Impact of Pre-Plant Fertilizer Rates in Combination with Polysulphate^® on Soil Nitrogen Distribution and Yield of Short-Day Strawberries (Fragaria × ananassa cv. Camarosa)

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

I have read this manuscript submitted in Agronomy. In this study, field trials to assess the impact of reducing nitrogen (N) in pre-plant fertilizers on strawberry yields and quality were conducted. The authors experimented with various N rates across two seasons in North Carolina (USA) and suggested that N content in pre-plant fertilizers could be reduced by up to 50% without negatively affecting short-day strawberry cultivars.

I provide the comments and questions as follows, which in my opinion deserve due attention:

1. Throughout the manuscript, I recommend that the authors provide better clarification to readers about the country where the research was conducted. For example, “Southeast” and “North Carolina” are mentioned several times without explicitly mentioning the country.

2. Both in the abstract and in the introduction as well as in the discussion, I recommend improving the global contextualization (instead of a local focus) for the current research topic.

3. The abstract, introduction, and discussion should provide more information about the global socioeconomic potential of the plant species in focus.

4. I recommend that the abstract provide more details of the obtained results, to better balance the amount of methodological information.

5. For a complete article, the list of references is very short. It could be expanded by citing recent articles on the subject as well as citing more comparative articles in the discussion.

6. The title may create expectations for readers by mentioning the word “physiology”. In a physiological context, it is expected that the authors incorporate and provide molecular and biochemical analyses (which includes analyses related to plant hormones). Therefore, I recommend that the authors incorporate more analyses as mentioned, and include perspectives for physiological analyses in future studies in the discussion.

Author Response

1. Throughout the manuscript, I recommend that the authors provide better clarification to readers about the country where the research was conducted. For example, “Southeast” and “North Carolina” are mentioned several times without explicitly mentioning the country.

We mention the country (US) now in several locations throughout the paper.

2. Both in the abstract and in the introduction as well as in the discussion, I recommend improving the global contextualization (instead of a local focus) for the current research topic.

We added some more general discussion points in abstract, discussion and conclusions. However, a global perspective will be difficult to establish, since every production system is different. What we found for the Southeast might not be true for another production system let’s say in Florida or California.

3. The abstract, introduction, and discussion should provide more information about the global socioeconomic potential of the plant species in focus.

Thanks for the suggestion. We added some economic perspective to the abstract and the introduction. Since this is a pre-plant fertilizer study in a very specific region, it is impossible to estimate a global perspective without further studies and models.

4. I recommend that the abstract provide more details of the obtained results, to better balance the amount of methodological information.

We added a sentence to the results in the abstract.

5. For a complete article, the list of references is very short. It could be expanded by citing recent articles on the subject as well as citing more comparative articles in the discussion.

Agreed. The student left without finishing the paper, and we added a few references that we felt are somewhat relevant. We also significantly changed the discussion. While not putting it into a socio-economic context, we have put it more into a US-wide strawberry production content.

6. The title may create expectations for readers by mentioning the word “physiology”. In a physiological context, it is expected that the authors incorporate and provide molecular and biochemical analyses (which includes analyses related to plant hormones). Therefore, I recommend that the authors incorporate more analyses as mentioned, and include perspectives for physiological analyses in future studies in the discussion.

We changed the title.

Reviewer 2 Report

Comments and Suggestions for Authors

Review of the manuscript Agronomy-2935584

My main comments are related to the section "Materials and methods"

1.      The design of the experiment is not clearly shown. A detailed revision is required. It is better to present the scheme of the experiment in the Figure form.  I have doubts about the correctness of the experiment.

2.      Why were tissue samples taken 2 times during the season in 2019-2020, and 4 times in 2020-2021 (Lines 161-163)? There is no principle of a single distinction between the experiments. How many biological and analytical repetitions of plant tissue samples were used for laboratory experiments? It is not clear for me.

3.      How reasonably can we talk about the effect of fertilizers on productivity as an agrochemical element for 1 growing season? The authors will not be able to estimate the variation of the trait over the years of the studies. For visual gradation of the commercial quality of berries, a percentage scale or a scale in points is necessary. The authors do not have it. This raises doubts about the assessment of product quality.

4.       How comparable are the data on the chemical composition of berries in frozen and fresh samples? When frozen, some of the qualitative characteristics of the berries are lost.

5.      Why did the authors not provide data on the agrochemical characteristics of 2 soil plots before fertilization?

The results are very contradictory and do not show a clear effect of Polysulfate® on soil agrochemistry over the years of the studies, as well as on the chemical composition of berries. In a number of reports, it has been proven that fertilization does not affect the chemical composition of fruits, weather conditions are an important factor. There is no novelty in this section of the studies.

6.      The "Conclusion" section does not make references to the list of sources. And this section also requires a thorough revision.

I think that the authors need to analyze the data carefully again, taking into account the edits in the design of the experiment, and present the main sections of the manuscript in a new interpretation.

Author Response

1. The design of the experiment is not clearly shown. A detailed revision is required. It is better to present the scheme of the experiment in the Figure form.  I have doubts about the correctness of the experiment.

We added language to the Material and Methods part to make the experimental design more clear. I don’t know what the reviewer means with ‘correctness’, so I can’t reply to that. I’d recommend to the reviewer to use more constructive language in future reviews.

2. Why were tissue samples taken 2 times during the season in 2019-2020, and 4 times in 2020-2021 (Lines 161-163)? There is no principle of a single distinction between the experiments. How many biological and analytical repetitions of plant tissue samples were used for laboratory experiments? It is not clear for me.

A cold weather event has restricted plant growth more than normal, and it was not warranted to take additional tissue samples due to reduced plant size early season. Once plants grew again, University wide Covid-19 restrictions prohibited us from entering the research farms. We added the explanation to the text body. We sampled 30 petioles per treatment.

3. How reasonably can we talk about the effect of fertilizers on productivity as an agrochemical element for 1 growing season? The authors will not be able to estimate the variation of the trait over the years of the studies. For visual gradation of the commercial quality of berries, a percentage scale or a scale in points is necessary. The authors do not have it. This raises doubts about the assessment of product quality.

I would agree with this statement if we would work in a perennial system. But strawberries are grown in annual systems. Pre-plant fertilizer is applied every year before hilling up and laying the plastic mulch. Strawberries in the US (and for that matter in most of the world) are not grown as a perennial crop. We added clarifying language to abstract, introduction and discussion.

Visual graduation of strawberries into marketable and non-marketable berries are based on industry wide adopted USDA-Standards. We cited the source in M&M.

4. How comparable are the data on the chemical composition of berries in frozen and fresh samples? When frozen, some of the qualitative characteristics of the berries are lost.

We do not compare fresh vs. frozen chemical composition anywhere, nor do we claim that frozen and fresh samples do have the same properties. All samples were processes in a similar way, as outlined in the M&M.

5. Why did the authors not provide data on the agrochemical characteristics of 2 soil plots before fertilization?

The results are very contradictory and do not show a clear effect of Polysulfate® on soil agrochemistry over the years of the studies, as well as on the chemical composition of berries. In a number of reports, it has been proven that fertilization does not affect the chemical composition of fruits, weather conditions are an important factor. There is no novelty in this section of the studies.

We added quite some language to the discussion part to point out the importance of this study and the context in which this study adds to the existing body of knowledge.

6. The "Conclusion" section does not make references to the list of sources. And this section also requires a thorough revision.

We completely revised the conclusion section.

I think that the authors need to analyze the data carefully again, taking into account the edits in the design of the experiment, and present the main sections of the manuscript in a new interpretation.

We have made substantial changes to abstract, discussion and conclusion of the document that will clarify most of the reviewers questions.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

I have no more comments.

Reviewer 2 Report

Comments and Suggestions for Authors

The authors paid close attention to the reviewers' feedback, so the publication can be accepted.