The synergistic effect of gas distribution and microbial composition on the co-composting process of different crop straws and chicken manure

Different crop straws have varying physical properties (e.g., porosity), which affect gas distribution during composting and in turn influence microbial composition. This study explored these synergistic effects during co-composting of different crop straws (e.g., rice stalk, corn stover, wheat straw) and chicken manure. CMRS had the highest porosity (0.78), followed by CMWS (0.75) and CMCS (0.62). CMCS had the highest static pressure (6.28 Pa), while CMRS and CMWS had lower pressures (2.97 Pa and 2.50 Pa, respectively). The turbulent kinetic energy were CMRS (0.43 m²/s²) > CMWS (0.41 m²/s²) > CMCS (0.32 m²/s²), and showed similar trend with the turbulent intensity. These parameters aligned with temperature trends, as CMRS and CMWS maintained higher temperatures (>55°C) than CMCS. The pH and EC in CMCS and CMWS were above 6.0 (P > 0.05). CMRS’s high porosity created more air space, but restricted oxygen diffusion with increasing pile depth, rapidly lowering pH and inhibiting microbial activity. During co-composting, Firmicutes dominated in CMRS, while in CMCS and CMWS, it was replaced by Proteobacteria and Bacteroidetes during the high-temperature phase. Firmicutes correlated positively with temperature and CO₂, while Proteobacteria correlated with O₂ and total nitrogen. Bacteroidetes and Actinobacteria were less influenced by environmental factors. High porosity enhanced oxygen diffusion, supporting efficient TCA cycles and ATP synthesis, maintaining high temperatures and stable CO₂ generation. Low porosity limited oxygen permeation, inhibiting Complex IV activity and causing temperature fluctuations. • The CMRS had relatively high temperature, and pH value with significant fluctuations. • The high porosity and low static pressure of CMRS improved O 2 permeability. • Firmicutes were positively correlated with temperature and CO₂ concentration. • High porosity supported efficient metabolic cycles and ATP synthesis. • Low porosity inhibited Complex IV activity, and causes temperature fluctuations