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Gewählte Master / Diploma Thesis:

Petra Huber (2014): CHARACTERISATION OF SOIL AGGREGATES AS INFLUENCED BY DIFFERENT LAND USE AND TIME SCALES.
Master / Diploma Thesis - Institut für Bodenforschung (IBF), BOKU-Universität für Bodenkultur, pp 68. UB BOKU obvsg

Data Source: ZID Abstracts

Abstract:: Soil structure is mainly determined by aggregates and plays a key role in soil stability and soil functions. Aggregate formation is strongly influenced by soil organic matter and its turnover times. Macroaggregates (> 0.25mm) are characterized by short turnover times (between months and 100 years) whereas microaggregates (< 0.25mm) show a turnover rate up to thousands of years. We investigated soil microaggregates (< 0.25mm) and macroaggregates (0.25-0.5, 0.5-1, 1-2, 2-5, 5-10 mm) developed in mollic Fluvisols and Chernozems in the Marchfeld/ Lower Austria. The aggregates were collected at a soil depth of 5- 10cm in forest (F), cropland (C) and grassland sites (G) with a soil age ranging between 10 and 16.000 years. After dry sieving chemical (e.g. carbonates, Fe) and physical (e.g. texture, POM, STA, Ultrasound aggregate stability) methods were applied to study the aggregate size distribution along a substrate age gradient under various land use. We found an increase of soil organic carbon along the substrate age gradient under forest and grassland, which was more intensive than under managed croplands. The aggregate stability decreases from G > F >> C and is influenced through particulate organic matter. The soils revealed alkaline conditions and decreasing carbonate contents along the substrate age gradient. The particle size distribution was similar in all land uses with prevalent sand, mainly fine sand, in the microaggregates and an increase of the clay fraction in the macroaggregates. The relatively homogenous distribution of dry sieved aggregates in all sites shows a peak in the aggregate class 2-5mm with highest amounts under grassland. It can be concluded that besides organic matter, shrinking and swelling may be also responsible for the very homogeneous aggregate size distribution measured under all three land uses. Moreover, soil texture has a strong impact on the soil formation in the Marchfeld area.; Beurteilende(r): Blum Winfried E.H.