Methane fluxes following slurry applications to grassland soils: Laboratory experiments

The effect of soil and slurry type on methane (CH4) emissions were investigated under laboratory conditions. CH4 emissions were influenced by soil type only when the slurries applied had low dry matter contents. Pig and dairy slurries were applied at 25 m(3) ha(-1) to intact soil cores of a sandy loam and a silty clay. CH4 emissions were immediate from all slurry amended soils and emissions decreased to background levels after 48 h. There was no effect of slurry type on CH4 emissions from the sandy loam (sand), but emissions were greater following pig slurry additions to the silty clay (clay) than following dairy slurry additions. Emissions were significantly greater from the clay than the sand for both slurry types. In contrast, a second experiment demonstrated no significant effect of soil type on CH4 emissions. This experiment also showed that most of the CH4 emitted was derived from the slurry itself and not from the soil. The explanation for such contrasting effects of soil type on CH4 emissions is discussed.