Carbon Footprint Assessment and Energy Budgeting of Different Annual and Perennial Forage Cropping Systems: A Study from the Semi-Arid Region of Karnataka, India
, Bommalapura Gundanaik Shekara 2, Shankarappa Sridhara 3, Mudalagiriyappa 4, Nagesh Malasiddappa Chikkarugi 2, Pradeep Gopakkali 3, Prakash Kumar Jha 5 and P. V. Vara Prasad 5,6
Round 1
Reviewer 1 Report
1. You should calculate the carbon footprint, viz., as unit of kg CE kg-1. This facilitates the comparison of product carbon footprints between different crop systems.
2. Farmyard manure is also a kind of fertilizers, so, you need to distinguish between chemical fertilizers and organic fertilizers, and distinguish them in the text. In Line 38 and Line 39, the “fertilizer” may change to “chemical fertilizers”.
3. In Line 34, what is the unit of energy use efficiency? (12.3 and 11.2 ??)
4. The Introduction part not only points out the gaps in research, but also reflects the importance of your study. Well written. However, in the Introduction, the references are a bit outdated. Therefore, it is recommended that you add references in the appropriate place, which are https://doi.org/10.1016/j.jclepro.2020.124041, https://doi.org/10.3389/fsufs.2022.948810, and https://doi.org/10.1016/j.resconrec.2021.105661. I promise, these articles are fresher and more fit your research.
5. Table 1. Maybe this table has some format mistakes. And some space symbols may be lost in the 2.1 section.
6. The formula is wrong. What is +12/44? And the representation of the units in the formula is inconsistent with the text.
7. Important! Carbon out should consider soil carbon sequestration. The calculation method refers to https://doi.org/10.1016/j.resconrec.2021.105661.
8. Have you considered indirect N2O emissions, i.e., NH3 volatilization and N leaching?
9. What is the reference for EF of Farmyard Manure in the Table 3?
10. Pay attention to the subscripts of the units in Table 3 and any other places.
11. Obviously, the information from Fig. 2 can be integrated into Table 5. And the same problem occurs in Fig. 4.
12. No unit in Fig. 5? Why there are no ANOVA in this figure?
13. It would be better to share one coordinate axis in Fig. 6 (as Fig. 6 a), and then add a scale diagram (as Fig. 6 b)
14. Don't over-split the results, some results can be combined. (Fig. 7-Fig. 10)
15. Not only do I want to know the general situation, I also want to know the situation of the various farming systems. It is obviously that these proportions are different in different farming systems.
16. I think some of your discussions are unnecessary, you are overly concerned with the composition of energy or carbon.
17. I suggest you add some discussion, is there anything else that can be done to further improve the carbon efficiency or the energy efficiency besides choosing the advantage system?
18. 4R should in the discussion, not in the conclusion.
19. The conclusion is too long, shorten it.
20. The quality of the references is not high, and many journals are not well-known. It is recommended to cite some high-quality journals.
Author Response
Dear Reviewer,
Thanks for invaluable suggestions. Please find the revised manuscript attached with the response to reviewer letter. The line numbers are mentioned in response letter as per the revised manuscript.
Sincerely,
Authors
Author Response File: 
Author Response.doc
Reviewer 2 Report
The manuscript provides valuable data on the carbon footprint of plant cultivation in a variety of cultivation systems. The manuscript is well compiled, the methods and results are satisfactory. The data was collected on the cultivation of plants on red sandy loam soil, which account for approximately 13% of the world's soil area - which guarantees a global rather than local dimension of this research. Authors should only consider increasing their understanding of the data presented in Table 1. It is unusually formatted. Moreover, the wording "Values observed" is incomprehensible. Organic carbon, nitrogen, phosphorus and potassium content must be expressed in g kg-1, not in% or kg ha-1. The authors should explain what fractions of phosphorus and potassium (total, available, exchangeable?) are presented in the table. With these corrections made, the manuscript will be available for printing.
Author Response
Dear Reviewer,
Thanks for invaluable suggestions. Please find the revised manuscript attached along with response to reviewer letter attached. The line numbers are mentioned in the response are according to the revised manuscript attached.
Sincerely,
Prakash
Author Response File: Author Response.doc
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
The manuscript of Manoj has the main aim to find the most energy efficient cropping system with the lowest carbon footprint. In present days, with such high rate of human population growth, along with their increasing demands and also with increasing atmospheric carbon level, which plays a major part in climate change, such studies are essential. New and developed cropping systems, with possible high production but low carbon output are needed. The need for a sustainable agricultural system is increasing. This study contributes to the development of such systems. By comparing different cropping systems the authors aimed to find the most efficient ones. I support the publication of such studies, but this one needs some improvement. Figures and figures/tables captions are not as informative as they should be. I also miss the global knowledge about this topic and how the studied cropping systems perform in other countries. The manuscript should be more clear and focused on the topic, mainly the Discussion part, which in this form seems only to be a wider version of the results. It has to have a clear directions and clear conclusions in global frame.
Major comments
Introduction: What is the situation globally in grain productivity, fertilizer use, animal and mechanical contribution, etc.?
L 75: I am confused of your use of the term “energy sources”. How are insecticides energy sources? Their production and application needs energy, is this what do you mean?
Please formulate clear questions or hypothesises beside the presentation of the main aim of the study.
Table 1: I suggest placing the parameters and their values above each other and use a long format instead of this confusing wide format.
L 122: Exactly when, in what months were crops sown? From where were seeds collected/purchased? What was the quantity of sown seeds? Where they stratified/scarified before sowing? What was the base of your crop species selection?
L 136: Please explain the timing of harvestings. There were at the peaks of biomass production or what was the reason to harvest when you did it?
L 155: How was root biomass calculated more specifically? from where did you get root:shoot ratios?
In Result, as anybody can read from the Tables, you should not include values in the main text. You could just indicate in which table to search for it.
You should add Figures, not only Tables, to improve the readability of the manuscript.
Figure 2,4, 6: There are not the results of the “different fodder cropping systems”, but their results pooled together. It would be more informative to present all treatments separately, as in this form this figure has no information value.
Figure 3: How is seed energy input? Or fertilizers? Or chemicals?
Figure 7-10: Seeing this Figures I am really confused of your categories of energy components. You should add a detailed explanation about their categorization criteria and also a Table to which category they belong to the Methods part.
Discussion: Discuss your result in global frame, not just Asia or India. I miss new and relevant references, which support or oppose your results. I miss references to global studies outside your focus area. What happened on other systems, what other alternatives are present which may be suitable also for India? There are other crops which could be also tested? Do not justify your result based on one or two supporting articles.
L 540: You named the best cropping system according to your data, but is this one enough to provide all necessary fodders or other alternatives will be still needed? Are farmers willing to adapt this cropping system?
Minor comments
L 54-55: Fuel appears two times. Is there a difference between the two and if yes, what?
L 58: When you start to discuss India you should start a new paragraph.
L 64: What is word average?
L 79: Please give some examples, especially explain what are indirect energy sources in your context?
L 105: Efficient in what?
L 117: What was the area of each cropping system (treatment)?
L 126-127: What was the quantity of manure and chemical fertilizers applied?
L 131: Were the systems irrigated regularly?
Table 2: Explain what is “Trt.”. Also, I would suggest to use instead just “Treatments” and below “T1, T2, T3, ….”, as this is used in your next tables.
L 144: What is “suitable height from ground level”?
Table 5, 6: Replace it or add a Figure to the manuscript with the information. Figures are easier to understand than Tables.
L 378-381: This sentence is hard to understand, please redefine it.
L390: I suggest starting a new paragraph here.
L 369: I suggest starting a new paragraph here. Also, the appearance of chemical fertilizers is too sudden, you should link it to the previous section.
L 502-504: There is no need to repeat your aims.
Author Response
Please find the revised manuscript attached and line by line revisions in the response to reviewer letter.
Thanks,
Authors
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Carbon footprint is an important indicator to show the carbon balance of human activities. Energy use efficiency contributes to a sustainable development of human society. The authors assessed the carbon footprint and energy budget of four different types of cropping systems in India. In general, the topic is important and the experiment design is solid.
After reading the whole paper, I feel that the indicators (either of carbon footprint or of energy use efficiency) considered by the authors are similar and redundant sometimes. For example, carbon sustainability index, carbon efficiency ratio and carbon efficiency are basically the same thing representing the same meanings. Are all them necessary for the conclusions/presentation in the paper? It would be more clear if the authors choose one most commonly used indicator for each of them to present the results.
Introduction: the contents should be reorganized. I can see many background knowledge about India’s agriculture. However, little information is about the four types of cropping systems and the criteria for the assessment of the carbon footprint and energy efficiency. I suggest the authors 1) give an introduction of the indicators they applied in the assessment, e.g., how these indicators are commonly used by other researchers in what kind of topics; 2) introduce the cropping systems they studied in this paper, e.g., why choose these cropping systems, what the features of these systems are. Such kind of information is necessary for the readers to understand the results and conclusions of this research.
Materials and Methods: I can see the authors studied 15 different fodder cropping systems and grouped them into 4 types of systems. The question is whether the different treatments will lead to significant different results within the 4 groups. If yes, how to make generalizations based on the types of cropping systems.
Table 3 & 4, any criteria in selection of the coefficient?
Table 5 & 6, is it necessary to calculate all of them (CSI, CER, etc.) or show the values here? Since they are basically representing the same thing. Numbers should be represented by the mean with standard error.
Too many pie charts in the text, please combine the figures to save space.
Specific comments:
Line 23: better show the four different types of cropping systems rather than how many systems evaluated.
Line 25-33: too many indicators. Mentioning two or three main indicators is enough. What are the differences between carbon output and energy output? carbon indices and energy indices? How to compare them if they are different concepts.
Line 34: what do you mean? same with what?
Line 36: what is “human energy profitability”? Too many concepts in the abstract, which make the readers very confused about their meanings, differences and relationships.
Line 38-39: is this the management practice for Bajra-Napier hybrid + legume ? How about the others?
Line 40: which is the “cereal + legume” cropping system? Bajra-Napier hybrid + legume ?
Line 145: is the fodder yield equal to the aboveground biomass? Any equations to show the calculation of fodder yield?
Line 163-164: do the carbon efficiency ratio and carbon efficiency mean different? They look like the same thing.
Line 174-175: these two don't have fundamental differences in the calculation. Why not just use one to represent the result?
Line 176: what is the “specific productivity”? Is it common in use?
Line 184: fertilizers are all non-renewable? How about manure? Does “Chemicals” here include the chemical fertilizer?
Line 186: what is “Green fodder yield”? Is it same with “fodder yield” in line 145? Please use the same term. Is the unit “Quintal” common in use? Please use the common unit.
Line 190: “significant difference” of what? At which significance level? What is “OPSTAT”? Please use the full name.
Line 211: At which significance level?
Line 251: detailed description of the figure is necessary. What do the x, line and the error bar represent? CSI and CER are basically representing the same thing. Is it useful to compare them?
Line 522-533: please avoid simple repetition of the results in the conclusion.
Author Response
Please find the revised manuscript attached and line by line revisions in the response to reviewer letter.
Thanks,
Authors
Author Response File: Author Response.pdf
