Methane emissions from fresh dairy cattle and pig slurry

During manure storage, methane (CH₄) is produced by anaerobic decomposition of organic matter by methanogens. Frequent removal and further processing of manure from the barn can reduce CH₄ emissions. However, little is known about how much CH₄ is lost during the adaptation of methanogens to the changing environment from the gut to storage. The objective was to determine the breakdown of organic matter and emission of CH₄ from dairy cattle and pig slurry in the first 3 days after excretion. CH₄ and carbon dioxide (CO₂) emissions from fresh slurry (<1 h old) were measured in climate respiration chambers. Three treatments were studied: (1) dairy cattle slurry with a temperature of 15°C (CS15), (2) dairy cattle slurry with a temperature of 20°C (CS20) and (3) pig slurry with a temperature of 20°C (PS20). CH₄ emissions from both dairy cattle and pig slurry were minimal during the first 3 days after excretion. Temperature influenced emission rates, resulting in higher CH₄ and CO₂ emissions from CS20 than from CS15. Cumulative CH₄ and CO₂ emissions from PS20 were not significantly different from those of CS20, but emission patterns of pig slurry differed from cattle slurry. Less than 0.3% of the methane potential and only about 0.7% of the IPCC Tier 1 emission factor were emitted as CH₄ during the first 3 days after excretion. In conclusion, quick removal of manure from the barn can reduce emissions, although immediate removal is not required from a CH₄ emissions perspective.