Wool Agro-Waste Biomass and Spruce Sawdust: Pellets as an Organic Soil Amendment

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Authors,

The manuscript currently undergoing assessment, titled "Wool Agro-Waste Biomass and Spruce Sawdust: Pellets as an Organic Soil Amendment," investigates the utilization of sheep wool and spruce sawdust in the development of novel pellets intended for sustainable agriculture. These pellets have the primary objectives of mitigating nitrogen and carbon losses, improving soil quality, and addressing environmental issues associated with wool waste. The research is in alignment with the objectives of the EU Green Deal, providing economic advantages for farmers and contributing to a more sustainable trajectory in agriculture. This research holds paramount significance due to its exploration of innovative pellets derived from sheep wool and spruce sawdust for sustainable agriculture. The study addresses critical issues such as reducing nitrogen and carbon losses, enhancing soil quality, and effectively repurposing wool waste, aligning with the objectives of the EU Green Deal. The outcomes of this research offer tangible economic benefits for farmers, contribute to the development of more sustainable agricultural practices, and provide potential solutions to environmental challenges associated with wool disposal.

The acceptance of this manuscript for publication is academically justified based on its significant contributions to various dimensions of sustainability and agricultural practices. The analysis of the innovative pellets, crafted from sheep wool and spruce sawdust, aligns with the DNSH (Do No Significant Harm) principle and supports additional environmental objectives related to the ecological transition, as outlined in Regulation (EU) 2020/852 of the European Parliament and Council.

The comprehensive characterization of the pellets offers valuable insights, providing preliminary information on optimal material combinations and considering both commodity and agricultural perspectives. The study's results, indicating high total nitrogen (N) and total organic carbon (TOC) content, along with favourable water retention dynamics, endorse the potential of these pellets as organic soil amendments in crop production. Additionally, the pellet profile identified in this research opens avenues for the development of technical textile products, addressing farmers' handling requirements and logistical considerations for transportation and storage.

The research makes a notable contribution by revealing a significant reduction in harmful microorganism content in the produced pellets compared to raw materials. This validates the pelletizing process as a valid and feasible methodology, offering an alternative to the costly industrial wool scouring phase required by regulations for using wool as a soil additive.

Moreover, this study is pioneering, being the first to investigate the suitability of raw wool for pellet production. The promising results encourage further research, emphasizing the potential of raw wool utilization in pellet processing. This not only promotes circular economy practices in the agriculture sector but also holds promise for enhancing the economic viability of sheep farming.

 

However, I have some questions based on what is stated in this manuscript. Clarify the significance of recorded moisture content and pellet temperatures and explain their impact on pellet characteristics and performance. Systematically present pellet characteristics with clear headings, discussing implications of variations in length, diameter, and particle size distribution. Provide a detailed explanation of water absorption dynamics in different pellet types and discuss how these dynamics may affect practical applications in agricultural settings. Clearly state the importance of microbiological analysis for assessing pellet safety and potential environmental impact, discussing results in the context of regulatory requirements and environmental considerations. Offer a more in-depth interpretation of chemical composition results, discussing the relevance of detected values for soil improvement and potential crop benefits. Include a comprehensive discussion on observed differences between the three types of pellets, addressing potential implications for agricultural applications. Emphasize the importance of adhering to safety standards, particularly in microbiological aspects, and discuss any regulatory requirements necessary for pellets to be used as organic soil amendments.

Congratulations to the authors for their commendable work on this subject.

Comments on the Quality of English Language

Author Response

Thanks for the helpful suggestions, we have better described the suggested aspects and added some references. (Lines 383-402; 403-401; 435; 529-530).

Reviewer 2 Report

Comments and Suggestions for Authors

By this research it is noted that the pellets show high content in total N and TOC and interesting dynamics of water retention. All of these factors can promote the use of pellets made of sawdust and greasy wool in crop production.

The method used by preparation of the raw materials and the pelleting tests that were conducted at the laboratory of the Institute of BioEconomy are very relevant in the field for the reason that the analysis of the pellets showed that they can be used as an organic soil amendment in compliance with the DNSH (Do No Significant Harm) principle and can contribute to achieving the additional environmental objectives of the ecological transition

The research is consistent and the method is well described so that it can be applied in other research.

The tables and the graphics are relevant for this research.

All cited articles can be found in the bibliography and the references are appropriate.

The conclusions are consistent with the evidence and arguments presented, and it is important that the conclusions specify that this is the first study to investigate the suitability of raw wool for pellet production.

Author Response

Thanks for the gratifying comments, the funded project will allow us to work for further insights.

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors,

The topic of the paper is interesting, you presented a lot of results, but I have some remarks and suggestions.

Modify the introduction.

Why did you use spruce and not some other wood or biomass, or did you use spruce and some other wood and then compare the results?

Why did you use that ratio, the proportion of wool and death that you gave in the work?

Paragraph 2.1 should be explained better and more concisely, and perhaps divided into segments for better understanding.

Picture 1. Enlarge, technically better arrangement

Also, picture 2. You can't see the difference very well

Regarding table 2. You have given some general characteristics. Why didn't you give some other things, for example mechanical or chemical characteristics?

Picture 4. Enlarge

Figure 5 should be better explained in the text of the paper.

Table 3. Compare with the literature.

I think you should have done some more analysis in your work and analyzed and connected your results better.

Author Response

 

The topic of the paper is interesting, you presented a lot of results, but I have some remarks and suggestions.

R.3.1 Modify the introduction.

Thanks for the suggestion, the introduction has been changed (Lines 64; 76-77; 81-83).

R.3.2 Why did you use spruce and not some other wood or biomass, or did you use spruce and some other wood and then compare the results?

A.3.2 Thanks for the question. Spruce sawdust was the most available wood waste/by product in the area where the preliminary test were developed (San Michele all'Adige, Trento, Italy). We have included a clarification in the paper (Lines 76-77).

R.3.3 Why did you use that ratio, the proportion of wool and death that you gave in the work?

A.3.3 Thanks for the question. The choice of ratios (1:1 and 2:1) was made because of the difficulty during the first pellettization trials to produce 100% wool pellets, and also because of the hypothesis of the possible increase in soil TOC due to the addition of wood materials (sawdust spruce).

R.3.4 Paragraph 2.1 should be explained better and more concisely, and perhaps divided into segments for better understanding.

A.3.4 Thank you, the suggestion was accepted.

R.3.5 Picture 1. Enlarge, technically better arrangement

A.3.5 Thanks for the suggestion, figure 1. has been enlarged (Line 169).

R.3.6 Also, picture 2. You can't see the difference very well

A.3.6 Thanks for the suggestion, Figure 2. has been replaced (Line 263).

R.3.7 Regarding table 2. You have given some general characteristics. Why didn't you give some other things, for example mechanical or chemical characteristics?

A.3.7 The observation is pertinent and further studies are necessary to test the pellet mechanical properties produced in this work. However, as we have highlighted in the text this is a preliminary experiment :the small quantities of pellets produced in our Institute laboratory were all used for the different analysis (mainly destructive) performed by the research team and co-authors.

R.3.8 Picture 4. Enlarge

A.3.8 Thanks for the suggestion, figure 4. has been enlarged (Line 307).

R.3.9 Figure 5 should be better explained in the text of the paper.

A.3.9 Thank you very much for the suggestion, the description of Figure 5. has been completed, and a typo has been also corrected (Lines 304-306).

R.3.10 Table 3. Compare with the literature.

A.3.10 Thanks for the suggestion, in the discussion we added a comment, and two references. (Lines 427-436).

R.3.11 I think you should have done some more analysis in your work and analyzed and connected your results better.

A.3.11 As previously mentioned in A.3.8. this is an exploratory study. The success of the 100% and mix sawdust-wool pellets is closely related to their application into soil and to their effects on plants and crops cultivation. Therefore, we think that, also within the economics of a research design, to perform further tests, such as the mechanical analysis, which are more related to the feasibility of pellets application on the field and to their properties as a commodity, needs to follow agricultural trials which are already planned by our research team. Nonetheless, we are grateful for your relevant suggestions we’ll be glad to pursue in the next research steps.