400°C cotton-stalk wood vinegar most strongly enhanced pig-manure compost humification

Cotton stalk-derived wood vinegar added during co-composting increased the humification of pig manure, with the formulation produced at 400°C showing the strongest measured outcome among four pyrolysis temperatures tested. Researchers compared an untreated control with compost amended using wood vinegars prepared at 300, 400, 500 and 600°C. All four wood vinegar treatments significantly improved the humification level relative to the control, while the 400°C treatment achieved the highest humic acid content: 23.360 grams per kilogram on day 15 of composting.

The study examined how pyrolysis temperature affected the transformation of compounds that can serve as humification precursors and how those chemical changes coincided with microbial community succession. Wood vinegar is a liquid product of biomass pyrolysis and contains multiple chemical components that can supplement humification precursors. The authors state that the yields of these components are significantly influenced by pyrolysis temperature, making the four additives a way to compare formulations with different compositions during pig-manure co-composting.

Inter-component correlation analysis and Fourier-transform infrared two-dimensional correlation spectroscopy indicated that the 400°C treatment promoted coordinated transformation of aromatic and nitrogenous precursors. The authors interpreted these results as evidence that this treatment accelerated condensation and polymerization reactions involved in humification. The same treatment produced the highest ratio of humic-like to protein-like fluorescence components, reaching 2.88:1. These chemical and spectroscopic observations accompanied the higher humic acid measurement, linking the treatment-specific precursor transformation with the strongest reported humification response.

Metagenomic analysis also distinguished the microbial response associated with the 400°C treatment. It enriched microorganisms assigned to the phyla Pseudomonadota, Actinobacteria and Bacillota, while the metabolic profiles indicated greater carbon metabolism and activity associated with glyoxylate and dicarboxylate metabolism. Taken together, the findings connect changes in humification precursors with succession in the compost microbial community: the 400°C wood vinegar treatment was associated both with chemical evidence of accelerated condensation and polymerization and with a microbial profile supporting those processes.

The reported result applies to cotton stalk wood vinegar prepared at 400°C and used as an additive in pig-manure co-composting. It does not establish that the same formulation would be equally effective with other feedstocks, at industrial scale or under different environmental conditions. Within the reported comparison of four pyrolysis temperatures, however, the study identifies 400°C wood vinegar as the most effective tested additive for enhancing compost humification, with the highest measured humic acid content, the strongest humic-like to protein-like fluorescence ratio and the most favorable reported microbial metabolic response.

Subject of Research: Effects of cotton stalk wood vinegar pyrolysis temperature on precursor transformation, microbial succession and humification in pig-manure co-composting.

Article Title: Precursor transformation and microbial responses during compost humification regulated by wood vinegar produced at different pyrolysis temperatures

Article References: Liu, J., Zhao, M., Xu, W., Li, S., Xue, Z., Yang, G., Gao, D., Yu, H., Lian, X., Chen, L., & Zhou, L. (2026). Precursor Transformation and Microbial Response in Compost Humification Regulated by Wood Vinegar at Different Pyrolysis Temperatures. Frontiers in Chemistry, 14, 1912238. https://doi.org/10.3389/fchem.2026.1912238

Image Credits: AI Generated

DOI: 10.3389/fchem.2026.1912238

Keywords: compost humification, cotton stalk, wood vinegar, pyrolysis temperature, pig manure, humic acid, microbial succession, metagenomics, aerobic composting, Precursor, transformation, microbial