Use of Digestate as Organic Amendment and Source of Nitrogen to Vegetable Crops

Round 1

Reviewer 1 Report

This paper studied the effect of digestate as organic amendment and nitrogen source on the growth and nitrogen use efficiency of vegetable crops, and this practice of land application of solid fraction digestate is very common in many countries, which has some practical guidance for land application of digestate. The results were not very attractive, which could be predictable from the experiment design, and the novelty need be pointed out. The comments are as follows:

1. Line 98-101, why the first and second topdressing fertilizers for lettuce and kale were different? If these different topdressing fertilizers were important for the plant growth, the author should discuss the effect of these fertilizers, compared to digestate.
2. Line 102-121, the paragraph could be expressed as a table, indicating the sequence of fertilizing activities in different period. And how to decide the amounts of digestate and mineral fertilizers?
3. Line 138, some heavy metals were tested, while there were little presented or discussed in the text. Since the large amounts of digestate were used in some treatments, the accumulation risk of heavy metals should be paid some attention for the long-term scenario, although the contents of heavy metals were below the thresholds.
4. In Table 1, the phosphorus contents of digestate were presented, and the balance of phosphorus should be considered for the plants and soils in the text.
5. In Figure 1, the figures of relative yields seemed meaningless, since the same patterns with biomass.
6. In discussion, the author should deeply discuss the improvement of digestate application with mineral fertilizer, in order to achieve the goals of higher yields and better soil environment, from the perspectives of extension.
7. The language of whole manuscript need be modified, especially there were many long sentences without punctuation.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

The article is simple and straightforward and that is its strength. In terms of methodology, it is well done. The effect of digestate on staple crops is well known, and from this point of view the article provides new information on less cultivated crops. From a methodological point of view, I have only one or two comments. Have you analyzed normality? You should state that. And further, check out the ANCOVA method. If you are looking at the effect of fertilizers on the soil, and you have the effect of fertilizers on yield, ANCOVA is a better method, it gives more accurate results.

IBM's SPSS ought to be cited better (country, city and so on).

From my point of view, this is a simple but well-written article. The effect of digestate is mapped well on a range of crops, this article analyzed the effect of digestate on lesser-grown crops, which is a boon. 

 

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors have carefully revised the manuscript, and I think it could be published in the journal. Some comments are as follows:

In Table 1, the fertilizers of Ammonium nitrate, Calcium
nitrate, Ammonium sulphate, etc. could be abbreviations, in order to save some spaces in the table.

Author Response

Dear reviewer

Table 1 is changed as suggested by the reviewer with the abbreviations of the mineral fertilisers. The authors send in the attachment the revised version of the manuscript, with the new version of Table 1 highlighted in yellow color.

Kind regards 

 

Author Response File: Author Response.pdf