Effects of Intercropping, Nitrogen Fertilization and Corn Plant Density on Yield, Crude Protein Accumulation and Ensiling Characteristics of Silage Corn Interseeded into Alfalfa Stand
Christian Huyghe
Round 1
Reviewer 1 Report
The manuscript presents the results of an interesting experiment that have great practical and application value. In my opinion, the experiment was planned and carried out correctly. Manuscript is well written, the methods are clearly described. The results are presented briefly and comprehensively. I have only minor editorial remarks:
Line [36] [41] - Latin names should be italicized
Line [123] – 22.5 kg ha-1 (insert a space)
Line [142] - remove a space (65 °C) or insert a space (48h)
Line [161] – m3
Figures 1 and 2 are hardly legible, they should be enlarged
Author Response
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Reviewer 2 Report
The topic is of high interest for the scientific community. All the study is related to the changes in Land Equivalent Ratio (in DM, protein production, digestible energy,...) as a consequence of intercropping.
The experimental design is appropriate. The protocol for analysis of the silage quality is good, all indicators are appropriate.
There are missing issues and points to be discussed
- the alfalfa-corn intercropping starts with alfalfa being sown before corn and with a first harvest of hay of alfalfa. No information is given on this harvest. Even though the FM and DM volumes are limited, this hay harvest is a contribution to the Land Equivalent Ratio.
- Little information is available on the density of the alfalfa swards. What do they look like after one and two years of corn production? How many plants per m2?
- It can be understood that the alfalfa-corn mixtures combined corn density and N fertilisation level, and that the control corn is the standard practice for the farmers. But density and N fertilisation of the pure corn never meet the corn mixtures. For instance N is 112 kg vs 120 for the mixtures.
- There is no discussion related to the effect of the varieties of corn and alfalfa used in this study. Would this have a possible effect on the results of the study.
- The multicriteria assessment is interesting. However, its representation in Figure 3 may be ambiguous and should be better justified.
Some editorial issues
- line 46: which instead of where
- line 84: increasing instead of increase
- line 404: I do not understand the word milkline in the present context.
Author Response
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Reviewer 3 Report
The paper, titled “ Effects of intercropping, nitrogen fertilization and corn plant density on yield, crude protein accumulation and ensiling characteristics of silage corn interseeded into alfalfa stand” by Ruixuan Xu et al., is very interesting and the content is based on reliable data. Although the authors did an excellent job on both the field and experimental parts of the paper, some improvements would make the paper more relevant to the scientific community.
Page 1, line 36 You should write the scientific name in Latin appropriately, Zea mays L. instead of Zea mays L. Do the same for Alfalfa.
Page 3, line 109-111 In order to inform future readers, it would be better to include an interpretation of the soil quality based on the pH value, organic matter, phosphorus, and potassium content.
Page 4, line 146 There is no reference to the method of calculating crude protein (CP) content. A reference should be provided.
Page 5, section 3.1. Forage fresh matter yield and alfalfa to corn ratio, Table 1 should follow this section. For the other tables and figures in the following sections, do the same.
In your previous work (reference 14 „Effects of nitrogen and maize plant density on forage yield and nitrogen uptake in an alfalfa–silage maize relay intercropping system in the North China Plain“), you wrote in Experimental design that you had a planting system: silage maize monocropping (MM), which had the same N rates and plant densities as alfalfa – silage corn intercropping system.
In this paper, you have included control of „Monocropping corn“ (CK) with different N rates and plant densities in relation to the study treatment of AC (alfalfa – silage corn intercropping system).
My question for the authors is whether there is a scientifically correct explanation for comparing alfalfa – silage corn intercropping system (AC) with nitrogen fertilization rates of 0, 60, 120, and 180 kg N ha – 1 and corn plant densities of 30,000, 45,000, and 60,000 plants ha – 1, with the monocultured corn (CK) managed using the local farmers ’practice (with a plant density of 75,000 plants ha – 1 and fertilization with 112 kg N ha – 1, 112 kg P2O5 ha – 1 and 112 kg K2O ha – 1 as NPK compound fertilizer 15: 15: 15).
My opinion is that it would be better to compare the yield (fresh and dry matter) and all other results of chemical analyzes between maize in monoculture and in the intercropping system if they both have the same N rates and plant densities.
Why did you use the control treatment which has different dosages of fertilizer and planting density than the tested treatment, instead of the control with same dosages of fertilizer and planting density (which was apparently used in the experimental set-up)?
Author Response
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Reviewer 4 Report
Dear Authors,
The manuscript, even if well written and justified, still presents some small issues that have to be clarified. Please find below my comments and suggestions in no specific order:
- Even if the authors are referring a linearly mixed model that they used in the analysis of intercropping effects, it will be useful for the readers to present in their work the mathematical form of the used empirical correlation.
- Table 1 (page 7, line 244) is presenting the different crop yields in respect to the nitrogen application rates. Even if most yield values are easily understandable, the Alfalfa yield and the alfalfa proportion in the silage, corresponding to year 2017, contains non-numerical characters. Could you please explain the meaning of these data? The same question arises for Tables 2 to 4.
- Please check the manuscript for typing errors (i.e page 4, line 157: “polythene bucket” should probably be “polyethylene bucket”).
Author Response
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Round 2
Reviewer 3 Report
Thank you for revising the manuscript carefully according to the suggestions. Your response regarding the control of your experiment was correct. In my opinion, it should be presented correctly in the manuscript. Authors should explain the choice of control of the experiment in detail in the materials and methods section (as the authors described to me in the cover letter), as well as additionally define the research objectives in the introduction. Explain that your study aimed to demonstrate how the new alfalfa-silage corn intercropping system was beneficial to farmers by comparing it to the common farming practices in your area. If possible, provide appropriate references to support your choice of the experiment setup.
Author Response
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