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

Allylsulfide dissolved in dimethyl sulfoxide (DMSO) has been used to distinguish between CH 4 oxidation and nitrification in organic soils and sediments. 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%) inhibited CH 4 oxidation but not nitrification, suggesting that DMSO can be used as a differential inhibitor in forest soils with a low natural CH 4 concentration. However, in sediment and in natural peat, DMSO at 14 mM could not be used to discriminate between CH 4 oxidation and nitrification because it had a minor effect on both processes.