Enhancing Agricultural Soil Carbon Sequestration: A Review with Some Research Needs
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsExcellent review and impressed reading it. learnt a lot. Technically sound and appropriate. No questions.
Author Response
Comment 1: Excellent Review and impressed reading it. Learnt a lot. Technically sound and appropriate. No questions.
Response 1: Thank you for taking the time to review our manuscript. Your feedback is greatly appreciated. The revised manuscript is attached.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Comments and Suggestions for AuthorsSpecific comments
L14 Citing references already in the Abstract is not common. Please check journal style rules!
L35 There is a newer version of Friedlingstein et al., i.e. Friedlingstein et al., 2023. Global Carbon Budget 2023. Earth Syst. Sci. Data 15, 5301-5369. By the way, the original reference [6] (L630) is wrong! Volume and pages of the cited paper correspond to Friedlingstein et al., 2020. Global Carbon Budget 2020. Earth Syst. Sci. Data 12, 3269-3340.
L36 Properly format unit: GtC yr-1
L62 Why italics?
L63 …are mainly driven…
L80-100 Like many others do, Authors forget that there are also perennial crops (like orchards, vineyards, etc.), which merit some attention. There are several papers discussing the role of perennials on C budget. See for instance: Novara, A., Favara, V., Novara, A., Francesca, N., Santangelo, T., Columba, P., Chironi, S., Ingrassia, M., Gristina, L., 2020. Soil Carbon Budget Account for the Sustainability Improvement of a Mediterranean Vineyard Area. Agronomy 10, 336; Vendrame, N., Tezza, L., Pitacco, A., 2019. Study of the Carbon Budget of a Temperate-Climate Vineyard: Inter-Annual Variability of CO2 Flux. American Journal of Enology and Viticulture 70, 34-41.
L156-184 Actually, the impact of cover crops is controversial. See for instance Eash, L., Ogle, S., McClelland, S.C., Fonte, S.J., Schipanski, M.E., 2024. Climate mitigation potential of cover crops in the United States is regionally concentrated and lower than previous estimates. Global Change Biology 30, e17372. Authors may want to mention some doubts.
L173 I do not know whether the journal asks for metric units. Personally, I would stick to hectares.
L180-181 See above. Use liters instead of gallons.
L196 Better pyrolysis than combustion.
L209-237 See also: Dupla, X., Bonvin, E., Deluz, C., Lugassy, L., Verrecchia, E., Baveye, P.C., Grand, S., Boivin, P., 2024. Are soil carbon credits empty promises? Shortcomings of current soil carbon quantification methodologies and improvement avenues. Soil Use and Management 40, e13092.
L312-327 Please see: Smith, P., Soussana, J.-F., Angers, D., Schipper, L., Chenu, C., Rasse, D.P., Batjes, N.H., van Egmond, F., McNeill, S., Kuhnert, M., Arias-Navarro, C., Olesen, J.E., Chirinda, N., Fornara, D., Wollenberg, E., Álvaro-Fuentes, J., Sanz-Cobena, A., Klumpp, K., 2020. How to measure, report and verify soil carbon change to realize the potential of soil carbon sequestration for atmospheric greenhouse gas removal. Global Change Biology 26, 219-241; Smith, P., 2004. How long before a change in soil organic carbon can be detected? Global Change Biology 10, 1878-1883.
L335-348 Authors may want to briefly mention the connection with LCA-based methodologies: Goglio, P., Smith, W.N., Grant, B.B., Desjardins, R.L., McConkey, B.G., Campbell, C.A., Nemecek, T., 2015. Accounting for soil carbon changes in agricultural life cycle assessment (LCA): a review. Journal of Cleaner Production 104, 23-39; Bessou, C., Tailleur, A., Godard, C., Gac, A., de la Cour, J.L., Boissy, J., Mischler, P., Caldeira-Pires, A., Benoist, A., 2020. Accounting for soil organic carbon role in land use contribution to climate change in agricultural LCA: which methods? Which impacts? The International Journal of Life Cycle Assessment 25, 1217-1230.
L349-357 See: Cariappa, A.A.G., Konath, N.C., Sapkota, T.B., Krishna, V.V., 2024. Evaluating the potential and eligibility of conservation agriculture practices for carbon credits. Scientific Reports 14, 9193
L384-401 See: Brandão, M., Levasseur, A., Kirschbaum, M.U.F., Weidema, B.P., Cowie, A.L., Jørgensen, S.V., Hauschild, M.Z., Pennington, D.W., Chomkhamsri, K., 2013. Key issues and options in accounting for carbon sequestration and temporary storage in life cycle assessment and carbon footprinting. The International Journal of Life Cycle Assessment 18, 230-240.
L623 Reference incomplete. Insert a link to the document.
L626 Correct reference should be: Shukla, P.R., Skea, J., Slade, R., van Diemen, R., Haughey, E., Malley, J., Pathak, M., Portugal Pereira, J., 2019. Technical Summary. In: Shukla, P.R., Skea, J., Calvo Buendia, E., Masson-Delmotte, V., Pörtner, H.-O., Roberts, D.C., Zhai, P., Slade, R., Connors, S., van Diemen, R., Ferrat, M., Haughey, E., Luz, S., Neog, S., Pathak, M., Petzold, J., Portugal Pereira, J., Vyas, P., Huntley, E., Kissick, K., Belkacemi, M., Malley, J. (Eds.), Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems, pp. 37-74.
L631 Reference incomplete. Insert a link to the document.
L675-676 Idem.
L679-680 Reference incomplete.
L694-695 Reference incomplete. Insert a link to the document.
L696-697 Idem.
L698-699 Idem.
L700 Idem.
L701 Idem.
L702 Idem.
L703 Idem.
L720-721 Reference incomplete.
L735-736 Reference incomplete. Insert a link to the document.
L869-870 Reference incomplete.
Author Response
Summary: Thank you for taking the time to review our manuscript and sharing your valuable comments. We have revised the manuscript (please see the attachment) integrating your comments and suggestions (highlighted in the manuscript). Please see below for the details.
Comments 1: L14 Citing references already in the Abstract is not common. Please check the journal style rules!
Response 1: We removed the citing references from the abstract.
Comments 2: L35 There is a newer version of Friedlingstein et al., i.e. Friedlingstein et al., 2023. Global Carbon Budget 2023. Earth Syst. Sci. Data 15, 5301-5369. By the way, the original reference [6] (L630) is wrong! Volume and pages of the cited paper correspond to Friedlingstein et al., 2020. Global Carbon Budget 2020. Earth Syst. Sci. Data 12, 3269-3340.
Response 2: The citing reference is corrected, and the related reference is added and integrated into the manuscript as follows (L35-38):
“Friedlingstein et al. [2] estimate that during 2010-2019, lands sequestered 2.5-3.4 Gigatons of C per year (GtC yr-1), and the land CO2 sink during the 2013-2022 decade was 2.5-4.1 GtC yr-1, which took up 31% of the total CO2 emissions [3].”
Comments 3: L36 Properly format unit: GtC yr-1
Response 3: The units were reformatted.
Comments 4: L62 Why italics?
Response 4: The italics are removed from the text.
Comments 5: L63 …are mainly driven…
Response 5: The sentence is revised.
Comments 6: L80-100 Like many others do, Authors forget that there are also perennial crops (like orchards, vineyards, etc.), which merit some attention. There are several papers discussing the role of perennials on C budget. See for instance: Novara, A., Favara, V., Novara, A., Francesca, N., Santangelo, T., Columba, P., Chironi, S., Ingrassia, M., Gristina, L., 2020. Soil Carbon Budget Account for the Sustainability Improvement of a Mediterranean Vineyard Area. Agronomy 10, 336; Vendrame, N., Tezza, L., Pitacco, A., 2019. Study of the Carbon Budget of a Temperate-Climate Vineyard: Inter-Annual Variability of CO2 Flux. American Journal of Enology and Viticulture 70, 34-41.
Response 6: We revised the paragraph to add the perennial crops discussion. We expanded it also to include perennial bio-crops and pasture to L83-91.
“Perennial crops, including but not limited to some bioenergy crops (e.g. switchgrass, miscanthus, and poplar), pasture, vineyards, and orchards, play a significant role in net ecosystem CO2 exchange and carbon budgeting due to their unique biological and management characteristics. Some studies show perennial crops can act as moderate carbon sinks with inter-annual variability notably affected by environmental conditions [8,9]. With the C sequestration rates ranging from 0.6 to 3.0 MgC ha−1 yr−1, the bioenergy crops have the potential to sequester approximately 318 TgC yr−1 in the United States (about 60 million hectares of land available for bioenergy crops) and 1631 TgC yr−1 worldwide (757 million hectares) [10].”
Comments 7: L156-184 Actually, the impact of cover crops is controversial. See for instance Eash, L., Ogle, S., McClelland, S.C., Fonte, S.J., Schipanski, M.E., 2024. Climate mitigation potential of cover crops in the United States is regionally concentrated and lower than previous estimates. Global Change Biology 30, e17372. Authors may want to mention some doubts.
Response 7: Thank you for your suggestion. We added the discussion to L185-189.
“Similarly, Eash et al. [41] found that cover crops increase soil carbon stocks and reduce the net GHG emissions based on the DayCent model simulation. They also found cover crops increase N2O emissions at a relatively small magnitude but greatly increase the uncertainty of total GHG emission reduction.”
Comments 8: L173 I do not know whether the journal asks for metric units. Personally, I would stick to hectares.
Response 8: Thank you for your feedback. We understand the preference for using hectares, but to maintain the integrity and accuracy of the original data from the technical report, we have chosen to retain the units as specified in the source material. This approach ensures consistency with the original report.
Comments 9: L180-181 See above. Use liters instead of gallons.
Response 9: We have revised and incorporated the unit conversion in the manuscript as requested. Previously, we used gallons to align with the units employed by the Energy Information Administration (EIA) and Environmental Protection Agency (EPA) in the original data. The revised content and values are as follows (L193-194):
“…the average fuel consumption at 0.62 gallons (2.35 liters) of diesel fuel per acre. Chemical cover crop termination used 0.3 gallons (1.14 liters) of this,…”
Comments 10: L196 Better pyrolysis than combustion.
Response 10: We have updated the manuscript to use the term "pyrolysis" instead of "combustion" as recommended.
Comments 11: L209-237 See also: Dupla, X., Bonvin, E., Deluz, C., Lugassy, L., Verrecchia, E., Baveye, P.C., Grand, S., Boivin, P., 2024. Are soil carbon credits empty promises? Shortcomings of current soil carbon quantification methodologies and improvement avenues. Soil Use and Management 40, e13092.
Response 11: We added the discussion of potential protocol design shortcomings based on the suggestions (L251-254).
“Specifically, attention should be paid to the protocol used to measure the initial soil carbon stock and the changes in stocks to improve the reliability of the soil carbon credit. Omitting situ soil analysis can lead to an overestimation of soil carbon stock by 2.5 times [55].”
Comments 12: L312-327 Please see: Smith, P., Soussana, J.-F., Angers, D., Schipper, L., Chenu, C., Rasse, D.P., Batjes, N.H., van Egmond, F., McNeill, S., Kuhnert, M., Arias-Navarro, C., Olesen, J.E., Chirinda, N., Fornara, D., Wollenberg, E., Álvaro-Fuentes, J., Sanz-Cobena, A., Klumpp, K., 2020. How to measure, report and verify soil carbon change to realize the potential of soil carbon sequestration for atmospheric greenhouse gas removal. Global Change Biology 26, 219-241; Smith, P., 2004. How long before a change in soil organic carbon can be detected? Global Change Biology 10, 1878-1883.
Response 12: The two references are added to the manuscripts (L338-341, L345-348).
“Coupled with the sensitivity and accuracy allowed by the sampling regime, no significant changes in soil C can be detected within 5 years unless there are great changes in soil C (over 20%) or a massive sample is drawn [89].”
“The credible and reliable measurement/monitoring, reporting and verification (MRV) platform, integrated short-term and long-term experiments, models, spatial soil sampling, remote sensing and data analysis, can be used to improve the accuracy in soil C measurement [91].”
Comments 13: L335-348 Authors may want to briefly mention the connection with LCA-based methodologies: Goglio, P., Smith, W.N., Grant, B.B., Desjardins, R.L., McConkey, B.G., Campbell, C.A., Nemecek, T., 2015. Accounting for soil carbon changes in agricultural life cycle assessment (LCA): a review. Journal of Cleaner Production 104, 23-39;
Bessou, C., Tailleur, A., Godard, C., Gac, A., de la Cour, J.L., Boissy, J., Mischler, P., Caldeira-Pires, A., Benoist, A., 2020. Accounting for soil organic carbon role in land use contribution to climate change in agricultural LCA: which methods? Which impacts? The International Journal of Life Cycle Assessment 25, 1217-1230.
Response 13: The references are added to the manuscript to discuss the impacts of LCA method selection on accounted results (L369-372).
“The accounted impacts of land use and agricultural land management changes on GHG emissions vary by the chosen LCA methodology [103]. Various LCA methods are suggested based on user expertise, methodological certainties, and data quality [103,104]."
Comments 14: L349-357 See: Cariappa, A.A.G., Konath, N.C., Sapkota, T.B., Krishna, V.V., 2024. Evaluating the potential and eligibility of conservation agriculture practices for carbon credits. Scientific Reports 14, 9193
Response 14: This is a good paper. But we didn’t add it as a reference here as it is not very relevant to the topic we discussed in this paragraph. Thank you for your suggestion!
Comments 15: L384-401 See: Brandão, M., Levasseur, A., Kirschbaum, M.U.F., Weidema, B.P., Cowie, A.L., Jørgensen, S.V., Hauschild, M.Z., Pennington, D.W., Chomkhamsri, K., 2013. Key issues and options in accounting for carbon sequestration and temporary storage in life cycle assessment and carbon foot printing. The International Journal of Life Cycle Assessment 18, 230-240.
Response 15: We don’t think this reference fits the discussion here. But we added it into the Section 6.2.1 (L446-448)
“LCA approaches for long time horizons can also be used to assess the impermanent mitigation strategies on climate change [117].”
Comments 16: L623 Reference incomplete. Insert a link to the document.
Response 16: This reference is removed from the abstract.
Comments 17:
L626 Correct reference should be: Shukla, P.R., Skea, J., Slade, R., van Diemen, R., Haughey, E., Malley, J., Pathak, M., Portugal Pereira, J., 2019. Technical Summary. In: Shukla, P.R., Skea, J., Calvo Buendia, E., Masson-Delmotte, V., Pörtner, H.-O., Roberts, D.C., Zhai, P., Slade, R., Connors, S., van Diemen, R., Ferrat, M., Haughey, E., Luz, S., Neog, S., Pathak, M., Petzold, J., Portugal Pereira, J., Vyas, P., Huntley, E., Kissick, K., Belkacemi, M., Malley, J. (Eds.), Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems, pp. 37-74.
L631 Reference incomplete. Insert a link to the document.
L675-676 Idem.
L679-680 Reference incomplete.
L694-695 Reference incomplete. Insert a link to the document.
L696-697 Idem.
L698-699 Idem.
L700 Idem.
L701 Idem.
L702 Idem.
L703 Idem.
L720-721 Reference incomplete.
L735-736 Reference incomplete. Insert a link to the document.
L869-870 Reference incomplete.
Response 17: Thank you for pointing out. We have updated all the references mentioned above.
Author Response File: Author Response.docx
Reviewer 3 Report
Comments and Suggestions for AuthorsThe manuscript is generally well written and a comprehensive survey of the literature on the topic, including biophysical and socioeconomic sciences. Some sections repeat lists of items either similar or identical to other areas, and most areas follow the format of using these lists, which made this reviewer wish that the blocks of text might be broken up with tables that both highlighted and simplified the factor lists often discussed. The review is very broad covering numerous areas of science but not particularly deep in the analysis of the literature and key inconsistencies and uncertainties in the sciences. Nevertheless, as a review article or book chapter style manuscript, the work gives the newcomer to the topics of agricultural soil carbon valuable insights on the work.
Comments on the Quality of English LanguageMinor editorial improvements could be caught with careful proofreading but it reads well overall.
Author Response
Comments 1: The manuscript is generally well written and a comprehensive survey of the literature on the topic, including biophysical and socioeconomic sciences. Some sections repeat lists of items either similar or identical to other areas, and most areas follow the format of using these lists, which made this reviewer wish that the blocks of text might be broken up with tables that both highlighted and simplified the factor lists often discussed. The review is very broad covering numerous areas of science but not particularly deep in the analysis of the literature and key inconsistencies and uncertainties in the sciences. Nevertheless, as a review article or book chapter style manuscript, the work gives the newcomer to the topics of agricultural soil carbon valuable insights on the work.
Minor editorial improvements could be caught with careful proofreading, but it reads well overall.
Response 1: Thank you for your positive feedback. We made proofreading to correct some grammar errors. The revised manuscript is attached with the revision in highlight.
Author Response File: Author Response.docx
