Nitrification and methane oxidation in forest soil: acid deposition, nitrogen input and plant effects

摘要

In a laboratory incubation experiment, nitrification potential, methane oxidation, N{sub}2O and CO{sub}2 release were studied in the organic soil layer (0-10 cm) of field lysimeters containing reestablished soil profiles from a 100-year-old Scots pine (Pinus sylvestris) forest of Norway. The experiment was designed as a fill factorial (3 factors; N fertilization rates, soil acidification, and plants), with three replicates. The more acidic irrigation (pH 3) significantly reduced nitrification potential and N{sub}2O fluxes, methane oxidation and CO{sub}2 release. We concluded that the reduction in soil N{sub}2O release by severe acid deposition is partly due to reduction in nitrification potential. The highest N{sub}2O fluxes were observed in the combination of fertilised planted and less acidic pH treatment. N fertilisation (90 kg N ha{sup}(-1)y{sup}(-1) with NH{sub}4NO{sub}3) increased soil N{sub}2O release by a factor of 8 and decreased CH{sub}4 oxidation by 60-80%. Plant effects on soil nitrification potential and methane oxidation rates are discussed.