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Gewählte Master / Diploma Thesis:

Joanne Alice O'Keeffe (2022): Determining the effects of different cover crops and liming on the stabilization of dissolved organic carbon in bulk and rhizosphere soil aggregates..
Master / Diploma Thesis - Institut für Pflanzenbau, BOKU-Universität für Bodenkultur, pp 113. UB BOKU obvsg

Data Source: ZID Abstracts
Abstract:
Dissolved organic carbon (DOC) represents a small fraction of the total organic carbon (C) stored in soils but has a disproportionality large effect on the processes that dictate the cycling of C through this large and influential terrestrial pool. Increased knowledge of the dynamics of DOC under common agricultural practices is necessary to evaluate their ability to contribute to increasing soil C stocks and improving general soil health. I investigated the effects of 9 different cover crops/mixtures, liming and the influence of root activities on the quantity and quality of DOC stabilised in soil structures. Aggregate dispersion via ultrasonication and UV-visible spectroscopy at 254 nm, after filtration < 0.45 μm, created continuous release curves proxying the release of DOC at increasing energy input, up to the peak specified energy of 11.65 J ml-1. Limed soil, bulk soil, and soils under white lupin (WL) released significantly more UVDOC from soil structures. However, non-purgeable organic carbon (NPOC) results only showed that rhizosphere soils released statistically significantly more total DOC than bulk soils. Limed soil DOC had a higher degree of aromaticity, as measured by specific UV absorbance (SUVA), while rhizosphere soils are characterised by a lower degree of aromaticity, as indicated by both SUVA and the integral ultraviolet absorbance ratio index (URI) values. Evidence from the UVDOC continuous release curves suggest both limed and rhizosphere soils promoted a higher degree of aggregate stability and/or aggregation. Overall, cover crops increased the DOC concentration extracted from soil aggregates and contributed to enhanced aggregate stability and/or aggregation. Significant differences in the URI values for different cover crops were detected, with MaizePro (MP) and WL displaying the highest values. It appears certain crops, such as bristle oat and oilseed flax, have the potential to improve DOC stabilization by promoting aggregation.

Beurteilende*r: Bodner Gernot
1.Mitwirkender: Keiblinger Katharina

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