Important Pedogenic Processes Research Articles

Ca, Sr and Ba stable isotopes reveal the fate of soil nutrients along a tropical climosequence in Hawaii

Nutrient biolifting is an important pedogenic process in which plant roots obtain inorganic nutrients such as phosphorus (P) and calcium (Ca) from minerals at depth and concentrate those nutrients at the surface. Here we use soil chemistry and stable isotopes of the alkaline earth elements Ca, strontium (Sr) and barium (Ba) to test the hypothesis that biolifting of P has been an important pedogenic process across a soil climosequence developed on volcanic deposits at Kohala Mountain, Hawaii. The geochemical linkage between these elements is revealed as generally positive site-specific relationships in soil mass gains and losses, particularly for P, Ba and Ca, using the ratio of immobile elements titanium and niobium (Ti/Nb) to link individual soil samples to a restricted compositional range of the chemically and isotopically diverse volcanic parent materials. At sites where P is enriched in surface soils relative to abundances in deeper soils, the isotope compositions of exchangeable Ca, Sr and Ba in the shallowest soil horizons (<10cm depth) are lighter than those of the volcanic parent materials and trend toward those of plants growing on fresh volcanic deposits. In contrast the isotope composition of exchangeable Ba in deeper soil horizons (>10cm depth) at those sites is consistently heavier than the volcanic parent materials. The isotope compositions of exchangeable Ca and Sr trend toward heavier compositions with depth more gradually, reflecting increasing leakiness from these soils in the order Ba<Sr<Ca and downward transfer of light biocycled Ca and Sr to deeper exchange sites. Given the long-term stability of ecosystem properties at the sites where P is enriched in surface soils, a simple box model demonstrates that persistence of isotopically light exchangeable Ca, Sr and Ba in the shallowest soil horizons requires that the uptake flux to plants from those near-surface layers is less than the recycling flux returned to the surface as litterfall. This observation implicates an uptake flux from an additional source which we attribute to biolifting. We view the heavy exchangeable Ba relative to soil parent values in deeper soils at sites where P is enriched in surface soils, and indeed at all but the wettest site across the climosequence, to represent the complement of an isotopically light Ba fraction removed from these soils by plant roots consistent with the biolifting hypothesis. We further suggest that decreasing heaviness of depth-integrated exchangeable Ba in deeper soils with increasing median annual precipitation across the climosequence reflects greater reliance on shallow nutrient sources as site water balance increases. While the Ca, Sr and Ba isotopes considered together were useful in confirming an important role for nutrient biolifting across the climosequence, the Ba isotopes provided the most robust tracer of biolifting and have the greatest potential to find application as an isotopic proxy for P dynamics in soils.

A micromorphological record of contemporary and relict pedogenic processes in soils of the Indo‐Gangetic Plains: implications for mineral weathering, provenance and climatic changes

AbstractMicromorphology has important application in earth surface process and landform studies particularly in alluvial settings such as the Indo‐Gangetic Plains (IGP) with different geomorphic surfaces to identify climatic changes and neotectonic events and their influence on pedogenesis. The soils of the IGP extending from arid upland in the west to per humid deltaic plains in the east developed on five geomorphic surfaces namely QIG1 to QIG5 originating during the last 13.5 ka. Four soil‐geomorphic systems across the entire IGP are identified as: (i) the western Yamuna Plains/Uplands, (ii) the Yamuna‐Ganga Interfluve, (iii) the Ganga‐Ghaghara Interfluve, and (iv) the Deltaic Plains.Thin section analysis of the soils across the four soil‐geomorphic systems provides a record of provenance, mineral weathering, pedogenic processes and polygenesis in IGP. The soils over major parts of the IGP dominantly contain muscovite and quartz and small fraction of highly altered feldspar derived from the Himalayas. However, soils in the western and eastern parts of the IGP contain large volumes of fresh to weakly altered plagioclase and smectitic clay derived from the Indian craton. The soils in western Yamuna Plains/Uplands dominated by QIG2–QIG3 geomorphic surfaces and pedogenic carbonate developed in semi‐arid climate prior to 5 ka. However, soils of the central part of the IGP in the Yamuna‐Ganga Interfluve and Ganga‐Ghaghara Interfluve regions with dominance of QIG4–QIG5 surfaces are polygenetic due to climate change over the last 13.5 ka. The clay pedofeatures formed during earlier wet phase (13.5–11 ka) show degradation, loss of preferred orientation, speckled appearance in contrast with the later phase of wet climate (6.5–4 ka). The soils over the deltaic plains with dominance of vertic features along with clay pedofeatures suggest that illuviation of fine clay is an important pedogenic process even in soils with shrink‐swell characteristics. Copyright © 2015 John Wiley &amp; Sons, Ltd.

Chemical, Mineralogical, and Morphological Characteristics of a Late Quaternary Sedimentary Rock–Derived Soils in Leyte, Philippines

To understand the genesis of soils derived from a late Quaternary sedimentary rock in Leyte, Philippines, the properties of four soil profiles were investigated. Two of the profiles (PS-1, PS-4) derived from coralline limestone were shallow with less developed horizons and alkaline pH conditions and higher potential cation exchange capacity and are classified as Calcaric Phaeozems in the World Reference Base or fine, calcareous, isohyperthermic, Rendollic Eutrudepts in Soil Taxonomy. The other two profiles (PS-2, PS-3) derived from calcareous shale were deeper with well-developed horizons and characterized by high loss of bases and were classified as Haplic Alisols (Hyperdystric, Rhodic) or fine, kaolinitic, isohyperthermic, Typic Hapludalfs. The calcareous shale parent materials have much faster weathering as shown by the higher clay content and the dominance of kaolinitic and halloysitic clay minerals. In those soils developed from limestone, clay minerals were mostly calcite, smectite, vermiculite, and interstratified kaolinite/smectite. The results of this study suggest a strong influence of external material contributions, particularly volcanic-ash deposition on the progression of the soils, as reflected by higher clay and silt contents in these comparatively young soils. The most important pedogenic processes that formed the soils in the area seem to be weathering and clay formation, loss of bases and acidification, inorganic C accumulation, structure formation, desilication, and ferrugination. The nature and characteristics of the parent material, topography, and the time of pedogenesis also have assertive effects on the development of the soils.

Characteristics and formation of rain forest soils derived from late Quaternary basaltic rocks in Leyte, Philippines

This study was conducted to evaluate the physical, chemical, and mineralogical characteristics of rain forest soils derived from late Quaternary basaltic rocks in Leyte, Philippines. Four sites along a catena were selected at an elevation of 75–112 m above sea level with an average annual rainfall of 3,000 mm and an average temperature of 28°C. Results indicate that the soils are deep, clayey, and reddish in color, which is indicative of the advanced stage of soil development. They also posses excellent physical condition (friable and highly porous) although they are plastic and sticky when wet as is usual for clayey soils. In terms of chemical characteristics, the soils are acidic with low CEC values and generally low in organic matter and nutrient contents. The clay mineralogy of the soils is dominated by halloysite and kaolinite with minor amounts of goethite and hematite, and they also have generally high dithionite-extractable Fe contents confirming the advanced stage of their development. The soils in the more stable slope positions (PL-1, PL-2, and PL-4) have generally similar characteristics and appeared more developed than the one in the less stable position (PL-3). The most important pedogenic processes that formed the soils appear to be weathering, loss of bases and acidification, desilification, ferrugination, clay formation and translocation, and structure formation. The nature of the parent rock and climatic conditions prevailing in the area as well as slope position appear to have dominant effects on the development of the soils.

Some Characteristics of Soils on the Man Made Mounds in The Harran Plain of Turkey

Morphological, chemical and some mineralogical characteristics of five soils, were researched to understand the genesis of soils on the man made mounds in the Harran Plain, in the Southeast Anatolia Region of Turkey. Five soil profiles developed on the man made mounds in the arid region. Time and climate have affected soil formation. Also, parent material has influenced the chemistry of soils. The parent material of man made mounds were carried from around soils in the Harran Plain by men in years ago. The parent materials of around soils are calcareous parent materials and alluvium materials. Pedon 1 was described on the Konuklu man made mounds the northeast of the study area and Pedon 5 was described on the Küplüce man made mounds the southeast of the study area. According to the place of man made mounds were ordered from north to south as following: Pedon 1, Pedon 2, Pedon 3, Pedon 4 and Pedon 5. The old of Konuklu mounds is approximately 5000-6000 years. The old of Sultantepe and Koruklu mounds are approximately 6000 years. Pedon 4 which was described on the old Harran city remnants have the youngest soils of study area. The Harran mounds was made in 1258 A.I. by Mongolians. Mongolians destroyed the Harran City and made the Harran mounds. The most important pedogenic processes is carbonate leaching and accumulation in the pedon 5 on the Küplüce man made mounds. The CaCO3 content of Pedon 5 may be attributed to eolian addition from Syria. Total Al2O3 contents of soils higher than total Fe2O3 content. According to the degree of soil formation the profiles were ordered as following: Pedon 3 > Pedon 5 > Pedon 2 > Pedon 1 > Pedon 4. The results of total elements analysis were used to determine the beta leaching factor according to Jenny. The leaching factor were determined as < 1 in the Pedon 1 (0.99), Pedon 2 (0.97), Pedon 3 (0.74) and Pedon 5 (0.92). The leaching factor were determined as >1 in the Pedon 4(1.13).

Quantitative mapping of the soil rubification process on sand dunes using an airborne hyperspectral sensor

Soil rubification is defined as a pedogenesis stage in which iron is released from primary minerals to form free iron oxides that coat quartz particles in soils with a thin reddish film. This study used an airborne hyperspectral sensor to spatially map soil rubification on the surface of coastal sand dunes in Israel. The area selected for this study is located south of the city of Ashdod, Israel, and is one of the last remaining coastal sand dune areas in the country. The study area occupied about 60 km 2, and was covered by two flight lines of the CASI 48-channel sensor from an altitude of 2650 m, providing a pixel size of about 3 m. A traditional way to estimate rubification is to chemically measure the iron oxide concentration in the sand. The Dithionite Citrate Bicarbonate (DCB) method, which is a laboratory “wet”-based procedure, was used to precisely measure the free iron oxide status of selected locations along the area. The soil reflectance properties of these samples were measured in the laboratory across the Visible and Near InfrarRed (VIS–NIR) region and was used with the DCB-Fe data to evaluate a spectral-based model for assessing the rubification extent solely from spectroscopy. After the CASI data were atmospherically, BRDF and geometrically corrected, they were run against the spectral model on a pixel-by-pixel basis, generating a rubification map from a far distance. Spectral validation of independent samples and field measurements of dune movement over 17 months showed that the map is reliable and significantly correlated with known stabilization processes throughout the area (the overall accuracy estimated as 78%). It was concluded that soil spectroscopy, either from field or air, enables the detection of small changes in the Fe absorption feature across the VIS region that provides information regarding the iron oxide minerals and content. This supports the utilization of a sensitive airborne hyperspectral sensor to rapidly and quantitatively evaluate spatial information concerning important pedogenic processes.

Distribution and possible immobilization of lead in a forest soil (Luvisol) profile*

Geochemical analyses using a sequential extraction method and lead adsorption studies were carried out in order to characterize the distribution and adsorption of lead on each genetic horizon of a Luvisol profile developed on a pelagic clayey aleurolite. Clay illuviation is the most important pedogenic process in the profile studied. Its clay mineralogy is characterized by chlorite/vermiculite species with increasing chlorite component downward. The amount of carbonate minerals strongly increases in the lower part of the profile resulting in an abrupt rise in soil pH within a small distance. The Pb content of the soil profile exceeds the natural geochemical background only in the Ao horizon, and its amount decreases with depth in the profile without correcting for differences in bulk density, suggesting the binding of Pb to soil organic matter. According to the sequential extraction analysis the organic matter and carbonate content of the soil have the most significant effect on lead distribution. This effect varies in the different soil horizons. Lead adsorption experiments were carried out on whole soil samples, soil clay fractions, as well as on their carbonate and organic matter free variant. The different soil horizons adsorb lead to different extents depending on their organic matter, clay mineral and carbonate content; and the mineralogical features of soil clays significantly affect their lead adsorption capacity. The clay fraction adsorbs 25% more lead than the whole soil, while in the calcareous subsoil a significant proportion of lead is precipitated due to the alkaline conditions. 10 and 5% of adsorbed Pb can be leached with distilled water in the organic matter and clay mineral dominated soil horizons, respectively. These results suggest that soil organic matter plays a decisive role in the adsorption of Pb, but the fixation by clay minerals is stronger.

SOIL GENESIS ON PERALKALINE FELSICS IN BIG BEND NATIONAL PARK, TEXAS

Soil genesis involving felsic rocks frequently involves understanding the roles of climate and time on the transformations of the primary minerals into secondary products. This study focuses on the weathering of peralkaline felsics in a semiarid climate. Soils and fresh parent materials were collected from different microclimate regimes in the Chisos Mountains of Big Bend National Park, Texas. Soils in the Chisos mountains generally have either a mollic-argillic-rock or a mollic-rock horizon sequence, whereas other sites at lower and drier locations have an ochric-rock horizon sequence. Atmospheric deposition of Ca and Sr and wind deflation of clay are important attributes of soil genesis. Elemental loss rates of Si, Al, K, Na, and other elements are appreciable, suggesting that leaching has been important to the soil formation. Iron oxide formation, which is related to the moisture regime, is greater in soils having wetter microclimates. Solution chemistry suggests that Mg concentrations are appropriate for smectite synthesis and maintenance, potassium concentrations reflect the presence of feldspar, sodium concentrations reflect their loss rates because of leaching, and calcium reflects the presence of calcite. The rare earth elements similarly demonstrate loss rates consistent with chemical weathering. In general, chemical weathering of feldspars, atmospheric deposition of Ca and Sr, and wind deflation are important pedogenic processes.

Effect of Bedrock Porosity on Soils Formed from Dolomitic Limestone Residuum and Eolian Deposition

AbstractDifferences in the weathering characteristics of dolomitic limestones have resulted in the formation of Haplustalfs and Calciustolls located in the northwestern Colorado Plateau of Arizona. The establishment of effective porosity in the parent rock has controlled important pedogenic processes such as decalcification and silicate clay illuviation. The underlying carbonate strata, the Kaibab Formation, are complex limestone‐dolomite‐chert marine rocks of Permian age. Pleistocene age meteoric waters have caused the dissolution and partial removal of CaCO3 and the establishment of a porous dolomite crystal framework. Under these conditions, soils forming in residuum are able to decalcify and to form argillic horizons. However, in more resistant limestones, compaction during burial has resulted in a nonporous micrite that retards calcite removal by meteoric waters. Under these conditions, soil profiles maintain a high CaCO3 content and silicate clay illuviation does not occur. Eolian dust is also important to soil formation on the Colorado Plateau; in particular, quartz in the coarse silt fraction (31–44 µm), and quartz and biotite in the very fine and fine silt fractions (2.0–11 µm). Micaceous clay minerals of residual and eolian origin are converted to montmorillonite in the Alfisols. A probable sequence of events for this transformation to occur is: (i) the removal of calcite from the dolomitic limestone bedrock and the formation of a dolomite crystal framework, (ii) the slow dissolution of dolomite and release of Mg2+ into solution, (iii) the incorporation of Mg2+ into the octahedral layer of the mica and the release of K+ from the mica interlayer position, and (iv) the illuviation of montmorillonite to form the argillic horizon.

Upper Cretaceous (Maastrichtian) paleosols in Trans-Pecos Texas

Research Article| February 01, 1989 Upper Cretaceous (Maastrichtian) paleosols in Trans-Pecos Texas THOMAS M. LEHMAN THOMAS M. LEHMAN 1Department of Geosciences, Texas Tech University, Lubbock, Texas 79409 Search for other works by this author on: GSW Google Scholar Author and Article Information THOMAS M. LEHMAN 1Department of Geosciences, Texas Tech University, Lubbock, Texas 79409 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1989) 101 (2): 188–203. https://doi.org/10.1130/0016-7606(1989)101<0188:UCMPIT>2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation THOMAS M. LEHMAN; Upper Cretaceous (Maastrichtian) paleosols in Trans-Pecos Texas. GSA Bulletin 1989;; 101 (2): 188–203. doi: https://doi.org/10.1130/0016-7606(1989)101<0188:UCMPIT>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Fluvial flood-plain deposits of the upper Aguja, Javelina, and El Picacho Formations in Brewster and Presidio Counties of West Texas record multiple episodes of soil formation during Late Cretaceous (Maastrichtian) time. These well-differentiated alluvial paleosols are characterized by pale gray leached (albic) A horizons and purple or red, clay-and iron oxide-enriched (cambic, argillic) B horizons. These characteristics indicate that podzolization and lessivage were important pedogenic processes and suggest that these paleosols are comparable to some modern AI-fisols. Texturally diverse accumulations of calcite nodules, coalesced masses of nodules, rhizocretions, and thin discontinuous hard-pans indicate that calichification also occurred. The extreme development of the petrocalcic horizons, partial silicification, association with sulfate minerals, and high position within the soil profiles indicate that calichification was in many cases not con-temporaneous with iron and clay illuviation. The compound paleosols thus formed indicate that the Maastrichtian climate in this region may have fluctuated between regimes of humid and semiarid character, each at least several thousand years in duration. This inferred long-term climatic cyclicity may correspond to climatically induced sedimentation cycles observed in the marine realm that are ascribed to Milankovitch cycles. Fossil wood suggests that the flood-plain paleosols supported coniferous forests, whereas adjacent stream courses were lined by angiosperm woodlands. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Micromorphological evidence of clay translocation in poorly dispersible soils

Clay translocation is an important pedogenic process. Field and laboratory studies are used herein to evaluate the process in some Ultisols and Oxisols having horizons with poor dispersion characteristics. Surface areas measured by ethylene glycol monoethyl ether (EGME) and micromorphological studies confirmed the presence of argillic horizons in the Ultisols. Two of the Oxisols also have illuviation argillans, but most of these are below oxic horizons. Staining and cementation by Fe and Al oxides in soils in the oxidic families appear to have masked evidence of clay accumulation except in lower horizons. Because overlying horizons do not disperse well, we conclude that either environmental conditions changed or else weathering became more intense following development of the argillic horizons. Climatic shifts and continued intense weathering apparently are responsible for formation of the low-activity clays, and the iron and aluminum oxide cementation causing the poor dispersion.