10.5061/DRYAD.50G8322
Ley, Martin
Swiss Federal Institute for Forest, Snow and Landscape Research
Lehmann, Moritz F.
University of Basel
Niklaus, Pascal A.
University of Zurich
Luster, Jörg
Swiss Federal Institute for Forest, Snow and Landscape Research
Data from: Alteration of nitrous oxide emissions from floodplain soils by
aggregate size, litter accumulation and plant–soil interactions
Dryad
dataset
2018
floodplain soils
litter
redox potentials
nitrous oxide
Salix viminalis
aggregate size
emission patterns
2018-11-28T16:15:41Z
2018-11-28T16:15:41Z
en
https://doi.org/10.5194/bg-15-7043-2018
80136 bytes
1
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Semi-terrestrial soils such as floodplain soils are considered potential
hot spots of nitrous oxide (N2O) emissions. Microhabitats in the soil –
such as within and outside of aggregates, in the detritusphere, and/or in
the rhizosphere – are considered to promote and preserve specific redox
conditions. Yet our understanding of the relative effects of such
microhabitats and their interactions on N2O production and consumption in
soils is still incomplete. Therefore, we assessed the effect of aggregate
size, buried leaf litter, and plant–soil interactions on the occurrence of
enhanced N2O emissions under simulated flooding/drying conditions in a
mesocosm experiment. We used two model soils with equivalent structure and
texture, comprising macroaggregates (4000–250 µm) or microaggregates
(<250 µm) from a N-rich floodplain soil. These model soils were
planted with basket willow (Salix viminalis L.), mixed with leaf litter or
left unamended. After 48 h of flooding, a period of enhanced N2O emissions
occurred in all treatments. The unamended model soils with macroaggregates
emitted significantly more N2O during this period than those with
microaggregates. Litter addition modulated the temporal pattern of the N2O
emission, leading to short-term peaks of high N2O fluxes at the beginning
of the period of enhanced N2O emission. The presence of S. viminalis
strongly suppressed the N2O emission from the macroaggregate model soil,
masking any aggregate-size effect. Integration of the flux data with data
on soil bulk density, moisture, redox potential and soil solution
composition suggest that macroaggregates provided more favourable
conditions for spatially coupled nitrification–denitrification, which are
particularly conducive to net N2O production. The local increase in
organic carbon in the detritusphere appears to first stimulate N2O
emissions; but ultimately, respiration of the surplus organic matter
shifts the system towards redox conditions where N2O reduction to N2
dominates. Similarly, the low emission rates in the planted soils can be
best explained by root exudation of low-molecular-weight organic
substances supporting complete denitrification in the anoxic zones, but
also by the inhibition of denitrification in the zone, where rhizosphere
aeration takes place. Together, our experiments highlight the importance
of microhabitat formation in regulating oxygen (O2) content and the
completeness of denitrification in soils during drying after saturation.
Moreover, they will help to better predict the conditions under which hot
spots, and “hot moments”, of enhanced N2O emissions are most likely to
occur in hydrologically dynamic soil systems like floodplain soils.
Environmental Data (Ley et al. 2018)Ley_et_al_2018.csv