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Environ Technol. 2020 Jan 27:1-8. doi: 10.1080/09593330.2020.1714744. [Epub ahead of print]

Dairy manure acidification reduces CH4 emissions over short and long-term.

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Department of Geography and Environmental Studies, Wilfrid Laurier University, Waterloo, Canada.
Ottawa Research and Development Centre, Agriculture and Agri-Food Canada, Ottawa, Canada.
School of Environmental Science, University of Guelph, Guelph, Canada.
Innovation Engineering and Program Delivery, Ontario Ministry of Agriculture, Food, and Rural Affairs, Kemptville, Canada.


Acidification with sulphuric acid and cleaning residual manure in tanks are promising practices for reducing methane (CH4), which is a potent greenhouse gas. To date, no data are available on CH4 reductions from acidifying only residual manure (rather than all manure). Moreover, long-term effects of manure acidification (i.e. inoculating ability of previously acidified residual manure in the subsequent storages) are not known. To address these gaps, fresh manure (FM; 150 mL) combined with treated or untreated inoculum (30 mL) were anaerobically incubated at 17°C, 20°C, and 23°C for 116 d. Acidified treatments, regardless of location of acid addition, reduced CH4 production by 81% at 17°C, 78% at 20°C, and 19% at 23°C compared to the control (untreated FM and untreated inoculum). To test long-term acidification effects, FM was inoculated with manure that had been acidified 6-months prior. This created comparable CH4 production to FM with no inoculum and reduced CH4 production by 99% at 17°C and 20°C, and 49% at 23°C compared to the control. Results indicate that residual slurries of acidified manure become poor inoculants in subsequent storage, hence manure acidification has a long-term treatment effect in reducing CH4 production. This could reduce how often acidification is needed in dairy manure tanks and also increasing its cost-effectiveness for farmers.


Greenhouse gases; acidification; dairy manure; methane

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