Potential of biochar integrated manganese sulfate for promoting pig manure compost humification and its biological mechanism

This study aimed to clarify the effect of the integrated addition of different proportions of biochar (0 and 5%) and MnSO4 (0, 0.25%, and 0.50%) to pig manure compost. The results indicated the integrated use of biochar (BC) and Mn2+ advanced the compost humification. In particular, the integrated use of 0.50% Mn2+ and 5% BC showed higher total organic carbon degradation (20.67%) and humic acid production (81.26 g kg-1) than other treatments. Microbial community analysis showed the integrated use of BC and Mn2+ regulated the diversity and community structure of organic matter-mineralizing microbes by maintaining the relative abundance of bacteria Firmicutes (54.62%) and Proteobacteria (38.05%) at high levels during the thermophilic period and boosting those of the fungi of Ascomycota (58.91%) and Actinobacteria (15.60%) during the maturity period of composting. This study illustrated the potential and biological mechanisms of integrating BC and Mn2+ as additives in compost humification.

Automated summary

This study investigated the integrated use of biochar (BC) and Mn2+ in pig manure compost and found that it advanced the compost humification. The treatment with 0.50% Mn2+ and 5% BC showed the highest organic carbon degradation and humic acid production. Microbial community analysis revealed that the integrated use of BC and Mn2+ regulated the diversity and structure of organic matter-mineralizing microbes.