Diverse Parent Materials Research Articles

The Fe/Na ratio, a framework for modelling trace element distributions in Jamaican soils

The trace element geochemistry of Jamaican soils (<150 μm) is extremely variable due to their development on diverse parent materials, varying maturity (ages range from recent to >5 Ma) and the variety of soil-forming processes. It is demonstrated that the Fe/Na ratio of the soils forms a useful quantitative framework for studying trace element distributions. The ratio varies 2.5 orders of magnitude from <2 in newly developed inceptisols to >500 in oxisols and terra rossas that have been developing for >5 Ma. The form of the trace element distributions with respect to Fe/Na ratio may be interpreted in the context of mineralogy of the parent material, removal of labile trace element fractions during soil development, sequestration in stable secondary forms, and ultimate concentration of stable primary resistate and secondary minerals by terra rossa soil formation processes that lead to elevated Fe and Al levels and the depletion of silica and base cations, Ca 2+ , Mg 2+ , Na + and K + . As examples, the distributions of U and As are modelled as functions of the Fe/Na ratio. Use of robust regression procedures identifies individual soil samples that exhibit divergent patterns of trace element concentration. Some of these can be linked to local bedrock sources, while others are more likely related to exotic volcanic ash-fall material from Central America deposited on proto-Jamaica in the late Miocene.

Poorly crystalline mineral phases protect organic matter in acid subsoil horizons

SummarySoil minerals are known to influence the biological stability of soil organic matter (SOM). Our study aimed to relate properties of the mineral matrix to its ability to protect organic C against decomposition in acid soils. We used the amount of hydroxyl ions released after exposure to NaF solution to establish a reactivity gradient spanning 12 subsoil horizons collected from 10 different locations. The subsoil horizons represent six soil orders and diverse geological parent materials. Phyllosilicates were characterized by X‐ray diffraction and pedogenic oxides by selective dissolution procedures. The organic carbon (C) remaining after chemical removal of an oxidizable fraction of SOM with NaOCl solution was taken to represent a stable organic carbon pool. Stable organic carbon was confirmed as older than bulk organic carbon by a smaller radiocarbon (14C) content after oxidation in all 12 soils. The amount of stable organic C did not depend on clay content or the content of dithionite–citrate‐extractable Fe. The combination of oxalate‐extractable Fe and Al explained the greatest amount of variation in stable organic C (R2 = 0.78). Our results suggest that in acid soils, organic matter is preferentially protected by interaction with poorly crystalline minerals represented by the oxalate‐soluble Fe and Al fraction. This evidence suggests that ligand exchange between mineral surface hydroxyl groups and negatively charged organic functional groups is a quantitatively important mechanism in the stabilization of SOM in acid soils. The results imply a finite stabilization capacity of soil minerals for organic matter, limited by the area density of reactive surface sites.

Dust accumulation in the New Zealand region since the last glacial maximum

Loess is widespread in New Zealand; deposits >1 m thick cover 10% of the land area. It has mainly been derived from dust deflated from river floodplains during the last glacial maximum (LGM). Dust accumulation continues today downwind of major river floodplains. Most loess is quartzofeldspathic, having its origins in Mesozoic and Neogene rocks of the axial ranges and hill country. In the central North Island there are deposits of volcanic loess derived from aeolian reworking of tephras. Loess morphology and properties vary greatly due to diverse parent materials, post-depositional climates and drainage conditions. The widespread 26,170 cal. yr Kawakawa Tephra provides a datum for calculating mass accumulation rates (MARs). Rates are mostly within the range 70–150 g m −2 yr −1, but enhanced deposition at one site gave a rate of 360 g m −2 yr −1. Contemporary MARs of 40–100 g m −2 yr −1 were determined for distances of 1.75–0.4 km downwind of the Rakaia River. LGM MARs of quartz for two marine cores (P69 & Q858) drilled 100–300 km east of New Zealand are 40–70 g m −2 yr −1. The MAR of the aeolian component of P69 is estimated to be ca 15 g m −2 yr −1.

Properties of soil kaolins from Thailand

AbstractPurified kaolins from Thai soil on diverse parent materials were characterized using analytical transmission electon microscopy, X-ray diffraction, thermogravimetric analysis and chemical analysis. The properties of Thai soil kaolins appear to be more diverse than Indonesian and Western Australian soil kaolins investigated using the same analytical procedures; this difference may reflect the greater range of parent materials for the Thai soils. The kaolins show a variety of crystal morphologies including euhedral hexagonal to subhedral platy crystals, tubes and laths and several morphologies were present in most samples. TEM-EDS enabled analysis of single crystals of each morphology present within a sample. Tubular or lath-shaped crystals usually have lower %Fe2O3 contents than hexagonal platy crystals in the same sample. The relationships between crystal size and Fe content within morphological populations were also examined by TEM-EDS. Generally, smaller kaolin crystals display a wider range of Fe concentration than the larger kaolin crystals in the same sample. Increasing Fe concentration in bulk samples is closely correlated to decreasing coherently scattering domain size (R2= 0.57), increasing cation exchange capacity (R2= 0.44) and increasing specific surface area (R2= 0.65). However the properties of the deferrated soil kaolins, including their Fe content, are not related to forms of Fe, (total Fe, amorphous or organic) in the untreated clay fraction of the soil.Inhibited vermiculite is a common minor constituent of these clay fractions and its average structural formula derived from EDS data indicates that it was formed by Al replacing K in muscovite. One Al3+ion occupies the interlayer space previously occupied by three K+ions. As the distances between these Al3+cations in the interlayer space is large it is proposed that isolated or loosely associated hydrated Al3+groups such as Al(OH2)63+exist that resist exchange by other cations due to hydrogen bonding with the adjacent tetrahedral oxygen surfaces

Propensity of Soils to Develop Redoximorphic Color Changes

Most soils with seasonally high water tables exhibit redoximorphic features, such as Fe depletions and concentrations. Some soils formed from red parent materials apparently are less typical in their behavior and have in this sense been described as problematic. Regulatory guidelines have mentioned such problematic red soils, and the Field Indicators of Hydric Soils in the United States attempts to address the issue by using test indicator TF2. This study was undertaken in an attempt to develop an approach for quantifying the inherent tendency of soils to form redoximorphic features under reducing conditions. Thirty soils from diverse parent materials in the Mid‐Atlantic region was studied, including 13 thought to be problematic soils formed from red parent materials. Samples were treated using a citrate‐buffer and Na dithionite at room temperature (25°C) for periods of time ranging from 0.5 to 72 h, and also at 80°C for 4 h. Colors were measured using a digital colorimeter to document changes in Munsell hue, value, and chroma. By comparing initial soil colors with those measured under the treatments of 25°C for 1 h and at 80°C for 4 h, a color change propensity index (CCPI) was developed that effectively discriminated between soils which were and were not thought to be problematic. The utility of the CCPI was tested using 14 additional soil samples, six of which came from outside the Mid‐Atlantic region. Recommendations are made to differentiate between problematic and nonproblematic soils based on values of CCPI.

Evaluation of organic carbon oxidation efficiencies of a modified wet combustion and Walkley‐black procedures in Nigerian soils

The organic carbon (C) oxidation efficiencies of the Walkley‐Black and modified wet combustion procedures were evaluated in soil samples taken from different ecological zones and diverse parent materials in Nigeria. Dry combustion using a C analyzer was the standard to evaluate the efficiency of the modified wet combustion method. The efficiency of the Walkley‐Black method was later compared to that of the modified wet combustion procedure. The results indicated that the modified wet combustion and the dry combustion procedures were highly correlated (r=0.99**)‐Significant correlation (r=0.96**) was also found between the Walkley‐Black and the modified wet combustion procedures. There was no correlation between the C data obtained using the modified wet digestion method and the % DCB‐Fe2O3. These results suggest the absence of strong organo‐mineral complexes in these soils. Organic C recoveries by the Walkley‐black method were not affected by fine‐grinding (<0.5 mm) of the soil samples. It is suggested that both the modified wet combustion and the Walkley‐Black methods may be used without a correction factor in Nigerian soils. The modified wet combustion procedure was also found to be an adequate substitute for the dry combustion procedure.

The vesicular layer and carbonate collars of desert soils and pavements: formation, age and relation to climate change

The vesicular, fine-grained A horizon (Av) is the widespread, ubiquitous surficial horizon of desert soils in diverse landforms and parent materials of varying ages. Now known to form mostly through accumulation of eolian dust, recent studies show that dust accumulation and concomitant soil development are genetically linked to stone pavement formation. Changes in the magnitude of eolian activity and effective leaching related to Quaternary climatic changes are also hypothesized to have influenced the evolution of the Av horizon. Numerical modeling, geochronologic, and field/laboratory studies elucidate the nature of pedogenic processes controlling compositional evolution of Av, how the changing Av horizon increasingly influences soil infiltration and carbonate translocation and accumulation, and the control that clasts of the evolving pavement exert on pedogenic processes. Results of a model that determines soil bulk chemical composition based on mixing of estimated proportions of externally derived (eolian) material and parent materials imply that the evolution of the soil bulk composition is strongly influenced by Av horizon formation. The early development of a weakly to moderately developed Av horizon directly over gravelly parent material in late and middle Holocene soils moderately influences soil infiltration, but significant leaching of very soluble materials and some carbonate in dust are permitted. In older, Pleistocene soils, however, the texturally more mature Av and underlying, cumulic nongravelly horizons more strongly limit the rate and depth of leaching, and soil bulk composition therefore more closely approximates a simple mixture of dust and parent material. Other aspects of Av horizon development and its relations to the pavement are evaluated through studies of pavement clasts with coatings of soil carbonate, referred to as carbonate collars. Development of a numerical model that integrates soil hydrology, a CO 2 production–diffusion model, calcite kinetics and thermodynamic considerations, composition and thermal characteristics of pavement clasts and the textural and structural properties of the surface horizon provides the basis for testing a hypothesis of collar formation. Model results, combined with results of δ 13C and δ 18O analyses of collar carbonate, demonstrate how precipitation of calcite on pavement clasts and within the Av is favored at a depth much shallower than that indicated by the classic carbonate depth–climate relationship of Jenny and Leonard [Jenny, H.J., Leonard, C.D., 1935. Functional relationships between soil properties and rainfall. Soil Science 38, 363–381] and Arkley [Arkley, R.J., 1963. Calculations of carbonate and water movement in soil from climatic data. Soil Science 96, 239–248], or simulated by numerical models of carbonate accumulation. Simultaneous development of thick carbonate collars and the Av horizon requires the sustained pavement clast–Av horizon coupling for at least centuries to possibly millennia. New thermoluminescence ages also indicate that much of the Av horizon formed in the Holocene, and that it is certainly much younger than the older Pleistocene pavements. This supports the previously proposed hypothesis that increased dust flux during the Pleistocene-to-Holocene transition triggered and/or greatly accelerated Av horizon development. An understanding of the genesis of collars provides not just an understanding of how carbonate can accumulate in surface environments, but it also provides important clues into processes of pavement evolution and preservation of Av horizons during long glacial periods. The Av horizon is not merely an insignificant surficial zone of recent dust accretion; instead, its development profoundly influences the genesis of desert soils and pavements.

Effect of pH of ammonium oxalate extracting solutions on prediction of plant available molybdenum in soil

Abstract Molybdenum (Mo) is an essential element of plants and animals and is of concern from human nutrition and environmental standpoints. Rational applications to soil of Mo in fertilizers, sewage sludges, or other soil amendments requires information of the concentrations of Mo in soils and plants. Two greenhouse experiments were conducted at Lexington, Kentucky, using surface samples of 12 soils (11 soil types) derived from diverse parent materials in Kentucky with soil pH ranging from 5.18 to 7.46. Molybdenum (Na2MoO4.2H2O) was added at rates equivalent to 0, 0.3, and 0.6 mg Mo kg‐1 soil. Tobacco (Nicotiana tabacum L., cv. Ky14) and soybean [Glycine max. (L.) Merrill cv. McCall] were grown to provide plant Mo data for Mo soil test correlations and comparisons. The primary purpose of these investigations was to determine the effect of pH of NH4‐oxalate extractant solution on the relationship of soil Mo and Mo uptake by tobacco and soybeans, and to evaluate the automated KI‐H2O2 procedure for use in determining Mo in soil extracting solutions. The mean dry weight and Mo concentration of tobacco and soybean were increased by applications of Mo fertilizer to soil in the greenhouse. Dry matter of tobacco was increased 11 to 25% and concentration of Mo from 40 to 82% by each increment of added Mo fertilizer. The results of this study suggest that many soils in Kentucky are not meeting the requirements for Mo sufficiency for tobacco and soybean plants. The average amount of soil Mo extracted by NH4‐oxalate decreased with increasing pH of extractant. Regression estimates for the relationship of Mo uptake by tobacco or soybean and extractable soil Mo show that the slope and the coefficients of determination increased with pH of NH4‐oxalate solution from pH 3.3 to 6.0 and then decreased again at pH 6.4. The greatest amounts of variation in Mo uptake by plants (67% and 20%, respectively, for tobacco and soybean) were accounted for by the soil Mo data at pH 6.0. Soil Mo values for the NH4‐oxalate extractant (pH 6.0) were related to values for anion exchange resin extractant (r2 = 0.61**), but not soil pH. However, values for anion exchange resin were more closely related to Mo uptake by tobacco (r2 = 0.86**) and soybean (r2 = 0.60**) than were values for NH4‐oxalate (r2 = 0.65** and r2 = 0.27**, respectively). Results of this study indicate that the automated KI‐H2O2 method used previously in analysis for plant Mo can be used to analyze Mo in soil extracts. Other instrumentation such as GFAAS and ICP may be effective in the analysis of extracts obtained by the NH4‐oxalate (pH 6.0) or by anion exchange resin procedures when the Mo concentration of extracts falls within the detection limits of the instrument.

The eolian origin of silty mantle in sedentary soils from Korea and Japan

The concentration, particle-size distribution and oxygen isotope composition ( δ 18O SMOW) of quartz were examined in order to determine the extent to which the accretion of long-distance eolian dusts from the interior of China had formed the sedentary soils overlying diverse parent materials in Korea and Japan. The quartz content of the surface soils developed on quartz-free basaltic materials varies from 8.9 to 47.7%. Generally, the soil quartz found in surface horizons is finer than of the subsurface horizons and/or substrata. The particle-size of the soil quartz decreases from the west coast to eastern coastal margins of Korea and to the Japanese islands. This follows the major trajectory of westerly winds which carry the eolian dusts from the interior of China to mid-latitude regions of the North Pacific. The oxygen isotope composition of the fine quartz (1–10 μm in diameter) when separated from surface and subsurface horizons, is found in a relatively narrow range of + 15.9 to + 17.7‰ The values are indiscernible from those of recent eolian dusts from the interior desert and loess plateau of China. The δ 18O values from the same sized quartz found in C horizons, + 10.4 and + 19.2%, consisting of saprolitic andesites and shales, respectively, differ from those of the overlying soils. The δ 18O values of soil quartz developed on igneous materials systematically decrease with increasing particle-size to 53 μm (∼ 14%). They abruptly decrease to + 8 to + 12% for fractions larger than 53 μm. A large apparent oxygen isotope fractionation (up to 10%) - between fine (+ 17%) and coarse (+ 8 to + 12%) grained quartz observed in the samples - does not represent an equilibrium oxygen isotope fractionation for normal magmatic processes. The data provide evidence for an eolian origin of the fine quartz incorporated during soil development.

日本海沿岸の土壌および古土壌中に堆積したアジア大陸起源の広域風成塵

A long-range, tropospheric eolian dust transported from the Saharan desert and the Asian continent has been deposited on the terrestrial and aquatic environments in the northern hemisphere. Soil loss due to wind erosion in the arid and semiarid source areas is more significant than previously assumed. Global emission of desert dust and mineral aerosol material is estimated to amount to more than 1.0×106ton yr-1. Long-range eolian dust is an important factor in soil formation and nutrient input in many deposition areas. Physical, chemical, and mineralogical characteristics of long-range eolian dust derived from the Takla Makan and Gobi deserts and the Loess Plateau in China and their influence and significance to the soil and paleosol formations in Japan and Korea are reviewed in this paper.The long-range eolian dust in East-Asia was characterized by a predominance of soil particles 3 to 30μm in diameter. Their dominant minerals were 2:1 layer silicates, kaolinite, quartz, and feldspar. Nonallophanic andosols, red-yellow soils developed on limestones, basalts, and other diverse parent materials, and paleosols buried in paleodunes in the area along the coast of Japan Sea, were strongly influenced by the long-range eolian dust derived from China. Oxygen isotope abundance of the fine-grained quartz (1 to 10μm) isolated from soils revealed that fine quartz and 2:1 layer silicates in diverse soils and paleosols in Japan and Korea and pelagic sediments in the Japan Sea were of eolian dust origin. The eolian dust flux from the atmosphere to terrestrial environments in Japan is significant in the heavy snowfall area along the coast of Japan Sea and was more prominent in the last Glacial age than in the Holocene. Dust flux from East China Sea, Yellow Sea, and Japan Sea pelagic sediments dried during the marine regression period in the last Glacial age to soils and paleosols was also significant in Japan. Thus the desert dust phenomenon is of relevance to geophysical science in general, e. g. geography, geochemistry, climatology, soil science, ocean sedimentology, and Quaternary studies. Desert dust emission and long-range transport are useful indicators for dynamic change in the tonal circulation system, influencing the discussion of future climatic change.

The lead content of pasture herbage

AbstractOn soils in north‐east Scotland derived from quite diverse parent materials, including granitic gneiss, sandstone, slate and mixed acidic and basic igneous rocks, the normal lead content of rotational mixed pasture herbage during the period of active growth is between 0·3 and 1·5 ppm in the dry matter. In autumn, at a date possibly determined by the cessation of active growth and therefore by climatic conditions, the lead content of the above‐ground portion of the plant begins to rise, reaching 10 pprn in late autumn, and may reach 30‐40 ppm in late winter or early spring before growth recommences. At this stage, young shoots with a low lead content appear and the senescent foliage withers away. The increase in lead content of the above‐ground portion when the plant is dormant may indicate movement from the root rather than active uptake of lead from the soil. The possibility of surface contamination by petrolengine exhaust fumes or other industrial materials has been ruled out, and soil contamination of the herbage cannot account for the effect observed. The level of lead in pasture herbage in late winter appears sufficiently high to justify consideration of possible effects on the health of the animal consuming appreciable quantities during this period.