The Use of Faba Bean Cover Crop to Enhance the Sustainability and Resiliency of No-Till Corn Silage Production and Soil Characteristics
Round 1
Reviewer 1 Report
Sustainable agriculture is one of the important elements of sustainable development. An important goal of sustainable agriculture is to reduce the negative impact on the environment and maintain soil fertility at a high level. This can be achieved, for example, through the optimal use of mineral fertilizers, especially nitrogen fertilizers, and the cultivation of plants as mulch. Therefore, in my opinion, the research presented in the manuscript is interesting and deals with important and current issues. The subject of the research is consistent with the thematic scope of the Agronomy journal.
The experiment presented in the manuscript was properly planned, it allows to explain the hypotheses put forward in the introduction. The research material is sufficient. The results were statistically analyzed and discussed and interpreted in detail. Tables and graphs are generally well prepared, understandable and legible. Literature is properly selected and cited.
However, the methodology chapter lacks some information
1. line [90-94] - it is not understandable to me. does it mean that in 2019 field beans were sown on plots where corn was harvested in 2018? so what does the sentence mean ‘The research site was fallow before the onset of the experiment but was covered with annual broadleaf weeds, mainly including common amaranth (Amaranthus retroflexus L.) and common lambsquarters (Chenopodium album L.) in both years’
2. If possible, it is worth providing long-term averages for weather conditions and comparing the years 2018 and 2019 with them
3. How were irrigation needs determined? Soil moisture can affect the mineralization rate of mulch biomass.
4. How was the biomass of faba bean roots determined?
5. When was the corn harvested (give date)
6. How the soil was cultivated before field bean sowing
7. What about weeds. Have any herbicides been used to control weeds in faba beans and corn?
8. In line [123] is ‘..Zn2+, K+, P, total N, lime, and base saturation,….’ why only the content of Zn was determined in the soil, and what about other microelements? results for lime and for base saturation are not listed in table 1.
9. In line [123-124] the authors write that ‘sub-samples were collected at a depth of 0–20 cm’ and in Table 1 they give soil properties for two levels 0-15 and 15-30?
10. Please specify the distance between the rows of maize
11. Please check the interpretation of results for stem and root biomass. Is the significance of the effect of faba bean plant density correctly marked?
12. Table 2 should be moved to the Results chapter. The numbering of the tables should be consistent with the order in which the results are discussed. Therefore, table 3 should be table 2 and table 2 should be table 3
13. the explanations under table 5 are incorrect – line [296-298]
14. line [476-494] - to remove
Author Response
Comments and Suggestions for Authors:
Sustainable agriculture is one of the important elements of sustainable development. An important goal of sustainable agriculture is to reduce the negative impact on the environment and maintain soil fertility at a high level. This can be achieved, for example, through the optimal use of mineral fertilizers, especially nitrogen fertilizers, and the cultivation of plants as mulch. Therefore, in my opinion, the research presented in the manuscript is interesting and deals with important and current issues. The subject of the research is consistent with the thematic scope of the Agronomy journal.
The experiment presented in the manuscript was properly planned, it allows to explain the hypotheses put forward in the introduction. The research material is sufficient. The results were statistically analyzed and discussed and interpreted in detail. Tables and graphs are generally well prepared, understandable and legible. Literature is properly selected and cited. However, the methodology chapter lacks some information:
Response:
The authors appreciate the reviewer’s comment. Please see our response to the reviewer's comments
- line [90-94] - it is not understandable to me. does it mean that in 2019 field beans were sown on plots where corn was harvested in 2018? so what does the sentence mean ‘The research site was fallow before the onset of the experiment but was covered with annual broadleaf weeds, mainly including common amaranth (Amaranthus retroflexus L.) and common lambsquarters (Chenopodium album L.) in both years’
Response:
We mentioned that the experimental site was fallow at the onset of the experiment (first year). However, we added 2018 to the sentence for more clarification.
- If possible, it is worth providing long-term averages for weather conditions and comparing the years 2018 and 2019 with them.
Response:
The authors tried to get long-term weather data from the local weather station, but unfortunately, the agency did not cooperate. They think this is a homeland security issue!
- How were irrigation needs determined? Soil moisture can affect the mineralization rate of mulch biomass.
Response:
Thank you for the comment. We used tensiometers to monitor the plots’ moisture status. We added the information to the M&M.
- How was the biomass of faba bean roots determined?
Response:
Thank you for the excellent comment. We have added the procedure that was used to the M&M.
- When was the corn harvested (give date)
Response:
The dates of corn harvest in 2018 and 2019 were added to the M&M
- How the soil was cultivated before field bean sowing
Response:
Cultivation before planting faba bean was added to the M&M.
- What about weeds. Have any herbicides been used to control weeds in faba beans and corn?
Response:
No weed control was exercised in faba bean cover crops. However, weeds, especially in low faba bean density plots, were handpicked a few times until the corn started its fast growth. This was added to the M&M
- In line [123] is ‘..Zn2+, K+, P, total N, lime, and base saturation,….’ why only the content of Zn was determined in the soil, and what about other microelements? results for lime and for base saturation are not listed in table 1.
Response:
Thank you for the comment. The only reason Zn was reported was that in some past studies at the experiment site, the only deficient micronutrient identified was Zn. However, we removed the Zn from the table to avoid any confusion. Sincere apology for mentioning base saturation and lime. These two measurements were not done in this experiment, therefore we corrected the M&M.
- In line [123-124] the authors write that ‘sub-samples were collected at a depth of 0–20 cm’ and in Table 1 they give soil properties for two levels 0-15 and 15-30?
Response:
Thank you for catching the error. 0-30cm is the correct value. It was corrected in the M&M
- Please specify the distance between the rows of maize
Response:
The row spacing (50 cm) was specified.
- Please check the interpretation of results for stem and root biomass. Is the significance of the effect of faba bean plant density correctly marked?
Response:
The interpretation of root and shoot results was checked and confirmed.
- Table 2 should be moved to the Results chapter. The numbering of the tables should be consistent with the order in which the results are discussed. Therefore, table 3 should be table 2 and table 2 should be table 3
Response:
Thank you for catching the mistake. The tables were moved and the numbering was corrected.
- the explanations under table 5 are incorrect – line [296-298]
Response:
The explanation of the table was corrected.
- line [476-494] - to remove
Response:
The lines were removed.
Thank you for your time and useful comments.
Reviewer 2 Report
The manuscript by Ghorbi et al. reports on a two-year study of corn silage production as affected by faba bean pre-culture and various N addition rates under no till conditions. While it is widely known that interventions such as no-till and cover-crop lead to long term improvements in soil fertility and then crop yield, these results are of interest because even after one and two cycles of cover crop, there are improvements in yield. Please see also9 below, but it would add value if there would be emphasis on progression – whether performance was the same after one and two years of faba bean, or if it increased.
The introduction is well written, and I appreciate that the authors tracked fate of above and below-ground faba bean tissue over time, to shed light on reasons for yield effect.
The manuscript has one strong weakness that runs through several of the tables and results text: lacking clarity on which sample is what.
1: Based on the abstract (line 15), and lines 91 and 187, as well as parts of some tables, the experiment was run for a full two years. Yet in some cases only one set of results is shown and then it is unclear whether these are from before the start (Table 1), or an average of two years of sampling and analysis. Please clarify this in each case.
2: Was the sequence a) remove weeds (how, and if not how), plant and then mow faba bean, plant and mow corn, plant and mow faba bean and plant and mow corn? Please make the specific set of steps clear in the methods section.
3: Was each rate of faba bean planting (0, 25, 35 etc) paired with the four rates of N – so 20 treatments in total, or not. Figures 4 and 5 indicate this was the case. This create confusion to me in Tables 2 -4 where there are a list of data for rates of faba bean, and later for rates of N. Does this mean that in each case the average was reported (e.g. for 25 faba bean the average of 0, 100, 200 and 300 N?).
4: For Figures 4 and 5, were these data from year 1 or year 2, or the average?
Specific comments:
1. Line 19: What roots are these – faba bean or corn?
2. Lines 91 – 94: As this was no-till, were these weeds removed or killed, or simply left in place?
3. Line 107: Define the inoculum (where purchased and species, or self-cultured?)
4. Line 109: change “flowing” to “flowering”.
5. Table 1: Do the dashes represent “not determined” or “not detected”.
6. Table 2: How were the roots and shoots obtained? Were the roots dug up? Were they washed, dried, etc???
7. Table 3: What time point do the years represent? Before planting faba bean, after removing faba bean, after removing corn silage?
8. Figure 3: What faba bean density is associated here?
9. Section 4.1: I agree that the experiment was too short, but at the same time you did see some significant effect.
10. Line 417: Line 350 states 133 N – please check and clarify
Author Response
The manuscript by Ghorbi et al. reports on a two-year study of corn silage production as affected by faba bean pre-culture and various N addition rates under no till conditions. While it is widely known that interventions such as no-till and cover-crop lead to long term improvements in soil fertility and then crop yield, these results are of interest because even after one and two cycles of cover crop, there are improvements in yield. Please see also9 below, but it would add value if there would be emphasis on progression – whether performance was the same after one and two years of faba bean, or if it increased.
The introduction is well written, and I appreciate that the authors tracked fate of above and below-ground faba bean tissue over time, to shed light on reasons for the yield effect. The titles of the tables were revised by adding “main effect” to the titles.
The manuscript has one strong weakness that runs through several of the tables and results text: lacking clarity on which sample is what.
1: Based on the abstract (line 15), and lines 91 and 187, as well as parts of some tables, the experiment was run for a full two years. Yet in some cases only one set of results is shown and then it is unclear whether these are from before the start (Table 1), or an average of two years of sampling and analysis. Please clarify this in each case.
Response:
When the interaction of year and majority of traits was not significant (for example Tables 2 and 3), we used the average of the two years. Otherwise, we presented the results of the two years separately.
2: Was the sequence a) remove weeds (how, and if not how), plant and then mow faba bean, plant and mow corn, plant and mow faba bean and plant and mow corn? Please make the specific set of steps clear in the methods section.
Response:
Thank you for the comment. The weed control in faba bean and corn was described and added to the M&M
3: Was each rate of faba bean planting (0, 25, 35 etc) paired with the four rates of N – so 20 treatments in total, or not. Figures 4 and 5 indicate this was the case. This create confusion to me in Tables 2 -4 where there are a list of data for rates of faba bean, and later for rates of N. Does this mean that in each case the average was reported (e.g. for 25 faba bean the average of 0, 100, 200 and 300 N?).
Response:
You are right. Each faba bean density was paired with four rates of N, as demonstrated in Figures 4 and 5. The tables 2-4 (now the numbers have changed) show the main effects, not the interactive effect.
4: For Figures 4 and 5, were these data from year 1 or year 2, or the average?
Response:
The Presented values in Figures 4 and 5 are averages of two years (2018 and 2019). The figures were revised.
Specific comments:
- Line 19: What roots are these – faba bean or corn?
Response:
Faba bean. The abstract was revised.
- Lines 91 – 94: As this was no-till, were these weeds removed or killed, or simply left in place?
Response:
Good comment. No weed control was practiced in faba bean cover crop. The weeds in corn (especially after no or low faba bean densities were controlled manually a few times. A statement about the weed control was added to the M&M.
- Line 107: Define the inoculum (where purchased and species, or self-cultured?)
Response:
The inoculum was purchased from a local company. The company did not provide the name of the species. They considered the information secret! We added, “the inoculum was purchased from a local company.”
- Line 109: change “flowing” to “flowering”.
Response: Thank you. Corrected
- Table 1: Do the dashes represent “not determined” or “not detected”.
Response:
The dashes in Table 1 (now is table 2) indicate not detected
- Table 2: How were the roots and shoots obtained? Were the roots dug up? Were they washed, dried, etc???
Response:
Very good comment. The detail of the procedure was added to the M&M.
- Table 3: What time point do the years represent? Before planting faba bean, after removing faba bean, after removing corn silage?
Response:
The year for soil characteristics presentation are related to the faba bean, at the termination.
- Figure 3: What faba bean density is associated here?
Response:
Very good catch. Figures 3 and 4 are related to the optimum density (40 plants m-2). We revised the figures.
- Section 4.1: I agree that the experiment was too short, but at the same time you did see some significant effect.
Response:
We indicated the improvement trend in some soil characteristics in this short-term study.
- Line 417: Line 350 states 133 N – please check and clarify
Response:
We are afraid, due to the changed line numbers, we were not able to detect the comment for checking and clarification.
Reviewer 3 Report
The authors investigated the influences of faba bean cover crop on corn silage production and soil properties. They found that faba bean cover crop can increase corn production. The below are some specific comments.
1. Why faba bean densities (0, 25, 35, 40, 80 plants m-2) and N fertilizer rates (0, 100, 200, and 300 kg ha–1) were chosen in this study? PS: Line 102 (0, 100, 200, and 300 kg ha–1) should follow N fertilizer rates in line 101. How many replications in each treatments? Please add these information to material and method section.
2. Figure 1 is not primary experimental data and might be displayed in supplementary material. The same as table 1.
3. Please modify keywords.
4. Weather condition can be described in material and method section rather than in results.
5. Please cite Table 2 in result section. Data should be described at result section. I am curious to know why table 2 was cited in data analysis part but descried in result part. I think data should be cited and descried in result section.
6. Please improve the discussion by adding underlying mechanisms of faba bean density on soil properties and crop production. For example, why faba bean cover crop increased soil organic matter, porosity and bulk density? Is there linkages between soil properties and crop production?
7. Conclusions should be a highly summarization of results. Discussion should not be included in conclusions. Please check and modify to form a concise conclusion.
The authors investigated the influences of faba bean cover crop on corn silage production and soil properties. They found that faba bean cover crop can increase corn production. The below are some comments.
1. Why faba bean densities (0, 25, 35, 40, 80 plants m-2) and N fertilizer rates (0, 100, 200, and 300 kg ha–1) were chosen in this study? PS: Line 102 (0, 100, 200, and 300 kg ha–1) should follow N fertilizer rates in line 101. How many replications in each treatments?
2. Figure 1 is not primary experimental data and might be displayed in supplementary material. The same as table 1. Mean±SE in table 1?
3. Please modify keywords.
4. Line 79: select soil characteristics?
5. Introduction: hypotheses?
6. Weather condition can be described in material and method section rather than in results.
7. Please cite Table 2 in result section. Data should be described at result section. I am curious to know why table 2 was cited in data analysis part but descried in result part. I think data should be cited and descried in result section.
8. Please improve the discussion by adding underlying mechanisms of faba bean density on soil properties and crop production. For example, why faba bean cover crop increased soil organic matter, porosity and bulk density? Is there linkages between soil properties and crop production?
9. Discussion should not be included in conclusions. Please check and modify to form a concise conclusion.
Author Response
The authors investigated the influences of faba bean cover crop on corn silage production and soil properties. They found that faba bean cover crop can increase corn production. The below are some specific comments.
- Why faba bean densities (0, 25, 35, 40, 80 plants m-2) and N fertilizer rates (0, 100, 200, and 300 kg ha–1) were chosen in this study? PS: Line 102 (0, 100, 200, and 300 kg ha–1) should follow N fertilizer rates in line 101. How many replications in each treatments? Please add these information to material and method section.
Response:
Faba bean is traditionally used as a vegetable and recently as a dual purpose. The optimum density for these purposes is 30-40 plants m-2. However, we hypothesized that using a higher density (80) as a cover crop may contribute more N to the corn. The interesting result obtained in this study rejected our original hypothesis meaning that there is a limit for symbiotic relationship between rhizobia and faba bean roots. The reason we used different N application rates was that we wanted to examine the interactive effect of faba bean and synthetic fertilizer. In other words we were interested to quantify the contribution of faba bean in N need of corn. For example, if the corn yield that was grown in 40 plants faba bean and received 200 kg N (100 kg less than recommended) is similar to the corn with 0 N but received 300 kg N. An interesting result from the current study revealed that corn yielded significantly lower in no-cover crop treatment, even when receiving the highest rates of synthetic N (300kg).
- Figure 1 is not primary experimental data and might be displayed in supplementary material. The same as table 1.
Response:
With all due respect, the authors believe that presenting Figure 1 in M&M is directly relevant to the results of the experiment. For example decomposition of conditions is higher when the temperature and soil moisture are higher.
- Please modify keywords.
Response:
The keywords were modified
- Weather condition can be described in material and method section rather than in results.
Response:
With all due respect, the authors believe that presenting the weather conditions at the beginning of the results is informative. This is a common practice in many manuscripts
- Please cite Table 2 in result section. Data should be described at result section. I am curious to know why table 2 was cited in data analysis part but descried in result part. I think data should be cited and descried in result section.
Response:
Thank you for picking up the mistake. The presentation of Table 2 (now Table 3) in the data analysis section was not intentional.
- Please improve the discussion by adding underlying mechanisms of faba bean density on soil properties and crop production. For example, why faba bean cover crop increased soil organic matter, porosity and bulk density? Is there linkages between soil properties and crop production?
Response:
The discussion in regard to the influence of faba bean cover crop on soil health was improved. It is well-known that the healthier the soil, the higher crop yield and quality.
- Conclusions should be a highly summarization of results. Discussion should not be included in conclusions. Please check and modify to form a concise conclusion.
Response:
The conclusion was revised.
Reviewer 4 Report
I have carefully reviewed the manuscript entitled "Use of faba bean cover crop to enhance sustainability and resiliency of no-till corn silage production and soil characteristics" submitted by Ghorbi et al. to the journal Agronomy. This study aimed to assess the effects of faba bean as a cover crop (different planting densities) and N fertilization rates on crop yield and quality and soil properties. Field experiment design is reasonable and statistical analysis is reliable. Overall, this is a good study and authors provides a lot of data and these data can advance local corn silage production. I only have a few small questions as follows:
1. (Line 132-133) Why were soil samples collected after faba bean termination in the second year, rather than at the harvest time of corn？I suggest further monitoring the long-term effects of cover crop and nitrogen fertilization rates on soil physicochemical and biochemical as well as microbes-related properties. It is not surprising that soil physicochemical properties did not have significant alteration in two years-duration field experiment.
2. The abstract section needs to be rewritten, especially to clarify the background, purpose, and significance of this study, as well as the conclusion and creativity of the study.
Author Response
I have carefully reviewed the manuscript entitled "Use of faba bean cover crop to enhance sustainability and resiliency of no-till corn silage production and soil characteristics" submitted by Ghorbi et al. to the journal Agronomy. This study aimed to assess the effects of faba bean as a cover crop (different planting densities) and N fertilization rates on crop yield and quality and soil properties. Field experiment design is reasonable and statistical analysis is reliable. Overall, this is a good study and authors provides a lot of data and these data can advance local corn silage production. I only have a few small questions as follows:
- (Line 132-133) Why were soil samples collected after faba bean termination in the second year, rather than at the harvest time of corn? I suggest further monitoring the long-term effects of cover crop and nitrogen fertilization rates on soil physicochemical and biochemical as well as microbes-related properties. It is not surprising that soil physicochemical properties did not have significant alteration in two years-duration field experiment.
Response:
The authors agree with the reviewer that it was more helpful if additional soil samples were taken after the corn harvest in the second year. Having said that, the main goal of the experiment was to investigate the influence of faba bean as a legume cover crop on soil characteristics, reducing synthetic N application to the corn, and the productivity of corn. So the focus was made on faba bean. We didn’t expect to see a short-term influence of cover crop on soil characteristics, but we hypothesized that may be increasing cover crop density (80 plants m-2, which is unusually high), can, to some degree, compensate for the short time influence.
- The abstract section needs to be rewritten, especially to clarify the background, purpose, and significance of this study, as well as the conclusion and creativity of the study.
Response:
The abstract was revised.
Thank you for your time and useful comments
Round 2
Reviewer 1 Report
The authors took into account most of the comments contained in the review. The manuscript has been revised and in my opinion can be accepted for publication in the journal Agronomy.
Reviewer 2 Report
Thank you for attending to my comments and revising the manuscript accordingly,
Author Response
Thank you for your time and constructive comments.
Reviewer 3 Report
Please check and modify key words.
soil health characterstics？soil characterstics.
Nitrogen content of roots and shoot？roots and shoot? nitrogen yield may be more suitable?
no
Author Response
The keywords were revised and two new keywords added
