Liquid manure storage facilities are sources of methane, nitrous oxide and ammonia emissions. Different materials for covering liquid manure storage facilities to reduce gaseous emissions were investigated on laboratory scale (65 l): perlite (Pegu¨ litTM), lightweight expanded clay aggregate (LecaTM) and chopped strawâ??both individually and combined with lactic acid or saccharose, respectively. Methane is the predominant greenhouse gas emitted from liquid manure storage facilities. Nitrous oxide plays a role when surfaces become encrusted when it occurs by using the cover materials investigated. Common cover materials have good reduction effects on ammonia but less on greenhouse gas emissions. Straw can increase emissions of methane and nitrous oxide, as can granules. Lowering the pH value of the slurry can reduce both methane and nitrous oxide emissions. Combinations of covering and acidifying should cause a pH value below 6.0 to reduce methane and nitrous oxide emissions effectively. Lower pH value seems to be necessary also to reduce ammonia emissions effectively.
