Weed Control and Soybean (Glycine max (L.) Merr) Response to Mixtures of a Blended Foliar Fertilizer and Postemergence Herbicides

Round 1

Reviewer 1 Report

1. The authors conducted two studies, in which they used a blended foliar fertilizer that was mixed with POST herbicides in soybean. In the first one (Weed control study), they evaluated weed control and soybean injury. In the second one (Agronomic study), they evaluated soybean response (growth and yield). It is not clear what was the reason to make these two separate studies. It would be more meaningful if they presented agronomic results and in the first study and then compared the data with the second study. In Table 2 they present soybean height and Yield, but is undefined if these results are from the weed or the agronomic study. The authors should make it clear and present in a simple and understandable way their results.
2. In general, the second study it is not efficiently conducted and presented in the Article. For example, in 2015 the soybean variety (Pioneer 48T53) that was used, was different compared to 2016 (Asgrow 4632), and this reduces the reliability of the experimental design. The variety is a factor of variability. Moreover, the authors in lines 146-150 say that they performed tissue analysis and the results are not presented (line 222). This part could be removed, as it is not providing any useful information. In addition, Table 6 that describes the results of the Agronomic study are missing from the manuscript.
3. The authors should provide in details the methodology they used to estimate the percentage of control of the weeds and soybean injury. The information that they provide is not sufficient and it degrades the reliability and the accuracy of the measurements that were taken.
4. In the Results of the Agronomic study, in lines 212-222 the authors present results concerning the soybean injury, while at the aims of this study they mention that they evaluated soybean response (growth and yield).
5. Introduction is too short and is not providing sufficiently the current state of the research field, mainly in the final three paragraphs.
6. The aim of the study is not described clearly.
7. The title of the Article is general and is not providing important information It should be changed to give some specific information.
8. The word “POST” should be changed to “postemergence” in the title.
9. In lines 6 to 14 the word “Affiliation” should be removed.
10. The binomial name of weed species should be mentioned in the abstract.
11. The abstract should be revised to include more solid information. For example, the sentence “Seven antagonistic effects were detected for both weed species regardless of herbicide treatment or foliar fertilizer rate” is not describing an important result.
12. Keywords need a revision to cover the subject of the Article.
13. Why did the authors select this specific foliar fertilizer? The absence of P and K in this fertilizer is supported by a soil analysis that indicated sufficient quantity of these elements?
14. In line 116 it should be changed to 13% as it is written in line 152.
15. In line 149 “HNO3” and “H2O2” should change to “HNO₃” and “H₂O₂”
16. In Tables 3 and 4, the authors should provide the equation for the expected values, or if the values are just the values of the control to mention them as control.

Author Response

Reviewer 1

1. The authors conducted two studies, in which they used a blended foliar fertilizer that was mixed with POST herbicides in soybean. In the first one (Weed control study), they evaluated weed control and soybean injury. In the second one (Agronomic study), they evaluated soybean response (growth and yield). It is not clear what was the reason to make these two separate studies. It would be more meaningful if they presented agronomic results and in the first study and then compared the data with the second study. In Table 2 they present soybean height and Yield, but is undefined if these results are from the weed or the agronomic study. The title of table 2 states all parameters within this table are for the Weed Control Study. The authors should make it clear and present in a simple and understandable way their results.
   

In the authors’ experience, it is difficult to truly evaluate agronomic response in a weed control study due to complications from early-season weed interference compromising yield. Although soybean height 14 d after treatment application and at maturity along with yield are presented from the weed control study, these data simply complement the soybean injury and weed control data collected in that study. The agronomic study was conducted as a companion study to the weed control study in order to capture the influence of the treatments in the absence of weed interference. The authors felt that it was inappropriate to compare agronomic parameters between the studies since one included weeds and one did not.

The title of Table 2 clearly states that data are presented from the Weed Control Study. Additionally, the Materials and Methods outlines which parameters were measured for each study.

1. In general, the second study it is not efficiently conducted and presented in the Article. For example, in 2015 the soybean variety (Pioneer 48T53) that was used, was different compared to 2016 (Asgrow 4632), and this reduces the reliability of the experimental design. The variety is a factor of variability. Variety is not technically a factor if data are pooled across variety and presented in that way.

Moreover, the authors in lines 146-150 say that they performed tissue analysis and the results are not presented (line 222). This part could be removed, as it is not providing any useful information. In addition, Table 6 that describes the results of the Agronomic study are missing from the manuscript.

Table 6 has been added to the document. It was left out accidentally during formatting.

The comment provides no insight into the perceived deficiency of the study with the exception of suggesting that soybean cultivar should be a factor in the analyses. By treating siteyear as a random effect, soybean cultivar becomes a random effect. This broadens the potential inferences from the data. Tissue analyses were performed as clearly described in the Materials and Methods. The statement that all tissue concentrations fell within the sufficiency range is “not providing any useful information” is a matter of opinion. The authors feel that negative data is important and can inform decisions at the manufacturing and farm level.

1. The authors should provide in details the methodology they used to estimate the percentage of control of the weeds and soybean injury. The information that they provide is not sufficient and it degrades the reliability and the accuracy of the measurements that were taken. The weed control and soybean injury data are sufficient, accurate, and reliable and have been cited utilized in weed science literature for many years and are a scientifically accepted method of data collection.
2. In the Results of the Agronomic study, in lines 212-222 the authors present results concerning the soybean injury, while at the aims of this study they mention that they evaluated soybean response (growth and yield).

Soybean injury is a form of soybean response. Literature on crop response to herbicide treatments that includes crop injury as well as yield is extensive. Crop injury could be severe and yield reduced substantially. Therefore, the authors feel that soybean injury was an important component of the soybean response to the treatments evaluated in the current research.

1. Introduction is too short and is not providing sufficiently the current state of the research field, mainly in the final three paragraphs.

The statement that the “Introduction is too short and is not providing sufficiently the current state of the research field” is merely a statement of opinion. It does not contain a constructive suggestion for how the reviewer would like the Introduction to be improved. The authors feel that the Introduction adequately covers the treatments of interest, weed species of interest, foliar fertilizers, and possible interactions when products are mixed and applied in a single application.

1. The aim of the study is not described clearly.

Lines 75-84 state the aim/objective/justification of the two studies conducted. The authors are unclear on the distinction between “aim of the study” and justification for the research.

1. The title of the Article is general and is not providing important information It should be changed to give some specific information.

The authors are willing to work with the reviewers if there is a suggestion on key words to better cover the subject. However, currently the authors feel that the keywords cover the subject of the article.

1. The word “POST” should be changed to “postemergence” in the title. corrected in text
2. In lines 6 to 14 the word “Affiliation” should be removed. corrected in text
3. The binomial name of weed species should be mentioned in the abstract. corrected in text
4. The abstract should be revised to include more solid information. For example, the sentence “Seven antagonistic effects were detected for both weed species regardless of herbicide treatment or foliar fertilizer rate” is not describing an important result.

As with other comments, the comment “not describing an important result” is an opinion. The abstract should highlight the research conducted and illicit interest in the reader for reading more of the manuscript. This was the authors’ intent with statements such as those highlighted in this comment.

1. Keywords need a revision to cover the subject of the Article.

The authors are willing to work with the reviewers if there is a suggestion on key words to better cover the subject. However, currently the authors feel that the keywords cover the subject of the article.

1. Why did the authors select this specific foliar fertilizer? The absence of P and K in this fertilizer is supported by a soil analysis that indicated sufficient quantity of these elements?

P and K were applied at 60 lbs P2O5 and 80 lbs K2O to the entire plot are to ensure these nutrients were not yield limiting. We apologize theses were not included in the M&M.

1. In line 116 it should be changed to 13% as it is written in line 152. Location of these line numbers mentioned do not correspond with a number or percentage.
2. In line 149 “HNO3” and “H2O2” should change to “HNO₃” and “H₂O₂” corrected in text
3. In Tables 3 and 4, the authors should provide the equation for the expected values, or if the values are just the values of the control to mention them as control

References to the statistical analyses are provided in the Materials and Methods section of the manuscript. Additionally, an explanation is provided in the footnotes to the tables.

Reviewer 2 Report

This paper investigated the interaction effects of a blended foliar fertilizer with various POST herbicide applications on soybean injury and weed control as well as other agronomic traits. The results showed that the foliar fertilizer did not alleviate soybean injury from POST herbicide application nor did it improve weed control of two species. In some cases the blended foliar fertilizer reduced weed control. Thus this paper has significance for growers considering weed control options for soybean, indicating that a blended foliar fertilizer is not suitable.

The experiments were designed well and therefore I only have some minor issues to be addressed in the paper. In Table 2 a significant difference is demonstrated between the yield of the control plants and the other treatments, yet line 261 in the Discussion states that blended foliar fertilizer did not affect soybean yield. Lines 210 - 211 in the Results section states that yields from the different treatments were "similar and greater than" the yield of the control. This needs to be clarified as the text is not justified by the results in Table 2. Next, it is stated throughout the paper that the results were pooled across years and foliar fertilizer rates, yet there is no indication of why these results were pooled. It should be stated in the methodology how you tested for difference between runs and between rates. If there is no difference, this needs to be mentioned as the reason why they are pooled. If there was a difference, then pooling the results needs extra justification. The methods section should also mention how the expected values for weed control were determined.

The results section reads more like a combined results/discussion, with references included to support the results, however, a separate discussion is also included. The results section should just contain the results with the supporting statements being moved to the discussion, or else the authors should combine the results and discussion into one section.

Below are a few minor typos:

Line 68: “research reported a reduction . . .”

Line 69: “with the reduction attributed . . .”

Line 174: typo “withF”

Table 5: the alignment of the heading "foliar fertilizer rate" should be fixed.

Author Response

Reviewer 2

This paper investigated the interaction effects of a blended foliar fertilizer with various POST herbicide applications on soybean injury and weed control as well as other agronomic traits. The results showed that the foliar fertilizer did not alleviate soybean injury from POST herbicide application nor did it improve weed control of two species. In some cases the blended foliar fertilizer reduced weed control. Thus this paper has significance for growers considering weed control options for soybean, indicating that a blended foliar fertilizer is not suitable.

The experiments were designed well and therefore I only have some minor issues to be addressed in the paper. In Table 2 a significant difference is demonstrated between the yield of the control plants and the other treatments, yet line 261 in the Discussion states that blended foliar fertilizer did not affect soybean yield.

Table 2 presents data from the weed control study. Yield differences there were between the plots receiving no herbicide and plots treated with herbicide. That is to be expected given the nature of weed interference referenced earlier. Line 261 in the original submission references the Agronomic Study.

Lines 210 - 211 in the Results section states that yields from the different treatments were "similar and greater than" the yield of the control. This needs to be clarified as the text is not justified by the results in Table 2.

See previous response. Comment is referring to two different studies.

Next, it is stated throughout the paper that the results were pooled across years and foliar fertilizer rates, yet there is no indication of why these results were pooled. It should be stated in the methodology how you tested for difference between runs and between rates. If there is no difference, this needs to be mentioned as the reason why they are pooled. If there was a difference, then pooling the results needs extra justification. The methods section should also mention how the expected values for weed control were determined.

Lines 116-128 in the original submission describe the statistical analysis and treating year as a random effect. The results section states when there were main effects and no interactions. The factorial treatment arrangement allows data to be pooled over levels of a factor when there is no interaction between the factors.

The results section reads more like a combined results/discussion, with references included to support the results, however, a separate discussion is also included. The results section should just contain the results with the supporting statements being moved to the discussion, or else the authors should combine the results and discussion into one section.

The authors’ feel this is personal preference of the reviewer. If the journal has particular guidelines related to the organization of the Results and Discussion sections, the authors will make appropriate revisions.

Below are a few minor typos:

Line 68: “research reported a reduction . . .” corrected in text

Line 69: “with the reduction attributed . . .” corrected in text

Line 174: typo “withF” corrected in text

Table 5: the alignment of the heading "foliar fertilizer rate" should be fixed. corrected in text

Round 2

Reviewer 1 Report

1. The Agronomic study has a major drawback concerning the experimental design (use of different soybean varieties). The authors pooled the data to overcome it but this is not scientifically correct. How authors could ensure (in term of experimental design) that the genetic differences between these two genotypes were not a main cause of different results rather than the treatments used? Moreover, the use of herbicides in a field experiment in the absence of weeds in order to measure agronomic characteristics doesn't produce novel results in terms of agricultural practices. This part could be supplementary to enhance the findings of the weed control study.
2. The authors don't provide information on how the measurements of visible estimates of soybean injury and weed control were recorded. What is the scale from 0 to 100%? They were counting plants per plot or a specific area? Did they use special equipment (e.g. drones)? Are these measurements accurate?
3. Introduction is consisted of only 42 lines. It provides only superficially some information related to the topic and it is not covering sufficiently the current state of the research field.
4. The title of the article doesn’t provide sufficient information about the study that was conducted. The topic is not the interaction, but how the interaction of these products affects weed control and agronomic characteristics in soybean cultivation.
5. The keywords also need revision.

Author Response

Comments and Suggestions for Authors

The Agronomic study has a major drawback concerning the experimental design (use of different soybean varieties). The authors pooled the data to overcome it but this is not scientifically correct. How authors could ensure (in term of experimental design) that the genetic differences between these two genotypes were not a main cause of different results rather than the treatments used?

The reviewer brings up a good question about genetics, however we feel that ample steps were taken to ensure this was not an issue. Prior to pooling the data, we tested site years for differences as a fixed variable, because there were no differences among site years, we chose to pool the data via random statement. If there was a difference among the two genotypes it would have showed up in the is step. Furthermore, both cultivars were similar in Maturity and both indeterminate. Cultivar turnover in the U.S. is quite rapid (2-3 yr before phaseout), to the point that neither of the cultivars evaluated in this research are currently on the market.

Moreover, the use of herbicides in a field experiment in the absence of weeds in order to measure agronomic characteristics doesn't produce novel results in terms of agricultural practices. This part could be supplementary to enhance the findings of the weed control study.

The reviewer is misunderstanding the objective of the research. the addition of herbicides with or without foliar fertilizers in a weed free environment could very easily produce a novel result. Moreover, the reviewer is suggesting that co-application of fertilizers and herbicides could not cause an antagonist effect, thereby reducing the impact of the foliar fertilizer. In the weed control part of the study we were focused on the addition of the foliar fertilizer impact on weed control of the selected herbicides. The agronomic study in the weed free environment, we were evaluating how the herbicide could or could not influence efficacy of the foliar fertilizer.

The authors don't provide information on how the measurements of visible estimates of soybean injury and weed control were recorded. What is the scale from 0 to 100%? They were counting plants per plot or a specific area? Did they use special equipment (e.g. drones)? Are these measurements accurate?

Line 109 indicates that these measurements were taken visually according to the methodology outlined by Frans, R., Talbert, R., Marx, D. and Crowley, H. (1986) Experimental Design and Techniques for Measuring and Analyzing Plant Responses to Weed Control Practices. In: Camper, N.D., Ed., Southern Weed Science Society, Research Methods in Weed Science, 3rd Edition, WSSA, Champaign, 29-46. And numerous other publications.

Introduction is consisted of only 42 lines. It provides only superficially some information related to the topic and it is not covering sufficiently the current state of the research field.

Additional information was included

The title of the article doesn’t provide sufficient information about the study that was conducted. The topic is not the interaction, but how the interaction of these products affects weed control and agronomic characteristics in soybean cultivation. Changed in Text

The keywords also need revision. Key words were revised

From Ferry Wang Email:

Instruction for authors:

• Authority on Latin binomial should be provided after each common name the first time referred to in the text. Corrected in Text
• Number of significant digits should be based on the precision of the analytical method and round accordingly and presented for a variable should be correct and consistent.

Control, heights, and injury goes to 1; therefore, they are at the correct significant digits. The yield was taken to the nearest hundredth.

• Conclusions: This section is mandatory, should be added to the manuscript. Included in Text
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Author Response File: Author Response.docx