Effect of nitrogen fertilization on atmospheric methane oxidation in boreal forest soils

Abstract

Importance of this Paper: The``greenhouse'' gas CH 4 is increasing in atmospheric concentration. Oxidation by methanotrophic bacteria in upland soils is the only biological sink for atmospheric CH 4 . Methanotrophs are inhibited by high soil N, raising concern that the contemporary worldwide increase in atmospheric N deposition will decrease soil CH 4 oxidation. The boreal forest occupies 13% of the earth's continental surface and is important in atmospheric CH 4 oxidation. We studied atmospheric CH 4 oxidation in fertilized boreal forest plots to determine the N sensitivity of the methanotrophic community and conclude that increased N deposition will not alter the rates of CH 4 oxidation in these soils. AbstractField plots of aspen and black spruce in the Alaskan boreal forest were fertilized repeatedly with nitrogen during the 1993 summer growing season, and weekly determinations of the in¯uence of fertilization on atmospheric CH 4 oxidation were made with static chambers. Repeated fertilization with (NH 4 ) 2 SO 4 solution or nutrient media used to culture methanotrophic or nitrifying bacteria gave a total addition of 140 or 580 kg N ha À1 . Time-integrated CH 4 oxidation was not signi®cantly dierent in fertilized soils versus watered controls because CH 4 oxidation was localized in a subsurface soil zone that was probably not penetrated by surface-applied aqueous phase fertilizer. Insensitivity of CH 4 oxidation by these soils to a high rate of N fertilization and the low current rate of atmospheric N deposition suggest that future increases in atmospheric N deposition will not alter the sink strength of high latitude boreal forest soils in the atmospheric CH 4 budget. Ó

The Effect of Increased N Deposition on Nitrous oxide, Methane and Carbon dioxide Fluxes from Unmanaged Forest and Grassland Communities in Michigan

“…Although it is well documented that CH 4 uptake can be depressed by increased availability of inorganic N, our results are supported by several other field studies demonstrating no response in CH 4 uptake to N applications at similar or even higher application rates (e.g. Whalen and Reeburgh 2000). As for N 2 O responses it can also be argued that the lack of response to N application is related to the N delivery method, i.e.…”

“…There is evidence that the sink strength of CH 4 can be suppressed by additions of nitrogen Adamsen and King 1993;Wang and Ineson 2003;Bodelier and Laanbroek 2004). However, several other studies in forest systems found little or no response of CH 4 oxidation to N additions (Whalen and Reeburgh 2000;Bradford et al 2001;Steinkamp et al 2001). Increased atmospheric N-inputs have also been demonstrated to reduce soil CH 4 oxidation (Butterbach-Bahl et al 2002).…”

The inhibiting effect of nitrate fertilisation on methane uptake of a temperate forest soil is influenced by labile carbon

“…The authors assumed that CH 4 oxidising bacteria may benefit from low N inputs, overcoming N limitation of bacterial growth. In contrast, repeated high inputs of a total of 140 and 530 kg N-NO 3 -ha −1 showed no effect on CH 4 uptake of a boreal spruce forest soil under field conditions (Whalen and Reeburgh 2000). Other field and laboratory approaches support our finding of reduced CH 4 uptake as a response to NO 3 − addition (Butterbach-Bahl et al 1998;Reay and Nedwell 2004;Ishizuka et al 2009).…”

Effect of nitrogen fertilization on methane flux in a structured clay soil cultivated with onion in Central Hokkaido, Japan

“…Many authors have reported that N fertilization affects CH 4 oxidation in upland soils (Steudler et al 1989;King and Schnell 1994;Sitaula et al 1995;Gulledge et al 1997;Whalen and Reeburgh 2000). The inhibitory mechanism of CH.j oxidation in soils by N fertilization has been attributed to the factor that in soil both NH.j + oxidizers (nitrifiers) and CH 4 oxidizers (methanotrophs) are responsible for CH 4 oxidation.…”