Regulating microbial dynamics by wood-derived tannic acids addition to mitigate gaseous emissions during liquid...

Gaseous emissions (i.e., CO₂, CH₄, NH₃, N₂O) pose significant environmental pollutions during manure storage. Plant-derived tannins exhibit properties conducive to microbial modulation through protein-binding and metabolic pathway inhibition, offering potential for mitigating these emissions. This study evaluated wood-derived tannic acids as sustainable microbial modulators for the synergistic mitigation of NH₃ and greenhouse gases (GHGs) emissions during liquid chicken manure storage. Four treatments were established: CK (control, no additive), CT (0.5 % condensed tannin), HT (0.5 % hydrolyzable tannin), and MIX (0.25 % CT + 0.25 % HT mixture). Results demonstrated that total nitrogen content increased by 6.74 %, 10.11 %, and 17.89 %, and organic matter content increased by 8.61 %, -0.49 %, and 3.54 % in CT, HT, and MIX treatments, respectively, compared to CK. Tannins amendments enriched Proteobacteria, Actinobacteriota, Synergistota, and Ascomycota, while suppressing Firmicutes and Basidiomycota. Compared to CK, CT HT, and MIX reduced NH₃ emission by 12.94 %, 21.14 %, and 22.61 %, and mitigated 51.44 %, 4.07 %, and 31.09 % of CH₄ emission, respectively. CO₂ emissions were also significantly reduced by 32.43 %, 10.90 %, and 15.43 %, respectively. CH₄ emissions were positively correlated with Basidiomycota, Rozellomycota, temperature, and pH, and negatively correlated with Aspergillus and Talaromyces. While NH₃ emissions showed a positive correlation with Firmicutes and Bacteroidota, and a negative correlation with Corynebacterium. Overall, the application of wood-derived tannic acids, especially the mixed formulation, demonstrates significant potential for mitigating gaseous emissions and improving nutrient conservation during liquid chicken manure storage. These findings present wood-derived tannic acid as a promising, natural additive for sustainable manure management, capable of synergistically reducing multiple environmental pollutants.