Emissions of greenhouse gases (methane and nitrous oxide) from cattle slurry storage in Northern Europe

Total greenhouse gas (GHG) emissions from stored manure corresponded to 14% of overall GHG emissions from Swedish agriculture in 2006 according to calculations using standard values for a cool climate. The present study identified storage conditions for cattle slurry in different regions of Sweden, developed methodology for measuring GHGs from slurry stored under similar conditions to full-scale storage, and determined annual GHG emissions (methane and nitrous oxide) from stored cattle slurry under Swedish conditions. Temperature measurements in full-scale storage of cattle slurry on farms showed a mean annual slurry temperature of 9.7°C in south-west Sweden and 5.6°C in the north. The closed chamber methodology and equipment developed for measuring GHG emissions were implemented for one year in a pilot-scale plant with similar conditions to full-scale storage as regards slurry temperature, climate and filling/emptying routines. During winter (Oct-April), methane emissions from stored cattle slurry were 3.6 g CH4-C per kg VS, while during summer (May-Sept) they were 6.5 g CH4-C per kg VS. This corresponded to an annual methane conversion factor (MCF) of 2.7%. Losses of nitrous oxide were close to zero.