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David S Leigh - One of the best experts on this subject based on the ideXlab platform.
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soil morphology of an alluvial chronosequence from the little river north carolina coastal plain usa
2020Co-Authors: Bradley E Suther, David S LeighAbstract:Abstract A soil chronosequence on terraces of the Little River in the North Carolina Coastal Plain was characterized to evaluate age-related trends in pedogenesis. Five representative pedons per landform were studied from six late Quaternary fluvial surfaces, and temporal trends were assessed by regression of morphological parameters against previously reported terrace optical age estimates. Solum, B horizon, and Bt horizon thickness, subsoil clay content, and Buntley-Westin Index rubification have strong, positive correlations with age and together distinguish between soils of the floodplain (≤200 yr BP), the first terrace (9.9 ± 2.0 ka), intermediate surfaces (T2, T3b, T4; 17.4 ± 4.2–74.6 ± 10.4 ka), and the oldest terrace (T5b, 94.0 ± 15.9 ka). Over time, soils develop from Entisols with respective A-C and A-E-Bw-C profiles on the floodplain and first terrace to Ultisols with increasing argillic horizon thickness, rubification, and clay content on T2-T5b. Solum thickness, Bt horizon thickness, and clay content display linear increases through time, with soil thickening reflective of downward pedogenesis through permeable, coarse-grained alluvium. Increasing argillic horizon clay content is attributable to Illuviation, and possibly also to a combined bioturbation-translocation process, whereby clays scattered throughout sandy parent sediments are delivered to the surface by bioturbation, then concentrated in B horizons by eluviation-Illuviation. Rubification increases with age and reflects transformation and subsoil concentration of inherited free iron, rather than iron oxide formation from primary mineral weathering. T5b pedons display morphologies comparable to those of 200 ka to >1 Ma soils along Coastal Plain rivers that also drain the Appalachian Piedmont, probably because sandy, Coastal Plain-derived Little River alluvium has a higher hydraulic conductivity that promotes faster rates of downward weathering, clay translocation, and rubification than the more finely-grained sediments of Piedmont-draining rivers. Thus, textural differences related to sedimentary provenance should be recognized when interpreting chronosequences from the region. Although rates of pedogenesis differ among Coastal Plain alluvial soils, linear trends in the ≤100 ka Little River chronosequence may nonetheless correspond to the early, more linear phases of development in studies from the region that span much longer intervals of time.
D K Pal - One of the best experts on this subject based on the ideXlab platform.
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evidence of clay Illuviation in soils of the indo gangetic alluvial plains igp and red ferruginous rf soils
2019Co-Authors: D K PalAbstract:In the US system of soil classification, specific criteria are detailed out to define objectively the minimum evidence of clay Illuviation required for an argillic horizon, which are particle size distribution relative to an overlying horizon and either clay skins on ped surfaces or oriented clay occupying 1% or more of the cross section. These criteria are not infallible when applied in many soil types occurring in semi-arid (SAT) and humid (HT) tropical climates of India. Pedologists while working in the micaceous Indo-Gangetic Alluvial (IGP) soils of the north-western India have often experienced clay-enriched textural B-horizons however without the identifiable clay skins by a 10 x hand lens. On the other hand, some pedologists considered the textural B-horizons as argillic on the basis of increased clay and the presence of field-identifiable clay skins or void argillans (impure type) and some of them considered the clay enrichment due to the sedimentation processes, geogenic origins and in situ weathering of biotite particles.
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Clay Illuviation and Pedoturbation in SAT Vertisols
2018Co-Authors: D K PalAbstract:For a long time the apparent uniform distribution of clay throughout Vertisols was considered to be effect of haploidisation within the pedon caused by pedoturbation and in some cases the observed gradual increase in clay content with depth was thought to be due to inheritance from parent material. Recent systematic pedological studies on Vertisols that have no stratification in the parent material and no clay skins, indicated that their Bss horizons contain clay even up to 20%; an increase from the eluvial horizon. Such depth distribution of clay is due to clay Illuviation process was confirmed by micro-morphological investigation of the thin sections, which indicated the presence of >2% impure clay pedofeatures. Thus the clay enriched Bss horizons in Vertisols suggests that pedoturbation was too much favoured as an important pedogenic process in Vertisols by the past researchers till early nineties, who envisaged pedoturbation would obliterate all evidence of Illuviation. But in reality, pedoturbation in Vertisols is only a partially functional process, which cannot overshadow the more significant long-term clay Illuviation process. Although the micro-morphological study of soil thin sections is a unique analytical tool to confirm clay Illuviation process, for many of the national soil science laboratories it is truly a very distant facility. In its absence some simple analytical data are of much help in ensuring the clay Illuviation process with certainty as major pedogenic process in Indian Vertisols, which are described in this chapter.
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clay Illuviation in calcareous soils of the semiarid part of the indo gangetic plains india
2003Co-Authors: D K Pal, P Srivastava, Tapas BhattacharyyaAbstract:Abstract In view of diverse understanding on the movement and accumulation of clay particles in calcareous parent material, a micromorphological study on 28 Alfisols of the semiarid part of the Indo-Gangetic Plains (IGP) was undertaken. The study indicates that the identified clay pedofeatures are typically of the type “impure clay pedofeatures” which have resulted from the impairment of the parallel orientation of the clay platelets induced by dispersion of both clay and silt size layer silicates in slightly to highly sodic environment. The study also indicates that the Illuviation of clay particles and their subsequent accumulation in the Bt horizons have occurred in sodic environment caused by the precipitation of soluble Ca 2+ ions as calcium carbonate (CaCO 3 ), thus discounting any role of soluble Ca 2+ ions and the presence of CaCO 3 in preventing the movement and accumulation of clay particles. The study thus suggests that the formation of impure clay pedofeatures and pedogenic CaCO 3 are two pedogenic processes occurring simultaneously in soils of the IGP as contemporary pedogenic events in the semiarid climate since the last 4000 years B.P.
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evidence of clay Illuviation in sodic soils of the indo gangetic plain since the holocene
1994Co-Authors: D K Pal, A R Kalbande, S B Deshpande, J L SehgalAbstract:Many of the micaceous soils of the Indo-Gangetic alluvial plain of northwestern India are sodic and have clay-enriched textural B horizons. These soils sometimes lack identifiable clay skins. In order to determine the genesis of the textural B horizons of these soils, both with and without identifiable clay skins, one Natrustalf (Sakit soil) and one Aeric Halaquept (Rahamabad soil) were selected for study. The results indicate that (i) the parent material and the mineralogy of the clay fractions are uniform, thus discounting stratification; (ii) the clay in the B horizon is not formed in place, as evidenced by increase in the K2O content of the sand and silt fractions with depth; (iii) the fine clay (
Ophelie Sauzet - One of the best experts on this subject based on the ideXlab platform.
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development of a novel image analysis procedure to quantify biological porosity and illuvial clay in large soil thin sections
2017Co-Authors: Ophelie Sauzet, Cecilia Cammas, Jeanmarc Gilliot, Manon Bajard, David MontagneAbstract:Among other driving forces, climate change may lead to significant modifications of soil properties through variations of the intensity and dynamics of a number of soil processes including the especially sensitive and ubiquitous processes of bioturbation and Illuviation. Progress toward the quantification of these processes needs to be made as a first step in order to ascertain or predict the impact of climate change. In this study, we develop, and validate through an exhaustive accuracy assessment, a digital 2D image analysis method adapted to large soil thin sections, leading to the quantification, characterization and classification of pores and illuvial clay features considered diagnostic of bioturbation and Illuviation, respectively. The need to consider large soil thin sections (14 x 6 cm) stems from observations that areas from 684 mm2 to more than 5 000 mm2 are needed to obtain representative measurements of fragments of illuvial clay (papules) and porosity associated with earthworms respectively. Whereas the soil heterogeneity in thin sections of such a large size prohibits the use of classical global and colorimetric image analysis procedures, we succeeded to quantify and characterize the porosity and illuvial clay features with accuracies as high as 96% for porosity and 92% for illuvial clay by carefully considering different levels of soil organization from aggregates to individual illuvial clay features. Quantification of the size and the shape of pores and of illuvial clay features makes it possible to develop morphological classifications distinguishing pores of biological origin (earthworms or roots) from others, or clay coatings and infillings from papules. All these data are particularly useful to better characterize underlying soil processes. Results suggest that the proposed methodology provides an accurate and representative quantification of biological porosity and illuvial clay features in large thin sections. We argue that the use of this approach could be extended to study and quantify bioturbation and Illuviation intensities at the profile scale.
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Illuviation intensity and land use change: Quantification via micromorphological analysis
2016Co-Authors: Ophelie Sauzet, Cecilia Cammas, P. Barbillon, M.-p. Etienne, D. MontagneAbstract:Abstract Among soil processes governing the clay size fraction distribution with depth, Illuviation is not only widespread but also particularly poorly understood. Using a micromorphological approach, this study aims at i) quantifying the intensity of Illuviation independently of all other competing soil processes, ii) testing the sensitivity of Illuviation to different land uses, and iii) assessing the relative contribution of Illuviation to the genesis of textural differentiation. Two Luvisols developed from loess in Northern France were selected: the first under a deciduous forest and the second under conventional agricultural management, both with no change in land use for at least 100 years. In addition to classical mass balance calculations, clay Illuviation features such as limpid and dusty clay coatings were used as diagnostic features of the Illuviation process and were quantified by a point-counting approach in large thin sections. In the two Luvisols under study Illuviation was found to be responsible for 75% and 86% of the textural contrast, respectively in the cultivated soil and the forested one. Illuviation was thus by far the dominant factor causing textural differentiation, even if accessory processes involving the clay size fraction were also at play such as lithological discontinuity, clay neoformation or biological and physical reworking. The recognition of dusty clay coatings considered as an indicator of cultivation in the soil under forest underlines the sensitivity of Illuviation to past periods of cultivation and the legacy of anthropedogenesis on the present soil properties. A qualitative change in the nature of the translocated particles without significant changes in the intensity of Illuviation was identified in the soil under cultivation in comparison with the soil under forest. These results support the conclusion that Illuviation is an active process in soils under present climatic conditions and must no more be considered as a fossil soil process.
D. Montagne - One of the best experts on this subject based on the ideXlab platform.
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Illuviation intensity and land use change: Quantification via micromorphological analysis
2016Co-Authors: Ophelie Sauzet, Cecilia Cammas, P. Barbillon, M.-p. Etienne, D. MontagneAbstract:Abstract Among soil processes governing the clay size fraction distribution with depth, Illuviation is not only widespread but also particularly poorly understood. Using a micromorphological approach, this study aims at i) quantifying the intensity of Illuviation independently of all other competing soil processes, ii) testing the sensitivity of Illuviation to different land uses, and iii) assessing the relative contribution of Illuviation to the genesis of textural differentiation. Two Luvisols developed from loess in Northern France were selected: the first under a deciduous forest and the second under conventional agricultural management, both with no change in land use for at least 100 years. In addition to classical mass balance calculations, clay Illuviation features such as limpid and dusty clay coatings were used as diagnostic features of the Illuviation process and were quantified by a point-counting approach in large thin sections. In the two Luvisols under study Illuviation was found to be responsible for 75% and 86% of the textural contrast, respectively in the cultivated soil and the forested one. Illuviation was thus by far the dominant factor causing textural differentiation, even if accessory processes involving the clay size fraction were also at play such as lithological discontinuity, clay neoformation or biological and physical reworking. The recognition of dusty clay coatings considered as an indicator of cultivation in the soil under forest underlines the sensitivity of Illuviation to past periods of cultivation and the legacy of anthropedogenesis on the present soil properties. A qualitative change in the nature of the translocated particles without significant changes in the intensity of Illuviation was identified in the soil under cultivation in comparison with the soil under forest. These results support the conclusion that Illuviation is an active process in soils under present climatic conditions and must no more be considered as a fossil soil process.
Bradley E Suther - One of the best experts on this subject based on the ideXlab platform.
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soil morphology of an alluvial chronosequence from the little river north carolina coastal plain usa
2020Co-Authors: Bradley E Suther, David S LeighAbstract:Abstract A soil chronosequence on terraces of the Little River in the North Carolina Coastal Plain was characterized to evaluate age-related trends in pedogenesis. Five representative pedons per landform were studied from six late Quaternary fluvial surfaces, and temporal trends were assessed by regression of morphological parameters against previously reported terrace optical age estimates. Solum, B horizon, and Bt horizon thickness, subsoil clay content, and Buntley-Westin Index rubification have strong, positive correlations with age and together distinguish between soils of the floodplain (≤200 yr BP), the first terrace (9.9 ± 2.0 ka), intermediate surfaces (T2, T3b, T4; 17.4 ± 4.2–74.6 ± 10.4 ka), and the oldest terrace (T5b, 94.0 ± 15.9 ka). Over time, soils develop from Entisols with respective A-C and A-E-Bw-C profiles on the floodplain and first terrace to Ultisols with increasing argillic horizon thickness, rubification, and clay content on T2-T5b. Solum thickness, Bt horizon thickness, and clay content display linear increases through time, with soil thickening reflective of downward pedogenesis through permeable, coarse-grained alluvium. Increasing argillic horizon clay content is attributable to Illuviation, and possibly also to a combined bioturbation-translocation process, whereby clays scattered throughout sandy parent sediments are delivered to the surface by bioturbation, then concentrated in B horizons by eluviation-Illuviation. Rubification increases with age and reflects transformation and subsoil concentration of inherited free iron, rather than iron oxide formation from primary mineral weathering. T5b pedons display morphologies comparable to those of 200 ka to >1 Ma soils along Coastal Plain rivers that also drain the Appalachian Piedmont, probably because sandy, Coastal Plain-derived Little River alluvium has a higher hydraulic conductivity that promotes faster rates of downward weathering, clay translocation, and rubification than the more finely-grained sediments of Piedmont-draining rivers. Thus, textural differences related to sedimentary provenance should be recognized when interpreting chronosequences from the region. Although rates of pedogenesis differ among Coastal Plain alluvial soils, linear trends in the ≤100 ka Little River chronosequence may nonetheless correspond to the early, more linear phases of development in studies from the region that span much longer intervals of time.
