Covers on slurry during storage are mainly adopted to reduce NH3 emissions. N2O emissions from liquid manure are negligible during storage without surface crust (VanderZaag et al., 2009). Potentials for nitrification and denitrification can develop and lead to N2O emissions if crust dries and oxygen enters the crust (Sommer et al., 2000; Petersen et al., 2013). Reported values (Table 5) show that covering slurry (from cattle or pigs) with either a solid cover or a straw cover often results in lower CH4 emissions (to -28 to +37% with straw cover and -70 to -14% with solid cover), higher N2O emissions (+57 to +100% with straw cover and -50 to +30% with solid cover), and in general a reduction of overall GHG emissions in CO2 equivalents when compared to uncovered slurry (VanderZaag et al., 2009; Guarinon et al., 2006; Berg et al., 2006; Amon et al., 2007; Clemens et al., 2006).

Source: AnimalChange (project supported by EU - FP7)

DELIVERABLE 6.2. Deliverable title: Report on the extent to which manure management might help decrease GHG gas from animal agriculture.