Impacts of Climate Variability and Change on Sorghum Crop Yield in the Babile District of Eastern Ethiopia

Round 1

Reviewer 1 Report

The current paper deals with the problem of climate variability in Ethiopia and its influence on sorghum production. This topic is particularly important under rain-fed production systems. However, one major flaw is that the line/page numbers are not included in the manuscript, making it difficult to make precise revisions. This study is quite simple without any additional conclusions.

Also, in manuscript, authors often refer to appropriate references (e.g. stated by (40)) that are enclosed in parentheses. Authors should adjust the text

 

Introduction:

 The first paragraph in the introduction section is quite general, without specific references and data on the impact of climate change on production in Africa or at the global level. The entire paragraph is based on the assertion that rainfall is decreased and more erratic, and all of this is affecting agriculture.

The font is not consistent throughout the text in the second paragraph. Please shortly provide specific data related to rainfall or temperature during the Kiremt or Belg parts of the season.

Based on an assessment done by (13), historical rainfall data indicates that semi-arid parts of the East Hararghe zone have experienced the worst extreme droughts to climate variability impact. The sentence is grammatically correct, but there seems to be a missing part.

Please use common units of measure such as kg/ha or t/ha, not quintals

Ordinal numbers of citations are not properly arranged and formatted.

Why do You capitalize the word sorghum occasionally

 

Material and methods

2.1.1 Climate

Please explain meaninig LGP - length of the growing period? You have some words and letters in bold in this section.

 

Results and discussion

Page 7. correct the capital letters in Number of Rainy Days

In the table, authors use "mean," while in the text  use "average." Also „annual“ or „yearly“. Authors should harmonize

Fig 2 is unclear, it must be explained on its own. the authors should explain this Fig, for example, what the blue and red lines represent. Also, The authors do not refer to Figure 2 in the text.

Figure 3 needs to be adjusted, the years should be lowered compared to the axis, as it is quite unclear this way. The same goes for Figures 4 and 5.

The year of greatest positive value RAI during JJAS was 2019, with an average RAI of 2.3, being therefore classified as very wet (Figure 4). what about 1983, 1986 or 1988

3.4.1. Sorghum grain yield trend line smoothers analysis. I don't understand what is the purpose of this analysis. What is the advantage of a cubic equation over a linear one? What is the practical or scientific aspect of this result?

 

3.5. Correlation and Regression of Sorghum versus its growing period Climate Variables; 3.5.1. Analysis of Sorghum grain yield response to climate variability; The authors first use correlation analysis between yields and time variables. Only two parameters have shown a significant relationship with yield. After that, they use regression analysis to indicate the relationship between yields and individual variables. I think it's enough to present one analysis. Also, if the authors decide to use regression analysis, they should show the R2 value on the graph itself, indicating whether the value is significant or not (*; **; or ns).

 

3.5.2. Sorghum yield simulation; Although the authors have determined an appropriate equation that best describes the relationship between yields and time variables, this scenario is not logical. It is unlikely that the yield will decrease by almost half in the period from 2020 to 2040 compared to the period from 2010 to 2020. However, Figure 7 showed a significant relationship between the year and sorghum yields. I think there should be much more discussion about this. Also, in Figure 7, it is probably necessary to highlight the role of breeding and creating new varieties that are more resistant to adverse weather conditions.

 

Based on the review of the paper, a major revision is proposed.

 

Author Response

Authors’ response to Reviewer 1:

 

The current paper deals with the problem of climate variability in Ethiopia and its influence on sorghum production. This topic is particularly important under rain-fed production systems. However, one major flaw is that the line/page numbers are not included in the manuscript, making it difficult to make precise revisions. This study is quite simple without any additional conclusions.

Also, in manuscript, authors often refer to appropriate references (e.g. stated by (40)) that are enclosed in parentheses. Authors should adjust the text

 

Authors:

We would like to thank the anonymous reviewer 1 who reviewed our manuscript tirelessly and in-depth. We considered each and every point raised in our revised version. We also considered all suggestions and comments in order to make appropriate corrections provided point by point as provided hereafter.

• In the revised version, the page and line number are included, accordingly.
• In order to provide more scientific rigor, we included additional narratives in the conclusion.
• All reference numbers are cited in the manuscripts in parenthesis as []. We thank the reviewer for pointing out the error.

 

 

Introduction:

 The first paragraph in the introduction section is quite general, without specific references and data on the impact of climate change on production in Africa or at the global level. The entire paragraph is based on the assertion that rainfall is decreased and more erratic, and all of this is affecting agriculture.

 

Authors:

We are grateful to acknowledge the comments of the Reviewer. The authors identified other climatic drivers, in addition to rainfall, temperature, and soil moisture that played significant roles in affecting the Sorghum crop, especially over the arid and semi-arid regions of sub-Sahara Africa. To qualify the scientific merits, we included additional references  

 

The font is not consistent throughout the text in the second paragraph. Please shortly provide specific data related to rainfall or temperature during the Kiremt or Belg parts of the season.

 

 

Authors:

Thanks. We provided specific data that characterize the main rain (Kiremt) and small rain (Belg) seasons.

 

Based on an assessment done by (13), historical rainfall data indicates that semi-arid parts of the East Hararghe zone have experienced the worst extreme droughts to climate variability impact. The sentence is grammatically correct, but there seems to be a missing part.

 

 

Authors:

Many thanks for pointing up such useful comments. Yes, in the new version, we re-write the sentence for further completeness.

 

Please use common units of measure such as kg/ha or t/ha, not quintals

 

 

Authors:

Thanks. Yes, we replaced kg/ha with t/ha throughout the manuscript.

 

Ordinal numbers of citations are not properly arranged and formatted.

 

 

Authors:

All citations are properly arranged as per the comments.

 

Why do You capitalize the word sorghum occasionally?

 

Authors:

In order to keep consistency in the manuscript, we use Sorghum as a capital letter.

 

Material and methods

2.1.1 Climate

Please explain the meaning of LGP - length of the growing period? You have some words and letters in bold in this section.

 

Authors:

• Many thanks to the reviewer for tracing this acronym. We clearly defined LGP as the length of the growing period of the Sorghum Crop, starting from sowing to harvesting periods during the season when climate conditions, particularly rains are suitable for this crop filling grain and attaining maturity at the end of the agricultural season.
• In the methodology chapter, we added an explanatory paragraph for the trend analysis.
• In our analysis, our focus was to provide a projection of future time Sorghum grain yield in the near century from (2010-2040). Only the RCP4.5 climate scenario was considered for the near term rather than the RCP8.5 scenario.
• The calculation of growing degree days (GDD) is intended to examine how Sorghum yield production would be dependent on this variable.
• Trend and Variability of the Sorghum Crop Yield Analysis subsection were also included in Chapter 2.

Results and discussion

Page 7. Correct the capital letters in Number of Rainy Days

 

 

Authors:

The capital letters are corrected accordingly.

 

 

In the table, authors use "mean," while in the text  use "average." Also „annual“ or „yearly“. Authors should harmonize

 

 

Authors:

Thanks. We corrected the use of words in the manuscript as similar to the table.

 

 

Fig 2 is unclear, it must be explained on its own. the authors should explain this Fig, for example, what the blue and red lines represent. Also, The authors do not refer to Figure 2 in the text.

 

Authors:

We thanked and convinced the reviewer for pointing out the less importance of Figure 2. We deleted and excluded the former Figure 2 from the new version.

 

 

Figure 3 needs to be adjusted, the years should be lowered compared to the axis, as it is quite unclear this way. The same goes for Figures 4 and 5.

Authors:

All comments have been taken adjusting Figures 3 (Figure 2 in the revised version) and Figures 4 and 5, as modified in the revised version as Figures 3 and 4.

 

 

 

The year of greatest positive value RAI during JJAS was 2019, with an average RAI of 2.3, being therefore classified as very wet (Figure 4). what about 1983, 1986 or 1988

 

 

Authors:

Many thanks to the reviewer for bringing this key point to our attention. The authors considered this point and addressed it in the revised version of Figure 4 (currently in Figure 3).

 

3.4.1. Sorghum grain yield trend line smoothers analysis. I don't understand what is the purpose of this analysis. What is the advantage of a cubic equation over a linear one? What is the practical or scientific aspect of this result?

 

Authors:

Thanks. We excluded this representation (old Figure 7) as per the reviewer’s comments.

 

 

3.5. Correlation and Regression of Sorghum versus its growing period Climate Variables; 3.5.1. Analysis of Sorghum grain yield response to climate variability; The authors first use correlation analysis between yields and time variables. Only two parameters have shown a significant relationship with yield. After that, they use regression analysis to indicate the relationship between yields and individual variables. I think it's enough to present one analysis. Also, if the authors decide to use regression analysis, they should show the R2 value on the graph itself, indicating whether the value is significant or not (*; **; or ns).

 

 

Authors:

Thanks for these valuable comments and suggestions. We have taken all suggestions into account in the revised version of the manuscript. The goodness-of-fit regression and the R2 values are depicted in each figure.

 

3.5.2. Sorghum yield simulation; Although the authors have determined an appropriate equation that best describes the relationship between yields and time variables, this scenario is not logical. It is unlikely that the yield will decrease by almost half in the period from 2020 to 2040 compared to the period from 2010 to 2020. However, Figure 7 showed a significant relationship between the year and sorghum yields. I think there should be much more discussion about this. Also, in Figure 7, it is probably necessary to highlight the role of breeding and creating new varieties that are more resistant to adverse weather conditions.

Authors:

Many thanks for this comprehensive feedback and suggestion on how the authors should address the Sorghum crop productivity under changing climate in the near term. We addressed your concern and showed the Sorghum crop yield trend in the near term in Figure 8. Our findings dictated that unless climate-smart agriculture is pace, Sorghum production, and productivity are more likely to decline. Our recommendation is an indication for proper adaption and intervention to increase productivity under moisture stress and higher temperature even under medium GHG emission scenarios (RCP4.5).

Author Response File: Author Response.docx

Reviewer 2 Report

Tolosa et al. (2023) studied “Impacts of Climate Variability and Change on Sorghum Crop Yield in the Babile District of Eastern Ethiopia. The study is very interesting and novel for a country like Ethiopia where the main agricultural production is based on rainfed, and the impact of climate variability and change are significantly affecting the rainfall occurrence, intensity, and magnitude from time to time. I would like to congratulate all the authors for their impressive and useful works!  

 

The following are minor comments:

·         Figure 6 resolution needs modification. It was hard to read the values on the y-axis.

·         Please delete the months within the bracket such as  Belg (MAM) rainfall than the Kiremt (JJAS), which you already defined in the introduction part of the paper.

·         Add the x and y – axis to Figure 7 and also delete the title “Sorghum grain Yield trend line smoothers”. You can add in the Figure caption, for example, something like this “Figure 7. The trend of Sorghum grain yield (1995 – 2020). Orange, green, and red lines are reparenting linear, quadratic, and cubic trends, respectively.”

 

·         Delete the title “Sorghum grain Yield Simulated in Near Century” from Figure 10 title and amend it in the Figure caption. This figure also needs proper x and y – axes. 

Author Response

Authors’ Responses to Reviewer 2:

 

Comments and Suggestions for Authors

Tolosa et al. (2023) studied “Impacts of Climate Variability and Change on Sorghum Crop Yield in the Babile District of Eastern Ethiopia. The study is very interesting and novel for a country like Ethiopia where the main agricultural production is based on rainfed, and the impact of climate variability and change are significantly affecting the rainfall occurrence, intensity, and magnitude from time to time. I would like to congratulate all the authors for their impressive and useful works!  

 

 

Authors:

The authors would like to acknowledge and accept the reviewer’s positive feedback and encouragement of our manuscript. We have critically reviewed our manuscript and provided a scientific response to all comments asap.

 

The following are minor comments:

• Figure 6 resolution needs modification. It was hard to read the values on the y-axis.

 

Authors:

Thanks for your insightful notice. In the revised version, we modified the Figure and enhance its readability.

 

• Please delete the months within the bracket such as  Belg (MAM) rainfall than the Kiremt (JJAS), which you already defined in the introduction part of the paper.

 

Authors:

Thanks. The months were deleted as they were provided in the introduction Chapter.

 

• Add the x and y – axis to Figure 7 and also delete the title “Sorghum grain Yield trend line smoothers”. You can add in the Figure caption, for example, something like this “Figure 7. The trend of Sorghum grain yield (1995 – 2020). Orange, green, and red lines are reparenting linear, quadratic, and cubic trends, respectively.”

 

Authors:

With the strong suggestion forwarded by Reviewer 1, we deleted this Figure as its added-value in this context would be less important.

 

 

• Delete the title “Sorghum grain Yield Simulated in Near Century” from Figure 10 title and amend it in the Figure caption. This figure also needs proper x and y – axes. 

 

Authors:

Thanks for this useful suggestion. We deleted the title embedded in the figure and kept the Figure title only. For your information, after deleting some figures from the manuscript old Figure 10 became Figure 8 in the revised Version.

 

 

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The authors have addressed most of the comments. Only a few minor corrections remain, which are listed below. A minor correction is suggested

 

On the charts, the years should be positioned all the way at the bottom. Small horizontal lines reduce the visibility of the graph, please remove them.

On images 6 and 7, the authors still have not indicated whether the regression is significant or not

"The relationship between climate variables and grain yield was found to be very weak (Line 556-557). Therefore, the statement that 'the results revealed that sorghum grain yield is directly proportional to monthly rainfall (Figure 6) and inversely proportional to monthly maximum and minimum temperature' is not appropriate."

 

Authors incosistently use lower and upper case latter for sorghum. After first revision, this was stated, and authos didnt correct the manuscript. Authors inconsistently use lower and upper case letters for sorghum. This was pointed out after the first revision, but the authors did not correct the manuscript complitely. Line 549, 563

In table 7, temperature (°C) should be marked with capital letters and enclosed in parentheses as you did with precipitation

Author Response

Responses from Authors:

The authors would like to extend their grateful appreciation to the anonymous reviewer for revisiting our manuscript for the second time and pointing out key scientific novelty that enable us to refine the manuscript in its final version. We believe that our in-depth review while addressing all comments the reviewer identified in the preview version. Our responses have been given for each comment as follows.

On the charts, the years should be positioned all the way at the bottom. Small horizontal lines reduce the visibility of the graph, please remove them.

Authors;

We thanked the reviewer for this comment. We have taken your suggestion and the years are positioned at the bottom line in Figures 2, 3, and 4.

 

On images 6 and 7, the authors still have not indicated whether the regression is significant or not.

Authors;

Thanks, again. We identified some inconsistencies in the paragraph and inserted the following sentences. "

Even though the goodness-of-fit of the regression equations is statistically not significant at alpha 0.05, the results revealed that Sorghum grain yield is weakly associated with monthly rainfall (Figure 6) and inversely proportional to monthly maximum and minimum temperature (Figure 7). As indicated in both Figures 6 and 7, each climate variable did not explain the variation in Sorghum yield performance separately. However, there is a tendency for Sorghum crop yield to increment with rainfall while declining with an increase in temperature." We thought that the inclusion of these sentences on page 16 would clarify the interlinkage between rainfall and Sorghum crop yield despite the fact that the regression equation is not statistically significant.

 

"The relationship between climate variables and grain yield was found to be very weak (Line 556-557). Therefore, the statement that 'the results revealed that sorghum grain yield is directly proportional to monthly rainfall (Figure 6) and inversely proportional to monthly maximum and minimum temperature' is not appropriate."

Authors;

Many thanks for putting this comment to our attention. We considered the comment positively and ammneded the narative accordingly by deleting inappropriate descriptiona while inserting the phrase, ... statistically not signidficant,

Authors incosistently use lower and upper case latter for sorghum. After first revision, this was stated, and the authos didnt corrected the manuscript. Authors inconsistently use lower and upper case letters for sorghum. This was pointed out after the first revision, but the authors did not correct the manuscript complitely. Line 549, 563

Authors;

Again, we are kindly grateful to the reviewer to provided us with this comment. As stated in the comment, we replace all small letter beginning as sorghum with Sorghum throughout the manuscript.

In table 7, temperature (°C) should be marked with capital letters and enclosed in parentheses as you did with precipitation

Authors;

Many thanks to the reviewer again. We substituted temperature in °c by temperature (°C), with C as a capital letter.