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Since water dispersible colloids (WDC) influence many aspects of soil processes, development of a better understanding and characterization of this soil fraction is necessary. This study involved the fractionation of WDC from 6 soil samples with diverse physicochemical and mineralogical composition and the evaluation of soil and colloidal properties affecting colloid dispersibility from soil aggregates...
Evidence in the literature supporting the hypothesis that inputs of sea salts from the atmosphere increase soil pH and exchangeable Na + and Mg 2+ concentrations in soils in which the release of base cations by mineral weathering is slow is briefly reviewed. It is postulated that if a sea salt effect indeed occurs, long-term incubation of such soils in a field moist state should result...
A fuzzy logic based model (called a similarity model) was developed to represent soil spatial information so that soil landscape is perceived as a continuum in both the parameter space and the geographic space. The similarity model consists of two components: the similarity representation component and a raster representation scheme. The similarity representation component uses a set of prescribed...
Magnetic resonance imaging (MRI) allows non-destructive and non-invasive measurement and visualisation of both static and dynamic water phenomena. Flow and transport processes can either be measured by following the local intensity in time-controlled sequential images, by mapping the effect of contrast agents or labelled molecules, or by mapping the (proton) displacement in a well known time interval...
Stable carbon and oxygen isotopes in soil carbonates provide an additional technique for investigating Quaternary ecogeomorphic changes in arid and semiarid regions. This study presents δ 13 C and δ 18 O values in surface and buried soils in a Basin and Range region of southern New Mexico and west Texas. Three landform categories were investigated for their isotopic content:...
The 18 O/ 16 O and D/H ratios of the structural oxygen and hydrogen of naturally occurring clay minerals carry information about the conditions under which the minerals formed. Clays generally form in isotopic equilibrium with the environment, and hence have isotopic compositions that reflect the temperature of formation and the 18 O/ 16 O and D/H...
The diffusion potential method was used to determine the Isoelectric Point (IEP) of the surface horizons of five soils (Typic Hapludoll, Typic Argiudoll, Vertic Argiudoll, Rhodic Kandiudalf and Lithic Kandihumult) in the following conditions: without treatment (natural), homoionized with K + (K + -soil) or Ca 2+ (Ca 2+ -soil) and after organic matter (OM)...
Global methane (CH 4 ) budgets depend on both CH 4 sources and sinks. We investigated CH 4 sink strength of cultivated Canadian prairie and forest soils using undisturbed soil columns and an incubation technique in the laboratory. The sink strength was estimated by determining the rate of CH 4 uptake by soils with variations in volume of air-filled soil voids, temperature...
Image analysis of photographs of surface cracks in cultivated soils for a variety of types (Vertisol, Andosol, Mollisol), and surface cracks in mud deposits shows various similar geometric characteristics. Analysis of the skeletal structure of these crack networks indicates that the relations of intersections and numbers of crack segments show a tendency to lie between those of square and hexagonal...
Analysis of sorption data is important for characterizing retention of chemicals by soil. In this paper I review the most common isotherm equations used in soil science. The mathematical descriptions of these equations are classified into rational, power, and transcendental functions which are related to the isotherm classification. I use most well-known isotherm equation as special cases of a general...
Phosphate adsorption and desorption studies provide insight for developing P management strategies. Very few studies have concentrated on P desorption which provides information on the reversibility of adsorbed P. Phosphate adsorption and desorption studies were carried out on seven rice-growing soils from three countries in West Africa, with the objective of relating these processes to P management...
Laser Induced Breakdown Spectroscopy (LIBS) is a recent analytical technique that is based upon the measurement of emission lines generated by atomic species close to the surface of the sample, thus allowing their chemical identification. In this work, the LIBS technique has been applied to the determination of total contents of heavy metals in a number of reference soil samples. In order to validate...
For the first time a method is presented to study the distribution of metals between humic and fulvic fractions in natural soils. Total organometallic complexes are separated by extraction with 0.1 M pyrophosphate. After acidification to pH 1.5 with H 2 SO 4 the fraction associated with humic acids is separated by precipitation and the remaining solution contains the complexes associated...
Fractal geometry concepts have been widely applied as a tool for describing complex natural phenomena, in particular, in mechanics and physics of rocks and soils. The introduction of scaling has allowed a fractal representation of particle-size distributions (PSDs) of geological materials. In many cases, both log-linear and nonlinear regressions on empirical data have showed a clear deviation from...
Considering that the reflected electromagnetic energy from a soil sample interacts with many of its components (mineralogy, texture and chemical properties), remote sensing can be important to detect the presence of industry residues in the soil. An example of these residues is the largely used vinasse, originated from the production of ethanol by fermentation of sugarcane. Therefore, the objective...
The proposed mathematical model consists of a first approach to estimate the soil composition from an experimental titration curve and the quantitative analysis of the soil mineral constituents.Mineral mixtures made using different percentages of kaolinite, illite and quartz were used to simulate a natural porous media and evaluate the proposed mathematical model assuming no interaction among the...
Isotopic signatures of soil components are commonly used to infer past ecologic and climatic shifts in the soil record. The theory behind the fractionation of isotopes that occurs during ecosystem processes is well understood; however, few isotopic studies have explored ecosystem relationships in modern soils. We discuss relationships of stable carbon isotopic signatures in plant tissue, soil organic...
This work consisted of determining the degree of humification of humic substances (HS) extracted from six different Amazonian soils collected from flooded and unflooded regions at different depths (0–10, 10–20, 20–40, and 60 cm). The humic substances were extracted according to procedures recommended by the International Humic Substances Society and characterized using elemental analysis, electron...
The lipid fraction of organic matter can serve as a diagnostic index of soil biological activity. Total lipid fractions isolated from Siltic Albeluvisol, Silti-Stagnic Albeluvisol and Stagni-Histic Albeluvisol (Siltic) were studied to determine the effect of soil moisture on the contents and molecular patterns of lipids. Using CPMAS 13 C NMR spectroscopy, lipids extracted in alcohol–benzene...
Occurrence of gypsum in soils from loess of the Central-German Chernozem region indicates that local climatic conditions with low precipitation (average <500 mm a −1 ) and a real evaporation between 450 and 460 mm do not allow leaching of weakly soluble gypsum from soils. At a site close to the strip mine Etzdorf, gypsum is accumulated in the Ck-horizon of a Haplic Chernozem down to a depth...
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