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Soil development along an elevational transect on the western slopes of the central Sierra Nevada was investigated to assess the effects of climate on soil properties and processes. The transect of seven soils formed in granitic residuum spans elevations from 198 to 2865 m with mean annual temperature and precipitation differences of 13°C (3.9-16.7) and 94 cm (33-127), respectively. Soil pH decreased...
We studied a chronosequence of three soils developed on andesitic lavas in humid tropical Costa Rica, in order to investigate mineralogical development and to evaluate the importance of time versus other soil forming factors. Morphological, chemical, and mineralogical methods were used to unravel evolution of the soils. Primary minerals in the <1-m deep, 2000-year-old Fulvudand show increasing...
The determination of the types and relative amounts of the minerals present in soil forms an essential component of most soil characterization efforts. This paper reviews protocols for XRD-based quantitative clay mineral analysis in soils, with emphasis on methods using mineral intensity factors in combination with the so-called 100% approach. We summarize methodological differences and characteristic...
The páramo soils of the mountainous upper Andean region (>3300 m a. s. l.) of the Rio Paute basin in central Ecuador are characterized by a thick, dark, highly organic epipedon and are classified as Andosols and Histosols. Their high water retention and buffering capacity play a key role in the hydrology of the region, which is subject to land use changes and increased cultivation. In the west...
Soil sterilisation with steam under pressure and additives, such as CaO or KOH that react exothermically in water, is an alternative technology to fumigants. The influence of soil sterilisation (system ‘Bioflash’, Ecoflash SC 600) on the chemical behaviour of organic matter, heavy metals (Cd, Cu, Zn and Pb) and clay mineralogy was investigated on three typical soil materials (Ap horizons) with different...
The variability of the clay mineralogy in the topsoil of agricultural fields has rarely been examined, although it is important to the construction of accurate potassium (K) availability models. The variability of clay mineralogy and the relationship to plant available nonexchangeable K (Step K) were examined in two steep-land fields in the southern North Island of New Zealand. The soils at the sites...
There has been growing interest in the use of diffuse infrared reflectance as a quick, inexpensive tool for soil characterization. In studies reported to date, calibration and validation samples have been collected at either a local or regional scale. For this study, we selected 3768 samples from all 50 U.S. states and two tropical territories and an additional 416 samples from 36 different countries...
Combining global soil-spectral libraries with local calibration samples has the potential to provide improved visible and near-infrared (VNIR, 400–2500 nm) diffuse reflectance spectroscopy (DRS) soil characterization predictions than with either global or local calibrations alone. In this study, a geographically diverse “global” soil-spectral library with 4184 samples was augmented with up to 418...
The relationship and mechanisms among weathering processes, cation fluxes, clay mineralogy, organic matter composition and stability were studied in soils developing on basaltic material in southern Italy (Sicily). The soils were transitions between Phaeozems and Vertisols. Intense losses of the elements Na, Ca and Mg were measured indicating that weathering has occurred over a long period of time...
Most models of soil humic substances include a substantial component of aromatic C either as the backbone of humic heteropolymers or as a significant component of supramolecular aggregates of degraded biopolymers. We physically separated coarse (0.2–2.0 μm e.s.d.), medium (0.02–0.2 μm e.s.d.), and fine (>0.02 μm e.s.d.) clay subfractions from three Midwestern soils and characterized the organic...
Stable isotope geochemistry is a unique technique to study the source of salts in soils and sediments. In the present research, sources of gypsum and other sulfur bearing minerals using stable isotope technique and clay mineralogy were studied in different landforms in Loot Desert, central Iran. Four geomorphic surfaces including Neogene conglomeratic formations, reg surfaces, yardangs, and Kaleshoor...
The relationship between soil aggregation at the silt-size scale, and soil organic C dynamics has scarcely been studied. In this work, we developed a fractionation protocol comprising complete dispersion of the fraction >50 μm of the original soil sample, and subsequent size and density fraction of the <50 μm fraction to isolate stable aggregates from the silt-size fraction of a silty cultivated...
In bisequal soils a complex combination of pedogenic processes has occurred and the minerals that arise from a specific soil forming process may have been modified by other processes. In this work we investigated the mineralogical composition of the clay fraction and related it to pedogenic processes in three soils of the Russian Taiga. The soils showed evidences of clay translocation, podzolisation,...
In volcanic soils of the Solofrana valley (south-western Italy), contamination by Cr and Cu occurs as a consequence of agricultural practices and surface deposition of polluted river sediments by periodic floods. In this study, the metal distribution in micromorphological features and clay fractions (<2.0µm and <0.1µm) of two selected soil profiles were investigated by microscopical (OM) and...
Boreal forests are one of the most important terrestrial carbon sink, and a large portion of C is allocated in soil for long-term storage. However forest harvesting may quickly affect soil carbon stocks and dynamics, especially where organic substances drive the soil-forming processes, such as in Podzols. To evaluate the effects of clear cutting on carbon dynamics and podzolisation process over a...
The influence of Macrotermes falciger activity on clays, sesquioxides and water-dispersible clay (WDC) content was investigated by a physico-chemical, mineralogical and micromorphological study of termite mound and control soil profiles at various sites near Lubumbashi, SE Katanga, D.R. Congo. X-ray diffraction reveals that the termite-mound materials are enriched in 2:1 clays, especially mica and...
Eight surface soil samples representing three soil orders viz., Inceptisols, Alfisols and Entisols were analyzed to characterize the non-exchangeable potassium (K) reserves. The mineralogical composition of the experimental soils varied widely. The reserves of Step-K and Constant rate K were computed by repeated extraction of soils with boiling1M HNO 3 . The cumulative release of non-exchangeable...
Sorption of organic carbon onto phyllosilicate clays and hydrous iron oxides influences the accumulation and stabilisation of organic carbon in soils. However, the effects of interactions between hydrous iron oxides and phyllosilicate clays on the sorption of dissolved organic carbon (DOC) are poorly understood. We carried out a batch experiment to examine the effects of goethite coatings on kaolinite,...
Planosols, characterised by a bleached, silt-textured surface horizon abruptly overlying a dense, clayey subsoil, are a very common soil type in Ethiopia. The origin of the abrupt textural change is still often debated in literature. One of the processes frequently put forward to explain the coarse textured material in the topsoil is ‘ferrolysis’: an oxidation–reduction sequence driven by bacterial...
The soils on four lithologies (basaltic conglomerates, Bohio; Andesite; volcanoclastic sediments with basaltic agglomerates, Caimito volcanic; foraminiferal limestone, Caimito marine) on Barro Colorado Island (BCI) have high exchangeable Ca concentrations and cation-exchange capacities (CEC) compared to other tropical soils on similar parent material. In the 0–10cm layer of 24 mineral soils, pH values...
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