Emissions of CH4, N2O, NH3 and odorants from pig slurry during winter and summer storage

Manure storage contributes significantly to greenhouse gas (GHG), NH3 and odour emissions from intensive livestock production. A pilot-scale facility with eight 6.5-m(3) slurry storage units was used to quantify emissions of CH4, N2O, NH3, and odorants from pig slurry during winter and summer storage. Pig slurry was stored with or without a straw crust, and with or without interception of precipitation, i.e., four treatments, in two randomized blocks. Emissions of total reduced S (mainly H2S) and p-cresol, but not skatole, were reduced by the straw crust. Total GHG emissions were 0.01-0.02 kg CO2 eq m(-3) day(-1) during a 45-day winter storage, and 1.1-1.3 kg CO2 eq m(-3) day(-1) during a 58-day summer storage period independent of storage conditions; the GHG balance was dominated by CH4 emissions. Nitrous oxide emissions occurred only during summer storage where, apparently, emissions were related to the water balance of the surface crust. An N2O emission factor for slurry storage with a straw crust was estimated at 0.002-0.004. There was no evidence for a reduction of CH4 emissions with a crust. Current Intergovernmental Panel on Climate Change recommendations for N2O and CH4 emission factors are discussed.