Differential inhibition of methane oxidation and nitrification in forest soils by dimethyl sulfoxide (DMSO)

Allylsulfide dissolved in dimethyl sulfoxide (DMSO) has been used to distin guish between CH4 oxidation and nitrification in organic soils and sediment s. We studied if this method could be applied also to forest soils. However , in three upland forest soils 14 mM DMSO itself strongly (84-87%) inhibite d CH4 oxidation but not nitrification, suggesting that DMSO can be used as a differential inhibitor in forest soils with a low natural CH4 concentrati on. However, in sediment and in natural peat, DMSO at 14 mM could not be us ed to discriminate between CH4 oxidation and nitrification because it had a minor effect on both processes. (C) 2001 Elsevier Science Ltd. All rights reserved.