Biochar Enhanced Growth and Biological Nitrogen Fixation of Wild Soybean (Glycine max subsp. soja Siebold & Zucc.) in a Coastal Soil of China

Round 1

Reviewer 1 Report

1. The physico-chemical properties of the soil and wood waste biochar are not given in Table S1. This table provides information on selected chemical and physical properties.
2. If the results in tables S2 and S3 are already given in the paper entitled "Biochar enhanced growth and biological nitrogen fixation of wild soybean", why are they duplicated in the next work.
3. Abstract should be improved (better edited).
4. The paper should be written in the past tense, please correct it.
5. The work should be improved in terms of language.

 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript, "Biochar enhanced growth and biological nitrogen fixation of wild soybean (Glycine soja Sieb.) in a coastal soil of China", draws parallels between woody biochar and plant nutrition and suggests that waste biochar can be used in plants (on saline soils) similar to other applications to enhance plant growth and nitrogen uptake. The concept is interesting and the manuscript is well structured and thorough. After a relatively brief literature review, the methodology is followed by a short experiment (6 weeks) without repetition (variants were repeated). Of course, this type of container experiment may show a trend in the experiment, but it cannot be taken as causal. It lacks verification in actual field conditions - how biochar would be incorporated into the soil, whether there is degradation or decomposition and reduction, yield parameters are not known compared to the control, etc.

1) The manuscript needs substantial improvement and language editing as some parts are unclear or difficult to understand. In addition, some sections give the impression that they were written by a less experienced scientist (e.g., a graduate student), compared to other sections that are indicative of a more experienced author. These sections do not necessarily differ in their scholarly quality, but they probably indicate the variable ability of the authors to produce a sophisticated text.

2) In title: correct scientific name: Glycine max subsp. soja (Siebold & Zucc.) H.Ohashi

Cite taxon page as 'WFO (2021): Glycine max subsp. soja (Siebold & Zucc.) H.Ohashi. Published on the Internet;http://www.worldfloraonline.org/taxon/wfo-0000192361. Accessed on: 24 Nov 2021'

3) The introductory section is one of those sections that need considerable improvement, particularly as it introduces perspective and theme. If readers do not understand this section well, they will not be interested in continuing. For example, in paragraph 1 (lines 39-40), it is not clear when one is talking about plants, the environment, or both, and the claimed associations are somewhat elusive. Lacking up-to-date and relevant papers on the subject, I recommend adding them: 10.1016/j.scitotenv.2021.150325; 10.1016/j.jenvman.2021.113220; 10.1016/j.scitotenv.2021.145869; 10.3390/biom11030448; 10.3390/agriculture11040310; 10.1016/j.jenvman.2018.10.117

4) The above actually relates to a broader criticism I had when I started reading the manuscript, although in later sections the concepts became increasingly clear. Missing from the methodology is when the biochar was removed or prepared and when the soil was prepared. Where did the wild soybean seeds come from? Were individual parameters (e.g. plant height) measured only at harvest? Are nine plants from each variant really enough? So you only grew 27 plants in total?

5) The results are not very conclusive - see fig. 1 - the correct labels are missing, and the colors do not match the labels. Similarly, with Fig. 2 there is confusion. Did you test other homogeneous groups?(HSD Tukey?) Duncan's test is very moderate on significance... For the PCA analysis there is no deeper description and analysis of the results - how much do the axes explain? Is it DCC or RDA? What are the symbols and what do they show? In general, I would recommend simplifying the figure and making the results clearer, including presenting only the significant ones. 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The authors have addressed all of the reviewers' comments and significantly improved the manuscript. The figures could still be larger and thus more readable for the reader.