Insights from meta-analysis on carbon to nitrogen ratios in aerobic composting of agricultural residues

• Published in: Bioresource technology 2024-12, Vol.413, p.131416, Article 131416
• Main Authors: Shen, Bo, Zheng, Lili, Zheng, Xiaoyan, Yang, Yang, Xiao, Dao, Wang, Yiqiang, Sheng, Zhanwu, Ai, Binling
• Format: Article
• Language: English
• Subjects: Aerobiosis; Agriculture - methods; Carbon - analysis; Composting - methods; Composting duration; Maturity indices; Natural logarithm of response ratio; Nitrogen - analysis; Ratio of final to initial C/N; Seed germination index; Soil - chemistry
• ISSN: 0960-8524; 1873-2976; 1873-2976
• DOI: 10.1016/j.biortech.2024.131416

[Display omitted] •Crucial impact of initial C/N on compost process confirmed through meta-analysis.•Recommended initial C/N for pig and chicken manure composting are 20–25.•Recommended initial C/N for sheep and cow manure composting are 25–35.•Extended durations are necessary for composting at high initial C/N ratios.•Use of microbial inoculants recommended for enhancing composting at low initial C/N. Given the heterogeneity of raw materials, the diversity of composting processes, and the complexity of biological transformations, systematically exploring the critical role of the initial carbon-to-nitrogen (C/N) ratio in the aerobic composting of agricultural residues is challenging within a single experimental study. This study employs meta-analysis to investigate this role. Statistical analysis of 192 scholarly articles confirmed that most studies adhere to the recommended optimal initial C/N range of 25 and 30, where enhanced compost maturity and nutrient accumulation are observed. The findings indicate that optimal initial C/N ratios vary by agricultural residue type. A C/N ratio of 20 to 30 facilitates controlling the composting duration within 45 days, while a C/N ratio of 30 to 35 necessitates extending the duration beyond 45 days. The study highlights the effectiveness of adjusting the C/N ratio and applying microbial inoculants and physical amendments to optimize composting outcomes and control the composting duration.