Zugl.: Hohenheim, Univ., Diss., 2005.

The genetic relationship between a Vertisol and an associated Mollisol with an argillic horizon was studied. These soils are taxadjuncts of the Hawkins and Ostler series, respectively. They occur in the Wasatch Mountains of northern Utah and have similar parent materials, altitudes, and slope percentages. Ostler soils have a dense cover of Gambel oak (Quercus gambelii) and occur preferentially on north aspects. Mule's ear (Wyethia amplexicaulis) is the dominant vegetation on Hawkins soils, which are most frequent on south aspects. Erosion is prevalent on Hawkins soils because the mule's ear does not adequately cover the soil surface during the fall, winter, and early spring. The dense oak woods and the litter cover on the Ostler soil protect it from erosion. Both soils dried sufficiently for cracks to develop in their clayey portions. The Ostler soil was drier, probably because it has more and longer transpiring vegetation than the Hawkins soil. The Ostler subsoil and the Hawkins solum both had cracks, slickensides, high clay contents, high COLE values, and smectite as the dominant clay mineral. These characteristics of high shrink-swell activity were most strongly expressed in the Hawkins soil. The Ostler subsoil clay was overlain abruptly by loam surface soil. The textural difference was attributed to lessivage, eolian contributions mixed with preexisting surface soil by soil animals, and in situ clay formation in the subsoil. Eolian additions were inferred from the presence of easily weathered silt and clay-size minerals in the Ostler A horizons and within the zone of mixing in the Hawkins soil. These minerals were not present or were less abundant in the Ostler subsoil and in the Hawkins C horizon. The formation of Hawkins soils (Vertisols) probably resulted from erosional exposure of the clay subsoil of Ostler soils or their precursors.

Human-environment interaction has significantly altered the pedosphere since the Neolithic, if not since the early Holocene. In the course of clearance, agriculture, and (wood) pasture soils have been deeply modified or eroded. These types of land use practices but above all forms of sedentariness spread alongside floodplains and trajectories were oriented towards loess covered areas where fertile soils could develop. Besides this, also peripheral / marginal regions were settled due to population pressure or other factors. Evidence for landscape history and development can be found within archeological sites but also overbank deposits and anthropogenic slope deposits document vast transformation processes. The presented investigations took place within the natural region of the Windsheimer Bucht which is locat-ed in the district of Middle Franconia in northern Bavaria, Germany. In this area, Holocene soils predomi-nantly developed within mudstones of the Middle to Upper Triassic. The soil texture is extremely clay-rich which renders the soils problematic with regard to cultivation management. As a peculiarity, the gypsum underlying the mudstones is prone to karstification processes and resulting proceeding geomorphological processes shape the surface of the landscape. In the course of gypsum mining the karst forms are being exposed and archeological findings are being documented. The latter mainly date back to a span from the Neolithic to the Iron Age, but partly are of Younger Paleolithic origin. Especially subsidence sinkholes are capable of storing pedosediments of several meters in thickness. Despite the high clay content and connect-ed pedoturbation processes, the excavated sequences are stratigraphically and pedologically well-differentiated. The archives occur in the context of settlement structures such as pits and postholes; there-fore, they developed at the interface of natural developments and human impact on their surroundings. The main original research questions that were formulated within the general frame of a project funded by the Deutsche Forschungsgemeinschaft (DFG-projects Te295/15-1 and -2 and Fa390/9-1 and -2) focused on the attractors of the peripheral region for early settlers, the pedological conditions before land use, but also the impact of humans on soils and karst dynamics through time. In the course of the in hand study, the pedosedimentary archives have been approached with a multimethodological toolset which consisted of field analyses, soil morphological analyses from micro- to macro-scale, spectrophotometric (color), (laser) granulometric, and (iron-) pedochemical analyses. The numerical chronological frame was spanned by radiocarbon dating of different organic remains and bulk material if soil organic carbon was supposed-ly high. The result is a multi-dimensional data set that consists of analyses on different spatial scales but also on different levels of measurement. Thus, qualitative, semi-quantitative, and quantitative data consti-tute the basis for discussion. While the grain-size analyses underline the general sedimentological differen-tiation of the records and further affirm the high clay content within the pedosedimentary layers, iron-pedochemical analyses indicate an interplay between oxidation of iron and its chemical reduction. This is also manifested within the spectrophotometric record. Especially the versatile pedogenic characteristics that have been identified by field analyses are confirmed within the thin sections and, by considering all different analyses, the polygenic character of the pedosediments is emphasized. After stressing the general pedological specificities among the different investigated sites within the re-search area, for the collected data, the research further branches into the subjects of general notions on pedogenesis in clayey material and the classification of the respective pedosediments according to paleo-pedological concepts but also recent schemes. Concerning the latter, it becomes evident that established principles cannot be applied to the studied pedosediments without major adaptions. This underlines the specific characteristics of the material. The basis for further interpretations is the evaluation of the multi-level data set for the single records with regard to profile development and pedogenic processes. Hereby, the main drivers of pedogenesis could be identified, which are karst dynamics, land use, and subtle changes in parent material due to the admixture of slope deposits that contain allochthonous eolian material. The latter underlines the importance of Pleis-tocene preconditioning for understanding Holocene landscape dynamics. At the same time, a differentia-tion between the mentioned factors and Holocene climate development is difficult. The following compila-tion of record and localities within the given time frame unveils synchronous as well as asynchronous de-velopments; however, a clear connection between phases of Holocene climate and pedogenesis within the pedosediments cannot be established. Instead, it becomes evident that site specific factors or those that act on the scale of the micro-catchment of the investigated records are decisive. The aforementioned main topics of the project are also considered in the in hand study from a soil-geographic perspective: it is possible that before land use, there was an insular or thin cover by loess sedi-ments or at least upper layers (according to the concept of periglacial cover beds) which constituted the parent material for Holocene soil formation. The according soils, which were superior for agricultural purposes compared to those developed on the autochthonous mudstones, were eroded which exposed the clayey Upper to Middle Triassic beds. Erosion was aggravated due to the impermeable mudstones which enhanced overland flow and interflow within the overlying silty (loessic) material. This is further support-ed by the notions on erodibility of the clayey material that are derived from the comparison of conven-tional and laser granulometric analyses: probably, the clayey pedosediments are capable of forming micro-aggregates that can easily be eroded during heavy rainfall events despite the general consent that material with heavy texture should be rather resistant. The study presents a comprehensive view on clay-rich pedosediments and the complex effects of human-environment interaction on pedogenic as well as sedimentary processes through time that have not been investigated in such detail before. In this context, the multi-level soil morphological analyses and their necessity for a genetic interpretation with regard to the influence of natural versus anthropogenic factors need to be emphasized. Based on quantitative laboratory analytical data only, a respective differentiation would not be possible. This underlines the importance of the chosen soil-geographic multi-methodological approach for answering questions with regard to human-environment interaction but also geoarcheology in general. / Seit dem Neolithikum, wenn nicht sogar seit dem frühen Holozän, hat die Interaktion des Menschen mit seiner Umwelt einen erheblichen Einfluss auf die Pedosphäre: Unter Rodung, Ackerbau und (Wald ) Wei-dehaltung wurden die Böden stark verändert oder erodiert. Diese Art der Landnutzung, aber vor allem Formen von Sesshaftigkeit verbreiteten sich entlang der großen Flüsse und orientierten sich in Richtung lößbedeckter Gebiete, wo fruchtbare Böden vorhanden waren. Daneben wurden aber auch Ungunsträume aufgrund von Bevölkerungsdruck oder anderen Faktoren besiedelt. Belege für die Landschaftsgeschichte und -entwicklung finden sich in archäologischen Funden, aber auch Auensedimente und Kolluvien / Kollu-visole dokumentieren weitreichende Transformationsprozesse. Die vorgestellten Untersuchungen sind im Naturraum der Windsheimer Bucht angesiedelt, die im Regie-rungsbezirk Mittelfranken in Nordbayern liegt. In diesem Gebiet sind die holozänen Böden überwiegend in Tonsteinen des Unteren und Mittleren Keupers entwickelt. Folglich sind die Bildungen extrem tonhaltig, was sie für die landwirtschaftliche Nutzung problematisch macht. Der im Liegenden der Tonsteine befind-liche Gips ist zudem tiefgreifend verkarstet und die daraus resultierenden geomorphologischen Prozesse prägen die Landschaftsoberfläche. Im Zuge des Gipsabbaus werden entsprechende Karstformen freigelegt und archäologische Funde dokumentiert, welche überwiegend in die Spanne von Neolithikum bis Eisenzeit, teils aber auch ins jüngere Paläolithikum datieren. Insbesondere Sackungsdolinen sind in der Lage, mehre-re Meter mächtige Pedosedimente aufzunehmen. Trotz des hohen Tongehaltes und der damit verbundenen Pedoturbationsprozesse sind die Abfolgen stratigraphisch und pedologisch außerordentlich gut differen-ziert. Die Archive treten im Kontext von Siedlungsstrukturen wie Gruben und Pfostenlöchern auf und be-finden sich somit an der Schnittstelle von natürlichen Einflüssen und denen des Menschen auf seine Um-welt. Die ursprünglichen Forschungsfragen, welche im Rahmen eines von der Deutschen Forschungsgemein-schaft geförderten Projektes (DFG-Projekte Te295/15-1 und -2 und Fa390/9-1 und -2) formuliert wurden, konzentrieren sich auf die Attraktoren der am Rande der Lössgebiete gelegenen Windsheimer Bucht für frühe Siedler und die bodenkundlichen Verhältnisse vor der Landnutzung. Auch der Einfluss des Men-schen auf die Böden und die Karstdynamik im Laufe der Zeit stellt einen Forschungsschwerpunkt dar. Im Zuge der Untersuchungen wurden die pedosedimentären Archive mit einem multimethodischen Instru-mentarium bearbeitet, das aus Feldanalysen, bodenmorphologischen Analysen von der Mikro- bis zur Makroebene, spektrophotometrischen (Farb-), (Laser ) granulometrischen und (eisen-) pedochemischen Analysen besteht. Die Ermittlung des zeitlichen Rahmens erfolgte durch Radiokohlenstoffdatierungen ver-schiedener organischer Überreste, aber auch anhand humosen Bodenmaterials mit hohem Gehalt an or-ganischem Kohlenstoff. Hierdurch wurde ein multidimensionaler Datensatz erzeugt, der verschiedene räumliche Skalen abdeckt, aber auch Analysen auf verschiedenen Messniveaus enthält. Somit bilden quali-tative, semi-quantitative und quantitative Daten die Diskussionsgrundlage. Während die Korngrößenana-lysen vor allem die sedimentologische Untergliederung der untersuchten Profile unterstreichen und an-sonsten den tonigen Charakter innerhalb der pedosedimentären Bereiche bestätigen, deuten vor allem die Eisen-pedochemischen Analysen auf ein Wechselspiel zwischen Oxidation und Reduktion von Eisen hin. Dies zeigt sich ebenfalls in den entsprechenden spektrophotometrischen Daten. Zusätzlich bestätigen Dünnschliffe die vielfältige pedogene Ausprägung der Pedosedimente, welche sich bereits im Rahmen der Geländeanalyse abzeichnete. Insgesamt wird bei der Betrachtung aller Datenebenen deutlich, dass die Pe-dosedimente einen polygenetischen Grundcharakter besitzen. Nach der Erarbeitung der Besonderheiten innerhalb des Datensatzes, differenziert nach Standort, stellt die Arbeit die Pedosedimente in den Kontext weiterer Themenkomplexe, wie allgemeine Vorstellungen zu pedogenen Prozessen in tonigem Material, Einordnung der Pedosedimente nach paläopedologischen Konzepten, aber auch Klassifizierung nach Richtlinien für rezente Böden. In Bezug auf die beiden letztgenannten Aspekte wurde deutlich, dass etablier-te Leitfäden und Schemata nicht ohne größere Anpassungen auf die untersuchten Pedosedimente ange-wendet werden können. Dies unterstreicht die Eigenheiten des untersuchten Materials. Die Diskussion des multiskaligen Datensatzes auf der Ebene der Einzelprofile-/befunde führt in der weite-ren Analyse zur Identifizierung der wesentlichen bodenbildenden Faktoren, nämlich Karstdynamik, Land-nutzung (im Allgemeinen) und schwache Veränderungen des Ausgangsmaterials durch die Beimischung von Material aus ehemaligen Solifluktionslagen, welche allochthones äolisches Material enthalten. Letzte-res unterstreicht die Bedeutung der pleistozänen Vorprägung der Landschaft für das Verständnis ihrer Entwicklung im Holozän. Gleichzeitig jedoch ist eine klare Trennung des Einflusses der genannten Fakto-ren und dem der holozänen Klimaentwicklung auf die Bodenentwicklung schwierig. Die anschließende Zu-sammenstellung der Befunde und Lokalitäten innerhalb des gegebenen zeitlichen Rahmen zeigt zwar syn-chrone und asynchrone Entwicklungen, ein kausaler Zusammenhang zwischen Klimaphasen des Holozäns und pedogener Ausprägung kann jedoch nicht hergestellt werden. Viel mehr zeigt die entsprechende Ge-genüberstellung der Archive, dass standortspezifische Faktoren oder solche, die auf der Skala des Mikro-einzugsgebietes der untersuchten pedosedimentären Archive wirken, ausschlaggebend sind. Die genannten Hauptthemen des Projektes wurden auch in der vorliegenden Studie betrachtet, vor allem jedoch aus bodengeographischer Sicht: Es ist möglich, dass es vor der Landnutzung eine Inselhafte Bede-ckung mit Lösssedimenten oder mindestens Hauptlagen (nach dem Prinzip der periglazialen Deckschich-ten) gegeben hat, welche zunächst das Ausgangsmaterial der holozänen Bodenbildung darstellte. Im Zuge der Landnahme wurden diese Böden, welche deutlich bessere Eigenschaften hatten als die tonigen Keuper-böden, zeitnah erodiert, so dass die Keupertone freigelegt wurden. Begünstigt wurde die Erosion durch die stauenden Eigenschaften der Tone und damit verbunden, erhöhtem Oberflächenabfluss und Zwischenab-fluss im überlagernden schluffigen Material. Gleichzeitig lässt der Vergleich zwischen konventionellen und Laser-granulometrischen Analysen Rückschlüsse auf die Erodierbarkeit des Keupermaterials zu: So scheint es möglich, dass die tonigen Pedosedimente in der Lage sind, Mikroaggregate zu bilden, die bei Starkregen-ereignissen leicht erodiert werden können, trotz der allgemeinen Vorstellung, dass Material mit entspre-chender Textur eigentlich eher erosionsresistent sein sollte. Zentraler Bestandteil der Arbeit sind die multiskaligen bodenmorphologischen Analysen. Sie sind beson-ders relevant bei der Interpretation der Ergebnisse im Hinblick auf natürliche und anthropogene Einfluss-faktoren auf die Pedogenese. Lägen der Diskussion lediglich rein quantitativ-laboranalytische Daten zu-grunde, wären entsprechende Unterscheidungen nicht möglich. Dies unterstreicht den Wert des multime-thodisch boden-geographischen Ansatzes für jene Forschung, die sich zum Ziel setzt, Mensch-Umwelt-Beziehungen näher zu erörtern, aber auch für geoarchäologische Fragestellungen im Allgemeinen. Da es bisher kaum systematische Studien über tonige Pedosedimente und deren Überprägung gibt, liefert die vorliegende Arbeit erstmals Einblicke in das komplexe Wirkungsgefüge zwischen Mensch und Umwelt und die Auswirkungen die sich aus dieser Beziehung für Pedogenese und Sedimentationsmechanismen ergeben.

The majority of soils in the Mississippi Delta are vertisols, which are prone to waterlogging and can negatively affect crop production. Thus, our goal was to investigate whether widening the spacing of irrigated furrows will relieve waterlogging and improve corn productivity. The effects of furrow irrigation spacing on corn grain yield and quality were investigated for three years at a research station and a commercial farm. Widening furrow irrigation spacing up to 8 m never decreased corn grain yield, and higher corn yields were documented in 8 m furrow spacing compared to narrower irrigation spacing. Irrigation water was found to spread underground at least 4 m perpendicular to the irrigated furrow and refill the soil from the bottom up. As irrigation spacing widened, water flow accelerated through the field and infiltration was reduced, especially for the soil away from the irrigated furrow. This suggests irrigation water savings of up to 30 % from adopting wide-spaced furrow irrigation in vertisols.

L'influence du vétiver sur le devenir des polluants métalliques (Cu et Cd) et organique (insecticide : endosulfan) dans le système sol-eau-vétiver a été étudiée dans deux sols représentatifs du Burkina Faso, un sol vertique et un sol ferrugineux. Des études d'adsorption en batch, des essais en vase de végétation en conditions contrôlées et en lysimètres en conditions naturelles ont été réalisées. Les sols plantés au vétiver montrent des coefficients d'adsorption (Kf) de l'endosulfan significativement plus élevés comparés à ceux des sols non plantés. En vases de végétation, le temps de demi-vie estimé de l'endosulfan dans les sols plantés est 1,1 fois moins important comparé aux sols non plantés, en relation avec l'augmentation significative de la microflore dégradant l'endosulfan en présence du vétiver. Par ailleurs, les teneurs en Cu et Cd dans le vétiver sont significativement plus élevées pour le sol ferrugineux que pour le sol vertique 6 mois après traitement. Le coefficient d'absorption biologique (CAB) de Cu et Cd et leurs facteurs de bioconcentration (FBC) et de translocation (FT) supérieurs à 1 dans le vétiver démontrent son efficacité à absorber et à accumuler Cu et Cd. En conditions extérieures, 6 mois après le traitement, les quantités lessivées de Cu sont très faibles pour l'ensemble des colonnes. Pour les sols plantés au vétiver, les quantités lessivées d'endosulfan et de Cd sont plus de deux fois inférieures à celles des sols non plantés, en relation avec leur adsorption plus élevée et la dégradation favorisée de l'endosulfan dans les sols plantés. / The influence of vetiver on the fate of two heavy metals (Cu and Cd) and an insecticide (endosulfan) in the soil-water-vetiver system was studied in two representative soils of Burkina Faso, a vertisol and a lixisol. Batch adsorption coefficient measurements, pot and leaching experiments, under phytotronic and outdoor conditions, respectively, were conducted. For both soils, adsorption coefficient values (Kf) of endosulfan, Cu and Cd were higher on planted soils than on unplanted soils. In the pot experiments, the estimated endosulfan half-life (DT50) in planted soils was 1.1-fold lower compared to unplanted soils, in accordance with the significant increase of the microflora degrading endosulfan in planted soils. Moreover, the Cu and Cd contents in vetiver grass were significantly higher for the lixisol than for the vertisol. The biological absorption coefficient (BAC), the bioconcentration and translocation factors (BCF and TF, respectively) of Cu and Cd were greater than 1 in vetiver, that showed the efficiency of vetiver to absorb and accumulate Cu and Cd. In outdoor conditions, 6 months after treatment, the leached Cu amounts were very low for all columns. In the presence of vetiver, the Cd and endosulfan leached amounts were more than 2-fold lower than those of unplanted soils, related to their higher adsorption and the faster degradation of endosulfan in planted soils.

L'objectif de cette thèse est d'améliorer les connaissances sur les processus et les facteurs de contrôle des flux d'altération chimiques à l'échelle d'un petit bassin versant tropical (Mule Hole, Inde du Sud). Le rôle de la minéralogie et du climat est étudié grâce à la modélisation. Dans la première partie du travail, les sols (fersialsols, vertisols) et la roche mère (gneiss) sont caractérisés minéralogiquement et chimiquement afin de procéder, dans la seconde partie, à la modélisation des processus. Le modèle géochimique est couplé avec un modèle hydrologique. Premièrement, les processus actuels sont étudiés. Le modèle est calibré grâce à la composition chimique du ruisseau et de la nappe. Les flux d'altération à l'échelle du bassin sont reproduits. Ils mettent en évidence le rôle prépondérant de l'altération des smectites (5% volumique dans les sols) sur le bilan d'altération du bassin. Finalement, des tests de sensibilité à la minéralogie et au climat sont réalisés.

Soil hydraulic properties, such as saturated hydraulic conductivity (Ks), have high spatial variation, but little is known about how to vary a few measurements of Ks over an area to model hydrology in a watershed with complex topography and multiple land uses. Variations in soil structure, macropores (especially in soil that shrink and swell), land use, and soil development can cause large variations in Ks within one soil type. Characterizing the impacts of soil properties that might vary systematically with land use and terrain attributes on Ks rates would provide insight on how management and human activity affect local and regional hydrology. The overall objective of this research was to develop a strategy for using published infiltration and Ks measurements by the Natural Resources Conservation Service for watershed hydrology applications in a Vertisol, and to extend this knowledge toward developing recommendations for future infiltration measurements. To achieve this goal, soil infiltration measurements were collected across three catenas of Houston Black and Heiden clays (fine, smectitic, thermic Udic Haplusterts) under three land uses (improved pasture, native prairie, and conventional tillage row crop). Measurement locations were selected to account for variation in terrain attributes. Overall, Ks values were not significantly different across different landscape positions; however, in fields under similar land uses, Ks values were found to be lower in the footslope positions and higher in the backslope positions. The pedotransfer function, ROSETTA, provided estimates of 64 percent of the overall variability in Ks while also providing accurate estimates of the mean of Ks when particle size distribution and bulk density are used as inputs in the model. Through the use of multiple regression analysis, soil antecedent water content, bulk density, clay content, and soil organic carbon along with two indicator variables for the catenas were highly correlated (r2 = 0.59) with Ks. The indicator variables explained 17 percent of the variation in Ks that could not be explained by measured soil properties. It is recommended that when NRCS measures Ks on benchmark soils, especially high clay soils, that they collect particle size distribution, bulk density, organic carbon, and antecedent water content data.

Vertisols cover a hydrologically very significant area of semi-arid regions, and thus understanding of water flow and solute accumulation is very relevant to agricultural activity and water resources management. Previous works suggest a conceptual model of desiccation-crack-induced salinization where salinization of sediment in deep section of the vadose zone (up to 4 m) is induced by subsurface evaporation due to convective air flow in desiccation cracks. This thesis presents a conceptual model of water flow and solute transport in vertisols, and its numerical implementation. The model uses a single-porosity material but unconventionally prescribes a boundary condition representing a deep crack in soil and uses the unsaturated hydraulic conductivity as one of the fitting parameters. The numerical model is bound to one location close to a dairy farm waste pond, but the application of the suggested conceptual model could be possibly extended to all semi-arid regions with vertisols. Simulations were conducted using several modelling approaches with an ultimate goal of fitting the simulation results to the controlling variables measured in the field: water content, and chloride salinity of pore water. The development of the model was engineered in numerous steps; all computed as forward solutions by...

The archaeological literature warns against trusting the context of artifacts found within a vertisol due to the constant mixing of sediments caused by the shrink/swell properties of clays. These churning processes were thought to be the defining characteristic of vertisols until only the past few decades. It is now apparent that vertisols vary drastically based on a wide spectrum of variables and are fully capable of forming without churning processes. The Buttermilk Creek Site, Block A represents a prime example of a minimally developed vertisol. In addition, the site itself is a heavily occupied lithic quarry that has been almost continuously inhabited since Clovis and possibly Pre-Clovis times. This thesis takes a detailed look at the sediments and distribution of lithic artifacts from Block A of the Buttermilk Creek site to address the two following research objectives: 1) to determine if the archaeological context within the floodplain sediments at Block A has been disturbed by post-depositional processes, and 2) to identify discrete occupation surfaces within the vertic floodplain sediments at the site. These objectives are addressed using a variety of methods, including: 1) plotting the stratigraphic position of diagnostic artifacts, 2) determining the size distribution of debitage and artifact quantities throughout the floodplain deposits, 3) examining the distribution of cultural versus non-cultural lithic material, 4) recording the presence or absence of heat alteration in the deposits, 5) creating maps showing the degree of fissuring across the site, 6) analyzing differences in patination on artifacts, and 7) analyzing the presence of calcium carbonate on artifacts from all levels. Results from these analyses show that, despite the classification of sediments at Block A as a vertisol, vertical displacement of artifacts is largely absent. Chronologically ordered diagnostic points, consistently size sorted artifacts, and a lack of constant mixing of calcium carbonate throughout the profile suggest that artifacts found as deep as 20 cm below the Clovis-aged horizon represent intact cultural horizons. These oldest components found in Block A may represent some of the earliest known evidence of people in the New World.

No description available.