Optimizing Cropping Systems of Cultivated Pastures in the Mountain–Basin Systems in Northwest China

Round 1

Reviewer 1 Report

The authors of this manuscript presented a good articulation of their study which investigated how to optimize cropping systems of cultivated pastures. While the subject matter is not entirely new, the results have been presented through a different approach and thus improve our understanding of the relationships and interconnectivity of cropping systems.

Minor concerns

Line 17 – for clarity the authors could explain or expand on what does suitable means or consider rephrasing. What is a suitable combination of forage? Suitable in respect to what?

Line 105-109 – Too long a sentence, the authors should consider splitting into two sentences.

Line 200 - could this table/data be represented by a graph with period on the x axis? Also check that the table headings (Period, variety) appear on one horizontal line.

Line 182, Table 2, the authors could consider rounding figures to one decimal place.  Or alternatively could provide this table as supplementary data.

Line 351 - extra space between thus and alfalfa.

Line 355-360 – the authors could consider including this paragraph into the discussion section.

Line 362-371 – the authors could consider merging this section into the conclusion or having a conclusion/implication section.

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript reports on a valuable study of relevance to the productivity and sustainability of peasant pasture-based agricultural systems, by evaluating the effect of species/vegetational diversity on crop productivity and stability. The study is in general well designed, with a straightforward methodology and the manuscript is well-written.

One weakness in the design of the study is the different planting densities for alfalfa among treatments (thus, no true controls), which creates a potential confounding factor, but this is often an inherent problem with these type of intercropping studies. It is also normally preferred that these type of studies be conducted at least over two-years, to better understand any potential environment x genetic/system interactions.

From both an ecological and practical standpoint (for peasants), net productivity or biomass may be considered among the most important variables in the study. Thus, the authors may consider changing the order of presentation in the Results, by first presenting the results of biomass/DM, following by a presentation of the the other variables. Thus the authors can then present and discuss the effect of the other variables in relation to its effect on system net productivity and stability.

When presenting the results of biomass/DM the authors should clarify that the data in question refers to the DM of alfalfa, if such is the case (e.g Lines 226-228). In the results section I suggest that, with respect to biomass, that the authors present additional data in the text with respect to alfalfa DM/productivity as affected by the different planting densities of the corresponding grass species. Because protein ratios have an effect on the nutritional quality of forage (increasing with the proportion of legumes in the feed), it may be valuable to highlight if any of the treatment combinations resulted in a greater proportion of legume biomass-- which may indicate an improved nutritional quality of the forage mix.

Additional comments on the text include,

L 120, Briefly describe why these alfalfa varieties were selected. Are they local varieties, and do they have distinct growth habits/canopy architecture? Also, if possible indicate the name of the oat and Sudangrass varieties used.

L 221, Statistics for Table 4?

L 264, I believe that in this case it should be ‘indicates’ rather than ‘demonstrates’ because planting density was not a specific focus of this study. In fact planting density may have been a confounding factor, as all alfalfa treatments were not treated equally.

L 323, re: “in terms of nutritive composition.” Please clarify, because in your study you did not evaluate nutrient composition in your treatments, so no conclusive statements can be made, one way or the other.

Additional minor editorial comments are included in the attached copy of the manuscript.

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Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

General comments

This is an interesting study on intercropping of grass and legume crops in pasture systems in a Chinese arid region. The topic is relevant, and implies for sustainable land-use, resource-use efficiency, ecosystem services, elemental cycling, and environmental quality, as well as for the livelihood of rural populations. The authors show that intercropping has the potential in improving pasture productivity, while better sustaining ecosystem functions. The importance of this topic exceeds the Chinese drylands, and applies for the international community. I think that the issue of facilitation vs. competition between the intercropped grasses and legumes is the key of this study. I would therefore recommend the authors to provide a sentence or two about that in the abstract, and to make sure that this point is clearly delivered in the discussion section. I wonder if it would be possible to include pictures of representative monocrops vs. intercrops, visually demonstrating the advantage of intercropping? This is expected to further increase the attractiveness of this paper. Also, would it be possible to include a picture that shows the field design, with the different treatment-plots? Specific comments are detailed below.

Abstract

Lines 26-28. The meaning of the sentence 'It can be concluded from the results that the plant traits of alfalfa in mixtures were determined by variety at the earlier stage and affected by companion grass at the later stage.' is unclear. Please rewrite.

Lines 28-29. The meaning of the sentence ' The annual forage grass companion impaired the growth of alfalfa and sudangrass displayed a stronger inhibiting effect than oat.' is unclear. Please rewrite.

Introduction   

The introduction's first paragraph reads somewhat like a folk story, rather than as a scientific background. Please rewrite.

Line 48. Please correct to: carbon sequestration and nitrogen assimilation

Line 103. I'm not sure that the word 'manipulated' best fits here. Please modify to a better word, and/or revise the entire sentence.

The last paragraph should clearly state the study objective. Therefore, make it: "The study objective was to …". The, it should follow by the study hypothesis. Please rewrite this paragraph.

Materials and methods

Line 121. Here you say that the experiments included 15 treatments, but Table 1 provides details for 8 treatments only. Please revise accordingly.

Results

The results section is very clearly written. Also, the tables are very clear.

Discussion

Please make sure you only discuss the results, and do not repeat the findings, which were already described in the results section (particularly in the beginning of the results section).

Line 251. I don't think that the term 'dwarf' applies here. Why not using a regular term, such as 'small'?  

Overall, the discussion section clearly demonstrates the interspecific relations along the plants' life cycle. I congratulate the authors for this fascinating discussion.

Conclusions

The conclusions section clearly demonstrates the study's insight. Well done.

Author Response

Please see the attachment.

Author Response File: Author Response.docx