long, the flow of emitters is required to maintain uniformity [19]." - do you mean when laterals are along a slope? What do you mean by "the flow of emitters is required" - do you mean a consistent flow is required? Clarify this point. 

In Figure 1, indicate on the diagram which component is a fin, the entry, and the detention width/height. 

L203 - "instalment" typo (should be "installment")

L211 - you need to properly report the uncertainty in your volume and time measurements so that the reader can assess the uncertainty in your flow rate measurements. Your volume measurement and your stop watch will both have uncertainties due to the precision of the measurement. For example, your beaker may have been a 100 mL beaker with tick marks every 10 mL. By eye, you may have been able to distinguish a difference in volumes in this beaker every half tick mark, or +/- 5mL. Thus your uncertainty in your volume measurement would be +/- 5%. Your stop watch would be stopped as fast as you could by eye, which might be within 1 second every time. Then your uncertainty in your time measurement would be +/- 1 sec. If you used alarms, it might be more than 1 second because you need to hear the alarm and react to it. Or perhaps it is less than 1 second if you have an automatic timer that is responding to the weight on weighing balance. Your weighing balance will also have an uncertainty based on the precision and accuracy of the instrument. The accuracy should be given in the specifications of the instrument, which you should be able to look up online or find in the booklet that came with the instrument. The precision, you can find from the number of digits available on the display. It depends on your setup. The point is, there is always an uncertainty for the volume and the time measurement and weight measurement and it must be reported. The proper way to report it here, if these were your uncertainties, would be "The discharge rates of emitters were measured volumetrically (+/- 5%) and collected water weighed three times (+/- 2%) for all replications. A stop watch with simultaneously alarming bells (+/- 1 sec) was used to measure flow times. Please report your uncertainties as appropriate. These are needed because now we can estimate the uncertainty in the flow rate that is calculated from these measurements. 

L294 - convert plot size to meters squared.

Author Response

Comments and Suggestions for Authors

I applaud the authors for an excellent revision. The manuscript is indeed very much improved and will make a solid contribution to the literature. I have only a few minor suggested revisions below, and I recommend publication. 

Suggested minor revisions: 

p.p1 {margin: 0.0px 0.0px 8.0px 18.0px; font: 12.0px 'Lucida Grande'} p.p2 {margin: 0.0px 0.0px 8.0px 18.0px; font: 12.0px 'Lucida Grande'; min-height: 15.0px}

L158  - "For the system layout, when laterals are long a slope or are very long, the flow of emitters is required to maintain uniformity [19]." - do you mean when laterals are along a slope? What do you mean by "the flow of emitters is required" - do you mean a consistent flow is required? Clarify this point. 

Response:

Thank you very for raising the research questions. I think, if the consistent flow is supplied to emitters through the laterals/sub-lateral lines, the uniformity is found satisfactory to excellent. The setting of emitters will depend on crops/plant (row to row and plant to plant spacing, inflow and outflow demand/requirement, as well as the design of the total system, etc.). I think it needs to further research for measuring uniformity using consistent and inconsistent flow.

In Figure 1, indicate on the diagram which component is a fin, the entry, and the detention width/height. 

Response: Figure 1 has been revised.

L203 - "instalment" typo (should be "installment")

Response: Installment has revised instead of instalment

L211 - you need to properly report the uncertainty in your volume and time measurements so that the reader can assess the uncertainty in your flow rate measurements. Your volume measurement and your stop watch will both have uncertainties due to the precision of the measurement. For example, your beaker may have been a 100 mL beaker with tick marks every 10 mL. By eye, you may have been able to distinguish a difference in volumes in this beaker every half tick mark, or +/- 5mL. Thus your uncertainty in your volume measurement would be +/- 5%. Your stop watch would be stopped as fast as you could by eye, which might be within 1 second every time. Then your uncertainty in your time measurement would be +/- 1 sec. If you used alarms, it might be more than 1 second because you need to hear the alarm and react to it. Or perhaps it is less than 1 second if you have an automatic timer that is responding to the weight on weighing balance. Your weighing balance will also have an uncertainty based on the precision and accuracy of the instrument. The accuracy should be given in the specifications of the instrument, which you should be able to look up online or find in the booklet that came with the instrument. The precision, you can find from the number of digits available on the display. It depends on your setup. The point is, there is always an uncertainty for the volume and the time measurement and weight measurement and it must be reported. The proper way to report it here, if these were your uncertainties, would be "The discharge rates of emitters were measured volumetrically (+/- 5%) and collected water weighed three times (+/- 2%) for all replications. A stop watch with simultaneously alarming bells (+/- 1 sec) was used to measure flow times. Please report your uncertainties as appropriate. These are needed because now we can estimate the uncertainty in the flow rate that is calculated from these measurements. 

Response:

We are completely agree with you. To overcome this problems, we used stop watch with simultaneously whistle for alarming. However, in this study, considering neglecting this errors, we tested and measured for determining the uniformity. However, according to your suggestions, we included the following sentences in the manuscript which may clear to the readers/users without any conflict.

“The discharge rates of emitters were measured volumetrically (+/- 5%) and collected water weighed three times (+/- 2%) for all replications. A stop watch with simultaneously alarming bells (+/- 1 sec) was used to measure flow times.”

L294 - convert plot size to meters squared.

Response: The plot size was revised by 210 square meter at Gazipur and 200 square meter at Khulna instead of decimal.

Author Response File: Author Response.docx