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The adsorption isotherm of zinc and the kinetics of the adsorption and desorption of zinc by the short-range ordered oxide of iron, which was formed both in the absence and presence of citric acid, were studied. The results showed that the presence of citric acid, one of the most common organic ligands in soil, during the precipitation of Fe oxide substantially modified the characteristics of surface...
Pedogenesis was investigated on soils which were rehabilitated following mining of Late Pleistocene sand dunes at Tomago, on the east coast of Australia. The soils were rehabilitated by spreading stockpiled A1 horizon material over mixed A2 and B horizon materials from the original humus podzols. A four stage chronosequence of 1, 5, 11, and 17 years since soil rehabilitation was established and changes...
Soils with plinthite and ironstone concretions are extensive in Maranha˜o State, northeastern Brazil. They formed from the Fe-rich Itapecuru sandstone in a tropical subhumid climate with distinct wet and dry seasons. Most plinthic soils in Brazil have properties associated with low-activity clays, but these soils were reported to have properties associated with high-activity clays.The main objectives...
The degree of weathering was investigated in four sandy soils at Hjelm Hede in northwest Jutland, Denmark. Previous studies showed that the degree of podzolisation was influenced by vegetation as follows: Quercus robur (oak) < Calluna uulgaris (heather) < Picea sitchensis (spruce). This study shows that the soil under grass is the least podzolized. The data show that the particle size and mineralogy...
The Hedley fractionation recognizes plant-available forms (Resin Pi, Bicarb Pi, and Bicarb Po) and refractory forms (NaOH Pi, NaOH Po, sonic Pi, sonic Po, HCl Pi, Residual P) of soil phosphorus. This updated survey of the recent literature shows that the sequential fractionation proposed by Hedley et al. can also be used to separate forms of organically bound soil phosphorus from the geochemically...
Neoformation of allophane, imogolite, and gibbsite has been studied extensively in soils in humid climates, but little is known about their micro distribution patterns. such information may provide insight about the conditions at the micro-site scale, responsible for their formation and disappearance.Our study describes amorphous and crystalline coatings in a Melanudand on a 18,000 yr old andesitic...
This article presents a review of applications of computed tomography (CT) in soil science and petroleum engineering. We discuss the use of CT images to obtain quantitative expressions for soil structure. We elucidate this approach with a case study of an infiltration experiment in an undisturbed clay soil. The clay sample was scanned in initially dry condition and after infiltration of water with...
The mineralogical composition of the 2–20 μm silt fraction from two soil profiles, developed upon loessial sediments in the southern Chaco region of Argentina, was studied by means of X-ray diffractometry, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). These fine silts from the Chaco region contained more quartz and less feldspar and glass than those pointed oit for...
Existing pools of soil chemical data may be used in the investigation of conceptual models about soil chemical processes. Data from more than 2000 soil samples from German forests were pooled and interpreted to establish parameter relations that are related to soil acidification. A saturated water extract and an extraction of exchangeable cations by ammonium chloride were used. Activities in the soil...
The rates of chemical weathering within forested catchments as reported in the literature have been determined principally from input-output budgets, with outputs being measured as streamflow at a weir. In the present study an alternative method has been investigated which uses natural chloride as a tracer and does not require construction of a weir. It is shown that estimates made of weathering release...
The micromorphology and elemental composition of celestobarite crystals in a duripan from central Australia are examined. These crystals are flabellate (fan-shaped), have a Ba/Sr ratio of 11.1, and are up to 50 μm in size. The location of the celestobarite crystals within silicified roots and in close association with calcite and clay coatings indicates that these celestobarite crystals are authigenic...
The influence of microbial surfaces in the formation of short-range ordered aluminosilicates of allophanic composition was studied in the presence of citric, tannic and fulvic acids (FA) and two metals (Cd and Zn). In all bacterial cases, the pH was raised from an initial value of 4.5 to close to neutrality (6 to 7), and the bacteria produced a mineral phase in which a higher proportion of silicate...
Changes in tensile strength with clay type, clay particle size, and amounts of spontaneously and mechanically dispersible clays were assessed for dry, remoulded samples of eight Australian Vertisols and Alfisols varying in clay mineralogy. The effects of different clay content and particle size on tensile strength were also measured. The average particle sizes of whole clay, and of spontaneously...
The potassium supplying capacity of soils formed on three geological deposits along an east-west transect in the Niger Delta region of Nigeria was investigated by determining the various forms of soil K and K uptake by repeated maize croppings in pots. Soils (Inceptisols and Entisols) formed on recent alluvial materials of the Meander Belt deposits (MBD) had mica and feldspars resulting in very high...
Four large lysimeters on the San Dimas Experimental Forest, each filled with similar parent material and planted with monocultures of native species in 1946, provide a unique opportunity to quantify short-term effects of plant species on soil properties. The four species under which soils were investigated are scrub oak (Quercus dumosa Nutt.), chamise (Adenostoma fasciculatum Hook. and Arn.), ceanothus...
Soils with relatively sandy topsoils over clayey subsoils are widespread, but their genesis is not always clear. We tested the hypothesis that earthworms stimulate the formation of the sandy surface soils by producing clay-rich worm casts that are susceptible to erosion, in an undisturbed forested watershed in southwestern Ivory Coast. Soils of the watershed were strongly weathered and acidic. ...
The knowledge of the unsaturated hydraulic conductivity is one of the prerequisites to describe water flow and solute transport in soils. In this paper we examined the quality of 11 different theoretical models to predict the unsaturated hydraulic conductivity for a wide variety of soils. The hydraulic conductivity models were fitted to 44 measured curves using a quasi Newton parameter estimation...
Soil development, particularly in relation to relative age of geomorphic surfaces, was studied in a high-altitude valley on the semi-arid western side of the Andes in southern Peru. Seven major fluvial surfaces in the Colca Valley were recognized, including floodplains, stream terraces, and fans associated with the Rio Colca and its tributaries. Soils were also briefly examined on Pleistocene andesite...
Movement of mineral dust by the atmosphere has been underway for ages, but efforts to assess its magnitude and significance have come largely in the last century. Attempts to identify and understand effects of the dust on soils are even more recent, mostly in the last 30 years. Airborne movements have several forms. Dust is transported by large storms that can be spectacular. Dust is also moved...
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