Interactions between nitrogenous fertilizers and methane cycling in wetland and upland soils

Recent dynamics and uncertainties in global methane budgets necessitate research of controls of sources and sinks of atmospheric methane. Production of methane by methanogenic archaea in wetlands is a major source while consumption by methane oxidizing bacteria in upland soils is a major sink. Methane formation as well as consumption is affected by nitrogenous fertilizers as has been studied intensively. This review synthesizes the results of these studies which are contradictory and await mechanistic explanations. These can be found in the community composition and the traits of the microbes involved in methane cycling. Molecular microbial investigations, use of stable isotope labeling techniques, discoveries and isolation of new species and pathways offer new insight into interactions between nitrogen and methane cycling.

► Methane emission globally will increase with increasing fertilizer application.
► Methane production is generally stimulated by nitrogenous fertilizers.
► Methane oxidation is generally reduced by nitrogenous fertilizers.
► Microbial diversity composition and traits are mechanistically related to fertilizer effects.
► Nitrogen as resource for methane cycling microbes needs further attention.