Nitrogen-transformation processes under conditions of climate-induced drought and heavy rain from agricultural soils in the Pannonian area

München

2018

1 S. + Poster

Sonderdruck

203552

IPCC models predict increasing drought periods and heavy rain falls in the Pannonian area in Austria. However,
there is a lack of understanding of how altered precipitation and thus soil moisture regime affect changes in N
gas fluxes and underlying processes. The objective of the present study was, therefore, to determine the effects of
climate-induced droughts and heavy rain on N gas fluxes (NO, N2O and N2) and to identify potential drivers.
For this purpose, the NO and N2O fluxes from three soils typical of the Pannonian area was determined regularly in
a field trial with controlled irrigation from April 2014 to November 2016. The field trial is located at the lysimeter
facility Hirschstetten, Vienna, Austria, which consists of 18 backfilled gravitation lysimeters (six replicates per soil
type). Three replicates of each soil type (calcic chernozem, calcaric phaeozem and gleyic phaeozem) were watered
according to the precipitation pattern predicted for the period from 2071 to 2100 simulating drought periods and
heavy rain events (variant “prog.rain”). The remaining nine lysimeters (control; variant “curr.rain”) were irrigated
with respect to the 30 year mean of rainfall (amount and distribution) in Großenzersdorf, Marchfeld, Austria. To
identify potential drivers of N gas fluxes in the soils investigated soil samples were taken at least four times per
year and analyzed for important chemical (pH, NH4+ and NO3- concentrations) and microbiological properties
(e.g. microbial biomass C and N). Emissions of N2 were determined in the lab using the gas flow soil core technique.
Additionally, a short-term lab experiment was carried out to investigate N gas fluxes (NO and N2O) after
fertilization (calcium ammonium nitrate) in greater detail. Process based modelling was applied amongst others to
study the impact of climate change on NO3 leaching of the Pannonian area.