Soybean Yield Does Not Rely on Mineral Fertilizer in Rotation with Flooded Rice under a No-Till Integrated Crop-Livestock System
, Amanda P. Martins 1, Leonardo M. Bastos 2, Ignacio A. Ciampitti 2, Ibanor Anghinoni 1, Fernanda G. Moojen 3, Paulo César de F. Carvalho 3, Min Huang 4 and Abad Chabbi 5,*Round 1
Reviewer 1 Report
I appreciate the efforts made by the authors to improve the quality of the manuscript.
Author Response
Re: Resubmission of manuscript Soybean yield does not rely on mineral fertilizer in rotation with flooded rice under no-till integrated crop-livestock system,
The Editors
Agronomy
Dear Editors:
Thank you for the opportunity to revise our manuscript, Soybean yield does not rely on mineral fertilizer in rotation with flooded rice under no-till integrated crop-livestock system. We appreciate the careful review and constructive suggestions. It is our belief that the manuscript is substantially improved after making the suggested edits.
Sincerely,
Luiz Gustavo de O. Denardin
Reviewer 2 Report
Excellent work on revising! I can tell a lot of hard work went into this revision. Most of my edits are to improve grammar and clarity. I do have two major concerns which need to be addressed:
- It is unclear why the description of the “full experiment” is included in the text when only the “reduced experiment” is applicable. I suggest removing details on the “full experiment” in the material and methods section since it is confusing and unnecessary. I would include a short statement that integrates with lines 97-100, such as “one of five potential fields was selected for the experiment based on its historically high rate of soybean cultivation under ICLS and no-tillage with soybean/flooded rice crop rotation during the summer season and annual ryegrass (Lolium multiflorum Lam.) under beef cattle grazing during the winter season.”
- The plots need to be fixed. Multiple x-axes is a clever idea, but it is confusing and misleading as a reader. Please consolidate the x-axes so readers can interpret the results easily. After this is done, please make sure the captions are adjusted to include the appropriate information.
Abstract
Line 18 and 61: “Favored” is used incorrectly here. This sentence currently implies that grazing animals prefer nutrient cycling.
Line 19: Change to “…soybeans…”
Line 21: It would be beneficial to add “yield” prior to response (i.e., “… the soybean yield response…”)
Line 24: I think rotations are usually specified with a hyphen (i.e., soybean-flooded rice). I could be wrong about this, but it would be beneficial to check with previously published articles in this journal to maintain consistency of format.
Line 24: Change to “In the 2015/2016…”
Line 24-25: This sentence is somewhat confusing. Is the meaning retained if you change the wording to the following: “Two field studies were conducted in a system that included a soybean-flooded rice rotation integrated with cattle grazing during the winter season”.
Line 25: Change to “In the 2015/2016…”
Line 25: The fertilizer treatments were not applied to soybeans, they were applied to the soil. Please change wording.
Line 26: Change to “…the relationships between soybean yield and soil chemical properties were evaluated under no fertilization treatment…”
Line 27: Change to “Soybean yield…”
Line 28-29: This sentence is confusing. Is the meaning retained if you change the wording to the following: “The associations between soybean yield and soil chemical properties were greatest in the 10–20 cm soil layer compared to the 0–10 cm soil layer, especially for available P, followed by pH and soil organic matter”.
Line 30: Change to “…reduced…”
Lines 31: This sentence seems quite certain given that the study was conducted in only a single year. I would change to something like: “Results of this study inform producers of possible fertilization adjustments, in which supplementing mineral fertilizer for soybeans may not be necessary.”
Introduction
Line 36: “Soybean” should be plural (i.e., “soybeans”) when used in this context. Please check this throughout the paper.
Line 47: This phrase is confusing. Is the meaning retained if you change the wording to the following: “…legume residues that increase the soil organic matter content…”
Lines 48-49: Change to “… both rice and soybeans benefit in this environment, which can be achieved under an integrated crop-livestock system (ICLS)…”
Line 51: Change to “Under no-till ICLS, the flooded rice efficiently utilizes N, P, and K; therefore, the flooded rice under no-till ICLS does not respond to P and K fertilization.”
Line 53: Change to “Soybeans are considered a highly…”
Line 59: Change to “…soybeans respond…”
Line 62: Change to “…soybean yield does not…”
Line 66: Change to “… should focus on…”
Line 68: Change to “… the recommendation is …”
Materials and Methods
Line 82: Should this be “annual cumulative rainfall” instead of “annual average rainfall”?
Line 85: Change to “… had been …”
Line 93: I am presuming that plots were blocked by similar soil characteristics and not different soil characteristics, as stated. If so, please change to “The plots were blocked by soil chemical properties…”
Lines 91-97: The design for the “full experiment” and ‘reduced experiment” are included. Which (i.e., the full or reduced) was used for the study? If the “full experiment” design was not used for this study, then I would recommend removing it from the text, as it is unnecessary and is confusing.
Line 102: n is used out of context. Change to “… the three ICLS plots…”
Line 107: change to “… plants per m2…”
Line 112: Remove “Neutered” since “steers” implies that they are castrated.
Line 125: change to “initial”
Results and Discussion
Line 223: I think what you mean is “The “ns” indicates absence of statistical difference according to the F-test for the main effect of treatment, which had p = 0.52.”
Line 233: Should be R2
Figure 2: Thank you for putting the soil depth together on the plot. However, this is not easy to interpret since there are 2 x-axes. Please use only 1 x-axis. I realize that the 10-20 points will be tight, but the current figure is quite deceiving. There are actually no VH samples so the x-axis should only range from 0 to 60, correct? Please remove the (a) and (b) specifications in the caption since there is only one plot.
Figure 3: These plots should be combined like described in Figure 2 comment.
Figure 4: Please fix reduce to 1 x-axis for plot b, as described in Figure 2 comment.
Figures 2 – 4: Please make sure that the captions are still correct after changing the figures.
Line 306: change to “All evaluated samples in the 0–10 cm soil layer…”
Line 324: change to “This study…”
Lines 334: change to “…soil chemical properties in the 0–10 cm layer…”
Lines 340-341: reword to “The results reported herein are novel and provide a direction on soybean nutrient management under ICLS, yet they should be interpreted within the context of the environment and year of measurements.”
Supplementary Figure
- Thank you for providing this beautifully detailed figure of weather data. Including the long-term average precipitation and temperature data in this figure would add value to the article, so that readers can assess whether the study was conducted during a “typical” year and use this information when applying the results of the study. However, I do not think this is dire and the information you provided should be enough for readers.
- Is the precipitation the monthly average? Or is the monthly precipitation? If the latter, please change the wording to “Monthly cumulative precipitation and average temperature…”
Author Response
Thank you for the opportunity to revise our manuscript, Soybean yield does not rely on mineral fertilizer in rotation with flooded rice under no-till integrated crop-livestock system. We appreciate the careful review and constructive suggestions. It is our belief that the manuscript is substantially improved after making the suggested edits.
Following this letter are the reviewer comments with our responses in red, including how and where the text was modified. Changes made in the manuscript are marked using track changes. The revision has been developed in consultation with all coauthors, and each author has given approval to the final form of this revision.
Sincerely,
Luiz Gustavo de O. Denardin
Author Response File: 
Author Response.pdf
Reviewer 3 Report
I have read the new version of the manuscript entitled “Soybean yield does not rely on mineral fertilizer in rotation with flooded rice under no-till integrated crop-livestock system”. After the last authors corrections, I consider they have improved the quality of the manuscript in order to adjust the content of the manuscript with the experimental design and available data. In addition, the discussion have been improved and they present very valuable agronomic information. Therefore, I consider that the manuscript fulfill the quality criteria to be accepted for publication. I only add some minor comments that the authors could consider to improve some sentences.
L86-88: I would soften the sentence because before to perform your experiment, you were not sure that soybean yield would not respond to fertilization. It could be also possible that the yield response was smaller than expected, for example. Furthermore, I would add another sentence at the end explaining that the evaluation of that hypothesis is necessary to improve the fertilization management.
L162: Check the comma.
L287: I think manure deposition would be more correct because manure addition could suggest that the manure was added by the farmer.
L290: I would start the sentence “Our results are supported by Denardin….” (or similar) Because I think you’re mentioning here the results obtained in rice to confirm the results obtained in the present study.
Author Response
Thank you for the opportunity to revise our manuscript, Soybean yield does not rely on mineral fertilizer in rotation with flooded rice under no-till integrated crop-livestock system. We appreciate the careful review and constructive suggestions. It is our belief that the manuscript is substantially improved after making the suggested edits.
Following this letter are the reviewer comments with our responses in red, including how and where the text was modified. Changes made in the manuscript are marked using track changes. The revision has been developed in consultation with all coauthors, and each author has given approval to the final form of this revision.
Sincerely,
Luiz Gustavo de O. Denardin
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
The manuscript can be improved in the "Results and Discussion" section.
3.1. Short-term (2013 vs. 2015) impact of ICLS in soil fertility
The authors have shown that ICLS after 30 months of management induces an increase in soil organic matter (SOM) and widely discuss this result, assuming an improvement in the physical properties of the soil (Table 1; page 5, lines 201-205). However, the discussion of the result concerning the increase in exchangeable polyvalent cations, in particular of Ca, has been omitted. Given the role of these elements in the formation of a stable soil structure, together with SOM, integration with this aspect of the discussion seems appropriate.
3.3 Relationship between soybean yield and soil chemical properties
Also in this paragraph, on page 9, lines 292-302, the relationship between soybean yield and SOM was discussed, highlighting the importance of the increase in soil colloids, but the simultaneous increase of exchangeable polyvalent cations is not mentioned.
In addition to hypotesize the improvement of the soil physical properties, the authors should also discuss the likely improvements concerning biological fertility, given that in the field experience with ICLS some positive effects may have been induced by: increase in SOM, undisturbed soil due to the effect of "no tillage", crop rotations introducing the cultivation of a leguminous species and grazing. All these factors can have an impact on soil biodiversity and activity of microorganisms and mesofauna. The integration of the text with this aspect, together with suitable bibliographic citations, can inspire and suggest the authors and the scientific community for the future.
Author Response
Response to Reviewer 1 Comments
Dear Reviewer,
We are grateful for the many contributions that the revision gave to our manuscript. We believe that were useful to the highest quality in the presentation of our study. All changes have been marked and you can access the revised version. Thanks again for your contributions.
Best regards,
Luiz Gustavo de O. Denardin (first and corresponding author).
Point 1: The manuscript can be improved in the "Results and Discussion" section.
3.1. Short-term (2013 vs. 2015) impact of ICLS in soil fertility
The authors have shown that ICLS after 30 months of management induces an increase in soil organic matter (SOM) and widely discuss this result, assuming an improvement in the physical properties of the soil (Table 1; page 5, lines 201-205). However, the discussion of the result concerning the increase in exchangeable polyvalent cations, in particular of Ca, has been omitted. Given the role of these elements in the formation of a stable soil structure, together with SOM, integration with this aspect of the discussion seems appropriate.
Response 1: Dear reviewer. Thank you very much for your comment. You are completely right. We recognise the importance of exchangeable polyvalent cations in improving stable soil structure together with SOM, and this discussion could be improved. However, another reviewer indicated that the soil fertility evaluation in short-term should be removed. Thus, we kept the Table 1 only with the soil fertility characterization, prior to the first experiment evaluating soybean response to P and K fertilization. Anyway, we thank you once again for your comment.
Point 2: 3.3 Relationship between soybean yield and soil chemical properties
In addition to hypotesize the improvement of the soil physical properties, the authors should also discuss the likely improvements concerning biological fertility, given that in the field experience with ICLS some positive effects may have been induced by: increase in SOM, undisturbed soil due to the effect of "no tillage", crop rotations introducing the cultivation of a leguminous species and grazing. All these factors can have an impact on soil biodiversity and activity of microorganisms and mesofauna. The integration of the text with this aspect, together with suitable bibliographic citations, can inspire and suggest the authors and the scientific community for the future.
Response 2: Dear reviewer, you are right. To demonstrate the importance of soil biological fertility and how the components of the ICLS affect them, we have added the following paragraph: “Besides the improvement related to physical and hydric soil properties, SOM and pH are also closely related to soil biological fertility. Soil microorganisms mediate a number of important soil processes related both to the availability of water and nutrients to plants [27]. In this case, the benefit of no-till adoption in paddy fields in improving soil quality through increases in SOM is already known [28]. These benefits can be improved under crop rotations and animal grazing, provided mainly by improving the soil biodiversity and microorganisms activity [29].” (Page 11 – Lines 3443-348)
Reviewer 2 Report
In general, the English grammar and language needs to be improved in order to provide a detailed peer review. Yet, I think this research is important and the article should be re-evaluated after language editing has been completed. I provided some examples of grammar correction in the first several lines of comments below. Throughout the article, references should be placed prior to punctuation.
The introduction seems adequate, but the methodology section needs major clarification. The treatments, the experimental units (the unit that the treatments were randomly assigned to), and the blocks should be explicitly documented. Furthermore, the size of the units need to be stated. It is stated that the study was performed in a randomized complete block design with 3 replications, but it is not clear what the block is nor what the replication is. Furthermore, the year in which the study took place is somewhat confusing because previous management of land is discussed intermittently throughout the methods section. I would recommend discussing previous management of experimental land all together in one paragraph.
It becomes more apparent in Table 1 that there was a single treatment of ICLS applied, which is compared to baseline values in 2013. If this is true then time is confounded with treatment, and the justification for this design needs to be documented in the methods section. It is apparent that live-stock integration studies are typically performed with low replication or lack of replication due to the size of plots required for grazing animals, but this needs to be addressed in the article. Furthermore, it is not clear what the difference is between the study design in the first and second years of the study. Are they 2 separate studies?
Line 23: change “was” to “were”.
Lines 19-23: It is unclear what the methods were. It is stated that 2 studies were performed but I think you mean 2 fields were used in the study.
Line 34: “… being responsible…”
Line 35: Put reference at end of sentence
Line 36: “… increasing pest and disease pressure while consequently reducing yields.”
Line 39: Define IRGA
Line 44: Define P and K
Line 91-98: It is unclear what are the blocks are what are the replications. What is the experimental unit for this study and how many are there?
Lines 107-113: Remove “neutered yearling”. Add binomial name for steers and average age. What was the size of the pasture? How many groups of steers were grazed each year?
Line 166-167: Explicitly state what the main effects and interactions are
Section 3.1: It becomes more apparent in this section that there is only one treatment (ICLS) applied to experimental units, which is compared to baseline values. If this is the case, then I believe time is confounded with treatment. Please explain to me how time is not confounded with treatment.
Table 1: Please include measurements of error, such as standard errors.
Author Response
Response to Reviewer 2 Comments
Dear Reviewer,
We are grateful for the many contributions that the revision gave to our manuscript. We believe that were useful to the highest quality in the presentation of our study.
Best regards,
Luiz Gustavo de O. Denardin (first and corresponding author).
Point 1: In general, the English grammar and language needs to be improved in order to provide a detailed peer review. Yet, I think this research is important and the article should be re-evaluated after language editing has been completed. I provided some examples of grammar correction in the first several lines of comments below. Throughout the article, references should be placed prior to punctuation.
Response 1: Thank you very much for the review and very rich contributions. The contributions were essential for improving the quality of the manuscript. Native speakers revised the English grammar throughout the manuscript. If there is still a need for changes, we can make more in-depth and detailed revisions. In fact, there were several citations of references in the middle of the sentences. However, all references were corrected throughout the manuscript prior to punctuation.
Point 2: The introduction seems adequate, but the methodology section needs major clarification. The treatments, the experimental units (the unit that the treatments were randomly assigned to), and the blocks should be explicitly documented. Furthermore, the size of the units need to be stated. It is stated that the study was performed in a randomized complete block design with 3 replications, but it is not clear what the block is nor what the replication is. Furthermore, the year in which the study took place is somewhat confusing because previous management of land is discussed intermittently throughout the methods section. I would recommend discussing previous management of experimental land all together in one paragraph.
Response 2: In order to improve the description of treatments, experimental design and experimental units, we made some changes in the M&M section. First, we add information regarding the areas of the experimental units of the blocks of each production system in the field: “The experimental area is divided into 15 plots, with areas varying from 0.78 to 1.48 ha.” (P. 6 – L. 106). For the first study, to evaluate the soybean response to different P and K fertilizer rates, the treatments were applied, in 5 x 5 m plots, in all blocks (three replications) in the field. To detail this, we added the following information: “The treatments were applied to all field replications. The experimental plot size was 5 by 5 m, 25 m-2.” (P. 4 – Lines 146 – 148).
Regarding the year in which the study took place, we do not understand exactly where it is confused. We divided the M&M section precisely to divide what is part of site description and historical characterization of the experimental area (subitem 2.1), the treatments description and studies conducted (subitem 2.2), the soil and plant analyses performed (subitem 2.3), and finally statistical analyses (subitem 2.4). If you have found any specific part difficult to understand, please let us know and we can correct it.
Point 3: It becomes more apparent in Table 1 that there was a single treatment of ICLS applied, which is compared to baseline values in 2013. If this is true then time is confounded with treatment, and the justification for this design needs to be documented in the methods section. It is apparent that livestock integration studies are typically performed with low replication or lack of replication due to the size of plots required for grazing animals, but this needs to be addressed in the article. Furthermore, it is not clear what the difference is between the study design in the first and second years of the study. Are they 2 separate studies?
Response 3: Exactly, only one ICLS treatment was tested. In fact, the effect of its conformation (Paddy-upland rotation and winter cattle grazing under no-till), on soil fertility in the short term, on soybean response to P and K fertilizer rates, and on the relationship between soybean yield and soil chemical properties assessed in different layers. However, as suggested by another reviewer, we ended up removing the short-term soil fertility assessment. Firstly, because the period is very short (30 months), and because we do not have the control (traditional system of rice cultivation) to compare.
Although livestock integration studies are typically performed with low replication or lack of replication, in our study we have enough area (18 ha) and field replications (three randomized blocks). Therefore, we have changed to better detail the study, in the following sentences: “The experimental area is divided into 15 plots, with areas varying from 0.78 to 1.48 ha.” (P. 6 – L. 106); and “The treatments were applied to all field replications. The experimental plot size was 5 by 5 m, 25 m-2.” (P. 4 – Lines 146 – 148). From these changes, it is easier to understand that there are no differences between the experimental designs between the two studies. Both studies were conducted in the three field plots (blocks) of ICLS. The only difference is that the first study counted with five different treatments applied on each plot (P and K rates) and the second one soil (0 – 10 and 10 – 20 cm layer) and soybean yield samples were collected along the whole plot, and related to each other.
Point 4: Line 23: change “was” to “were”.
Response 4: It was modified, as requested.
Point 5: Lines 19-23: It is unclear what the methods were. It is stated that 2 studies were performed but I think you mean 2 fields were used in the study.
Response 5: Thanks for the comment. In fact, it was not clear how the studies were conducted. However, in fact the two studies were carried out in the same experimental area, however in different years (cropping seasons). To make it clearer, we changed the abstract by inserting the following information: “Two soybean field studies were conducted, in a soybean/flooded rice rotation system and cattle grazing in winter season. In 2015/2016 cropping season, five levels of P and K fertilization were applied to soybeans. In 2017/2018 cropping season, soybean yield and soil chemical properties were evaluated and related, without soybean fertilization.” (Lines 25 – 29)
Point 6: Line 34: “… being responsible…”
Response 6: It was inserted, as requested.
Point 7: Line 35: Put reference at end of sentence
Response 7: The reference was reallocated, as requested.
Point 8: Line 36: “… increasing pest and disease pressure while consequently reducing yields.”
Response 8: Thanks. It was modified, as requested.
Point 9: Line 39: Define IRGA
Response 9: We defined IRGA, as “According to IRGA (Rio-Grandense Rice Institute) [3]…” (L. 40)
Point 10: Line 44: Define P and K
Response 10: We defined P and K as “phosphorus (P) and potassium (K)…” (Lines 45 and 46)
Point 11: Line 91-98: It is unclear what are the blocks are what are the replications. What is the experimental unit for this study and how many are there?
Response 11: In fact, it was confused that information. We removed unnecessary information. The experimental area for study 1 are the treatments imposed on each field replication (5 x 5 m-2) “The experimental subplot size was 5 by 5 m, 25 m-2” (L. 152). For study 2, soil and plant samples were collected throughout the field replication “For the evaluation of the relationship between soybean yield and soil chemical properties, five samples were collected per experimental replication plot at the crop sowing stage” (Lines 157 – 158).
Point 12: Lines 107-113: Remove “neutered yearling”. Add binomial name for steers and average age. What was the size of the pasture? How many groups of steers were grazed each year?
Response 12: We removed “neutered yearling” and added binominal name for steers and average age, as suggested. “Neutered Angus steers (Bos taurus taurus) with initial body weight of 200 kg and seven months of age were used for grazing in 2013, 2014, 2015, 2016, and 2017 winter seasons.” (P. 6 – lines 126 – 128).
The average height of the pasture was 15 cm and the animal stocking was 831 kg ha-1, always respecting at least 3 tester animals from the beginning to the end of the grazing cycle, only putting or taking the regulators to maintain the ideal height. This information is contained in the manuscript, as follows: “Average pasture height was 15 cm and average stocking was 831±114 kg live weight ha-1, simulating cattle fattening or finishing system during 62±15 days of grazing.” (P. 3 – Lines 128 and 129).
Point 13: Line 166-167: Explicitly state what the main effects and interactions are
Response 13: As we removed the soil fertility assessment in the short term, there is no more interaction between two factors, just main factors.
Point 14: Section 3.1: It becomes more apparent in this section that there is only one treatment (ICLS) applied to experimental units, which is compared to baseline values. If this is the case, then I believe time is confounded with treatment. Please explain to me how time is not confounded with treatment.
Response 14: Exactly, only one ICLS treatment was tested. In fact, the effect of its conformation (Paddy-upland rotation and winter cattle grazing under no-till), on soil fertility in the short term, on soybean response to P and K fertilizer rates, and on the relationship between soybean yield and soil chemical properties assessed in different layers. However, as suggested by another reviewer, we ended up removing the short-term soil fertility assessment. In this case, because the two effects (time and system) are confounded, we decided to remove this comparison and keep the Table 1 only for soil fertility characterization before the first soybean study.
Point 15: Table 1: Please include measurements of error, such as standard errors.
Response 15: How we have removed the statistical analysis of the year's effect on soil fertility in the short term, it is no more necessary to insert all these descriptive analysis parameters.
Reviewer 3 Report
I have been reading the manuscript entitled “Integrating livestock and soybean in no-till rice paddy fields improves soil fertility and decreases yield reliance on mineral fertilizer”. The manuscript aims to evaluate the potential benefits of integrated crop-livestock systems (ICLS) as alternative to rice monoculture in Brazil lowlands. The main aims are to evaluate the potential effect of ICLS on soil properties and the response of soybean yields to fertilization and soil properties. I consider the topic very interesting and it fits into the Agriculture Journal scope. However, I consider the manuscript in the current form does not reach the standards of quality and interest of the journal. In summary (the main flaws are described below) the purpose of the study it is not clear; according to the introduction, the authors aim to evaluate ICLS as an alternative of rice mono-cropping, but then, the study it is mainly focused in the evaluation of soybean yield response to fertilizer application. In addition, the ICLS is not compared with rice monoculture in any case. I consider the authors should change the focus of the study because with their experimental design (I consider it inappropriate to evaluate the impact of ICLS on soil properties) and available data, the evaluation of ICLS cannot be done (a control treatment is missing). Therefore, the paper (title, abstract, introduction, discussion, conclusions…) should be focused on the evaluation of soybean response to different fertilization doses.
The main flaws of the manuscript are:
-The introduction is poorly developed. For example, the role of livestock grazing in ICLS is completely obviated despite it is a key of the system. Similarly, the benefits of rice-soybean rotation are poorly described (only briefly L37-38 and L42-44). Finally, the contrasting P and K requirements of rice and soybean are mentioned, but it is not clear which are the requirements of the whole ICLS. If an alternative agricultural system is proposed, the potential benefits and drawbacks should be very well described in the introduction. I think that is very important in a journal as Agriculture.
-The objectives are poorly described and the hypothesis are missing, therefore the purpose of the study it is not clear. Reading the introduction, it looks like the evaluation of ICLS is the objective of the study, but then, the objectives of the study are the evaluation of soybean yield response to fertilization. Therefore, the introduction and the objectives of the study do not fit. The intro (and title, abstract, conclusions…) should be changed to fit with the objectives of the study.
-The experimental design does not fit the objective i) to evaluate ICLS impact on soil properties because there is no control (rice monoculture) to compare the changes between March 2013 and October 2015. it is not clear for me why the evaluated the changes in soil properties between March 2013 and October 2015 prior of the installation of the first soybean cropping system (L122-123). If the purpose would be to evaluate the impact of ICLS on soil properties, at least two or three complete ICLS cycles should be conducted before of the sampling. Therefore, I consider the experimental design is not adequate to evaluate the ICLS impact on soil properties because the control is missing and the evaluation time is very short.
- Results and discussion: I consider the results and discussion presented in the section 3.1 is not valid because the inadequate experimental design (mentioned above).
In summary, the manuscript should be written again but with another focus because the experimental design does not allow assessing the impact of ICLS on soil properties.
Author Response
Response to Reviewer 3 Comments
Dear Reviewer,
We are grateful for the many contributions that the revision gave to our manuscript. We believe that were useful to the highest quality in the presentation of our study. The manuscript was practically rewritten again. All changes have been marked and you can access the revised version. Thanks again for your contributions.
Best regards,
Luiz Gustavo de O. Denardin (first and corresponding author).
Point 1: I have been reading the manuscript entitled “Integrating livestock and soybean in no-till rice paddy fields improves soil fertility and decreases yield reliance on mineral fertilizer”. The manuscript aims to evaluate the potential benefits of integrated crop-livestock systems (ICLS) as alternative to rice monoculture in Brazil lowlands. The main aims are to evaluate the potential effect of ICLS on soil properties and the response of soybean yields to fertilization and soil properties. I consider the topic very interesting and it fits into the Agriculture Journal scope. However, I consider the manuscript in the current form does not reach the standards of quality and interest of the journal. In summary (the main flaws are described below) the purpose of the study it is not clear; according to the introduction, the authors aim to evaluate ICLS as an alternative of rice mono-cropping, but then, the study it is mainly focused in the evaluation of soybean yield response to fertilizer application. In addition, the ICLS is not compared with rice monoculture in any case. I consider the authors should change the focus of the study because with their experimental design (I consider it inappropriate to evaluate the impact of ICLS on soil properties) and available data, the evaluation of ICLS cannot be done (a control treatment is missing). Therefore, the paper (title, abstract, introduction, discussion, conclusions…) should be focused on the evaluation of soybean response to different fertilization doses.
Response 1: Dear reviewer, thank you very much for your comments. They have certainly enriched the quality of the manuscript. You are right about the focus of the study. Because we do not have a control (traditional system of flooded rice cultivation), we chose to remove the assessment of soil fertility in the short-term and focus more on the response of soybean to the P and K rates applied and the relationship between soybean yield and soil chemical properties. Therefore, as you reread the manuscript you will see that we made several changes, in all sections, including title, introduction, M&M, results and discussion, and conclusions. I hope now it is ready to be accepted, but if there is anything else we can change, we are available.
Point 2: The introduction is poorly developed. For example, the role of livestock grazing in ICLS is completely obviated despite it is a key of the system. Similarly, the benefits of rice-soybean rotation are poorly described (only briefly L37-38 and L42-44). Finally, the contrasting P and K requirements of rice and soybean are mentioned, but it is not clear which are the requirements of the whole ICLS. If an alternative agricultural system is proposed, the potential benefits and drawbacks should be very well described in the introduction. I think that is very important in a journal as Agriculture.
Response 2: Thank you. To further demonstrate the benefits of both ICLS and crop rotation, we have introduced some paragraphs in both the introduction and the discussion, as follows: “Paddy-upland rotation is an important system for sustainable agriculture [3]. This system can alter either soil physical or chemical properties, improve soil quality and fertility, and optimize rice yields [4, 5]. The benefits of legumes in rotation are not only caused by biological nitrogen (N) fixation but also by increased nutrient availability, and enriched soil fertility, which could help to sustain the long-term productivity of cereal-based cropping systems [6].” (Page 2 – Lines 48 – 52).
“Besides the improvement related to physical and hydric soil properties, SOM and pH are also closely related to soil biological fertility. Soil microorganisms mediate a number of important soil processes related both to the availability of water and nutrients to plants [27]. In this case, the benefit of no-till adoption in paddy fields in improving soil quality through increases in SOM is already known [28]. These benefits can be improved under crop rotations and animal grazing, provided mainly by improving the soil biodiversity and microorganisms activity [29].” (Page 11 – Lines 343 – 348). We believe that this additional information is sufficient to demonstrate the importance and potential benefits that these practices can provide to the subject of study.
The information provided regarding the P and K fertilization methodologies for rice and soybean in the introduction section is due to the fact that it justifies the possible response of soybean to mineral fertilization. However, the benefits of crop rotation and ICLS subsidize the possibility of soybean non-response, mainly by nutrient cycling benefits. As for ICLS total nutrient requirements, there are no recommendations or methodologies for these systems, but only for isolated crops. Since our study did not test different fertilizers in the system as a whole, we preferred not to address this topic in the introduction, as it would not be in accordance with our subject of study. However, the study provides important results regarding the lack of response of soybean to P and K fertilization, which can be used for future studies that assess the best time to replace these nutrients exported by soybean.
Point 3: The objectives are poorly described and the hypothesis are missing, therefore the purpose of the study it is not clear. Reading the introduction, it looks like the evaluation of ICLS is the objective of the study, but then, the objectives of the study are the evaluation of soybean yield response to fertilization. Therefore, the introduction and the objectives of the study do not fit. The intro (and title, abstract, conclusions…) should be changed to fit with the objectives of the study.
Response 3: As recommended, we changed the main focus of the manuscript and kept the main focus on assessing the soybean response to different P and K fertilizer rates and the relationship between soybean yield and soil chemical properties. Therefore, we changed all sections of the manuscript, removing all parts which made inference to the evaluation of soil fertility in the short term, mainly because we did not have a control (traditional flooded rice system) to compare. In addition, we improved the hypotheses and objectives as follows: “However, we hypothesized that, due to the nutrient cycling process favored by animal grazing in winter fertilized pastures, soybean does not respond to P and K fertilization under no-till ICLS, even in rotation with flooded rice.” (Page 2 – Lines 77 – 80) and “Thus, the objectives of this study were to evaluate: (i) the soybean response to different P and K fertilization levels; and (ii) the relationship between soybean yield and soil chemical properties sampled in different soil layers, in a no-till ICLS in Subtropical lowlands.” (Page 2 – Lines 90 – 94).
Point 4: The experimental design does not fit the objective i) to evaluate ICLS impact on soil properties because there is no control (rice monoculture) to compare the changes between March 2013 and October 2015. it is not clear for me why the evaluated the changes in soil properties between March 2013 and October 2015 prior of the installation of the first soybean cropping system (L122-123). If the purpose would be to evaluate the impact of ICLS on soil properties, at least two or three complete ICLS cycles should be conducted before of the sampling. Therefore, I consider the experimental design is not adequate to evaluate the ICLS impact on soil properties because the control is missing and the evaluation time is very short.
Response 4: Thank you, you are right. Because we don't compare it to the control, we thought better to remove the soil fertility assessment as a focus and objective of the study. Therefore, you will see that we have changed the manuscript as a whole, from the title to the conclusions. We only kept the Table 1 with the soil chemical properties prior to the first soybean experiment (2015/2016 cropping season).
Point 5: Results and discussion: I consider the results and discussion presented in the section 3.1 is not valid because the inadequate experimental design (mentioned above).
Response 5: Ok, we removed this whole item from the results and discussion section.
Point 6: In summary, the manuscript should be written again but with another focus because the experimental design does not allow assessing the impact of ICLS on soil properties.
Response 6: The manuscript was practically rewritten again. All changes have been marked and you can access the revised version. Thanks again for your contributions.
Round 2
Reviewer 2 Report
Overall: I think the article has improved since the previous review. I do have some minor concerns and suggestions for the paper. Since the fertilizer study was conducted over a single year, I think it is necessary to include more information about that year, such as the temperature and precipitation compared to historical averages. I also think a statement should be included in the conclusions to emphasize that this study was conducted over a single year and therefore results from this study may not be reproducible under different conditions.
Lines 108-110: How were the plots blocked? Were they blocked by location, baseline soil characteristics, etc.?
Lines 190-195: Were the average values of soil subsamples per plot used for the statistical analysis? Or were the soil subsamples for each plot mixed into a composite prior to soil composition analyses? These methods should be specified either in the statistical analyses section or soil fertility evaluation and soybean studies section, respectively. Also, were baseline soil characteristics considered in the model as covariates to control for pre-study variation between plots? Why or why not?
Line 191: Please specify that you used simple linear regression. But why not use linear regression with additional fixed effects of soil depth and the soil depth x soil characteristic (P, K, or SOM) interaction? With the additional effects, you can compare depths and their interactions with soil characteristics on yields.
Table 1: Are these arithmetic means or least squares means? Please specify and include measurements of error (e.g., SEs).
Figures 2 to 3: Change to “… in (a) 0–10 and (b) 10–20 cm soil layers …”. I recommend that the 2 plots per figure have the same x-axis scale or show the soil depths in the same figure as done for Fig 4.
Figure 4: Change to “… (a) soil pH and (b) soil organic matter (SOM) …”.
Figures 2 to 4: I just want to clarify what the “*” means. Does it indicate that the model is different than the intercept-only model at p ≤ 0.05? Or does is mean that the slope is different than 0 at p ≤ 0.05? Figure 3 uses “5%”. Please keep consistency.
Line 325: Similar to my previous comment on p-values in figures, what statistical test is this p-value here for and what is it suggesting?
Author Response
Response to Reviewer 2 Comments
Dear Reviewer,
We are grateful for the many contributions that the revision gave to our manuscript. We believe that were useful to the highest quality in the presentation of our study. We comply with the majority of the considerations made by all the reviewers and the manuscript was modified in some of its aspects. Below follows a detailed letter of response to each of these considerations.
Best regards,
Luiz Gustavo de O. Denardin (first and corresponding author).
Point 1: I think the article has improved since the previous review. I do have some minor concerns and suggestions for the paper. Since the fertilizer study was conducted over a single year, I think it is necessary to include more information about that year, such as the temperature and precipitation compared to historical averages. I also think a statement should be included in the conclusions to emphasize that this study was conducted over a single year and therefore results from this study may not be reproducible under different conditions.
Response 1: Thank you for your comment. We included the following paragraph in the conclusions section to emphasize the limitations of the current study: “Because the goal of this study was to evaluate the soybean phases in the ICLS rotation, different analysis were limited to data from a single growing season. Thus, although the results reported herein are novel and provide a direction on soybean nutrient management under ICLS, they should be interpreted within the context of the environment and year of measurements. Future studies should address this gap by conducting similar experiments in a larger number of sites and years.” (Page 14 – Lines 460 – 464)
In addition, we have added a supplementary figure containing the monthly average precipitation and temperature data for the two years of study (2015/2016 and 2017/2018).
Point 2: Lines 108-110: How were the plots blocked? Were they blocked by location, baseline soil characteristics, etc.?
Response 2: Thank you. We have inserted that information as required: “The plots were blocked by different soil chemical properties found in the experimental area.” (Page 3 – Line 119 – 120)
Point 3: Lines 190-195: Were the average values of soil subsamples per plot used for the statistical analysis? Or were the soil subsamples for each plot mixed into a composite prior to soil composition analyses? These methods should be specified either in the statistical analyses section or soil fertility evaluation and soybean studies section, respectively. Also, were baseline soil characteristics considered in the model as covariates to control for pre-study variation between plots? Why or why not?
Response 3: Thank you. Regarding the subsamples: there was a total of five subsamples per plot sent for analysis, where each subsample was comprised by sampling 6 nearby points that were thoroughly mixed. On the statistical analysis, all 5 subsamples per plot were used and modelled properly to ensure that the error degrees of freedom was specified correctly. We have clarified the soil sampling method in lines 152-156, and the statistical analysis approach in lines 213-218.
Baseline soil characteristics were not considered in the model as covariates to control for pre-study variation. The main reason was to maintain model simplicity due to the already-limited number of observations. We do not believe that our choice compromised the results because i) although background noise is expected, the area had been under the same management prior to study installation, and ii) the interference of pre-study variation between plots ended up pooled into the block effect, which was non-significant in the analysis of variance.
Point 4: Line 191: Please specify that you used simple linear regression. But why not use linear regression with additional fixed effects of soil depth and the soil depth x soil characteristic (P, K, or SOM) interaction? With the additional effects, you can compare depths and their interactions with soil characteristics on yields.
Response 4: It was modified, as requested. We have inserted that information. “Mixed-effect linear regression models were used to explore the relationships between soybean yield and individual soil chemical properties in the 0–10 cm and 0–20 cm soil layers in 2017/2018 cropping season using the lme function from the nlme package in R [15, 16].” (Page 5 – Lines 213 – 215).
Our choice of analysing depths separately is directly related to the study objectives, which were to evaluate different depths and answer the question of whether the 0–10 cm upland commonly-used diagnostic layer was the most correlated with yield in a lowland no-till ICLS environment. The same can be said for the choice of analysing soil characteristics separately. Our objective was not to understand how different soil characteristics interact in affecting yield, but the individual soil characteristic impact on yield. This approach is commonly used when establishing correlation/calibration studies that assist in creating fertilizer recommendation guidelines.
Point 5: Table 1: Are these arithmetic means or least squares means? Please specify and include measurements of error (e.g., SEs).
Response 5: The values are expressed in arithmetic mean. We have added the standard error values in the Table 1 and this information in the footnote of the Table 1. “The values are expressed as arithmetic mean ± standard error of the mean.” Please see Table 1.
Point 6: Figures 2 to 3: Change to “… in (a) 0–10 and (b) 10–20 cm soil layers …”. I recommend that the 2 plots per figure have the same x-axis scale or show the soil depths in the same figure as done for Fig 4.
Response 6: It was changed, as requested.
Point 7: Figure 4: Change to “… (a) soil pH and (b) soil organic matter (SOM) …”
Response 7: It was changed, as requested.
Point 8: Figures 2 to 4: I just want to clarify what the “*” means. Does it indicate that the model is different than the intercept-only model at p ≤ 0.05? Or does it mean that the slope is different than 0 at p ≤ 0.05? Figure 3 uses “5%”. Please keep consistency.
Response 8: After considering and addressing reviewer comment #3, we noticed that the initial regression analysis did not account for the proper level of replication in the study and overestimated the error degrees of freedom. All correlation analysis were rerun with the proper model where subsampling did not contribute to the experimental error degrees of freedom. The new, correctly-specified models were not statistically significant because of the limited number of true observations. Therefore, the * was removed from the legend of Figures 2 to 4.
Point 9: Line 325: Similar to my previous comment on p-values in figures, what statistical test is this p-value here for and what is it suggesting?
Response 9: As detailed in the statistical analysis section of M&M section, the test used was Tukey's test: “Fertilizer treatment least squared means were calculated and compared using Tukey’s adjustment.” (P. 5 – Lines 206 – 207).
After re-running the regression analysis with the proper error degrees of freedom (explained in more details in response to point 8) and finding non-significant slopes, we removed asterisks and p-values from figures.
Reviewer 3 Report
I have read the new version of the manuscript entitled “Integrating livestock and soybean in no-till rice paddy fields decreases soybean yield reliance on mineral fertilizer” and I consider that the new version have been greatly improved from the previous one that I reviewed. In the present version, the manuscript is focused on the evaluation of soybean yield, which fits with the experimental design and obtained data. I also acknowledge their careful response to my comments.
Therefore, I consider the present version of the manuscript could be potentially accepted, although I still consider that further improvements could be done in order to achieve a better article quality. In addition, I consider that an editing of the English language could be necessary to improve the final manuscript quality.
I consider the next questions should be solved before of the acceptance of the manuscript:
-The title in the present version is “Integrating livestock and soybean in no-till rice paddy fields decreases soybean yield reliance on mineral fertilizer”. It would suggest to start the title with the object of the study, (the soybean yield), second the obtained result (low response to mineral fertilizer) and finally mention the integrated system. It would be easier to understand.
-Abstract: L20: I consider it would be necessary to mention that the soybean grow under ICLS is expected to do not be very responsible to mineral fertilization because of the reasons explained in the introduction. In addition, I consider the last sentence of the abstract very vague (L34-35) to conclude the abstract. The authors have more interesting conclusions in the “conclusions” section which could be used to finish the manuscript.
-The introduction is too long and a little chaotic. I consider the authors should change the structure to make it easier to read. In my opinion, a better structure could be:
1) Describe the potential advantages of ICLS as alternative to rice continuous cropping in Brazil
2) Mention that the inclusion of livestock promotes a higher nutrient recycling and reduces the effect of fertilizer application on rice yields (citing Denardin et al., 2020).
3) Describe briefly the characteristics of soybean crops and mention that the soybean yield
response to fertilizer could be also affected by the livestock presence.
4) Further information about the soybean yield response to fertilizers
5) Hypothesis and objectives.
In order to reduce the length of the introduction, I consider the authors can delete the paragraph from L81-87 (I consider that information is not essential) and they could reduce the length of the paragraph L61-69 (To focus only in soybean requirements).
L50-52: I consider the authors should clarify that sentence. The most known impact of legume inclusion in a crop rotation is related with a higher availability of N for the next crop (see for example Yu et al., 2014). However, the authors mentioned that there are other mechanisms but are vaguely described (increased nutrient availability and enriched soil fertility). They should provide more details.
Yu, Y., Xue, L., & Yang, L. (2014). Winter legumes in rice crop rotations reduces nitrogen loss, and improves rice yield and soil nitrogen supply. Agronomy for sustainable development, 34(3), 633-640.
L70-71: I am not a soybean specialist, but in general, all the legumes are very responsive to P addition since they require large amounts of P for N2 fixation. For example:
Valentine, A.J., Kleinert, A., Benedito, V.A., 2017. Adaptive strategies for nitrogen metabolism in phosphate deficient legume nodules. Plant Science. doi:10.1016/j.plantsci.2016.12.010
L157: Please, change was by were.
L166 and L247: How did you calculate the SOM? If you use the Walkley-Black method, in general the obtained value is the soil organic carbon, no the SOM. Did you apply a conversion factor to calculate it?
L251-259: I think the ryegrass high fertilization rates (several times higher than the soybean fertilization rates) could lead to an accumulation of nutrients which could remain in the soil when the soybean cropping starts. So it is not only the effect of the manure depostion or plant residues, also the leftovers from ryegrass fertilization could contribute to reduce the efficiency of soybean fertilization.
L266-268: I think that the main result of your study is that the pasture fertilization and cattle grazing reduce the requirements of soybean fertilization prior to cropping. The reason seems to be the applied fertilizers to ryegrass, linked with the manure deposition and plant residues, which can provide enough nutrients to maintain high yields. Therefore, your study shows that in that systems, the fertilization regimes must be adjusted and probably soybean fertilization is not necessary.
L277-279: Ranged between plots? Field replications?
L280: mg dm-3? Is the correct unit?
L288-L290: Why? That idea has not been discussed previously, therefore you cannot conclude the section with it. You need to discuss it previously.
L321-323: But I think the lack of response is more related with the high levels caused by the ryegrass fertilization (and dung deposition and plant residues) than the spatial heterogeneity of the nutrients in soil.
L327: N2 fixation
L329: Increased over time? From the beginning of the experiment? I think it would be more correct to say that the SOM is high because ILCS leads to an accumulation of SOM and add a citation.
L332: BNF? Please, describe the abbreviation or use the full name.
L357-381: For me, it looks like a repetition of the conclusion section, therefore these paragraph could be reduced in order to avoid the repetition and shorten the manuscript. In case there is new information in these paragraphs, it could be added to the previous discussion or to the conclusions. In general, I think you can reduce the length of the discussion because several passages of the text repeat the same information.
L387-389: I think that section could be deleted because basically, it is a repetition of L395-398.
Author Response
Response to Reviewer 3 Comments
I have read the new version of the manuscript entitled “Integrating livestock and soybean in no-till rice paddy fields decreases soybean yield reliance on mineral fertilizer” and I consider that the new version have been greatly improved from the previous one that I reviewed. In the present version, the manuscript is focused on the evaluation of soybean yield, which fits with the experimental design and obtained data. I also acknowledge their careful response to my comments.
Therefore, I consider the present version of the manuscript could be potentially accepted, although I still consider that further improvements could be done in order to achieve a better article quality. In addition, I consider that an editing of the English language could be necessary to improve the final manuscript quality.
I consider the next questions should be solved before of the acceptance of the manuscript:
Point 1: The title in the present version is “Integrating livestock and soybean in no-till rice paddy fields decreases soybean yield reliance on mineral fertilizer”. It would suggest to start the title with the object of the study, (the soybean yield), second the obtained result (low response to mineral fertilizer) and finally mention the integrated system. It would be easier to understand.
Response 1: Dear reviewer, thank you for the corrections and contributions. We have changed the title, as suggested, to “Soybean yield does not rely on mineral fertilizer in rotation with flooded rice under no-till integrated crop-livestock system”
Point 2: Abstract: L20: I consider it would be necessary to mention that the soybean grow under ICLS is expected to do not be very responsible to mineral fertilization because of the reasons explained in the introduction. In addition, I consider the last sentence of the abstract very vague (L34-35) to conclude the abstract. The authors have more interesting conclusions in the “conclusions” section which could be used to finish the manuscript.
Response 2: We inserted in the abstract a sentence referring to the possibility of soy not responding to mineral fertilization: “Due to the nutrient cycling process favored by animal grazing in winter fertilized pastures, soybean may not respond to mineral fertilization under no-till integrated crop-livestock system (ICLS).” (Page 1 – Lines 23 – 25).
Furthermore, we are grateful for all contributions to improve the quality of the manuscript. According to the suggestions, we completed and changed the final part of the abstract: “The crop rotation and ICLS adoption under no-till reduce the soybean reliance for mineral fertilization prior to cropping. Therefore, the fertilization regimes must be adjusted and probably the supply of mineral fertilizer for soybean is not necessary.” (Lines 40 – 42)
Point 3: The introduction is too long and a little chaotic. I consider the authors should change the structure to make it easier to read. In my opinion, a better structure could be:
1) Describe the potential advantages of ICLS as alternative to rice continuous cropping in Brazil; 2) Mention that the inclusion of livestock promotes a higher nutrient recycling and reduces the effect of fertilizer application on rice yields (citing Denardin et al., 2020); 3) Describe briefly the characteristics of soybean crops and mention that the soybean yield response to fertilizer could be also affected by the livestock presence; 4) Further information about the soybean yield response to fertilizers; 5) Hypothesis and objectives.
In order to reduce the length of the introduction, I consider the authors can delete the paragraph from L81-87 (I consider that information is not essential) and they could reduce the length of the paragraph L61-69 (To focus only in soybean requirements).
Response 4: Dear reviewer, you are right, thank you very much for the contribution. We have restructured the introduction section and removed an entire paragraph (L. 69 – 77).
However, the information contained in the other paragraph (L. 81-87) we will not be able to remove, as it justifies the assessment of the different soil layers (0 – 10 and 10 – 20 cm) and the relationship between soybean yield and soil chemical properties. However, I believe the introduction is better now, and not so long (only one page).
Point 5: L50-52: I consider the authors should clarify that sentence. The most known impact of legume inclusion in a crop rotation is related with a higher availability of N for the next crop (see for example Yu et al., 2014). However, the authors mentioned that there are other mechanisms but are vaguely described (increased nutrient availability and enriched soil fertility). They should provide more details. (Yu, Y., Xue, L., & Yang, L. (2014). Winter legumes in rice crop rotations reduces nitrogen loss, and improves rice yield and soil nitrogen supply. Agronomy for sustainable development, 34(3), 633-640.)
Response 5: Dear reviewer, you are right, the sentence was not entirely clear. We were referring to the higher microbial carbon use efficiency from legumes residues in increasing the soil organic matter content. From that, we changed the sentence to: “The benefits of legumes in rotation are not only caused by biological nitrogen (N) fixation but also by increased nutrient availability through higher microbial carbon use efficiency from legumes residues in increasing the soil organic matter content, which could help to sustain the long-term productivity of cereal-based cropping systems.” (Page 2 – Lines 57 – 58).
Point 6: L70-71: I am not a soybean specialist, but in general, all the legumes are very responsive to P addition since they require large amounts of P for N2 fixation. For example:
(Valentine, A.J., Kleinert, A., Benedito, V.A., 2017. Adaptive strategies for nitrogen metabolism in phosphate deficient legume nodules. Plant Science. doi:10.1016/j.plantsci.2016.12.010)
Response 6: You are right. I believe that some error occurred at some point in the writing of the sentence. However, we have corrected it for “Soybean is considered highly responsive crop to P fertilization and nutrient application rates have increased grain yield in Subtropical soils, especially under no-till conditions [11, 12, 13].” (Page 2 – Lines 78 – 80).
Point 7: L157: Please, change was by were.
Response 7: Dear reviewer, I believe that the "was" is right, because it is "the relationship" between soybean yield and soil chemical properties that has been evaluated, so it would not be "were".
Point 8: L166 and L247: How did you calculate the SOM? If you use the Walkley-Black method, in general the obtained value is the soil organic carbon, no the SOM. Did you apply a conversion factor to calculate it?
Response 8: Thank you. We had put this information just in the footer of the Table 1, but it was not present in the M&M section (only that the method was by wet combustion). Therefore, we inserted this information, as well as the conversion factor, in the M&M section: “…SOM content (Walkley-Black method – conversion factor = 1.72)…” (Page 4 – Lines 186 and 187).
Point 9: L266-268: I think that the main result of your study is that the pasture fertilization and cattle grazing reduce the requirements of soybean fertilization prior to cropping. The reason seems to be the applied fertilizers to ryegrass, linked with the manure deposition and plant residues, which can provide enough nutrients to maintain high yields. Therefore, your study shows that in that systems, the fertilization regimes must be adjusted and probably soybean fertilization is not necessary.
Response 9: Thank you. Thank you very much for your help and contribution. We have changed the sentence and supplemented it, for better understanding: “Thus, the use of pasture fertilization and cattle grazing in the winter season in lowlands ensure high grain yields and reduce the fertilization requirements of soybean prior to cropping (Fig. 1). Therefore, in these systems, the fertilization regimes must be adjusted and probably the supply of mineral fertilizer for soybean is not necessary.” (Page 7 – Lines 297 – 301).
Point 10: L277-279: Ranged between plots? Field replications?
Response 10: Ranging among all the values obtained and used in the regression. We are sorry, but we find it unnecessary to insert this kind of information in the sentence.
Point 11: L288-L290: Why? That idea has not been discussed previously, therefore you cannot conclude the section with it. You need to discuss it previously.
Response 11: Thank you. You are right; we had not discussed it previously. Therefore, we have rewritten and completed the sentence, for a better understanding: “The mechanisms of vertical movement of P in the soil profile by diffusion are closely related to soil physical and hydraulic properties [11, 20]. Therefore, improvements in soil physical and hydraulic conditions can potentially help with root growth and exploration bringing water and nutritional benefits to soybean plants [20].” (Page 8 – Lines 325 – 327).
Point 12: L321-323: But I think the lack of response is more related with the high levels caused by the ryegrass fertilization (and dung deposition and plant residues) than the spatial heterogeneity of the nutrients in soil.
Response 12: Ok, I agree with that. To make the information more complete, I have also inserted this information in the text, in a complementary way: “This, combined with the return of nutrients supplied to the pasture via animal manure and plant residues, may explain the lack of response of soybean to P and K fertilization and the lower dependence on the use of fertilizers in soybeans (Fig. 1).” (Page 12 – Lines 364 – 366).
Point 13: L327: N2 fixation
Response 13: Thank you, it was corrected.
Point 14: L329: Increased over time? From the beginning of the experiment? I think it would be more correct to say that the SOM is high because ILCS leads to an accumulation of SOM and add a citation.
Response 14: You are right. We forgot to update this sentence after adjusting the removal of the soil fertility assessment over time to the manuscript’s objectives. We adjusted and corrected the sentence to: “The SOM content presented an average of 2.6% in 0–10 cm soil layer in 2017/2018 cropping season, classified as a medium content (Fig. 4b) [11].” (Page 12 – Lines 372 and 373)
Point 15: L332: BNF? Please, describe the abbreviation or use the full name.
Response 15: It was corrected, as requested.
Point 16: L357-381: For me, it looks like a repetition of the conclusion section, therefore these paragraph could be reduced in order to avoid the repetition and shorten the manuscript. In case there is new information in these paragraphs, it could be added to the previous discussion or to the conclusions. In general, I think you can reduce the length of the discussion because several passages of the text repeat the same information.
Response 16: Ok, thank you. In fact, we have reallocated one paragraph (Lines 386 – 391), with some adjustments, and excluded another paragraph (Lines 406 – 413) at the end of the discussion section. Finally, we completed the last paragraph summarizing the main results as well as perspectives for future studies: “In summary, our results showed that the crop rotation and no-till ICLS adoption reduce the requirements of soybean on mineral fertilizer prior to cropping. Hence, in these systems, the fertilization regimes must be adjusted and P and K removed in soybean seeds can be replaced during the pasture phase, enhancing forage and animal production [8, 10, 19]. Lastly, our results serve as a springboard for further investigation of soybeans performance in lowlands under no-till ICLS. Therefore, new calibration studies should be conducted in lowlands soils used by paddy fields and rainfed crops under no-till to re-define the right soil layer to be sampled for improving the nutrient diagnosing recommendations.” (Lines 422 – 429)
Point 17: L387-389: I think that section could be deleted because basically, it is a repetition of L395-398.
Response 17: Ok, it was deleted, as suggested.
Point 18: L280: mg dm-3? Is the correct unit?
Response 18: Thank you. It was not correct and we have already adjusted.
Point 19: L251-259: I think the ryegrass high fertilization rates (several times higher than the soybean fertilization rates) could lead to an accumulation of nutrients which could remain in the soil when the soybean cropping starts. So, it is not only the effect of the manure depostion or plant residues, also the leftovers from ryegrass fertilization could contribute to reduce the efficiency of soybean fertilization.
Response 19: Thank you. We inserted a sentence in the paragraph: “The high pasture fertilization rates can lead to an accumulation of nutrients in the soil, contributing to a reduction in the efficiency of mineral fertilizer in soybean.” (Page 7 – Lines 284 – 286)
