Pedogenesis is considered a long-term environmental process; however, it can be accelerated
by periodic water saturation (hydric conditions). The exact nature and effectiveness
of hydric conditions in the intensification of soil development are not clear yet.
Our understanding of the timescales of the mineralogical changes occurring in soils
is limited; however, the timeframe of soil organic matter accumulation is broadly
known. Here, we described soil development over a period of 50 years.The studied soils
Calcaric Mollic Gleysol (Endoarenic, Epiloamic, Hyperhumic) and a Calcaric Calcic
Histic Gleysol (Endoarenic, Epiloamic) are located in a swampy meadow in Hungary,
Central Europe. The start of the soil formation process is well documented here; the
parent material was deposited during a major flood event in 1963. Therefore, the examined
soil profile represents development over the last 50 years. We also studied the parent
material of an adjacent dune as a reference. We used a CN elemental analyser to determine
soil organic carbon and total bound nitrogen content. Selective extractions were also
used to determine amorphous and crystalline Fe and Mn content alongside X-ray phase
analysis (XRD) and transmission electron microscopy (TEM) for mineralogical analysis,
X-ray fluorescence spectroscopy (XRF) for elemental analysis, and laser diffraction
for particle size analysis of the bulk soil samples. Simple chemical tests were also
performed in the field. Redox potential (Eh) and pH were measured by a field monitoring
station.Fifty years under hydric conditions resulted in rapid vertical differentiation
within the soil profile, including remarkable soil organic matter enrichment in the
topsoil and the formation of smectite and Fe accumulation in the zone of groundwater
fluctuation. A high proportion of amorphous and colloidal phases indicated that very
intense processes had taken place in the most intensive redox oscillation zone. The
presence of more crystalline goethite in the bulk soil reflects frequent Eh changes
associated with chemical or microbial processes. In contrast, the presence of amorphous
ferrihydrite indicates the effect of plant roots. Permanently reductive and alkaline
subsoil conditions also facilitated intense carbonate precipitation.The presentation
is based on Szalai et al. 2021 GEODERMA https://doi.org/10.1016/j.geoderma.2021.115328
and Ringer et al. 2021. HUNGEOBULL https://doi.org/10.15201/hungeobull.70.4.6.The
research was supported by the Eotvos Lorand Research Network (SA41/2021) and the Hungarian
Scientific Research Fund (K123953).
