Effects of Fertilizer Level and Intercropping Planting Pattern with Corn on the Yield-Related Traits and Insect Community of Soybean

Round 1

Reviewer 1 Report

-          he manuscript is an important supplement the research regarding  soybean and maize,

-          the manuscript is a valuable supplement to  research carried out so far in other research centers,

-          the obtained results will be an indication for farmers dealing with  breeding ruminant  animals,

   - the results presented will be a guide to corn and soybean growers

     -  important is the conclusion that it  is:

- intercropping of corn and soybean can increase the stability of insect community and reduce the occurrence of insect pests,

- the increase of the population number of green leafhopper did not reduce soybean – yield,

- intercropping can reduce the number of pests, but it maybe not a major safeguard for soybean yield,

- corn and soybean intercropping is not conducive to the improvement of enzyme activities related to nitrogen metabolism in soybean, that is, intercropping has a negative effect on soybean yield,

- corn and soybean intercropping can reduce the occurrence of soybean pests, but this is not enough to compensate for the negative effects of intercropping on soybean yield,

- it is suggested to set the corn/soybean row ratio as 2:4 in practical field production.

-the work may be published,

Author Response

Dear reviewer,

Many thanks for your review of this manuscript. At the same time, thank you for your affirmation of this research result.

Author Response File: Author Response.docx

Reviewer 2 Report

Authors tried to investigate on effects of intercropping (corn and soybean interaction) and fertilizer aplication on soybean growth characteristics. The manuscript is well structure and with adequate information in introduction, results and discussion sections. It has potential to be poblish but there is still some points that I remarked into the file. Please find comments there.

Comments for author File: Comments.pdf

Author Response

Dear reviewer,

Thank you very much for your valuable comments on the manuscript. At the same time, thank you for your affirmation of this study. According to the question you mentioned, we have made improvements one by one, as shown below：

Comment in Line 12: Rephrase it!

Answer: This sentence has been redescribed into“However, there are few studies on the effect of intercropping and fertilizer reduction on soybean yield.”

Comment in Line 29: This is the first time that you are mention this and it's not clear what is it!

Answer: A supplementary description “C2S4 (2 corn rows with 4 rows of soybean)” is given for the first appearance of C2S4. NR (nitrate reductase) is also given for the first appearance of NR.

Comment in Line 54: Delete it!

Answer: we delete “But”.

Comment in Line 61: It would be better if you mention chemical fertilizer.

Answer: “Excessive application of nitrogen fertilizer” has been redescribed “Excessive application of chemical nitrogen fertilizer”.

Comment in Line 95: What is it? The current study should be stand by itself! A reader can't go to your other research and find experimental description for this one. It's NOT good idea. By the way, the current study is a field work. So, it certainly needs to environmental description of experimental site including weather condition and soil properties in a table. Give reader a wide view of your research site!

Answer:  Meteorological data of Jiyang area in2018 and 2019 was given in the form of graph according to the suggestion.

Comment in Line 99: It's too long paragraph which is not well described. Please split it into some sentences and clearly describe treatments again.

Answer: The test setup is redescribed to make the sentence more concise, logic more clear.

The rewording is as follows: “There were four planting patterns that including three intercropping planting patterns of corn intercropped with soybean as two corn rows to 2, 3 and 4 rows of soybean, and one sole crop planting patterns of soybean. Two fertilizer levels were set in the experiment (i.e., normal (600 kg/ha) and reduced (375 kg/ha) levels of NPK (N: P2O5: K2O=15: 15: 15) fertilizer). So there are total 4 planting patterns (P) × 2 fertilizer levels (F) = 8 treatments, completely random design, 3 repetitions.”

Comment in Line 401: Don't need to repeat this, Delete it.

Answer: we delete “In present study of soybean intercropped with corn, soybean was taken as the research object, different corn-soybean row ratios and different fertilizer levels were set up.”.

Comment in Line 471: Whole this paragraph is repeated from results section and additionally, it's NOT belong here. Merge this paragraph with results section and just consider the second paragraph as your conclusion. Also at the end of it, add one suggestion our view for future works in this area.

Answer: On the basis of this suggestion, the first paragraph of discussion was deleted. ”On the basis of resent experiment, corn and soybean varieties suitable for compound strip planting with corn should be screened to produce higher soybean seed yield.” is added as future works

Finally, we would like to express our heartfelt thanks again for your careful and responsible review of this manuscript.

Author Response File: Author Response.docx

Reviewer 3 Report

Dear Authors,

This is an interesting manuscript and has the potential to be of interest to agronomists. However, I have some suggestions and comments:

The Authors write that their aim is to assess the effect of intercropping and fertilizer reduction on the growth and yield of soybean (also in the title of the paper, the Authors indicate the soybean yield). Meanwhile, the yield was treated very superficially. Practically throughout the entire manuscript, the Authors focused primarily on the enzyme activities related to nitrogen metabolism and insect diversity. These are obviously very important issues for scientists, but farmers are interested in yields. I suggest that the manuscript focuses more on the influence of experimental factors on the yield of soybean as one of the most important plants in the world.

In my opinion, the research would be more interesting if the Authors took into account not only the yield of soybean, but also the yield of corn.

Abstract:

Lines 22 and 29: Abstract should not contain any undefined abbreviations, when abbreviations are used, they should be explained appropriately when they are used for the first time.

The introduction should include the research hypothesis.

Materials and methods:

There is no information on the forecrop, in what form mineral fertilizers were applied?

It is worth adding a brief description of the soybean variety.

Line 124: Please, specify the growth stages of soybean plants using BBCH scale.

Lines 99 – 104: In my opinion the sentence describing experimental factors is too long and improperly constructed (very complicated) – this should be explained more clearly.

Lines 111-112: “the planting cultivation was adopted as the same field management measures in local fields” - What this means? Readers are unfamiliar with field management measures in the local fields. There is little information about agrotechnical side of this experiment.

Lines 112-114: it would be better to mention the active substances of the plant protection products instead of the trade names.

It would be interesting to answer the question whether it is justified to reduce the level of fertilization in the conditions of using inter-row soybean cultivation? Unfortunately, the Authors of the article do not refer to interactions at all? They describe separately the effect of fertilization and the effect of intercropping planting pattern. It does not make sense to describe the influence of individual experimental factors on the individual examined features, especially when a statistically significant interaction between them has been demonstrated.

The Authors use the names intercropping planting pattern and monoculture interchangeably. It is rather not appropriate. Monoculture has a slightly different definition. In this experiment, it is difficult to talk about soybean monoculture.

Discussion:

4.3. What about fertilizers? The authors only refer to the intercropping planting pattern, there is practically nothing about the second experimental factor.

Conclusions:

Conclusions should not be a duplicate of the test results. Providing too much detailed information in this chapter is difficult to read. Conclusions should contain general statements resulting from the conducted experiment and should give a specific answer to the research hypothesis. Recommendations for farming practice should also be provided.

Author Response

Review 3

Dear Authors,

Comments：This is an interesting manuscript and has the potential to be of interest to agronomists. However, I have some suggestions and comments:

The Authors write that their aim is to assess the effect of intercropping and fertilizer reduction on the growth and yield of soybean (also in the title of the paper, the Authors indicate the soybean yield). Meanwhile, the yield was treated very superficially. Practically throughout the entire manuscript, the Authors focused primarily on the enzyme activities related to nitrogen metabolism and insect diversity. These are obviously very important issues for scientists, but farmers are interested in yields. I suggest that the manuscript focuses more on the influence of experimental factors on the yield of soybean as one of the most important plants in the world.

In my opinion, the research would be more interesting if the Authors took into account not only the yield of soybean, but also the yield of corn.

Answer: The research content of this paper involves 100 seed weight, biomass, yield and the enzyme activities related to nitrogen metabolism. But it would be too long to put all of them in the title, so I changed it to yield related traits.

The effects of several intercropping types and patterns on the yield of corn have been published and are cited in our discussion as a supplement. “The grain weight per plant and grain yield of corn intercropped with soybean were significantly increased with the increase of the row ratio of soybean even under reduced fertilizer application [39].”

Comments：Abstract:

Lines 22 and 29: Abstract should not contain any undefined abbreviations, when abbreviations are used, they should be explained appropriately when they are used for the first time.

Answer: A supplementary description “C2S4 (2 corn rows with 4 rows of soybean)” is given for the first appearance of C2S4. NR (nitrate reductase) is also given for the first appearance of NR.

Comments：The introduction should include the research hypothesis.

Answer: We have added the relevant content in the introduction. “It was assumed that the yield and insect community of soybean would be affected by intercropping mode with corn and fertilizer reduction, and the nitrogen-fixing capacity of soybean maybe reduce the impact of fertilizer reduction on seed yield itself.” have been added the tail of introduction.

Comments：Materials and methods:

Much information is missing in this chapter. In field conditions, the plant is influenced by agroecological factors. The characteristics of soil type (soil condition) should be provided - origin, geological structure, granulometric composition, etc. If, in the experiment, the influence of different levels of mineral fertilization on the yielding of plants was assessed, it seems reasonable to specify the content of nutrients in the soil. As soybean was cultivated under field conditions, information about air

Answer: Soybean was cultivated under field conditions, information about air temperature and rainfall is important (giving the reference [36] is not enough). temperature and rainfall is important. So it's given in the form of a graph.

Comments：There is no information on the forecrop, in what form mineral fertilizers were applied?

It is worth adding a brief description of the soybean variety.

Answer: We added information on the forecrop, “The forecrop is winter wheat, the same variety and planting pattern with unified management of water and fertilizer was applied.”. We added also a brief description of the soybean variety, “This variety has high quality, good taste, high oil and high protein.”.

Comments：Line 124: Please, specify the growth stages of soybean plants using BBCH scale.

Answer: In biology, the BBCH-scale for maize describes the phonological development of maize using the BBCH-scale. But in soybean, researchers widely use the description of norms in [38].     i.e. Fehr, W.R., Caviness, C.E., Burmood, D.T., Pennington, J.S. Stage of development descriptions for soybeans, Glycine max (L) merrill. Crop Science. 1971, 11, 929.

Comments：Lines 99 – 104: In my opinion the sentence describing experimental factors is too long and improperly constructed (very complicated) – this should be explained more clearly.

  Line 102: Please, change the oxygen forms of P and K for pure nutrients of P and K; which form of N have been used? On what basis did you determine the doses of mineral fertilizers? Why do you write that 600 kg is normal level? We don't know anything about the fertility of the soil, we don't even know what kind of soil it is.

Answer: We have added kind of soil, and supplemented in the form of fertilizer. “The soil type in this area is mud-silt sand white soil, which belongs to tidal sand soil, and the cultivated layer is about 20 cm. The soil PH was 7.96, and the basic fertility parameters were total carbon 0.67g/kg, total nitrogen 0.76g/kg, available phosphorus 28.97mg/kg, available potassium 99.84 mg/kg, and organic carbon 6.63 g/kg.” We have reorganized the description of this part in chapter “2.2. Experimental design and field management”. Make the sentence more concise, logic more clear.

Comments：Lines 111-112: “the planting cultivation was adopted as the same field management measures in local fields” - What this means? Readers are unfamiliar with field management measures in the local fields. There is little information about agrotechnical side of this experiment.

Answer: We add a brief description of agrotechnical side this experiment according to the suggestion. “Before sowing, apply the compound fertilizer to the field while plowing the soil.” was added into the part of “Experimental design and field management”.

Comments：Lines 112-114: it would be better to mention the active substances of the plant protection products instead of the trade names.

Answer: We mention the active substances of the plant protection products according to the suggestion. one time spraying of herbicides before planting, acetochlor (Lasso provided by the Monsanto Company) and atrazine (Clethodim provided by the Chevron Phillips Chemical Company LP) for corn  and soybean, respectively.

Comments：It would be interesting to answer the question whether it is justified to reduce the level of fertilization in the conditions of using inter-row soybean cultivation? Unfortunately, the Authors of the article do not refer to interactions at all? They describe separately the effect of fertilization and the effect of intercropping planting pattern. It does not make sense to describe the influence of individual experimental factors on the individual examined features, especially when a statistically significant interaction between them has been demonstrated.

In addition, the authors included years of the study in the experimental design. Meanwhile, in the manuscript they do not refer to weather conditions at all (tables 1, 3, 5, 6 confirm the significant influence of years on the examined features).

Answer: There was significant interaction between fertilizer and intercropping only in biomass per plant and 100-seed weight in tables 1, 3, 5, 6. And the significance of the interaction is small compared with the difference between the single factor levels, while other most indicators do not have significant interaction between the two factor. So this article describes separately the effect of fertilization and the effect of intercropping planting pattern. According to this comments in Materials and methods, information about air temperature and rainfall is given in the form of a graph and the source of the data is given.

Comments：The Authors use the names intercropping planting pattern and monoculture interchangeably. It is rather not appropriate. Monoculture has a slightly different definition. In this experiment, it is difficult to talk about soybean monoculture.

Answer: Yes, in present experiment, it is difficult to talk about soybean monoculture.  We replaced monoculture with sole crop soybean.

Comments：Discussion:

4.3. What about fertilizers? The authors only refer to the intercropping planting pattern, there is practically nothing about the second experimental factor.

Answer: We add a discussion of the effect of fertilizer levels on soybean yield. Add a reference to soybean as a nitrogen fixing crop according to the suggestion.

Comments：Conclusions:

Conclusions should not be a duplicate of the test results. Providing too much detailed information in this chapter is difficult to read. Conclusions should contain general statements resulting from the conducted experiment and should give a specific answer to the research hypothesis. Recommendations for farming practice should also be provided.

Answer: The first paragraph of discussion has been deleted. ”On the basis of present experiment, corn and soybean varieties suitable for compound strip planting with corn should be screened to produce higher soybean seed yield.” is added as future works.

Finally, we would like to express our heartfelt thanks again for your careful and responsible review of this manuscript.

Author Response File: Author Response.docx

Reviewer 4 Report

Dear Authors,

In my opinion, the manuscript presents interesting research results and is well written. However, I have some comments, mainly of an editorial nature, which could easily be corrected.

Specific comments:

- (L 13-14) “In present study, corn and soybean were interplant in 2:2, 2:3 and 2:4 under different fertilizer levels (normal: 600 kg/ha VS reduced: 375 kg/ha) - this sentence should be reworded. It is only in chapter “2.2. Experimental design and field management” the reader learns that "There were four planting patterns (including three intercropping planting patterns of corn intercropped with soybean as two corn rows to 2, 3 and 4 rows of soybean, and one sole crop planting patterns of soybean), and two fertilizer levels (i.e., normal (600 kg/ha) and reduced (375 kg/ha) levels of NPK (N: P2O5: K2O=15: 15: 15) fertilizer ..." .

- (L 155-157) Please also explain the "H" for Pielou evenness index.

- I suggest significantly shortening the Conclusion chapter. The authors present the results of the study here, which are valuable, but should be presented in the Results or Discussion chapters.

- (L 537) Error in the name of the journal.

Author Response

Dear reviewer,

Comment: In my opinion, the manuscript presents interesting research results and is well written. However, I have some comments, mainly of an editorial nature, which could easily be corrected.

Answer: Thank you very much for your valuable comments on the manuscript. At the same time, thank you for your affirmation of this study. According to the question you mentioned, we have made improvements one by one, as shown below：

Comment:- (L 13-14) “In present study, corn and soybean were interplant in 2:2, 2:3 and 2:4 under different fertilizer levels (normal: 600 kg/ha VS reduced: 375 kg/ha) - this sentence should be reworded. It is only in chapter “2.2. Experimental design and field management” the reader learns that "There were four planting patterns (including three intercropping planting patterns of corn intercropped with soybean as two corn rows to 2, 3 and 4 rows of soybean, and one sole crop planting patterns of soybean), and two fertilizer levels (i.e., normal (600 kg/ha) and reduced (375 kg/ha) levels of NPK (N: P2O5: K2O=15: 15: 15) fertilizer ..."

Answer: We have reorganized the description of this part in chapter “2.2. Experimental design and field management” and “Abstract”. Make the sentence more concise, logic more clear. The rewording is as follows: “There were four planting patterns that including three intercropping planting patterns of corn intercropped with soybean as two corn rows to 2, 3 and 4 rows of soybean, and one sole crop planting patterns of soybean. Two fertilizer levels were set in the experiment (i.e., normal (600 kg/ha) and reduced (375 kg/ha) levels of NPK (N: P2O5: K2O=15: 15: 15) fertilizer). So there are total 4 planting patterns (P) × 2 fertilizer levels (F) = 8 treatments, completely random design, 3 repetitions.”

Comment:- (L 155-157) Please also explain the "H" for Pielou evenness index.

Answer: We have added a supplementary explanation for H after these formulas.

Comment:- I suggest significantly shortening the Conclusion chapter. The authors present the results of the study here, which are valuable, but should be presented in the Results or Discussion chapters.

Answer: The first paragraph of discussion has been deleted. ”On the basis of resent experiment, corn and soybean varieties suitable for compound strip planting with corn should be screened to produce higher soybean seed yield.” is added as future works.

Comment:- (L 537) Error in the name of the journal.

Answer: Thanks for your careful inspection. We completed the correction for the error.

Finally, we would like to express our heartfelt thanks again for your careful and responsible review of this manuscript.

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

Dear Authors,

 Thank you very much for submitting your revised manuscript. Some of my comments were taken into account by the Authors, but I still have some doubts (below). 

When you intercrop soybeans with maize, the end result is not only soybean yield but also the yield of maize. If this species was included in the experiment, it is worth adding corn yields, which can be treated as additional profit from intercropping planting pattern.

 The hypothesis should be added before the aim of the study.

 As I wrote previously, weather conditions significantly affect the growth and development of crops. The authors confirmed this in their research (Tables 1, 3, 5, 6), pointing to the significant influence of years on biomass per plant, glutamate synthetase, nitrate reductase, species number of insects, Shannon-Wiever index, Simpson dominate index, Pielou evenness index, Greenhouse whitefly, Green leafhopper, Bean bug, Asiatic migratory Locust, Common cutworm , Beet armyworm  as well as on Bean bumo night moth. However, in the description of the research results, the authors do not refer to the years of research at all. The weather conditions were not even described, only figures illustrating temperature and precipitation were added (the figures show that the weather varied significantly over the years of the study).

Unfortunately, it is still unknown on what basis the authors established the doses of mineral fertilization.

Author Response

Comments：When you intercrop soybeans with maize, the end result is not only soybean yield but also the yield of maize. If this species was included in the experiment, it is worth adding corn yields, which can be treated as additional profit from intercropping planting pattern.

Answer: Adding corn yields are indeed a more meaningful result. However, the results have been published before ([39]). i.e. “39.   Li, L., Zou, Y., Wang, Y., Chen, F., Xing, G. Effects of corn intercropping with soybean/peanut/millet on the biomass and yield of corn under fertilizer reduction. Agriculture. 2022, 12, 151.”

  So, this article focuses on the effects of intercropping on soybeans, corn yields cannot be used in this manuscript, but they have been further cited and discussed in the discussion section. We added to the discussion section an overall discussion about the yields of the two crops. It also expresses what you said in your comments.

Comments：The hypothesis should be added before the aim of the study.

Answer: The test hypothesis has been shifted according to the comments. Put it ahead of the aim of the study.

Comments：As I wrote previously, weather conditions significantly affect the growth and development of crops. The authors confirmed this in their research (Tables 1, 3, 5, 6), pointing to the significant influence of years on biomass per plant, glutamate synthetase, nitrate reductase, species number of insects, Shannon-Wiever index, Simpson dominate index, Pielou evenness index, Greenhouse whitefly, Green leafhopper, Bean bug, Asiatic migratory Locust, Common cutworm , Beet armywormas well as on Bean bumo night moth. However, in the description of the research results, the authors do not refer to the years of research at all. The weather conditions were not even described, only figures illustrating temperature and precipitation were added (the figures show that the weather varied significantly over the years of the study).

Answer: Based on the comments, we have described the weather conditions and combined the results with weather conditions in each part of the results. It reflects the influence of different weather conditions on the test results in different years. In addition, we added a new discussion in the discussion section based on relevant results.

Comments：Unfortunately, it is still unknown on what basis the authors established the doses of mineral fertilization.

Answer: As described by the author, the aim of present research is to find more reasonable planting patterns and fertilizer level for local farmers. The normal fertilizer level used in present experiment was based on the fertilizer levels applied by local farmers when growing their crops, and this is also a recommendation from the local agricultural department. On this basis, we set the treatment mode of fertilizer halved to explore more rational ways of application of fertilizer. “The normal fertilizer level used in present study was based on the fertilizer levels applied by local farmers when growing their crops.” is added into 2.2. Experimental design and field management.

Finally, we would like to express our heartfelt thanks again for your careful and responsible review of this manuscript.

Author Response File: Author Response.docx