However, the varied physicochemical properties of biochar and the complexity of composting conditions have led to inconsistent results regarding its effectiveness. A new global meta-analysis of 125 studies offers critical insights into how biochar properties influence compost maturation, gas emissions, and nutrient dynamics. This research aims to provide practical guidelines for optimizing composting strategies by integrating biochar into the process.
Composting, a biotechnological process for organic waste management, faces challenges like inconsistent quality, prolonged processing times, and significant greenhouse gas emissions. The addition of exogenous materials, such as biochar, has gained attention for its ability to enhance composting outcomes by improving microbial habitats, reducing emissions, and speeding up organic matter degradation. Despite these benefits, the effects of biochar on composting vary significantly due to differences in biochar properties, such as feedstock type, pyrolysis temperature, and particle size, as well as initial composting conditions, including C/N ratio and moisture content. This meta-analysis synthesizes 269 observations from 125 studies to clarify these complex interactions and identify the most influential factors.
A study (DOI:10.48130/bchax-0025-0005) published in Biochar X on 16 October 2025 by Fei Shen’s team, Sichuan Agricultural University, highlights the critical role of biochar in enhancing composting efficiency, improving compost quality, and mitigating greenhouse gas emissions.
This study conducted a meta-analysis to examine the impact of biochar properties and initial compost parameters on compost maturation, utilizing 269 observations from 125 peer-reviewed studies. The heterogeneity analysis showed significant between-group differences (p < 0.05), indicating variability in composting outcomes across different biochar properties and conditions. The results also revealed the presence of publication bias, particularly related to biochar size, which influenced gas emissions like CO2, CH4, and N2O, while biochar pH mainly affected N2O emissions. Despite these biases, the analysis maintained reliability, with Pearson correlation analysis confirming that biochar properties—such as feedstock type, pyrolysis temperature, pore volume (PV), and surface area—had significant effects on compost maturity indicators, including the C/N ratio, germination index (GI), and nitrogen content (NH4+−N, NO3−−N). Biochar's role in reducing greenhouse gas emissions was also emphasized, with significant reductions observed in CH4 (51.31%), N2O (43.49%), and NH3 (47.59%). Structural equation modeling (SEM) further highlighted that biochar's PV, feedstock type, and amendment rate were crucial in optimizing composting efficiency, particularly with straw-derived biochar and higher amendment rates (>12%). These findings provide a comprehensive framework for selecting biochar properties and adjusting composting conditions to enhance compost quality and environmental sustainability. The research underscores the importance of biochar in improving composting performance and suggests that future studies should focus on refining data quality and considering additional maturity indicators for more robust conclusions.
This research provides valuable guidelines for optimizing composting processes. By selecting biochar with specific properties—such as straw-based feedstock, a pyrolysis temperature above 400°C, and a high amendment rate—compost producers can enhance the quality and efficiency of their products. The reduction in greenhouse gas emissions during composting not only makes the process more environmentally friendly but also improves the sustainability of waste management systems. These findings are crucial for municipal waste management facilities and agricultural composting operations looking to improve compost quality and reduce environmental impact.
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References
DOI
10.48130/bchax-0025-0005
Original Source URL
https:///doi.org/10.48130/bchax-0025-0005
Funding information
The authors acknowledge funding provided by the National Key Research and Development Program of China - Key Technologies and Equipment for Collaborative Emission Reduction of Ammonia/Greenhouse Gases and New Pollutants (Grant No. 2023YFD1701600).
About Biochar X
Biochar X is an open access, online-only journal aims to transcend traditional disciplinary boundaries by providing a multidisciplinary platform for the exchange of cutting-edge research in both fundamental and applied aspects of biochar. The journal is dedicated to supporting the global biochar research community by offering an innovative, efficient, and professional outlet for sharing new findings and perspectives. Its core focus lies in the discovery of novel insights and the development of emerging applications in the rapidly growing field of biochar science.