PhoD Harboring Microbial Community and Alkaline Phosphatase as Affected by Long Term Fertilization Regimes on a Calcareous Soil

Round 1

Reviewer 1 Report

This article by Lu et al. entitled “PhoD harboring microbial community and alkaline phosphatase as affected by long term fertilization regimes on a calcareous soil”. They concluded that the long-term fertilization, especially the addition of organic supplements, profoundly modified the soil properties and subsequently changed the diversity and relative abundance of phoD harboring bacteria. I have gone through the manuscript and it is an interesting work. Overall, the whole manuscript is well written, the study is well designed and executed, data properly analysed, methodology of detailed, and results well discussed and discussion section is organized.  The manuscript also need language correction.

Materials and methods

How many replicates did the authors use in each treatment?

L208: Please mention the concentration (%) of agarose gel

L218-220: Please add a reference for this thermal cycle

Authors are suggested to add a data availability statement mentioning the BioProject and/or GenBank accession numbers.

 

Best of luck

Author Response

This article by Lu et al. entitled “PhoD harboring microbial community and alkaline phosphatase as affected by long term fertilization regimes on a calcareous soil”. They concluded that the long-term fertilization, especially the addition of organic supplements, profoundly modified the soil properties and subsequently changed the diversity and relative abundance of phoD harboring bacteria. I have gone through the manuscript and it is an interesting work. Overall, the whole manuscript is well written, the study is well designed and executed, data properly analyzed, methodology of detailed, and results well discussed and discussion section is organized.  The manuscript also need language correction.

Response: Thanks for your positive comments to our manuscript! We incorporated your suggestions in this MS revision and further had the language of this MS polished.

 

1. Materials and methods

How many replicates did the authors use in each treatment?

Reply：We used three replicates in each treatment.

 

2. L208: Please mention the concentration (%) of agarose gel

  Reply：The concentration of agarose gels is 0.8%, and we've added it in the manuscript.

 

3. L218-220: Please add a reference for this thermal cycle

Reply：Done.

 

4. Authors are suggested to add a data availability statement mentioning the BioProject and/or GenBank accession numbers.

Reply：The data that support the findings of this study have been deposited in the BioProject with accession number of PRJNA923783.

Author Response File: Author Response.docx

Reviewer 2 Report

This manuscript is well written, and its overall structure is not coherent and consistent. I think this manuscript can be accepted for publication in its current form. 

Author Response

This manuscript is well written, and its overall structure is not coherent and consistent. I think this manuscript can be accepted for publication in its current form. 

Response: Thanks for your positive comments to our manuscript!

Author Response File: Author Response.docx

Reviewer 3 Report

Reviewer comments to the manuscript ID-2167078:

PhoD harboring microbial community and alkaline phosphatase as affected by long term fertilization regimes on a calcareous soil

 

The manuscript is about the long-term effects of the fertilization on the community of phoD harboring bacteria which can increase the P availability through secretion of alkaline phosphatase (ALP). This work has also the aim to clarify the contribution of the organic P (Po) to soil available P.  The work was developed in calcareous soils from a long-term field experiment during 29 years. The manuscript has valuable results about the effects of the fertilization practices, not only on the changes of the physical-chemical properties of the soil but mainly of the microbial community in the long-term.  The results highlighted the particular role of the microbial community in the mineralization of the soil Po trough the activity of ALP contributing to increase the soil P availability. The topic of this manuscript is relevant not only to clarify the role of the fertilization practices on the activity of the ALP but also to provide insights to improve soil P availability in a currently scenario of phosphate natural resources depletion. 

The manuscript is well done, with appropriate methodology and detailed information about the results obtained. The results are well presented and discussed, and conclusions are also well supported by the field results. 

So, I agree with the publication of the manuscript after minor revision:

 

2. Methodology

Line 136- Sine the work is developed in a calcareous soil can the the authors provide the values of the “total carbonates” and the “active carbonate”?

Line 137- the initial value of Olsen P (9.57 mg/kg) is considered a low value in these calcareous?

Line 146- Since the control treatment didn’t have any fertilization I suggest to refer it only as C and not CK since the letter K is used for the potassium fertilization. 

 

Lines 139 and 175 – It is not clear how many replicates have the experiment. In line 175 seems that there are three replicates which are the three sections of each plot. But in the line 140 it was referred that the treatments were replicated once. Please clarify the experimental design. 

 

 

2. Results

Line 270 (Table1) – The values of Olsen P of the CK and NK treatments at the end of the experiment are very low, 2.82 and 4.62 mg/kg respectively. Can the authors clarify how the crop production is affected by this so low soil P levels? I wonder if the crops can even grow. 

 

In the Figures 1, 4 and 5 the dots are too large, please put the dots smaller.

 

Author Response

The manuscript is about the long-term effects of the fertilization on the community of phoD harboring bacteria which can increase the P availability through secretion of alkaline phosphatase (ALP). This work has also the aim to clarify the contribution of the organic P (Po) to soil available P.  The work was developed in calcareous soils from a long-term field experiment during 29 years. The manuscript has valuable results about the effects of the fertilization practices, not only on the changes of the physical-chemical properties of the soil but mainly of the microbial community in the long-term.  The results highlighted the particular role of the microbial community in the mineralization of the soil Po trough the activity of ALP contributing to increase the soil P availability. The topic of this manuscript is relevant not only to clarify the role of the fertilization practices on the activity of the ALP but also to provide insights to improve soil P availability in a currently scenario of phosphate natural resources depletion. 

The manuscript is well done, with appropriate methodology and detailed information about the results obtained. The results are well presented and discussed, and conclusions are also well supported by the field results. 

So, I agree with the publication of the manuscript after minor revision:

 

Response: Thanks for your positive comments to our manuscript! We incorporated your suggestions in this MS revision. The details gave bellow.

 

1. Methodology

Line 136- Sine the work is developed in a calcareous soil can the authors provide the values of the “total carbonates” and the “active carbonate”?

Reply：The total carbonate content in our soil was 91.66 g/kg on average, unfortunately, we have no data on “active carbonate”, and we've added this information in the Materials and Methods section.

 

2. Line 137- the initial value of Olsen P (9.57 mg/kg) is considered a low value in these calcareous?

Reply：Yes, it was a relatively lower value for crop production in the studied region based on the agronomic threshold value of soil Olsen P, that was about 17 mg/kg for winter wheat and 13 mg/kg for summer maize on loess soil (Tang et al., 2009; Bai et al., 2013). But it was the representative value for the local arable land at the time when the long-term experiment established.

 

Bai Zhaohai, Li Haigang, Yang Xueyun, Zhou Baoku, Shi Xiaojun, Wang Boren, Li Dongchun, Shen Jianbo, Chen Qing, Qin Wei, Oene Oenema, Zhang Fusuo. The critical soil P levels for crop yield, soil fertility and environmental safety in different soil types[J]. Plant and Soil, 2013, 372(1–2): 27–37.

Tang Xu, Ma Yibing, Hao Xiying, Li Xiuying, Li Junmei, Huang Shaomin, Yang Xunyun. Determining critical values of soil Olsen-P for maize and winter wheat from long-term experiments in China[J]. Plant and Soil, 2009, 323(1–2): 143–151.

 

3. Line 146- Since the control treatment didn’t have any fertilization, I suggest to refer it only as C and not CK since the letter K is used for the potassium fertilization. 

Reply: There are many abbreviations used for control/check treatments, such as Nil and CK, or others. Here the CK represent the Check/ Control, and to keep consistent with many published articles from these trial and other long-term experimental sites as well, it would be better to use this CK rather than C. Further, the C is also commonly used to represent carbon. Anyway, thanks for your advice.

 

4. Lines 139 and 175 – It is not clear how many replicates have the experiment. In line 175 seems that there are three replicates which are the three sections of each plot. But in the line 140 it was referred that the treatments were replicated once. Please clarify the experimental design. 

Reply: we have revised the description accordingly.

 

5. Results

Line 270 (Table1) – The values of Olsen P of the CK and NK treatments at the end of the experiment are very low, 2.82 and 4.62 mg/kg respectively. Can the authors clarify how the crop production is affected by this so low soil P levels? I wonder if the crops can even grow.

Reply: With the depletion of soil nutrients that cannot be replenished from fertilization, such as nitrogen (N), phosphorus (P) and potassium (K) in CK treatment, and phosphorus in NK treatment, the crop production would be declined inevitably with decreasing nutrients, especially so for N and P nutrients in soils. However, because of the transformation of P from nonlabile inorganic forms, which is dominant in the tested soil, to forms that can be readily available; in addition, the mineralization of soil organic phosphorus/carbon can also supply some P that is available for crop. For these reasons, the lower soil Olsen P values in case of CK and NK treatments can support a minimum and relatively constant crop yield of 0.95-1.20 t/ha of wheat grain yield and 2.50-3.40 t/ha of maize grain yield (Yang et al. 2014).

Yang X, B.H Sun, S.L Zhang. 2014. Trends of yield and soil fertility in a long tern wheat maize system. Journal of Integrated Agriculture. 13(2): 402-414.

  

6. In the Figures 1, 4 and 5 the dots are too large, please put the dots smaller.

Reply：we revised that based on your suggestion.

Author Response File: Author Response.docx