Increase In Clay Content Research Articles

Gilgai microtopography of soil from carbonate rocks

Gilgai microtopography is a characteristic topography of soils that develops from carbonate rocks influenced by smectite clay minerals. The process of forming a gilgai can inhibit the development of plant growth and soil stability. Soil genesis is an interesting topic to study, especially concerning how moving clay forms a gilgai microtopography. The objective was to study forming a gilgai microtopography formed from the parent material of carbonate rock in Mangarabombang District, Takalar Regency. The methods used are survey methods, analysis of soil physical characteristics and soil chemistry, and soil mineral. The results showed an increase in clayeyness at the top horizon in line with decreasing permeability on the top horizon and inversely proportional to soil porosity. The cation exchange capacity is higher at the top horizon, which indicates an increase in clay content. The mineral content of clay is nontronite as a member of the smectite group. Nontronite mineral formation subsidized by calcium and magnesium cations from carbonate rocks. This mineral absorbed more water and caused the saturation conditions triggering lateral pressure and forming a gilgai micro-topography.

Sedimentary processes of shallow-marine turbidite fans: An example from the Huangliu Formation in the Yinggehai Basin, South China Sea

The shallow-marine turbidite fans in the Upper Miocene Huangliu Formation of the Yinggehai Basin in the northwestern South China Sea (SCS) provide an excellent opportunity to understand their sedimentary processes in a shelf depositional environment. The down-slope gravity flow processes and along-slope bottom-current reworking processes of shallow-marine turbidite fans were interpreted by using seismic, well logging, core, petrographic, geochemical, and petrophysical data. Several depositional elements were identified in the shallow-marine turbidite fans, namely, channel-fill high-density turbidites (HDTs), channel-fill low-density turbidites (LDTs) and associated frontal splays, sand-rich/mud-rich lobe deposits, and bottom-current reworked channel-fill/lobe deposits. Deep U-shaped (or V-shaped) seismic reflections and low root-mean-square (RMS) amplitudes characterize the channel-fill HDTs that consist of massive fine-grained sandstones with mud clasts. The channel-fill LDTs, characterized by V-shaped or worm-shaped reflections, mostly consist of normally graded, laminated and rippled, very fine-grained sandstones. Frontal splays are generally associated with channel-fill LDTs. The sand-rich lobe deposits show continuous high-amplitude sheet-like reflections and consist of HDTs and LDTs, whereas the mud-rich lobe deposits show continuous moderate-amplitude reflections and consist of muddy debrites. The bottom-current reworked sandstones (BCRSs), which comprise well-sorted, fine-grained sandstones with traction-current structures, are usually located in the upper parts of thick sandbodies. The variability of depositional elements from large-scale channel-fill HDTs with strong basal erosion in fan-1 to small-scale channel-fill LDTs in fan-2 is closely linked with sea-level fluctuations that result in variable gravity-flow energy and sediment input. However, the reoccurrence of large-scale channel-fill HDTs in fan-3 at sea-level highstands may possibly be attributed to enhanced sediment input from the source areas. Down-slope flow transformation from turbidity flows into muddy debris flows within an individual channel-lobe complex (CLC) resulted in a dramatic increase in clay content and resultant decreasing reservoir quality from the channel-fill HDTs to the mud-rich lobe deposits, because muddy sediments are incorporated into the precursor turbidity flows and turbulence is suppressed. Additionally, it is suggested that the widely developed traction-current structures and tidal signatures (double mud layers, mud-draped ripples, discrete wavy bedding, internal truncation surface, and convex-up laminae) are the products of reworking by internal waves and -tides. During periods of sea-level highstands, the upper parts of gravity-flow sandstones would undergo bottom-current reworking, thus resulting in the retransportation of muddy fines and the formation of reworked sandstones with traction-current structures and tidal signatures. In this study, a combination of traction-current structures, tidal signatures, vertical sequences showing sharp upper contacts and non-gradational upper contacts, and trace elements is considered to be convincing diagnostic criteria in distinguishing reworked sandstones from gravity-flow sandstones. The representative bottom-current reworked sandstones should be preferable hydrocarbon targets in further exploration because of their better reservoir properties compared with gravity-flow sandstones. This research offers some insight into gravity-flow processes and bottom-current reworking processes in a shallow marine environment.

Single Well Petrophysical Analysis: A Case Study of Belle Fourche Shaly-Sand, Hatton Gas Field, Southwest Saskatchewan

This case study shows the petrophysical evaluation of the Belle Fourche Formation, Hatton Gas Field, Southwest Saskatchewan, using conventional well log interpretation techniques. The Belle Fourche reservoir analysed is indicated as shaly-sand formation, while petrophysical parameters calculated includes gross thickness, net thickness, volume of shale, porosity, and water saturation. Cross plots, in conjunction with previous core sedimentology study was used to identify lithology as shale dominated by mixed clay. The potassium content remains relatively constant as the clay content increases. In contrast, the thorium content increases with an increase in the clay content presenting thorium potassium ratio of 12, composed of montmorillonite and mixed-layer clay. Shale content increases as the thorium and uranium content increases. Results from the petrophysical evaluation revealed a gross reservoir thickness of 6.36 m, an average net shaly-sand thickness of 2.13 m, an average volume of clay of 13 %, the porosity of 15 %, and average water saturation of 43 %. Rock petrophysics cross plot of density versus P-wave (Vp) velocity was attempted to identify hydrocarbon saturation. The calculated velocities using the Greenberg and Castagna relation indicate slight increase in Vp and a decrease in density in shaly-sand data indicating hydrocarbon saturation in the reservoir interval. This paper has presented conceptually simple petrophysical method, structured in a manner that is easy to understand for a shaly-sand formation evaluation.

Adsorption of cetyltrimethyl ammonium bromide surfactant for organophilization of palygorskite clay

AbstractThis work determines the optimal palygorskite (Plg) content (maximum surfactant adsorption point) to achieve organophilization using the cationic surfactant cetyltrimethyl ammonium bromide (CTAB) at various concentrations. Adsorption assays were carried out in a finite bath after varying the content of Plg and CTAB in solution. In those assays, the effects of time, temperature, pH and thermodynamic characteristics were studied. The results were analysed using the Langmuir, Freundlich, Dubinin–Radushkevich and Tempkin adsorption models. The increase in clay content in the dispersion leads to a decrease in adsorption of surfactant on the clay. It was possible to obtain the optimal Plg content to achieve organophilization at various concentrations of CTAB surfactant. The experimental data fitted well to the Freundlich model. The Dubinin–Radushkevich and Tempkin isotherms confirmed the chemical adsorption of CTAB on Plg clay.

Pore structure and heterogeneity of shale gas reservoirs and its effect on gas storage capacity in the Qiongzhusi Formation

Fine characterization of pore systems and heterogeneity of shale reservoirs are significant contents of shale gas reservoir physical property research. The research on micro-control factors of low productivity in the Qiongzhusi Formation (Fm.) is still controversial. The lower Cambrian Qiongzhusi Fm. in the Qujing, Yunnan was taken as the object to investigate the influence of mineral compositions on the physical properties of the reservoir and the heterogeneity of shale, using the algorithm to improve the characterization ability of Atomic Force Microscopy (AFM). The results showed that: (1) The pores are mainly wedge-shaped pores and V-shaped pores. The pore diameter of the main pore segment ranges from 5 to 10 nm. Mesopores are mainly developed in the Qiongzhusi Fm. shale in Well QD1, with the average pore diameter of 6.08 nm. (2) Microscopic pore structure and shale surface properties show strong heterogeneity, which complicates the micro-migration of shale gas and increases the difficulty of identifying high-quality reservoirs. (3) The increase of clay mineral content intensifies the compaction and then destroys the pores. Conversely, brittle minerals can protect pores. The support and protection of brittle minerals to pores space depend on their content, mechanical properties and diagenesis. (4) Compression damage to pores, large microscopic roughness and surface fluctuations and strong pore structure heterogeneity are the reasons for the poor gas storage capacity of the Qiongzhusi Fm., which will lead to poor productivity in the Qiongzhusi Fm.

Bibliometric analysis and research progress of Mu Us Sandy Land soil biological crust based on CNKI

Based on CNKI data, this paper analyzes the number of papers, keywords and research content of biological soil crusts in the Mu Us Sandy Land. It was reviewed that the effects of biological soil crust on water infiltration, photosynthesis, respiration and succession characteristics and the influence of the technology of the compound soil of feldspathic sandstone and sand to create land on the development of biological crusts is considered in the Mu Us Sandy Land. The increase in clay content will significantly promote the expansion of sand biological crusts. At the same time, it is recommended to further carry out research on the development and succession characteristics of sand biological crusts after compounding of feldspathic sandstone and sand.

Impact of cement industries dust on soil properties in Bhatapara,Chhattisgarh

The present investigation was carried around cement industries at Bhatapara during 2017-18, to study the different soil properties as affected by the dust of cement Industries in Bhatapara Chhattisgarh. Two hundred fifty six composite soil samples were taken from around the cement industries i.e., from eight radiant wind directions viz., North, South, East, West, Northeast, Northwest, Southeast and Southwest in clockwise manner at the distances 0.5, 1, 2, and 3 km from the surface (0-15 cm) and sub-surface (15-30 cm) soil depths. Statistical analysis was done in 3-factors factorial designed experiment using CRD and the effect of cement dust on soil properties were also correlated with wind directions (X1), distances(X2) and soil depths (X3). Thephysico-properties of soils showed a significant increase in sand and silt in south-west and west wind directions. Significant increase in clay content was also observed in west and south-wind direction. An increase in pH, electrical conductivity and calcium carbonate content in soil (0-15 cm) soil up to 0.5 km distance in the southwest wind direction was also observed. Organic carbon content in soils also increased significantly with increase in distance at surface soilin the southwest wind direction.

In the shadow of giants: Calcareous nannoplankton and smaller benthic foraminifera from an Eocene nummulitic accumulation (Transylvanian Basin, Romania)

Nummulitic accumulations are an important component of the Eocene sedimentary record in the Neotethyan realm. Their age, paleoenvironmental significance and depositional model are almost exclusively based on the interpretation of the larger benthic foraminiferal assemblages. We show here, however, that the high-resolution study of the other, often neglected, microfossils (calcareous nannoplankton and benthic foraminifera) is crucial to better constrain the diversity and paleoenvironmental gradient along the nummulitic accumulation(s). The studied micropaleontological assemblages, recovered from the large Eocene (Bartonian) nummulitic accumulation in the northwestern Transylvanian Basin (Romania), suggest an inner shelf depositional environment. A depth and nutrient gradient along the nummulitic accumulation from the south to the north could be recognized. In the southern part of the study area the environment was shallow and oligotrophic with Zygrablithus bijugatus, Blackites inflatus, Neococcolithes dubius, Ericsonia spp., larger sized reticulofenestrids and epiphytic foraminifera taxa (Pararotalia, Lobatula and Cibicides) on a sandy substrate. The progressive deepening toward the north led to an increase in clay content and more nutrient-rich marine waters in which calcareous nannoplankton (especially Reticulofenestra minuta), agglutinated foraminifera and calcareous infaunal foraminifera (Nonion, Protelphidium and Reusella) proliferated. The calcareous nannoplankton and smaller benthic foraminiferal assemblages confirm and further constrain the Bartonian age of the studied nummulitic accumulation, previously based on the larger benthic foraminiferal SBZ 17 zone.

Nanocomposite Polymer Electrolytes of Sodium Alginate and Montmorillonite Clay.

Nanocomposite polymer electrolytes (NPEs) were synthesized using sodium alginate (Alg) and either sodium (SCa-3-Na+)- or lithium (SCa-3-Li+)-modified montmorillonite clays. The samples were characterized by structural, optical, and electrical properties. SCa-3-Na+ and SCa-3-Li+ clays’ X-ray structural analyses revealed peaks at 2θ = 7.2° and 6.7° that corresponded to the interlamellar distances of 12.3 and 12.8 Å, respectively. Alg-based NPEs X-ray diffractograms showed exfoliated structures for samples with low clay percentages. The increase of clay content promoted the formation of intercalated structures. Electrochemical Impedance Spectroscopy revealed that Alg-based NPEs with 5 wt% of SCa-3-Na+ clay presented the highest conductivity of 1.96 × 10−2 S/cm2, and Alg with 10 wt% of SCa-3-Li+ showed conductivity of 1.30 × 10−2 S/cm2, both measured at 70 °C. From UV-Vis spectroscopy, it was possible to infer that increasing concentration of clay promoted a decrease of the samples’ transmittance and, consequently, an increase of their reflectance.

The frequency exponent of artificial sandstone's complex resistivity spectrum

ABSTRACTThe complex resistivity spectra of 16 artificial sandstone samples with different physical property at different water and solution saturations were measured and fitted with the Cole–Cole model in the frequency band of 40 Hz to 110 MHz. The frequency exponent in the model indicates the ideal degree of the sample's capacitive property. The experimental result shows that the frequency exponents of the samples are concentrated mainly between 0.82 and 0.88 and present a segmented law that decreases first and then increases with decreasing the water saturation. The minimum frequency exponent has a linear relationship with porosity and cementation index and an exponential relationship with formation factors. The frequency exponent is expected to be used in the study of the oil–water distribution in the reservoir. The frequency exponents of the samples decrease with an increase in clay content. Frequency exponents are independent of the ion type in the solution. Numerical simulation results support that the capacitive property generated by the connected pore‐throat spaces is near ideal, but the capacitive property contributed by the closed pore‐throat spaces is non‐ideal. This could be the possible reason why the frequency exponents of the samples are less than one. The pore‐throats with higher capillary pressure can be blocked and become secondary closed pore‐throat space during the flooding process and result in a decrease in frequency exponent. This can explain the influence of reservoir parameters on frequency exponent and can further clarify the physical significance of the Cole–Cole frequency exponent on the rock's complex resistivity.

A numerical study of field strength and clay morphology impact on NMR transverse relaxation in sandstones

Nuclear magnetic resonance (NMR) relaxometry is a common technique for the petrophysical characterization of sedimentary rocks. The standard interpretation of NMR transverse relaxation responses is based on the assumptions of the fast diffusion limit, dominant surface relaxation, and weak coupling between pores, allowing an interpretation of the NMR response as pore size distribution. In general, three asymptotic relaxation regimes can be defined by comparing dephasing, structural and diffusion length scales. The shortest length scale defines the dominating relaxation regime, which is either the free diffusion, motional averaging, or localization regime. Complex mineralogy and morphology of rocks, especially due to clay minerals, may lead to the co-existence and coupling of multiple relaxation regimes in the presence of surface relaxivity heterogeneity and internal gradient effects.In this work the relationship between morphology of rocks, strength of applied magnetic field, resulting relaxation regimes and observed NMR relaxation responses is studied numerically. Limitations in the discretization of clays typical for micro-CT images are addressed by introducing a fine-scale kaolinite model based on SEM images. The model is utilized to evaluate the field-dependent mean transverse relaxation time and effective diffusion coefficient of clay regions. These effective parameters are incorporated into random-walk simulations on micro-CT images. Relaxation regimes are analysed spatially for three different types of sandstone as function of external magnetic field strength. Increase of paramagnetic clay content, field strength and echo-time increases the fraction of spins relaxing in the localization regime within macro-pores, typically being localised in the regions neighbouring clay pockets and grain surfaces. We demonstrate that a significant contribution of the localization regime to relaxation may lead to incorrect predictions of pore-size distributions and fluid typing. The prefactor of permeability correlations varies significantly due to clay effects. Accounting for these effects should enable more robust petrophysical interpretations.

Evidence of hydrothermal fluid circulation driving elemental mass redistribution in an active fault zone

Important fault zone processes can be discerned from the characterization of fracture damage and chemical transformations associated with active seismic sources. To characterize the 2010 M7.2 El Mayor-Cucapah rupture zone, continuous samples of fault core and 23 samples of damaged rock were collected perpendicular to strike of the Borrego fault. Samples were analyzed for clay mineralogy, bulk geochemistry, and bulk and grain density from which porosities and volumetric strains were derived. Prior to the Borrego fault forming, the tonalitic protolith, containing chlorite, epidote, and titanite, was subjected to temperatures of ∼330–340 °C during deuteric alteration. Rocks within the damage zone are partially pulverized and contain abundant cataclastic seams. Porosity and volumetric strain peak in zones 1.5 m–10.5 m from the core. Within these zones, losses in Ca and P mass, increases in Mg and Na mass, along with the conservation of Fe and Si mass are consistent with oxidizing acidic conditions at < 200 °C. Gains in LOI are attributed to increases in clay content. The above data support a model of Mg- and Na-rich oxidizing fluid circulation within the damage zone of the Borrego fault.

Comparison Between Monotonic, Cyclic and Post-Cyclic Pullout Behavior of a PET Geogrid Embedded in Clean Sand and Clayey Sand

A series of monotonic and multistage pullout tests were performed using a large pullout apparatus to study the monotonic, cyclic and post-cyclic pullout behavior of a uniaxial woven geogrid under different conditions. The monotonic and multistage pullout tests were performed for clean sand and sand containing 10% and 20% clay. The effect of vertical effective stress on the pullout resistance and deformation along the geogrid was investigated using monotonic testing. In the multistage pullout test, the influence of vertical effective stress, cyclic load amplitude and the frequency and the number of tensile load cycles on the post-cyclic pullout resistance and deformation during the cyclic stage was studied. The monotonic test results indicated that an increase in clay content increased the pullout resistance at the lower effective vertical stress (20 kPa), while at higher vertical stresses (40 and 60 kPa), this effect was insignificant. Moreover, when a geogrid was embedded in clean sand and 20% clayey sand, the post-cyclic peak pullout resistance was slightly lower than the values attained in monotonic tests at a vertical effective stress of 20 kPa. The reductions varied from 3.5 to 8% for clean sand and 5.5 to 7% for 20% clayey sand. An increase in the cyclic load amplitude had no effect on the post-cyclic resistance of the geogrid-embedded in clean sand, but post-cyclic resistance of geogrid embedded in 20% clayey sand decreases with increasing cyclic load amplitude.

Soil Texture Alters the Impact of Salinity on Carbon Mineralization

Soil salinization typically inhibits the ability of decomposer organisms to utilize soil organic matter, and an increase in soil clay content can mediate the negative effect of salinity on carbon (C) mineralization. However, the interactive effects of soil salt concentrations and properties on C mineralization remain uncertain. In this study, a laboratory experiment was performed to investigate the interactive effects of soil salt content (0.1%, 0.3%, 0.6% and 1.0%) and texture (sandy loam, sandy clay loam and silty clay soil with 6.0%, 23.9% and 40.6% clay content, respectively) on C mineralization and microbial community composition after cotton straw addition. With increasing soil salinity, carbon dioxide (CO2) emissions from the three soils decreased, but the effect of soil salinity on the decomposition of soil organic carbon varied with soil texture. Cumulative CO2 emissions in the coarse-textured (sandy loam and sandy clay loam) soils were more affected by salinity than those in the fine-textured (silty clay) soil. This difference was probably due to the differing responses of labile and resistant organic compounds to salinity across different soil texture. Increased salinity decreased the decomposition of the stable C pool in the coarse-textured soil, by reducing the proportion of fungi to bacteria, whereas it decreased the mineralization of the active C pool in the fine-textured soil through decreasing the Gram-positive bacterial population. Overall, our results suggest that soil texture controlled the negative effect of salinity on C mineralization through regulating the soil microbial community composition.

Effects of clay in a sandy soil on saturated/unsaturated pore water flow and dissolved chloride transport from road salt applications.

Saturated/unsaturated pore water flow induced by rainwater infiltration in a soil column composed of a mixture of Toyoura sand and a small amount of clay (kaolin minerals) and the rinsing rate (mass transfer) of dissolved NaCl accumulated in the pore system from previous road salt application were investigated by experiments and simulations. Experiments were conducted with variable kaolin minerals mass contents (mixing ratios) in the soil columns. Measured saturated hydraulic conductivity (Ks) diminished with increased clay contents, i.e., Ks=0.00771, 0.00560, 0.00536, 0.00519, and 0.00314 cm s-1, for clay contents = 0.2, 0.5, 1, 2, and 5%, respectively. Experimental NaCl concentrations in the effluent from the bottom of the soil columns were about constant for times t ≈ 800, 1200, 1300, 1400, and 3400 s from the beginning of a rinsing experiment for the clay contents = 0.2, 0.5, 1, 2, and 5%, respectively. These NaCl concentrations then decreased with time quickly, and finally, approached zero. The presented model can reproduce experimental time variations of NaCl concentration in the effluent from the soil column reliably. Simulated salt mass left in the soil column with time also matches the experimental results for the clay contents = 0.2 and 0.5%. An inconsistency between simulated and experimental salt mass left in the soil columns becomes more significant as the clay content increases. These results suggest that the soil-water retention curve for the pure Toyoura sand can be applied to the soil column composed of kaolin minerals/Toyoura sand mixture when the clay content is small, i.e., less than 1%. Prediction of rinsing process becomes more difficult with increased clay content. However, the time required to remove saline water from the soil column to less than 1% of its initial value simulated by the model agrees closely with experimental results of 1000, 1500, 1700, 2100, and 5400 s, respectively.

Spatial organization of soil microaggregates

The physical arrangement of compounds in soil microaggregates is controlling many ecosystem functions such as soil stability and C sequestration. However, little is known about the spatial arrangement of organic and inorganic compounds in soil microaggregates, due to the lack of in-situ analyses of undisturbed material. We hypothesized that microaggregates are spatially organized due to interactions between organic matter and mineral phases. To test this, we separated the water stable, occluded, large and small microaggregate fractions (250–53 and 53–20 µm, 60 J ml−1 dispersion energy) from Ap horizons of a toposequence of sandy to loamy Luvisols (Germany) with increasing clay contents (19 to 35% clay), and subjected in total 60 individual aggregates to elemental mapping by electron probe micro analysis (EPMA), which recorded C, N, P, Al, Fe, Ca, K, Cl, and Si contents at 1 × 1 µm resolution. Stoichiometric element ratios characteristic for organic and inorganic matter were used to define discrete components of the aggregates and analyze their spatial arrangement. We found a pronounced heterogeneity in content and arrangement of discrete aggregate components, which was not reproducible for different specimens from the same soil microaggregate fraction, and thus largely independent of clay content in soil. However, nearest neighbor analyses revealed close spatial correlations between plant detritus (C:N app. 100:10) and microbial organic matter (C:N app. 10:1) indicating a spatial relationship between source and consumer. There was no systematic relationship between soil minerals and organic matter, suggesting that well-established macroscale correlations between contents of pedogenic oxides and clay minerals with soil organic matter storage do not apply to soil microaggregates.

Experimental Study on Main Physical Parameters Controlling Shear Strength of Unsaturated Loess

It is particularly important to study the strength of unsaturated loess, and its accurate determination is crucial to the stability analysis of soil slope and foundation and calculation of earth pressure. In order to reveal the control mechanism of physical parameters on the shear strength of unsaturated loess, the intact and remolded loess were used as the research object; sandy silt, quartz flour, and quartz sand were used as contrast; the systematic direct shear tests of unsaturated loess, sandy silt, and quartz sand under different conditions of water content, dry density, and clay content were carried out. The results show that the cohesion, internal friction angle, and shear strength of unsaturated loess piecewise functionally decrease with the increase of water content, its shear strength increases linearly with the increase of dry density, and its internal friction angle shows an upward quadratic function relation with the increase of clay content. The law results of comparing sandy silt, quartz flour, and quartz sand with loess considering water content and dry density are the same; therefore, the equation of shear strength of unsaturated loess is proposed for practical engineering reference, and by the first derivative analysis of the equation, it is feasible to determine the control proportion of the three parameters on the shear strength of unsaturated loess. A stage-like difference between the three control proportions is observed, depending on the combination variations of water content and clay content.

Anthropogenic impact on grain-size distribution and agrophysical properties of soils of cultivated rice lands of Kuban

This work reviews the relation of the grain-size distribution and impact of the use of rice rotation soils on the main agrophysical indicators of soils that determine the composition and properties of soil cover of modern delta of Kuban. The regularities of dependence between the density of the matrix soil and the grain-size distribution that consist of mineral composition of alluvial soils and rocks have been identified. The trend towards increase in soil density with increase in physical clay and silt content, as well as increase in matrix soil density has been established. No significant differences in agrophysical properties of subsurface soil horizons and underlying formations have been identified. The agrophysical indicators of soils of rice fields and boharic analogues during their agricultural use have been assessed. The hydromorphic soil-forming processes did not lead to considerable changes in agrophysical properties of alluvial formations and soils involved in rice rotation.

The impact of landscape evolution on soil physics: evolution of soil physical and hydraulic properties along two chronosequences of proglacial moraines

Abstract. Soil physical properties highly influence soil hydraulic properties, which define the soil hydraulic behavior. Thus, changes within these properties affect water flow paths and the soil water and matter balance. Most often these soil physical properties are assumed to be constant in time, and little is known about their natural evolution. Therefore, we studied the evolution of physical and hydraulic soil properties along two soil chronosequences in proglacial forefields in the Central Alps, Switzerland: one soil chronosequence developed on silicate and the other on calcareous parent material. Each soil chronosequence consisted of four moraines with the ages of 30, 160, 3000, and 10 000 years at the silicate forefield and 110, 160, 4900, and 13 500 years at the calcareous forefield. We investigated bulk density, porosity, loss on ignition, and hydraulic properties in the form of retention curves and hydraulic conductivity curves as well as the content of clay, silt, sand, and gravel. Samples were taken at three depths (10, 30, 50 cm) at six sampling sites at each moraine. Soil physical and hydraulic properties changed considerably over the chronosequence. Particle size distribution showed a pronounced reduction in sand content and an increase in silt and clay content over time at both sites. Bulk density decreased, and porosity increased during the first 10 millennia of soil development. The trend was equally present at both parent materials, but the reduction in sand and increase in silt content were more pronounced at the calcareous site. The organic matter content increased, which was especially pronounced in the topsoil at the silicate site. With the change in physical soil properties and organic matter content, the hydraulic soil properties changed from fast-draining coarse-textured soils to slow-draining soils with high water-holding capacity, which was also more pronounced in the topsoil at the silicate site. The data set presented in this paper is available at the online repository of the German Research Center for Geosciences (GFZ; Hartmann et al., 2020b). The data set can be accessed via the DOI https://doi.org/10.5880/GFZ.4.4.2020.004.

INFLUENCE OF SOIL TYPE ON WOOD DENSITY AND MEAN ANNUAL INCREMENT IN TWO COMMERCIAL Eucalyptus CLONES

In forest plantations, the productive potential of a given site results from the interaction between genetic materials and environmental conditions. Both are fundamental factors for wood quality and Mean Annual Increment. Knowing the performance of different Eucalyptus urophylla commercial clones under different soil conditions is important for forest planning. Our objective is to evaluate the infuence of soil types on Wood Basic Density and Mean Annual Increment - MAI in two E. urophylla clones. We analyzed the Wood Basic Density of 3- to 8-year-old trees and MAI from two clones grown in four soil types in 14 localities of São Paulo state. ANOVA and Tukey test at 5% probability were performed to test the effect of soil type on Wood Basic Density and MAI. Linear and exponential regression equations were performed between Wood Basic Density x MAI and between MAI x Clay Content, respectively. In general, some soils showed signifcant differences in Wood Basic Density, possibly from climatic variation among sites. Also, the MAI increased exponentially with increase of Soil Clay Content (up to about 25 to 35% of clay), but no correlation was observed between MAI and Wood Density.