Use of Dual-Purpose Winter-Grain Cover Crops as Emergency Forage and for Management of High Soil Phosphorous in Manured Fields

Round 1

Reviewer 1 Report

 I suggest some major revisions to the manuscript. Please find my comments below:

 

General comments:

1. In the “abstract” section, please give more information about the aim of our study, plus, as far as I understand it, we need to describe more about the differences in productivity and economic benefits, etc. between cover crops, rather than year-to-year comparisons.

2. In the “materials and method”, the information of experimental design missed, such as the the detail of layout plan of the field plot and replicate.

3. In discussion, the authors focus too much on the interannual variation, ignoring the main purpose of this study. Therefore, I suggest that the authors strengthen the question of difference in the performance of different cover crops in same years.

 

Special comments:

Abstract:

Line 12-13 should be deleted or merged into the above sentence, for the description of the experimental site.

In the “abstract” section, there is no explanation of the abbreviation for T1, T2, and T3.

Introduction:

This structure of this section is clear. However, maybe we should add more information  the performance differences of different cover crops, as well as the uncertain impact of climate differences and management systems (with or without straw returning to the field and sowing time).

Material and methods

Please convert all phosphorus (calcium) content indicators in the article to international units, similar to mg/g. (Page 2, Line 85-86; Table 3).

Section 2.2, for the experimental design, the detail of layout plan of the field plot and replicate should be supplied.

For the water moisture, please give more information of how to calculate the water remove,  please change the unit of water removal amount to mm or m³.

Results:

Please divide 3.1 into 3 parts, consistent with the discussion, one part of it is dry matter yield, moisture content; one part for the absorption of N and P; the last part is soil P and organic matter changes.

Discussion:

In general, we see more variation between five cover crops in the first year, particularly for the wheat. Thus, maybe we should discuss the response of wheat to climate change and the manure application. Nevertheless, we could not ignore the reason why the five crops showed different performance in the same year.

The section of “4. section missed”.

In addition, Repeating "4.2", and “4.3 and 4.4” missed.

Figures:

For all column charts, please keep the horizontal line color blurred and add standard deviation or standard error for comparison between treatments.

Figure 1A, What do the 4 curves mean? Please give more notes about that.

Figures 4, Please keep the width of the upper and lower rows the same, and reduce the space between figures.

Tables:

Table 3, please change the unit of P to mg/g.

 

Author Response

REVIEWER ONE:

General comments:

1. In the “abstract” section, please give more information about the aim of our study, plus, as far as I understand it, we need to describe more about the differences in productivity and economic benefits, etc. between cover crops, rather than year-to-year comparisons.

This comment has been addressed. The abstract was rewritten to shift the focus on to overall results and eliminated the year to year focus.

2. In the “materials and method”, the information of experimental design missed, such as the detail of layout plan of the field plot and replicate.

This comment has been addressed. It is correct that the plot size was missing and this has been added. The strips (blocks) themselves were not replicated due to the constraints of large scale on farm research with a farmer managing planting. In the statistical analysis section of the methods, this is noted with additional detail on how the stats compensated for this element of the design, including a Bonferroni  corrected p-value to be more rigid in declaring statistical differences. Acknowledgement of a potential drawback of the field design is also noted in this section.

3. In discussion, the authors focus too much on the interannual variation, ignoring the main purpose of this study. Therefore, I suggest that the authors strengthen the question of difference in the performance of different cover crops in same years.

This comment has been addressed. Thank for you for this feedback; after review, we agree that too much emphasis was placed on the differences between years, and in other places it was not clear that the discussion was focusing on in-year or overall variation. Substantial additions and edits/rearrangements have been made within the discussion section to expand upon and clarify the in-year variation, the overall variation, and in the interannual variation. 

Special comments:

Abstract:

Line 12-13 should be deleted or merged into the above sentence, for the description of the experimental site.

Due to the rewrite of the abstract, this content this comment referred to is no longer present.

In the “abstract” section, there is no explanation of the abbreviation for T1, T2, and T3.

This comment has been addressed.

Introduction:

This structure of this section is clear. However, maybe we should add more information  the performance differences of different cover crops, as well as the uncertain impact of climate differences and management systems (with or without straw returning to the field and sowing time).

This comment has been addressed. Additional details have been added regarding climate change and species performance. These crops are not grown for grain in the Northeast, therefore there is no straw return to the field. When grown solely for cover crops, the plant in the vegetative state would be returned. However, additional research (currently in editorial review) will address at length the residue returned to the field and the implications. The available research is presently very limiting on this topic. 

Material and methods

Please convert all phosphorus (calcium) content indicators in the article to international units, similar to mg/g. (Page 2, Line 85-86; Table 3).

This comment has been addressed; all content indicators have been converted to mg/g.

Section 2.2, for the experimental design, the detail of layout plan of the field plot and replicate should be supplied.

This comment has been addressed, as noted above.

For the water moisture, please give more information of how to calculate the water remove, please change the unit of water removal amount to mm or m³.

This comment has been addressed. The unit of water removal has been changed to m³. Additional detail was also added to the methods section to explain how this number was derived. Further contextualization of this data is found in the discussion.

Results:

Please divide 3.1 into 3 parts, consistent with the discussion, one part of it is dry matter yield, moisture content; one part for the absorption of N and P; the last part is soil P and organic matter changes.

This comment has been addressed.

Discussion:

In general, we see more variation between five cover crops in the first year, particularly for the wheat. Thus, maybe we should discuss the response of wheat to climate change and the manure application. Nevertheless, we could not ignore the reason why the five crops showed different performance in the same year.

I believe this comment echoes the comment made my reviewer one to focus more on the interannual variation. If our interpretation of this comment is correct, then this comment has been addressed.

The section of “4. section missed”.

This comment has been addressed.

In addition, Repeating "4.2", and “4.3 and 4.4” missed.

This comment has been addressed.

Figures:

For all column charts, please keep the horizontal line color blurred and add standard deviation or standard error for comparison between treatments.

We believe the horizontal line color comment refers to the letters in the mean separation interrupted the background line. If our understanding is correct, this only applied to figure four and has been corrected.

As a mean separation has been performed, the significant differences are distinguishable and error bars are not necessary additions. We call the reviewers to other Agronomy articles where no error bar is present on similar figures with a mean separation.

Adeyemi, O.; Keshavarz-Afshar, R.; Jahanzad, E.; Battaglia, M.L.; Luo, Y.; Sadeghpour, A. Effect of Wheat Cover Crop and Split Nitrogen Application on Corn Yield and Nitrogen Use Efficiency. Agronomy 2020, 10, 1081. https://doi.org/10.3390/agronomy10081081

Tursun, N., Işık, D., Demir, Z., & Jabran, K. (2018). Use of Living, Mowed, and Soil-Incorporated Cover Crops for Weed Control in Apricot Orchards. Agronomy, 8(8), 150. doi:10.3390/agronomy8080150

Schappert, A., Schumacher, M., & Gerhards, R. (2019). Weed Control Ability of Single Sown Cover Crops Compared to Species Mixtures. Agronomy, 9(6), 294. doi:10.3390/agronomy9060294

Mohammed, Y. A., Patel, S., Matthees, H. L., Lenssen, A. W., Johnson, B. L., Wells, M. S., Forcella, F., Berti, M. T., & Gesch, R. W. (2020). Soil Nitrogen in Response to Interseeded Cover Crops in Maize–Soybean Production Systems. Agronomy, 10(9), 1439. https://doi.org/10.3390/agronomy1

Figure 1A, What do the 4 curves mean? Please give more notes about that.

This comment has been addressed; figure legend has been updated to identify missing information.

Figures 4, Please keep the width of the upper and lower rows the same,and reduce the space between figures.

This comment has been addressed; Figure 4 has been reformatted.

Tables:

Table 3, please change the unit of P to mg/g.

This comment has been addressed.

 

Reviewer 2 Report

1. Please mark the geographical coordinates of the experimental area, i.e. …°, N, …°…`W)

2. Please use SI units correctly (unit ha² does not exist, it has to be m² or ha).

3. Figure 1(A) is difficult to understand. The temperature indicators could be a solid line and the precipitation indicators could be a dashed line (precipitation indicators are expressed in mm in the Si system). Please include the average annual precipitation and average annual temperature of the test area. Whether the test years were normal in terms of weather or not?

 

4. What does it mean if the amount of precipitation is, for example, -25 cm?

5. You sowed the different cereals in the experiment with the same seeding rate, i.e. 109 kg ha^-1. Since these cereals have very different 1000 kernels wweight, the number of germinated seeds per m² is also very different. Therefore, it is incorrect to compare the biomasses and heights, also removed N and P amounts of different cereals if their number of grains per unit area is diferent. What was the seeding rate of these diferent cereals in the experiment?

6. What was the dry matter content of the manure and how much N and P was transferred to the soil with the manure? Or was it slurry?

 

 

Author Response

REVIEWER 2:

1. Please mark the geographical coordinates of the experimental area, i.e. …°, N, …°…`W)

This experiment was conducted on a private farm, for which it is not appropriate to provide the coordinates. The county name has been added to provide a more detail understanding of the location.

2. Please use SI units correctly (unit ha²does not exist, it has to be m²or ha).

This comment has been addressed.

3. Figure 1(A) is difficult to understand. The temperature indicators could be a solid line and the precipitation indicators could be a dashed line (precipitation indicators are expressed in mm in the Si system). Please include the average annual precipitation and average annual temperature of the test area. Whether the test years were normal in terms of weather or not?

This comment has been addressed. Precipitation indicators have been adjusted and are now expressed in mm. We believe the confusion was because the previous version had the legend cut off, which we have corrected. We believe this should rectify the lack of clarity.

The average values were added in text to the methods section. In addition, the climatic variation has been incorporated into the discussion of species differences. Thank you for this suggestion.

4. What does it mean if the amount of precipitation is, for example, -25 cm?

This error has been addressed.

5. You sowed the different cereals in the experiment with the same seeding rate, i.e. 109 kg ha^-1. Since these cereals have very different 1000 kernels wweight, the number of germinated seeds per m²is also very different. Therefore, it is incorrect to compare the biomasses and heights, also removed N and P amounts of different cereals if their number of grains per unit area is diferent. What was the seeding rate of these diferent cereals in the experiment?

We do not agree with this comment. These plants are seeded at a recommended rate and are in alignment with standard agronomic practices. In addition, there was no discernable difference in stand establishment. While a population based approach is appropriate for some studies, it is not appropriate for this study. In addition, these cereals can have different 1000 kernel weight, but that is not a universal statement. This study asks questions about how an agronomic system performs when managed in accordance with existing recommendations, and this study has addressed this question.

6. What was the dry matter content of the manure and how much N and P was transferred to the soil with the manure? Or was it slurry?

This comment has been addressed. The N and P content of the manure has been added to the experimental design. The material is slurry, as indicated by the units in liters. To improve clarity of the material, a note has been added to the methods indicating the manure was applied as slurry.

Round 2

Reviewer 1 Report

Line 10: Please change the sentence to “A two-year field experiment with five small grain winter cover crops (rye (Secale cereale), wheat (Triticum aestivum), and three triticale (×Triticosecale) varieties) was conducted on an active dairy farm.”

 Line 22, pleased add “on average”

 For the abstract, if we make appropriate recommendations based on the results of the article, such as which cover crops are most suitable for planting in general, this will provide effective guidance to growers.

Author Response

Reviewer 1 (second round)

1- Line 10 was changed according to the suggested sentence.

2- The abstract changed and now includes the overall results of the experiment.

Reviewer 

Reviewer 2 Report

Please correct in line 114: P level I assume should be ...mg/g ( not g/mg).

Author Response

Reviewer 2 (second round)

the unit of p level was changed to mg/g