Influence of different methods of covering slurry stores on greenhouse gas and ammonia emissions

Slurry storage contributes considerably to NH3 and GHG emissions. Different methods of covering slurry stores may influence NH3 and GHG emissions. Emissions were analysed for five scenarios: storage of untreated dairy cattle slurry (1) with and (2) without a wooden cover; anaerobically digested dairy cattle slurry (3) without any cover, (4) with a layer of chopped straw, and (5) with a layer of chopped straw and a wooden cover. Experiments were carried out under cold winter and warm summer conditions. Anaerobic digestion was found to be an effective mitigation option for GHG emissions from slurry stores. A wooden lid placed on the slurry tank reduced CH4 and NH3 emissions, whereas NH3 emissions from uncovered anaerobically digested slurry were high. A layer of chopped straw was less effective in reducing NH3 emissions and has the potential to increase GHG emissions. It is recommended that slurry tanks, particularly those used for storage of slurry treated in biogas plants, be equipped with a solid cover.