Estimating Nitrogen Release from Organic Fertilizers for Soilless Production by Analysis of C and N Pools
Round 1
Reviewer 1 Report
Abstract: please specify here that the tests are conducted in growing media.
There is a statement on salts and nitrate in the conclusion, but the topic not covered in the paper. Mineral N may contribute to the EC in the growing medium, but some crops may also be affected by higher NH4-N than NO3-N concentrations? This equilibrium is also depending on the blend composition (peat blends: slow nitrification) and the organic fertilizer used. Please discuss.
For peat-based growing media, a lower nitrification than in peat-reduced blends was observed, mainly when these blends contain compost. Here also compost was used in the blend. Would the outcome change when blends without compost would be used for the incubation trial? Does adding the compost have a large effect on the results?
The compost type and compost dose may also affect the results of the tests. Adding compost to the blend has a huge effect on the incubation trial, by providing the other nutrients, more microbial activity and microbial biomass. There can be interaction between (the microbial biomass in) composts and the organic fertilizers. There can be interaction of the N release from the organic fertilizer with the type of compost, i.e., the net N release may be higher for composts with higher initial mineral N concentrations than for composts with a lower initial mineral N concentration.
Organic fertilizers were reported to release like 50% of the total N during the incubation. How representative are the results in the current transition towards peat-reduced or peat-free growing media. New blends may have higher microbial activity/microbial biomass which may affect the N release. Please discuss.
How representative are the results for the abovementioned new growing media blends with a higher risk for N immobilization? Do the authors expect that the N release for all tested fertilizers will be comparable in a blend with a high risk for N immobilization, or will the effect be fertilizer-specific? Doe the models allow to differentiate between organic fertilizers in terms of N drawdown in these blends? Or is this a topic for further research?
in a blend with a higher risk for N immobilization, a reduction would happen over time, since the N is already in mineral form at the onset of the experiment. For the organic fertilizers, the mineral N still needs to be released in the first weeks and will thus only be immobilized later on in the incubation trial?
see also comments made in the pdf
Comments for author File: 
Comments.pdf
Author Response
Dear Reviewer,
We‘d like to thank you for your suggestions to improve the manuscript. We incorporeted all editorial notes (orthography, rephrasing of sentences etc.) and most of your suggestions regarding analysis and interpretation of data. Attached you find detailed information about our implementations.
On behalf of all authors
Dieter Lohr
Author Response File: 
Author Response.docx
Reviewer 2 Report
The manuscript is discussing and providing a comparable method for measuring the C and N that are very important to give idea about the availability of the nutrients for the plant in a mineral form.
The manuscript is well-written, all the literatures in the introduction are relevant and recent while covering all previous works.
The objective of the study is clear and the conclusion is following the objective.
The method is very clear and detailed and the experiment design is appropriate.
The data provided is well-presented and the discussion is interpret the data very well.
The reference are all formated and mentioned in the text.
This manuscript is one of the stander paper I have read in the field of the horticulture nutrition.
Author Response
Dear Reviewer,
We‘d like to thank you for reviewing our manuscript.
On behalf of all authors
Dieter Lohr
Reviewer 3 Report
In order to explore the characteristics of nitrogen release of organic fertilizers in the production of soilless potted plants, the current research analyzed the carbon and nitrogen pools of 14 kinds of commercial organic fertilizers under different intensity extraction methods, and conducted incubation experiments to match the dynamic model of organic fertilizer nitrogen release, which has significance for guiding the application amount of organic fertilizer nitrogen in the production of soilless potted plants. The language expression is accurate and the research methods and results are reasonable. I just have a few points that need to be addressed:
1. Line 83: Please describe the data processing and graphing software in the Materials and Methods section.
2. Lines 251 and 273: 3.8 up to 38%, should be 3.8% up to 38%; 19 to 88, 57 to 96 and 51 to 88%, should be 19% to 88%, 57% to 96% and 51% to 88%.
3. Line 252: Please specify the specific value in the quoted literature.
4. Line 257: Is this analysis based on Table 2 and Figure 2, if so please indicate (Table 2 and Figure 2).
5. Line 286: ammonium- and nitrate-N should be ammonium-N and nitrate-N.
6. Line 288: The expression may be more reasonable as with the decreasing strength of the extractant
7. Line 363: Please indicate that this conclusion was derived from the analysis in Figure 4, please indicate (Figure 4).
8. Line 403: For FBG and FBG, seems to be corrected to For FPG and FBG.
9. Line 415: Did the data in Figure 5 come from Table 4? If the data is reused, keep one of them to make the article more concise.
10. Line 503: Please explain the formula of the model, so that the producer can use it directly.
11. Line 506: It should be stated that the particle size of the commercial organic fertilizer under the test conditions is not as important as the chemical composition.
Author Response
Dear Reviewer,
We‘d like to thank you for your suggestions to improve the manuscript. We incorporeted all editorial notes (orthography, rephrasing of sentences etc.) and most of your suggestions regarding analysis and interpretation of data. Attached you find detailed information about our implementations.
On behalf of all authors
Dieter Lohr
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Dear authors,
thanks for the revised version. All requested changes were made. One small remark: line 530: structur => structure
The paper can now be accepted.
