Inhaltszusammenfassung

For the assessment of soil structural stability against hydraulic stress, wet-sieving or constant head permeability tests are typically used but rather limited in their intrinsic information value. The multiple applications of several tests is the only possibility to assess important processes and mechanisms during soil aggregate breakdown, e. g. the influences of soil frag-ment release or differential swelling on the porous systems of soils or soil aggregate columns. Consequently, the...For the assessment of soil structural stability against hydraulic stress, wet-sieving or constant head permeability tests are typically used but rather limited in their intrinsic information value. The multiple applications of several tests is the only possibility to assess important processes and mechanisms during soil aggregate breakdown, e. g. the influences of soil frag-ment release or differential swelling on the porous systems of soils or soil aggregate columns. Consequently, the development of new techniques for a faster and more detailed wet-aggregate stability assessment is required. 1H nuclear magnetic resonance relaxometry (1H NMR relaxometry) might provide these requirements as it has already been successfully applied on soils. We evaluated the potential of 1H-NMR relaxometry for the assessment of wet-aggregate stability of soils, with more detailed information on occurring mechanisms at the same time. Therefore, we conducted single wet-sieving and constant head permeability tests on untreated and 1textures and organic matter contents, subsequently measured by 1H-NMR relaxometry after percolation. The stability of the soil aggregates were mainly depending on their organic matter contents and the type of aggregate stabilization, whereby additional effects of clay swelling on the measured wet- aggregate stability were identified by the transverse relaxation time (T2) distri-butions. Regression analyses showed that only the percentage of water-stable aggregates could be determined accurately from percolated soil aggregate columns by 1H-NMR re- laxometry measurements. 1H-NMR relaxometry seems a promising technique for wet-aggregate stability measurements but should be further developed for non-percolated aggre-gate columns and real soil samples» weiterlesen» einklappen

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