Toward Cleaner Production: Can Mobile Phone Technology Help Reduce Inorganic Fertilizer Application? Evidence Using a National Level Dataset

Round 1

Reviewer 1 Report

The authors have demonstrated a lack of understanding of the role of fertilizers in agriculture and a lack of understanding of the issues of excessive fertilization. The conclusions the authors draw are irrelevant at best and more dangerously, highly misleading. If policy makers would follow up on the recommendations this would lead to a decline in productivity and soil degradation in a country already suffering from extreme poverty.

Comments for author File: Comments.pdf

Author Response

Respected,

We thank you for your valuable comments and suggestions to improve the quality of this manuscript. 

Author Response File: Author Response.pdf

Reviewer 2 Report

This manuscript is very well-written and provides an interesting study and conclusions about the use of mobile phone consequences for the use of inorganic fertilizers. Below I have some minor recommendations.

 

Introduction

Line [39-40] Among other…

Line [42] Wrong formulation, because when the fertilizer is not used precisely it is because the plants will not take everything. So, I would recommend writing the sentence in another way.

Line [46-47] why? The sentence is unclear, why is it the most used on India and China and causes loss of dollars? Write again in another way stating that IF use is highly inefficient and that it costs money and that by using it largely you end up by wasting money and degrading the environment.

Line [48-52] authors focus on ground water quality damage in Iran and Bangladesh but this is true for many countries in my continents. I would suggest just to write a global sentence and pinpoint these two examples and their references.

Line [70-73] At this point it is not clear how the mobile phones will help to reduce the IF application. Authors mention correctly that farmers need to have easy information and get communication about crop nutrition, but there is a clear link missing between exactly what is shared by the mobile phones that helps farmers to be precise in the IF application.

Line [82-84] Here again this sentence is very interesting, but it misses to inform the reader on how the computers can help to achieve these goals. Authors need to be a bit more precise in here, just complement the sentence by providing a general information on how the computers effectively help farmers.

Line [106-111] I find it too detailed for the introduction. I think it fits better in the Methods.

Line [112-122] This paragraph is odd. This is part of the “state of the art” and should come earlier in the text.

 

Materials and Methods

Figure 1 – It is not clear what is the benefit of having such figure, since it does not provide any relevant information. It would be nice to have each box more detailed. The framework of the study is not really understandable form it.

Line [174-192] The description of these farmers characteristics is very important, it maybe better to describe this first in the study framework.

Line [195-203] At this point methods section seems to much as the Results section. Authors need to “clean” this section and summarize what is important for the methods. How you need the analysis, what have you included and why. Do not reflect upon those data that you used to make decisions.

 

Results

Generally, on results I would expect to see some analysis by region. Since authors state that the country has many differences,  either geographical and social it would be interesting to see if these results that show that the use of mobile phones is correlated to the lower use of IF is also true for all the regions or of the average value is a result of big asymmetries in the country.

Author Response

Most Respected Reviewer 

We are grateful for your precious time and help to improve the manuscript’s quality by your constructive comments and suggestions.

Author Response File: Author Response.pdf

Reviewer 3 Report

• Select the appropriate references for each assertion. For instance, line 37 or line 48.
• Explain better the consequences of the environmental degradation from the agricultural point of view, including soil and air pollution. Line 43-53.
• Follow the sequence of citations. Line 66, 92, 148, 151, etc.
• Introduce examples of other countries with benefits for farmers. Line 66.
• Identify clearly the reference of the literal quote. Line 66-69.
• Introduce examples of all the assertions from lines 70-73.
• Paragraph from lines 112-122 should be in the section 5. Conclusion and Recommendations.
• Locate Figure 1 properly.
• Meaning of symbols in line 151.
• Figures and Tables of the authors do not need the reference “Source Authors”.
• Replace Fig. by Figure. Line 172 and 173.
• Section 2.2.3. Model specification. It is necessary a more compressible explanation of the model.
• Table 2, 3 and 4. It is necessary a more compressible explanation of tables, their data and results.
• Conclusions and recommendations have to be clearly related to results. This relationships have to be included in the text.

Author Response

Most Respected Reviewer please find the response attached

Author Response File: Author Response.pdf

Reviewer 4 Report

land-1286826

 Toward Cleaner Production: Can Mobile Phone Technology  Help using Inorganic Fertilizer Effectively? Empirical Evidence  From Afghanistan

COMMENTS

Introduction

Contributions in LINES107-117 should come after the authors enunciate the paper goals, relocating the text is suggested.

Fourth contribution doesn´t make much sense. Is a methodological aspect, hence if the author contribute to the production of evidence through this way of modelling data, that must be clear, and before introducing the method and even the paper goals it looks misplaced. And the use of panel dta and modelling should be introduced, otherwise is not comprehensible.

Section 2, maybe better if title is Methods and materials

What is described as conceptual framework, is actually the empirical framework, isn´t about concepts.

LINES 172-173 No need for repeating and creating subtitles, suggest independent subsections

• Study area
• Sampling and data
• Data modelling
•  

Data collection was done when? In what year? At some point authors say the “investigator” (should be interviewer) conducted annual follow-up, the authors or the CSO? Writing is confusing respecting the survey did you used pre-existing data, o did you actually applied a questionnaire? If yes when, how, by who

Equation 5, what beta 2 means? The description of the equation doesn´t mention it. The data present four estimate, per years, so maybe additional explanation helps

Table 1, if it intends to describe the variables and respective descriptive, no need to include “name”  in the tile”, however columns expected sign and source, make no sense, id authors are presenting results

Table 2, Column should be renamed as models, because it present the estimates of models with interactions, when a variable is in interaction is arguable to be estimating it simultaneously as an independent variable C2)

 

Minor

LINE 37, ref 2-8 o 2 and 8? And previous sentence jus ref 1, t’s pretty much the same. References should be chosen to ground the statement, not because they also mention the same in respective introductions

Lines 44-48 re basically a repletion of what has been said are these necessary? This paragraph is not based on references, what doesn’t look well. I suggest merging with the previous one, avoiding repetition.

Author Response

We are very grateful for your valuable time and your constructive comments and suggestions to help improve the quality of the manuscript. We have improved the manuscript according to your suggestions.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

I am happy to see that you have finally taken my criticism on fertilizer use in Afghanistan a bit more serious. You have changed the title, the introduction and the objective of the study. 

But then I am seriously disappointed in how you proceed.

I would haver then expected the choice of methods to analyze the new research question to have changed accordingly. However, you have not changed the analysis at all.  Hence, the model does not address the research question if MPU has an effect on effective fertilizer use.

Good science is posing a relevant research question, developing a methodological approach to address that question, getting the right data for the analysis, then doing the analyisis and reporting on it.

You cannot go searching for a research question to fit an analysis you have done, let alone use an analysis you have done for a research question for which it was not intended. This is really bad science.

You still manage to wiggle in a few lines that lower levels of fertilizer use is a good thing, which, while true in some countries (China, the Indo-Gangetic plains of India), it is not the case in Afghanistan. see your lines 353-354.

Now that the biggest concern I had with the paper is starting to be addressed, many other  minor issues still remain, which I have not yet commented on. An example is your use of the term organic farming. In line 344 you basically state that the farmers in Paktya province are organic farmers. Many Afghan farmers do not use high levels of external inputs because of high costs or limited availability or both.  

I would advise you to retract the manuscript, rethink the concepts that you are trying address and redo the analysis and write a completely new paper.

Author Response

Thank you so much

Author Response File: Author Response.pdf

Reviewer 3 Report

Some of the Round 1 reviews have not been correctly completed. Please reply to the following points again:

• Select the appropriate references for each assertion. For instance, line 37 or line 54.
• Follow the sequence of citations. Problems with references 64, 81-85 and 94-100.
• Identify clearly the reference of the literal quote. Line 74-77.
• Section 2.2.3. Model specification. Explanation of the model remains weak. Include a more understandable explanation of the model.
• Table 2, 3 and 4. It is necessary a more understandable explanation of tables, their data and results.
• Conclusions and recommendations must be clearly related to results. These relationships should be included in the text.

Author Response

We are very grateful for your valuable time and your constructive comments and suggestions to help improve the quality of the manuscript. We have improved the manuscript according to your suggestions.

Author Response File: Author Response.pdf

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

After reading the title and abstract, I was very interested in the article because of the interesting research scope, which combines modern ICT with agriculture and the possibilities of more environmentally friendly agricultural production thanks to the use of mobile phones.  Unfortunately, reading the full version brings me more doubts and reservations than explaining the problem and justifying the conclusions proposed by the authors.

The introduction mentions that there is a problem of feeding the growing number of people on Earth, but it is not clear from this research whether having phones will solve this and how it translates into agricultural production (cultivation system, harvest size) and whether it is more conducive to "green" production? Reading the results and conclusions of the authors, one can get the impression that where there are mobile phones, crop production is reduced in favor of other activities (including non-agrarian) and therefore the consumption of inorganic fertilizers in these farms decreases, not because having a telephone contributes to a more rational use of fertilizers and increasing production efficiency while reducing the amount of fertilizers used. In my opinion, just examining the fact that a farmer has a mobile phone reduces the consumption of IF fertilizers on his farm is not enough, because we do not know how it translates into the production level and (as the authors themselves suggest) whether the decrease in fertilization is not a result of that farmers' awareness is growing and agricultural production is being abandoned in favor of other non-agricultural activities that bring income not resulting from agricultural production. Therefore, drawing the conclusion that the use of a mobile phone reduces the amount of IF fertilizers used, but poorly explains the reasons and effects of this compound, has little to do with the important problems of feeding the human population and trying to reduce environmental contamination due to improper production agricultural. This is the weakness of this paper and requires either improvement or explaining why the authors interpret the results in this way.

 

Other comments and suggestions for changes:

1) I propose to expand the methodological chapter and change its structure into three parts: (i) conceptual framework of studies (in my opinion it is part of the methodology, not a separate chapter), (ii) research area and data sources, (iii) model specification. I suggest shortening the introduction, because the text in lines 94-117 concerns research methodology and should be in the second chapter.

2) On line 102, there is an error in the name of the method used - it should be "difference-in-differences".

3) In lines 146-147 there are errors abbreviated as hectare - it should be "ha".

4) Only Figure 1 has the source given. Please complete this in the remaining figures and tables.

5) Figure 2 (map) should be slightly higher and directly below the text about the research area, not among the text about data sources.

6) Table 1 should be moved up - directly below line 187 (above the subsection "Model specification").

7) I do not agree with the information from line 290 that the prices of mobile phones depend on whether they are used in the city or in the countryside or in the highlands (I agree that there are higher costs for infrastructure and mobile network development, but this does not apply to differences in the price of the phone model).

8) The last chapter with conclusions and recommendations should be changed. In my opinion, the results show the key importance of human capital and educational needs among farmers. The use of a mobile phone and access to infrastructure is only meant to help in accessing to education and training that cannot be done in-house, or the cost is too high in a form other than mobile. Improving the education and awareness of farmers is a factor that increases the efficiency of agricultural production and the use of inorganic fertilizers, and reduces environmental pollution. Having a telephone and access to a cellular and internet network are only a technical means to achieve this goal. That is why governments should support the development of ICT networks.

 

Author Response

Comments and Suggestions for Authors

After reading the title and abstract, I was very interested in the article because of the interesting research scope, which combines modern ICT with agriculture and the possibilities of more environmentally friendly agricultural production thanks to the use of mobile phones. Unfortunately, reading the full version brings me more doubts and reservations than explaining the problem and justifying the conclusions proposed by the authors.

Response: Thank you for your suggestions and corrections which would definitely improve our manuscript. We have modified the manuscript and made it more aligned to the pivot point of our purpose. Many modifications have been done in different places in the manuscript. We hope that now, the content is more focused and to the point.

The introduction mentions that there is a problem of feeding the growing number of people on Earth, but it is not clear from this research whether having phones will solve this and how it translates into agricultural production (cultivation system, harvest size) and whether it is more conducive to "green" production? Reading the results and conclusions of the authors, one can get the impression that where there are mobile phones, crop production is reduced in favor of other activities (including non-agrarian) and therefore the consumption of inorganic fertilizers in these farms decreases, not because having a telephone contributes to a more rational use of fertilizers and increasing production efficiency while reducing the amount of fertilizers used. In my opinion, just examining the fact that a farmer has a mobile phone reduces the consumptions of IF fertilizers on his farm is not enough, because we do not know how it translates into the production level and (as the authors themselves suggest) whether the decrease in fertilization is not a result of that farmers' awareness is growing and agricultural production is being abandoned in favor of other non-agricultural activities that bring income not resulting from agricultural production. Therefore, drawing the conclusion that the use of a mobile phone reduces the amount of IF fertilizers used, but poorly explains the reasons and effects of this compound, has little to do with the important problems of feeding the human population and trying to reduce environmental contamination due to improper production agricultural. This is the weakness of this paper and requires either improvement or explaining why the authors interpret the results in this way.

Response: Thank you for your concern about the quality of the content of our manuscript. The focus of this manuscript is to highlight many factors including human capital, farmer characteristics, farming characteristic, external environmental factors, and the contributory role of mobile phones towards cleaner production. All these factors are interconnected, and one cannot negate any of them towards green production. We proved by the application of different models/formulas (e.g., observed the influence of MPU on IF, the impact of cereal crop production on the association between ICTs and IF usage, human capital to study the feasible potential interactions between the usage of mobile phones and IF). The data showed that MPU has a significant negative impact on growers’ IF usage, cereals as the major crops can increase the impact of MPU on IF application, and MPU enhances growers' human capital, especially NAEST, which ultimately decreases the use of IF. Hence in the light of the above results, one can conclude that there is a close association between MPU and IF usage reduction.

Other comments and suggestions for changes:

1) I propose to expand the methodological chapter and change its structure into three parts: (i) conceptual framework of studies (in my opinion it is part of the methodology, not a separate chapter), (ii) research area and data sources, (iii) model specification. I suggest shortening the introduction, because the text in lines 94-117 concerns research methodology and should be in the second chapter.

Response: Thanks for identifying this important error. We have modified the methodological chapter as you suggested.

2) On line 102, there is an error in the name of the method used - it should be "difference-in-differences".

Response: Please follow line 115, the word “difference-in-difference” has been changed to “difference-in-differences” in the revised version

3) In lines 146-147 there are errors abbreviated as hectare - it should be "ha".

Response: Please follow lines 177-179, the word “he” has been changed to “ha” in the revised version.

4) Only Figure 1 has the source given. Please complete this in the remaining figures and tables.

Response: Thanks for identifying this important error. We have cited the remaining figures and tables.

5) Figure 2 (map) should be slightly higher and directly below the text about the research area, not among the text about data sources.

Response: Thank you, figure 2 (map) has been changed, and it is below the text about the research area.

6) Table 1 should be moved up - directly below line 187 (above the subsection "Model specification").

Response: Done. Please follow table 1 in the revised version.

7) I do not agree with the information from line 290 that the prices of mobile phones depend on whether they are used in the city or in the countryside or in the highlands (I agree that there are higher costs for infrastructure and mobile network development, but this does not apply to differences in the price of the phone model).

Response: Thank you so much, we have modified the sentence as you suggested. Please refer to the line number (341-343).

8) The last chapter with conclusions and recommendations should be changed. In my opinion, the results show the key importance of human capital and educational needs among farmers. The use of a mobile phone and access to infrastructure is only meant to help in accessing to education and training that cannot be done in-house, or the cost is too high in a form other than mobile. Improving the education and awareness of farmers is a factor that increases the efficiency of agricultural production and the use of inorganic fertilizers, and reduces environmental pollution. Having a telephone and access to a cellular and internet network are only a technical means to achieve this goal. That is why governments should support the development of ICT networks.

Response: Thank you for highlighting the text modifications. The content has been modified per your suggestions and we think that by doing this our purpose would effectively be conveyed to the end readers.

 

 

Author Response File: Author Response.pdf

Reviewer 2 Report

This article addresses a topic of great interest and current relevance. It is written in a clear style, so it is easy to read. Its discursive structure is organized in a coherent sequence, in such a way that each argument leads to another, so there is a clear common thread among the different paragraphs and epigraphs of the manuscript. Likewise, the manuscript is well founded theoretically and methodologically. The authors also acknowledge some of the limitations of their work when they state on page 12 of the manuscript:

“However, this study has a few limitations. We only had the total quantity of overall IF sources utilized by farmers/growers due to limited information, but not the total amount of particular types of fertilizers (such as compound fertilizer or phosphorus, nitrogen, potassium). In the future, more comprehensive research on various types of fertilizers can be considered. Besides, we studied samples of the household from Afghanistan; therefore, it is necessary to conduct comparative studies with data from multiple developing countries to understand better the relationship between mobile phones and IF usage in various socio-economic contexts.”

In any case, I suggest to the authors some changes that I hope will contribute to improving the manuscript. Such changes are as follows:

1. A) The authors should add some lines explaining what they understand by human capital, as well as citing some references in this regard. I do not mention any references on this matter. I leave it to the choice of the authors to select some references from the abundant existing bibliography on the matter, depending on the way in which they explain what they understand by human capital.
2. B) The authors should also explain in a little more detail what kind of information and specific advice can be transmitted via smartphones technology to farmers by the Afghan government (or in fact are already transmitted). This in order to improve their skills in cultivation, and thus seek that they use less inorganic fertilizers.
3. C) Last but not least, the authors should cite more bibliographic references and explain in more detail what kind of advice is appropriate and necessary to transmit to farmers in order to train them to reduce the use of inorganic fertilizers (IF). The authors already cite a work on this matter: Fabregas, R .; Kremer, M .; Schilbach, F. Realizing the potential of digital development: The case of agricultural advice. Science 474 2019, 366. This work states that "mobile phone technology, especially smartphones, can bring advanced science-based agricultural advice to small growers to increase productivity, particularly in the context of rapid variations in economic and ecological conditions".

However, the authors of the present manuscript that I am reviewing should go a little further by explaining what kind of agricultural advice, adding more bibliographic references, etc.

I hope that the previous comments will be of help in order to improve a manuscript that, I reiterate once again, deserves to be taken into consideration, since it is useful to know it to explain and / or address the present transformations towards the modernization of agriculture that are being undergone in different developing countries of the world.

Author Response

Comments and Suggestions for Authors

This article addresses a topic of great interest and current relevance. It is written in a clear style, so it is easy to read. Its discursive structure is organized in a coherent sequence, in such a way that each argument leads to another, so there is a clear common thread among the different paragraphs and epigraphs of the manuscript. Likewise, the manuscript is well founded theoretically and methodologically. The authors also acknowledge some of the limitations of their work when they state on page 12 of the manuscript:

“However, this study has a few limitations. We only had the total quantity of overall IF sources utilized by farmers/growers due to limited information, but not the total amount of particular types of fertilizers (such as compound fertilizer or phosphorus, nitrogen, potassium). In the future, more comprehensive research on various types of fertilizers can be considered. Besides, we studied samples of the household from Afghanistan; therefore, it is necessary to conduct comparative studies with data from multiple developing countries to understand better the relationship between mobile phones and IF usage in various socio-economic contexts.”

Response: We are grateful for your precious time to improve the manuscript quality. Thank you for your valuable comments and suggestions.

In any case, I suggest to the authors some changes that I hope will contribute to improving the manuscript. Such changes are as follows:

Response: Thank you for your valuable suggestions.

1. A) The authors should add some lines explaining what they understand by human capital, as well as citing some references in this regard. I do not mention any references on this matter. I leave it to the choice of the authors to select some references from the abundant existing bibliography on the matter, depending on the way in which they explain what they understand by human capital.

Response: we have added references regarding human capital as you suggested, Please follow the references (315-318 and 440-445) in the revised version of the manuscript.

2. B) The authors should also explain in a little more detail what kind of information and specific advice can be transmitted via smartphones technology to farmers by the Afghan government (or in fact are already transmitted). This in order to improve their skills in cultivation, and thus seek that they use less inorganic fertilizers.

Response: Thank you, we have added the information including references about the benefits of mobile phones in the development of the agriculture sector in Afghanistan. Please follow the line (62-70) in the revised version of the manuscript.

3. C) Last but not least, the authors should cite more bibliographic references and explain in more detail what kind of advice is appropriate and necessary to transmit to farmers in order to train them to reduce the use of inorganic fertilizers (IF). The authors already cite a work on this matter: Fabregas, R .; Kremer, M .; Schilbach, F. Realizing the potential of digital development: The case of agricultural advice. Science 474 2019, 366. This work states that "mobile phone technology, especially smartphones, can bring advanced science-based agricultural advice to small growers to increase productivity, particularly in the context of rapid variations in economic and ecological conditions".

Response: we have added references regarding, small growers to reduce IF and increase productivity. Please follow the references (40, and 43) in the revised version of the manuscript.

However, the authors of the present manuscript that I am reviewing should go a little further by explaining what kind of agricultural advice, adding more bibliographic references, etc.

Response: Thank you for your suggestions. Desired changes have been made in the manuscript with the addition of the latest references. Please refer to the revised version of the manuscript.

I hope that the previous comments will be of help in order to improve a manuscript that, I reiterate once again, deserves to be taken into consideration, since it is useful to know it to explain and/or address the present transformations towards the modernization of agriculture that are being undergone in different developing countries of the world.

Response: We are extremely grateful for your precious time and detailed comment/suggestion that highly improved the manuscript quality.

 

Author Response File: Author Response.pdf

Reviewer 3 Report

The topic is interesting but the waythe analysis was doen is problematic. Given the data availability, I do not see how the authors can actually answer the research question they pose.

For detailed comments, see attached file.

Comments for author File: Comments.pdf

Author Response

 

Review of Manuscript 1210722 submitted to Land: “Toward Cleaner Production: Can Mobile Phone Technology 2 Help Reduce Inorganic Fertilizer Usage? Empirical Evidence 3 From Afghanistan”

 

General

There are many typographical errors and poor English sentences. The paper would benefit from editing by a native English speaker.

Response: Thank you very much. We have modified our manuscript taking help from a native speaker to improve the grammatical and technical errors. Please consult the modified version of the manuscript.

 

Fertilizer use in Afghanistan.

The authors state that IF use in Afghanistan has been excessive but the reference, they use does not address this issue. Table 1 indicates that the average IF consumption was 113.20 kg/ha. This is not an indication of excessive use. In general, globally, across geographies and crops the recommended fertilizer doses are:

• • N: 50-150 kg/ha
• • P2O5: 20-80 kg/ha
• • K2O: 20-60 kg/ha

Response: Thank you for your comments, the 113.20 kg/ha is a result of our study, but this is not only studied showing excessive use of IF but there are also other studies which show even higher consumption of IF like (of 250 kg/ha for urea and 125 kg/ha for DAP).

Please follow reference no (100) World Bank. Islamic Republic of Afghanistan agricultural sector review: revitalizing agriculture for economic growth, job creation and food security 2014, pp 107.

 

In the manuscript no distinction is made between different kinds of fertilizer. All fertilizer is added, where that is not useful at all in terms of looking at excessive use or not. This is mentioned in the conclusions as a limitation.

It is not just a limitation, but it invalidates the analysis as this is focused on cleaner production and this cannot be identified from the data. In terms of nutrient use the relationship with the environment is linked to the optimal use of fertilizers. Agriculture is an extractive activity. Not using fertilizers leads to soil mining with in the long-term disastrous effects such as erosion due to shallow soils, biodiversity loss and desertification. Over-use leads to water, soil and air pollution, in turn leading to loss of biodiversity, human health problems. Getting fertilization right is therefore important. Not having that data available makes it impossible to do the analysis correctly.

Response: Thank you very much. We have modified our manuscript, and added information regarding human capital and governmental support in the use of mobile phone and Internet technology by vulnerable households. In a poor country like Afghanistan, it is very difficult to collect extensive data due to limitation of resources and being a warfare country causes another hurdle in data collection. Hopefully, Our future research would  cover this limitation along with other novel findings. Currently, our focus was the total quantity of overall IF sources utilized by farmers/growers.

 

Methodology

The authors use propensity score matching. This is a very problematic approach because it discards units, can change the target estimand, and is non-smooth, making inference challenging. Using propensity scores to match adds additional problems.

The most famous critique of propensity score matching comes from King and Nielsen (2019). They have three primary arguments: 1) propensity score matching seeks to imitate a randomized experiment instead of a block randomized experiment, the latter of which yields far better precision and control against confounding, 2) propensity score matching induces the "propensity score paradox", where further trimming of the units increases imbalance after a point (not shared by some other matching methods), see Ripollone et al. (2018), and 3) effect estimation is more sensitive to model specification after using propensity score matching than other matching methods.

The authors use a two-way fixed effect panel model. However, they do not take into account endogeneity issues. Mobile phone usage is likely to be related to age, education, internet technology, assets, and income. This means that there is a very likely selection bias. Hence an endogenous switching regression model approach (Pitt, 1983), or Heckman’s approach (Heckman, 1979) with an inverse Mills ratio is justified. The Methods section does not mention the term “selection bias”, which is a surprise because that is the main concern in any quasi-experimental method. In fact, I think that the term is not mentioned anywhere in the paper.

The 2SLS-IV estimation requires a careful selection of the instrumental variable. IV produce estimates of causal effects that are specific to farmers whose behavior can be manipulated by the instrument at hand. The use of instrumental variables is common in impact evaluation, although the method is usually not preferred because it is not very good at correcting selection bias as good instruments are often hard to come by. A valid instrument must satisfy two basic conditions: it must affect the adoption (or participation rate) but should not correlate with the characteristics of adopters/non-adopters. This is not the case.

It would have been good to the descriptive statistics of observations in the Paktya province compared to the other regions in order to understand differences analyzed in the DID approach.

 

Response: Thank you, please the issue of “selection bias” is dealt with in this paper by applying the PSM-DID technique. Please refer to the line number (270-273), where this is stated, and also referenced number 75-79.

 

References

(75). Yang, Y.; Wu, F.; Zhang, Q.; Hong, J.; Dong, C. Is it sustainable to implement a regional payment for ecosystem service programme for 10 Years? An empirical analysis from the perspective of household livelihoods. Ecological Economics 2020, 176, 106746.

(79). Tang, K.; Qiu, Y.;  Zhou, D. Does command-and-control regulation promote green innovation performance? Evidence from China's industrial enterprises. Science of the Total Environment, 2020, 712, 136362

References

Heckman, J. J. (1979). Sample selection bias as a specification error. Econometrica: Journal of the econometric society, 153-161.

King, G., & Nielsen, R. (2019). Why Propensity Scores Should Not Be Used for Matching. Political Analysis, 1–20. https://doi.org/10.1017/pan.2019.11

Pitt, M. (1983) "Farm Level Fertilizer Demand in Java: A Meta-Production Function Approach." Amer J. Agr. Econ. 65(August):502-8

Ripollone, J. E., Huybrechts, K. F., Rothman, K. J., Ferguson, R. E., & Franklin, J. M. (2018). Implications of the Propensity Score Matching Paradox in Pharmacoepidemiology. American Journal of Epidemiology, 187(9), 1951–1961. https://doi.org/10.1093/aje/kwy078.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The paper in its current form incorporates all the proposed changes from the first review. Thank you for your cooperation and I recommend publishing the paper. 

Reviewer 3 Report

I am deeply disappointed that the authors did not respond in depth to the substantial comments provided. 

Fertilizer use in Afghanistan

My initial comments were:

“The authors state that IF use in Afghanistan has been excessive but the reference they use does not address this issue. Table 1 indicates that the average IF consumption was 113.20 kg/ha. This is not an indication of excessive use. In general, globally, across geographies and crops the recommended fertilizer doses  are:

• N: 50-150 kg/ha
• P2O5: 20-80 kg/ha
• K2O: 20-60 kg/ha”

To which the authors responded:

“Thank you for your comments, the 113.20 kg/ha is a result of our study, but this is not only studied showing excessive use of IF but there are also other studies which show even higher consumption of IF like (of 250 kg/ha for urea and 125 kg/ha for DAP).

Please follow reference no (100) World Bank. Islamic Republic of Afghanistan agricultural sector review: revitalizing agriculture for economic growth, job creation and food security 2014, pp 107.”

The reference they cite states:

p.15. “Irrigated wheat farmers are already doing most things right. They are using moderate to high levels of fertilizer” and

p.24 “Currently, farmers are using 68 percent and 83 percent of the recommended fertilizer application rates (of 250 kg/ha for urea and 125 kg/ha for DAP); available evidence suggests that increasing their usage would be profitable.”

This implies that the authors are recommending a solution to something that is not a problem. This is bad science and morally and ethically wrong!

The response to the second part of my comment was completely inadequate. They did not respond to the comment itself but added some window dressing to the text.

Methodology

The authors did not respond to the comments but reiterated that they used the flawed PSM-DID technique. The fact that it is widely used is no excuse to use a flawed methodology.