The mechanical strength of agricultural soils depends on many soil properties and functions. The database, “soil strength and consequences for sustainable land use and soil management SOILMECHDAT-Kiel”, originates from the “Horn Research Group” includes analyses of undisturbed soil samples taken from more than 460 profiles in and is developed in collaboration with BONARES, a funding initiative of the German Federal Ministry for Education and Research that focuses on the sustainable use of soils. For over 40 years, over 42 different authors recorded 59 physical and 29 chemical parameters for complete soil profiles. In order to the aim of the initial analyses of this data is to determine the influence of bulk density (BD) organic matter (OM) and time (year) on precompression stress (Pc) and saturated hydraulic conductivity (ks) as a function of Pc. Three main textural groups sand, loam, and silt for both topsoils and subsoils (SS) were studied. In loamy and silty subsoils BD and OM are not related to Pc (R2 = 0.17 and R2 = 0.25). OM and bulk density are more related to Pc in sandy soils (R2 0.55–0.59). The link between ks and Pc showed that sandy soils have a significantly higher Pc (>150 kPa) and conductivities did not change much. In loamy soils, with a Pc > 90 kPa, 50% of the ks fell below the critical value of 10 cm d−1. For silty soils, at a Pc of 60 kPa, 50% of the data fall below the critical value of ks. These findings suggest that the stability of loamy and silty soils not only depends on OM and BD, but requires further data to explain the variation in the measurements. With respect to ks, the results show that fertile silty soils are more sensitive than formerly defined.
Zusammenfassung Die vielseitigen Funktionen von Moorlandschaften sind in kulturhistorischer und klimatischer Hinsicht von immer größer werdendem Interesse. Da Moore über lange Zeiträume anthropogene Zeugnisse konservieren und als Kohlenstoffsenke gelten, gilt es einen umfangreichen Schutz dieser Ökosysteme zu etablieren, um diese Funktionen aufrechtzuerhalten. In dieser Untersuchung wurden Informationen von über 140 Moorstandorten aus Schleswig-Holstein zusammengetragen und ausgewertet, anhand einer einheitlichen Bewertungsmatrix evaluiert und nach Güteklassen (A–D) kategorisiert. Als Grundlage der Güteklassen wurden Bewertungskriterien gewählt, welche durch ein Punktesystem (1–5) definiert sind. Die Bewertungskriterien gliedern sich in drei Hauptkategorien: „kulturelle Bedeutung“, „ökologische Bedeutung“ und „bodenkundliche/geologische Bedeutung“. Die Auswertung ergab, dass 15 % der ausgewerteten Moorstandorte als „konkrete Archivböden“ angesprochen werden können. Diese erfüllen ökologische Anforderungen in einem hohen Maße und erreichen somit eine Punktzahl von > 4, weshalb sie in die höchste Güteklasse „A“ fallen. Aufgrund unzureichender Dokumentation oder sichtbaren anthropogenen Einflüssen werden 46 % der Archivböden der Güteklasse „B“ zugeordnet und gelten als „potenzielle Archivböden“. Der Güteklasse „C“ werden 23 % der Moore zugeordnet und gelten ebenfalls als „potenzielle Archivböden“ und befinden sich in einem stark anthropogen geprägten Zustand, welcher kosten- und zeitintensive Renaturierungsmaßnahmen zur Folge hätte. In die niedrigste Güteklasse „D“ fallen 16 % der bewerteten Moore. Diese unterliegen einer irreversiblen Degradation und sind nicht mehr / kaum als Archivböden anzusprechen. Mit der ausgearbeiteten Bewertungsmatrix wird letztendlich eine flächendeckende Evaluierung und Kategorisierung der Moorstandorte in Schleswig-Holstein angestrebt, um den Erhalt dieser Ökosysteme langfristig sichern zu können.
Critical angle wave propagation measurements were taken at atmospheric pressure on slate and Green River shale pressure on slate and Green River shale samples to study the effect of stratification on dynamic elastic rock properties. The rock samples were taken in 10 degrees increments, from 0 degrees to 90 degrees to the plane of cleavage or bedding. Ultrasonic pulses with a frequency of approximately six megacycles per second were used to determine the velocity of dilatational and shear waves through rock samples immersed in a mineral oil bath. Results indicate a considerable variation of elastic properties with orientation of the bedding or cleavage plane. Data for slate samples indicate general constant values of dynamic elastic properties for cleavage plane orientation properties for cleavage plane orientation angles from 20 degrees to 60 degrees. Anisotropy was indicated for orientation angles near parallel and near normal to the cleavage planes. Green River shale lean in kerogen content exhibited a sharp change in values for elastic properties as orientation of the bedding planes increased from 0 degrees to 30 degrees. The measured rock properties continued to change, but at a lesser rate, as the bedding plane orientation increased from 30 degrees to 90 degrees. Data for samples of Green River shale rich in kerogen content were so widely scattered for individual orientations that only general trends were evident. Generally, S-wave velocities and shear modulus values were higher for GRS-2 than GRS-1, while values for bulk modulus and Poisson's ratio were lower. Poisson's ratio were lower Introduction The transmission of acoustic waves through a discontinuity surface has been studied both theoretically and experimentally by many investigators. Although the law of reflection for light waves was known to Euclid and that of refraction was discovered experimentally by Snell, Knott seems to have been the first to derive general equations for reflection and refraction of acoustic waves at a plane boundary.
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