Effects of Applying Different Organic Materials on Grain Yield and Soil Fertility in a Double-Season Rice Cropping System

Round 1

Reviewer 1 Report

The authors cultivated rice in a field experiment with six growing seasons within three  successive years ,to determine the effects of different organic materials (bio char, Chinese milk vetch, rice straw, rapeseed cake fertilizer, manure and the combination between some of them)  on rice grain yield and soil fertility in addition to saving 25% of chemical nitrogen fertilizer

The paper is well organized and well written, while there are some limitations which should be rectified, please find the comments below:

·         Please mention the soil type and its physical properties

·         It is preferred to calculate the CN ratio of organic additives in table 1 because it give an indication on the degradation behavior of this materials in soil.

·         The sources and other physical and chemical characters of used organic materials should be inserted especially bio char and manure because it varies greatly depending its source and methods of preparation so if someone wants to repeat this work he should use the materials with the same properties (for bio char; source, pyrolysis temperature and time, pH, water holding capacity)

·         The CN ratio of manure mentioned in table 1 is very high and the CN of rice straw is very low. What the source of information in table 1. Please try to insert references compatible to your finding regarding to this values.

·         If we supposed that the values of C and N in table 1 are correct so the results are acceptable while according to many other workers the CN ratio of rice straw is about 50 so this residue consume nitrogen and oxygen to be degraded so it is not logic to decrease the recommended nitrogen dose in this treatment.

·         Control treatment receiving 75% of chemical fertilizer without organic materials addition is preferred.  

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Title:  Effects of Applying Different Organic Materials on Grain Yield 2 and Soil Fertility in a Double-Season Rice Cropping System  

 

Overview and general recommendation:

 

Applying organic materials can be used as a practical strategy to maintain soil fertility and improve grain yield in the double-season rice cropping system. For this purpose, field experiments with six growing seasons with three years, from 2016 to 2018, were conducted to assess the effects of five organic materials (biochar, Chinese milk vetch, rice straw, rapeseed cake fertilizer, manure) on grain yield and soil fertility, aiming to save about 25% of the chemical nitrogen (N) fertilizer required for the entire rice growth stages. The manuscript is interesting and has global significance. Chemical fertilizers are a global agricultural problem, and authors address this important issue in this study.

 

The area of research is very influential in maintaining sustainable agriculture.

This is an important topic that is relevant to the journal and important to the readership. The methodology is sound, and the results are generalizable and add significantly to what is already known about this topic. There are no problems with ethics or conflict of interest."

 

General comment: The manuscript is well constructed, but it needs to be improved in several segments and in English grammar and style. The author needs to confirm and clarify the novelty of their manuscript, it is not presented. 

 

CK treatment (100% chemical fertilizer) is something that doesn't existing in real practice; therefore, I believe comparing treatment with chemical fertilizer doesn't make any sense. I suggest authors compare treatment with either recommended dose of fertilizers or with general/most common dose of fertilizers adopted in this study region.

 

In conclusion: This article must be accepted for publication in present form because is an important topic that is relevant to the journal.

 

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

The manuscript "Effects of Applying Different Organic Materials on Grain Yield and Soil Fertility in a Double-Season Rice Cropping System" not recommend for publication and need additional improvement and correction before resubmission.

 

In table 1 please add other nutrients of different organic material. For example biochar main nutrients (Carbon, Nitrogen, Potassium, Phosphorus) consist only 16.8% of total sample weight.

 

Organic material has a different nutrients characteristic. Please explain what was the main assumption of experiment to compare a biochar that has a ratio of C: N 115.8: 1 with a rapeseed cake with a ratio C:N of 4.6: 1. The track of mineralization of these two organic materials is very different and nitrogen viability.

 

Various amounts of potassium have been applied in the biomass: from 9 kg pe ha (rapeseed cake fertilizer) to 68-78 kg per ha (from rice straw and biochar respectively). Potassium from organic materials consist from 5.6 to 31% of total. Should the effect of potassium on rice yield and soil fertility be specified in more detail?

 

Organic material replaced 25% of applied Nitrogen from total 150 kg N per ha (i.e. 37.5 kg N per ha). Please explain why from biochar amount of nitrogen was much lower (18.8 kg per ha). Biochar usage 13.49 t per ha concentration of nitrogen 1.39 g per kg of biochar. Other organic materials replaced 25% of total nitrogen.

 

Additionally manuscript requires in-depth editorial improvement. It is written with no punctuation rules in many places or editorial requirements. For example line 27, 62, 83 and others).

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

It is well known that the addition of biodegradable material with high CN ratio to fertile soil will increase the microbial activity and consume nitrogen from soil to bring the CN ratio to about 20 which is suitable for microbial activity. So, addition of rice straw with wide CN ratio (40.75) to the soil will consume nitrogen not add nitrogen to the soil.

Please discuss your finding in this point clearly.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

The authors responded positively to the proposed correction and improved  manuscript.

I recommend the manuscript for publication in the journal Agronomy.

Author Response

Thanks for your comments. Your work was very important for our study not only in this manuscript, but also will be of great value in our studies in the future.