METHANE FLUXES FOLLOWING SLURRY APPLICATIONS TO GRASSLAND SOILS - LABORATORY EXPERIMENTS

The effect of soil and slurry type on methane (CH4) emissions were inv estigated under laboratory conditions. CH4 emissions were influenced b y 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 le vels after 48 h. There was no effect of slurry type on CH4 emissions f rom the sandy loam (sand), but emissions were greater following pig sl urry additions to the silty clay (clay) than following dairy slurry ad ditions. Emissions were significantly greater from the clay than the s and for both slurry types. In contrast, a second experiment demonstrat ed no significant effect of soil type on CH4 emissions. This experimen t also showed that most of the CH4 emitted was derived from the slurry itself and not from the soil. The explanation for such contrasting ef fects of soil type on CH4 emissions is discussed.