Wood Vinegar Shows Promise for Reducing Odour in Dairy Manure Composting

New research has found that wood vinegar can significantly reduce odour intensity during dairy cattle manure composting while improving compost quality. The study, published in the Malaysian Journal of Soil Science, tested wood vinegar both alone and in combination with rice husk biochar and beneficial bacteria, with results that could interest Australian dairy producers managing manure composting operations.

Researchers evaluated three amendments added to dairy cattle manure: wood vinegar (pyroligneous acid) at 5% concentration, rice husk biochar at 10%, and a microbial inoculant containing Bacillus licheniformis, Bacillus megaterium, and Lactobacillus acidophilus. They tested these materials individually and in various combinations over a composting period, measuring odour intensity, temperature, pH, moisture content, and nutrient levels.

The most effective treatment for odour reduction was the combination of all three amendments — wood vinegar, biochar, and the bacterial inoculant. This combination achieved the lowest odour intensity scores throughout the composting process. Wood vinegar played a key role in this odour control, with treatments containing wood vinegar consistently performing better than those without it.

Beyond odour control, the amendments improved compost quality. Treatments with wood vinegar and biochar accelerated the composting process, reaching higher temperatures during the thermophilic phase — the hot stage of composting where beneficial microbes break down organic matter rapidly. Final compost products showed improved nutrient content and better physical properties compared to untreated controls.

The study measured specific parameters including total nitrogen, available phosphorus, exchangeable potassium, and organic carbon content. Treatments combining wood vinegar with biochar and beneficial bacteria produced compost with higher nutrient availability, suggesting potential value for soil fertility when the finished compost is applied to fields.

This research adds to the growing body of evidence examining wood vinegar’s role in agricultural waste management. While most wood vinegar research has focused on direct soil or plant applications, this study demonstrates potential benefits in the composting process itself — particularly for operations where odour management is a concern. For dairy producers near residential areas or managing large-scale composting operations, odour reduction can be as important as compost quality.

The researchers noted that wood vinegar’s acidic properties and antimicrobial compounds likely contributed to odour suppression while still supporting beneficial composting microorganisms. The synergistic effect of combining wood vinegar with biochar and selected bacteria suggests that integrated approaches may deliver better results than single amendments alone.

Source: Effects of Rice Husk Biochar, Wood Vinegar, and a Bacillus-Lactobacillus Inoculant on Odour Intensity and Quality of Dairy Cattle Manure Compost in Cu Chi — Malaysian Journal of Soil Science, 2026

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