Open research questions in Composting and Vermicomposting Techniques

What the literature leaves open

• Future studies should explore the specific roles these microorganisms play and how they contribute to the overall efficiency and stability of the bioconversion processes. Since archaea, such as Euryarchaeota and Crenar- chaeota, are predominant in anaerobic digestion, future studies should focus on their specific functional roles, adaptation mechanisms, and potential to improve bio- gas production. The use of bioaugmentation (adding specific microor- ganisms) and biostimulation (enhancing the growth of indigenous microorganisms) could be investigated as strategies to boost the efficiency of food waste biocon- version.

  A short review on microbial ecology of food-waste valorization: insights from anaerobic digestion, fermentation, and composting · 2026 · DOI

• Second, future investigations will focus on the recycling and reuse of the spent cultivation substrate post-harvest. Nevertheless, further large-scale trials are warranted to enhance data precision and validate these outcomes.

  An Integrated Crop Management Strategy Using Wood Chips and Pumice Under Feather Compost for Sustainable Ginger Soilless Production and Endophytic Bacteria Composition in Open Field · 2026 · DOI

• In contrast to common commercial composting agents that mainly promote decomposition but have unclear harm- less effects, this technology is hypothesized to achieve pathogen suppression via thermal physical inactivation and microbial competition, though this potential effect remains to be verified by dedicated pathogen viability tests.

  Rapid High-Temperature In Situ Decomposition Technology of Corn Straw in Fields: Process, Mechanism and Application Potential · 2026 · DOI

• Future studies should extend the duration of the experiment to evaluate the long-term effects of the organic fertilizer on plant yield and fruit production. Researchers are also encouraged to test additional fertilizer concentrations to determine the most effective application rate. Clear guidelines for comparison treatments should be provided to improve reproducibility. Home gardeners and farmers may use the 10 mL organic fertilizer formulation as a practical and affordable alternative to chemical fertilizers. The ingredients can also be manually crushed when blending equipment is unavailable. REFERENCES Bhargaw, A., Dasgupta, R., V. P. D., Hadimani, A., Shetty, M. G., & Ghosh, S. K. (2024). PRANAM-Ca: An eggshell derived calcium fertilizer and its impact on blossom end rot in tomato cultivation. Journal of Experimental Agriculture International, 46(2), 78–85. https://doi.org/10.9734/jeai/2024/v46i22310 Chandini, Kumar, R., Kumar, R., & Prakash, O. (2019, February). The impact of chemical fertilizers on our ecosystem. ResearchGate. https:// environment and www.researchgate.net/publication/331132826_ The_Impact_of_Chemical_Fertilizers_on_our_ Environment_and_Ecosystem Faisal, A. F., & Mustafa, Y. F. (2025). Chili pepper: A delve into its nutritional values and roles in food-based therapy. Food Chemistry Advances. https://doi.org/10.1016/j. focha.2025.100928 Fernando, J. R., Tenizo, A. J., & Villa, R. (2023). The effect of organic hydroponic solution from banana (Musa acuminata) peel, orange (Citrus sinensis) peel, and eggshell on the growth of pepper plants. Unpublished senior high school research paper; Exequiel R. Lina High School, Poblacion Norte, Licab, Nueva Ecija. Itamah, E., Bello, T. K., & Waziri, S. M. (2025). Production and characterization of liquid bio-fertiliser from orange peels, banana peels, and eggshell. Discover Agriculture, 3(1). https://doi.org/10.1007/s44279- 025-00342-0 Khaitov, B., Yun, H. J., Lee, Y., Ruziev, F., Le, T. H., Umurzokov, M., Bo Bo, A., Cho, K. M., & Park, K. W. (2019). Impact of organic manure on growth, nutrient content and yield of chilli pepper under 5 9 https://journals.e-palli.com/home/index.php/ijsa Page Int. J. Smart Agric. 4(1) 91-96, 2026 various temperature environments. International Journal of Environmental Research and Public Health, 16(17), 3031. https://doi.org/10.3390/ijerph1617303 Khandale, S. P., Tapadiya, G. G., Rajput, S. P., et al. (2022). An effect of onion peel water on various plant disease and plant growth. International Journal of Scientific Development and Research (IJSDR), 7(1), 333–335. https://www.ijsdr.org/papers/IJSDR2201052.pdf Miller, E. (2024, May 3). Fish amino acid - Food for the garden. https://www.fishfulfuture.com/ Fishful Future. seafood-recipes/faa Nabayi, A

  Effectiveness of a Natural Fertilizer from Organic Household Waste (Banana Peel, Orange Peel, Eggshell, and Onion Peel) versus Chemical Fertilizer on The Growth of Chili (Capsicum Annuum L.): A Comparative Analysis · 2026 · DOI

• Future research should focus on complementary assessments not addressed in the present study to provide a more comprehensive evaluation of compost quality, environ- mental safety, and agronomic performance. Additional investigation into dissolved organic carbon and humification indices (humic and fulvic substances) would contribute to a deeper understanding of organic matter stabilization and compost maturity.

  Feasibility of Co-Composting Sewage Sludge with Vine Pruning Residues for Sustainable Waste Management · 2026 · DOI

• This review presents the most recent experimental evidence regarding the use of compost tea to optimize the growth of horticultural crops. From this paper, all authors adopted the aerated method for compost tea extraction. This is probably because compost tea fermentation is mainly adopted when the goal is to improve crop resistance to biotic stresses [26]. Most of the experiments reviewed were conducted in the greenhouse, and Horticulturae 2025, 11, 433 22 of 27 both the effects attributed to foliar and root applications were observed. The positive effects induced by the foliar application of compost tea were related to the faster adsorption of nutrients in compost tea through stomatal openings [80]. Root applications of compost tea, on the other hand, can stimulate the proliferation of root absorptive [110]. However, it should be remembered that the effects explicated by compost tea can vary greatly de- pending on the material used for compost tea production, and by the interaction between application dose and the horticultural species to which it is being applied. Therefore, one of the main challenges consists of the difficulty of standardizing CTs due to their heterogeneity. Nevertheless, currently several manufacturing companies, especially in the United States, have formulated commercial compost tea products, indicating both their composition and their potential effects on crops [12]. However, it would be desirable to standardize the method of CT production and application not only nationally but also internationally, in order to achieve a standardized product quality that is able to guarantee specific perfor- mance [14]. However, the thing that would improve the environmental and economic sustainability of farms would be the self-production of compost tea. The self-production of CT at a farm level would improve the sustainability of the horticultural supply chain by reducing not only the amount of waste produced but also the use of production inputs such as pesticides and synthetic fertilizers. CT-based formulations could also contribute to improving the economic and environmental sustainability of organic farms because of their microbiological and nutritional component that promotes crop growth [9]. For this reason, self-production should be a more-encouraged practice because it could enhance the value of farm waste in a circular economic perspective. Not only would this approach reduce the costs associated with the disposing of waste in landfills, but it would also allow the identifi- cation of specific cultivation protocols that take into consideration both the nature of the farm waste used and the species to which compost tea would be applied. Especially when the possibility of self-producing CT at a farm level is considered, it is recommended that farmers attend training courses. This will also help to standardize CT farm self-production methods. Several CT studies have been carried out precisely with the aim of providing more use

  Sustainable Agriculture Through Compost Tea: Production, Application, and Impact on Horticultural Crops · 2025 · DOI

• Based on the pH value and available phosphorus (AP) content results, further investigation into the effects of applying varying phosphorus levels on Idesia polycarpa seedlings is warranted.

  Influence of Varied Phosphorus Fertilizer Ratios on the Rhizosphere Soil Microbial Community in Idesia polycarpa Seedlings · 2024 · DOI

• Future research should focus on field trials in vineyards to quantify long-term effects on soil properties, microbial communities, yield, and grape quality, while test- ing how different vineyard residues and vermicomposting conditions influence the final product.

  Grape Marc and Beyond: A Critical Review of Decoding Vermicompost Applications in Viticulture - Impacts on Soil, Microbiota, Plant Nutrition, and Dark Aspects · 2026 · DOI

• Future research should investigate the potential of alternative organic and inorganic binders beyond starch and clay, such as molasses, gum Arabic, or natural resins.

  <p>Characterization of Selected Agricultural Waste Residues for Briquette Production</p> · 2026 · DOI

• A key limitation is that the experiment did not resolve direct earth- worm effects from indirect effects mediated through altered environ- mental conditions.

  Earthworm-associated microbial community reassembly accompanies higher inorganic-N concentrations in spent mushroom substrate · 2026 · DOI

• While previous research has often explored the individual effects of biochar or compost, the combined use of these amendments has rarely been investigated, particularly when the biochar originates from date palm biomass.

  Synergistic effects of integrating date palm biochar, compost, and compost tea: an agroecological approach to enhancing tomato growth and soil fertility · 2026 · DOI

• Therefore, direct comparison between co-pyrolysis and post-pyrolysis physical blending warrants further investigation.

  Adsorption Characteristics and Ecological Risk Control of Multi-Metals in Biogas Slurry Using Blended Cow Dung and Corn Straw Biochar · 2026 · DOI

• Accordingly, the scope of inference should be limited to the specific operational conditions evaluated in this study.

  Do Bio-Inoculants Improve Composting Under Field Conditions? Comparative Study of Homemade, Commercial, and Laboratory-Developed Bio-Inoculants · 2026 · DOI

• Hydrochar and biochar are increasingly proposed as sustainable soil amendments within circular economy strategies, yet their comparative effects on rhizosphere bacterial communities and plant performance remain poorly understood, particularly for hydrochar.

  Hydrochar post-treatment and biochar impose differential selective pressures shaping rhizosphere microbiomes and plant performance · 2026 · DOI

• Although earthworm-assisted remediation is considered a promising and eco-friendly biostimulation strategy, remediation performance among different earthworm species in BaP-contaminated soils and the associated microbial regulatory mechanisms remain insufficiently compared.

  Effects of different earthworm species on the remediation efficiency of BaP-contaminated soils and microbial community structure · 2026 · DOI

• Also, the antibiotic resistance gene (ARG) dynamics were critically underestimated as a biosafety concern in manure-based composting systems; the archaeal community, poorly characterized, is functionally important for nitrogen cycling and greenhouse gas dynamics.

  Microbial Communities in Composting Processes:Succession, Functional Ecology, and Biotechnological Applications · 2026 · DOI

• The incorporation of food and garden organics (FOGO) compost into horticultural systems is promoted to improve soil health and advance circular economy goals; however, its impact on flavour quality and consumer perception remains poorly understood.

  Food and garden organics (FOGO) compost application improves post-harvest chemical and sensory profiles of conventionally grown tomatoes · 2026 · DOI

• Some low-cost and low-tech recycling methods, such as vermicomposting and bokashi (lactic fermentation) are currently understudied in Europe.

  Reciprocal interactions between roots and earthworms in the presence of vermicompost and bokashi · 2026 · DOI

• This review presents a range of alternative substrates, some of which remain underutilized and insufficiently explored in container production systems.

  Alternative substrates and substrate stratification in nursery weed management: a comprehensive review · 2026 · DOI

• However, the comparative effectiveness of different soil management strategies, particularly organic amendments derived from agro-industrial residues, remains insufficiently clarified.

  Agro-Industrial Residue Amendments as Circular Tools for Soil Stewardship and Greenhouse Gas Mitigation · 2026 · DOI

• Yet, waste streams from production and declassified products remain underexplored as resources to produce high quality soil amendment.

  Combining fermentation and vermicomposting for sustainable pet food waste management: Effects of waste profile and inoculum source · 2025 · DOI

• Compost tea, an alternative to synthetic fertilizer, is incredibly important for sustainable plant growth and soil health; however, many of its biochemical characteristics remain poorly understood.

  Evaluating compost tea recipes for enhanced nutrient cycling: An innovative management practice for sustainable soil health · 2025 · DOI

• However, harnessing traditional innovations to conserve and promote niche-specific microbiome management in agriculture has not been explored in detail.

  Deciphering the microbiome potential and metabolic profiling of animal waste co-composting reveals the co-occurrence network of non-microbial and microbial biostimulants to strengthen conservative practices in sustainable agriculture · 2025 · DOI

• The influence of plant fermentation products on diverse soil functions and their underlying connections with soil microbial communities remains elusive.

  Effects of different plant-derived fermentation products as soil amendments on microbial community structure and mitigation of soil degradation caused by replanting · 2025 · DOI

• However, intensive culture of anecic earthworms (ICAE) is a distinctive agricultural practice in South China that encompasses both monoculture and coculture systems, and its impacts on SOC content and fractions remains poorly understood.

  Intensive culture of anecic earthworms (Amynthas aspergillum) under monoculture and coculture: impacts on vertical soil organic carbon accumulation via regulating microbial biomass and community structure in South China · 2025 · DOI

Most-cited papers in Composting and Vermicomposting Techniques

• Potassium Control of Plant Functions: Ecological and Agricultural Implications · Plants · 2021 · 562 citations
• Manure management and soil biodiversity: Towards more sustainable food systems in the EU · Agricultural Systems · 2021 · 294 citations
• Additives for reducing nitrogen loss during composting: A review · Journal of Cleaner Production · 2021 · 263 citations
• Key factors affecting seed germination in phytotoxicity tests during sheep manure composting with carbon additives · Journal of Hazardous Materials · 2021 · 237 citations
• Microbial Community in the Composting Process and Its Positive Impact on the Soil Biota in Sustainable Agriculture · Agronomy · 2023 · 230 citations
• Utilisation of agro-industrial waste for sustainable green production: a review · Environmental Sustainability · 2021 · 220 citations
• Vermicompost: Enhancing Plant Growth and Combating Abiotic and Biotic Stress · Agronomy · 2023 · 217 citations
• Biochar addition reduces nitrogen loss and accelerates composting process by affecting the core microbial community during distilled grain waste composting · Bioresource Technology · 2021 · 201 citations
• Selection of sensitive seeds for evaluation of compost maturity with the seed germination index · Waste Management · 2021 · 193 citations
• Management of crop residues with special reference to the on-farm utilization methods: A review · Industrial Crops and Products · 2022 · 187 citations

Most recent work

• Comparative effects of siderite, goethite, and hematite on nitrogen loss and nitrogenous gases release during municipal sludge aerobic composting · Bioresource Technology · 2026
• Composting as a pathway for organic waste valorization: substrate performance, process strategies, and quality benchmarks · Journal of Material Cycles and Waste Management · 2026
• Bio-Based Fertilizers from Waste: Nutrient Recovery, Soil Health, and Circular Economy Impacts · Toxics · 2026
• Insights into Fe0, Fe2O3, and Fe3O4-Mediated humification and nitrogen transformation during composting · Bioresource Technology · 2026
• Driving forces of the humification process in composting: from a microbial perspective · Applied and Environmental Microbiology · 2026
• Source-dependent selenium fractionation in spent mushroom substrate composting: Unraveling the key role of DOM-bacterial interaction in humification for selenium-enriched organic fertilizer production · Biomass and Bioenergy · 2026
• The implication of continuous thermophilic composting for the resource recovery from slaughterhouse waste · Biomass and Bioenergy · 2026
• Effects of different waste feather pretreatment methods on nitrogen conservation, humification enhancement and bacterial community succession in chicken manure composting · Waste Management · 2026
• Comparative effectiveness of composting sun-dried versus insect-bioconverted chicken manure: Impacts on maturity, early plant development, gaseous emissions, and microbial communities · Waste Management · 2026
• Waste-derived multicomponent fertilisers: production, agricultural performance and economic viability · Biomass and Bioenergy · 2026

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