Abundance and activity of nitrate reducers in an arable soil are more affected by temporal variation and soil depth than by elevated atmospheric [CO2]

Abstract

Elevated atmospheric carbon dioxide concentrations ([CO(2) ]) might change the abundance and the function of soil microorganisms in the depth profile of agricultural soils by plant-mediated reactions. The seasonal pattern of abundance and activity of nitrate-reducing bacteria was studied in a Mini-FACE experiment planted with oilseed rape (Brassica napus). Three depths (0-10, 10-20 and 20-30 cm) were sampled. Analyses of the abundances of total (16S rRNA gene) and nitrate-reducing bacteria (narG, napA) revealed strong influences of sampling date and depth, but no [CO(2)] effects. Abundance and activity of nitrate reducers were higher in the top soil layer and decreased with depth but were not related to extractable amounts of nitrogen and carbon in soil. Dry periods reduced abundances of total and nitrate-reducing bacteria, whereas the potential activity of the nitrate reductase enzyme was not affected. Enzyme activity was only weakly correlated to the abundance of nitrate-reducing bacteria but was related to NH(4) (+) and NO(3) (-) concentrations. Our results suggest that in contrast to the observed pronounced seasonal changes, the elevation of atmospheric [CO(2) ] has only a marginal impact on nitrate reducers in the investigated arable ecosystem.

Functional Response of a Near-Surface Soil Microbial Community to a Simulated Underground CO2 Storage Leak

“…In a previous study, Marhan et al (2011) reported temporal variations, with decreases in denitrifiers linked to lower moisture levels during June - August, similar to what was observed in the current study, but they did not detect the CO 2 effect that we describe [24]. Here, we observed that the first component of a PCA mostly accounted for the effect of CO 2 , while the second component accounted mostly for seasonal effects when all variables were examined (Figure 2 and Table S3).…”

Effects of multiple global change treatments on soil N2O fluxes

“…2 (Mosier et al 1996;Xu et al 2008). The temporal variability we observed is typical of soil N 2 O emissions, which can be quite dynamic (Kaiser et al 1998;Marhan et al 2011). Changes in N 2 O efflux over time are caused in part by changes in conditions and substrate availability (Laville et al 2011) and associated with changes in microbial communities (Chèneby et al 2009).…”

Vertical distribution of the soil microbiota along a successional gradient in a glacier forefield

“…; Marhan et al . ; Štursová et al . ) and are directly linked to changes in microbial biomass, activity and diversity (Ekelund et al .…”