Soil greenhouse gas fluxes under conditions of climate-induced drought and heavy rain from agricultural soils in the Pannonian area

Wien

2013

Poster

Monographie

11212S

180394

IPCC models for the development of the precipitation in the Pannonian area in Austria predict increasing drought periods due to an overall reduction of precipitation. The remaining amount of precipitation is thought to be concentrated to a few heavy rain falls. However, there is a lack of understanding of how altered precipitation and thus soil moisture regime affect changes in greenhouse gas (GHG) emissions and underlying processes. The objective of the present study is, therefore, to determine the effects of climate-induced droughts and heavy rain on GHG fluxes (CO2, N2O and CH4) and to identify potential drivers. For this purpose, the GHG fluxes from three soils typical of the Pannonian area have been determined biweekly in a field trial with controlled irrigation using the closed-chamber method since spring 2011. The field trial is located at the lysimeter facility Hirschstetten, 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) are 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) are irrigated with respect to the 30 year mean of rainfall (amount and distribution) in Großenzersdorf, Marchfeld, Austria. To identify potential drivers of GHG fluxes in the soils investigated soil samples are taken at least four times per year and analyzed for important chemical (pH, NH4 + and NO3 - contents) and microbiological properties [e.g. microbial community composition using phospholipid fatty acid analysis (PLFA)] In the first half year of the field measurements higher N2O and CO2 fluxes and increased CH4 uptake rates under prog.rain compared to the control were observed. In the further course of the experiment gas fluxes in the two irrigation treatments were rather similar. Differences between the three soil types have not been detected so far. Changes in the precipitation pattern tended to result in higher NO3-N contents in the soils of the variant prog.rain. Microbial biomass as indicated by the contents of total PLFA was affected by precipitation manipulation only in the first year of the experiment.