Physical Properties Of Clay Soils Research Articles

Effect of rotary plow with different blades, plow cover height and different forward speed on some soil physical traits

This research was conducted to study the effect of different forms of rotary plow blades s on clay loam soils, through the use of three forms of blades (traditional blades (T1) and locally manufactured blades (T2 and T3)), and two forward plowing speeds (3.85 and 6.04) km. ̄ ¹ hour, two rotary tiller hood opening angles (35˚ and 70˚)and the study of its effect on the physical properties of clay soil: penetration resistance, average volume of stirred soil, percentage of earth masses with diameters less than 5 cm m², bulk density of soil, and total porosity. The research was carried out using the split split plank method according to the randomized complete block design (C.R.D) and with three replicates for each treatment. The results showed that the forward speed (3.85) kmh ̄ ¹ has achieved the best soil resistance to penetration. While the forward velocity (6.04) kmh ̄ ¹ achieved the best values for each soil volume rate, soil bulk density and total porosity. The angle (35˚) recorded the best values for each of the soil resistance to penetration and the proportion of soil masses, while the angle (70˚) excelled in recording the best values for each average of the volume of the soil stirred up, bulk density and porosity. The blades ((T3) was significantly excelled on the two blades (T1 and T2) in achieving the best values of penetration resistance, average volume of soil stirred up, mass ratio, bulk density, and porosity. As for the overlap between the two forward speeds and cover angles of the plow, the speed was (3.85) km per hour ̄ ¹ With angle ((35˚) best values for penetration resistance,As for the speed (6.04) km h ̄ ¹ with an angle ((70˚), the best values were recorded for the average volume of the stirred soil, bulk density and porosity. As for the interaction between the two speeds and the shape of the blades, the blades (T3) excelled at the forward speed (3.85) km/h ̄ ¹ in giving the best value for resistance to penetration. While the blades itself gave at the speed (6.04) kmh ̄ ¹ the best values for the average volume of soil stirred up. As for the overlap between the angles of cover for the plow and the shape of the blades, the blades (T3) excelled at the angle (70˚) in achieving the best values for the average volume of soil stirred up and density virtual and porous, At the angle (35˚), the blades achieved the best value of penetration resistance and the percentage of soil masses. As for the interaction between the two forward speeds of plowing, the angles of the opening of the rotary plow cover and the shape of blades, there were no significant differences in the physical traits of soil.

Pengaruh Penambahan Abu Arang Tempurung Kelapa Pada Tanah Lempung Terhadap Hasil Uji Kompaksi

The purpose of this research is to determine the physical properties of clay soil and to analyze the effect of adding coconut shell charcoal ash to the clay soil. The soil samples used in this study came from Tanralili District, Maros Regency, two sample points were taken and the variations in the levels of addition of coconut shell charcoal ash is 0%, 4%, 6%, 8%, 10%. The test method used refers to ASTM (American Society for Testing Materials). The tests carried out were testing the physical properties of the soil in the form of moisture content, specific gravity, Atterberg boundaries, filter analysis, and hydrometer analysis, then a compaction test was carried out to determine the maximum soil density. The results of the test obtained a moisture content value of 28.811%, a specific gravity of 2.58 g / cm3 so that it is classified as organic clay. As well as the plasticity index value of 9.926% with moderate plasticity from the 7% -17% interval. Then from the test results of soil compaction testing with the addition of coconut shell ash, the dry density (gdry) equal to 0.862, 0.886, 0.914, 0.943, 0.962, this means that the soil sample experienced an increase in dry density (gdry) of 11.60%. From the research results it can be concluded that the addition of coconut shell charcoal ash can increase the value of soil dry density so that it can be used to increase the value of the carrying capacity of clay soil.

Pengaruh Penambahan Abu Cangkang Kelapa Sawit Pada Tanah Lempung Paccinongang Kabupaten Gowa

Soil has an important role in a highway construction planning that serves to pass the load from the top layer, but not always the basic soil layer is able to function properly. Therefore, in this study was conducted to find out the effect of the addition of oil palm shell ash on clay soil to UCT (Unconfined Compression Test). The type of soil that will be usedfor penelitian is clay soil taken in Paccinongang area, Gowa Regency. The methodology in this study conducted several soil physical properties testing then Kompaksi testing to obtain optimum moisture content value, and Unconfined Compression Test to get strong press value (qu). The results of the study showed that the soil meets the physical properties of clay soil. From The Free Press Strong test on the ash content of the palm shell 0%, 3%, 6%, 9%, 12% and 15% at point 1 the free press strength value decreased from 0% by 0.362% and increased at 9% by 0.424%. Meanwhile, at point 2, it decreased by 0% by 0.445% and increased at 12% by 0.423%. From the Unconfined Compression Test on Paccinongang clay, Gowa Regency with the addition of oil palm shell ash from both samples, there was an increase in the addition of 9% and 12% of normal clay soil.

Investigation of the effect of water repellents on the rolling border and the yield stress of clay soils of the base and subgrade of the road

During the construction of roads, the main factor affecting the operational characteristics of a linear facility is the climatic conditions of a particular area where the future road will pass. In the article, the authors consider the problem of building roads on weak soils with insufficient strength characteristics, such soils cause difficulties in the design and operation of the structure. The purpose of this study is to change the physical properties of cohesive soils to increase their strength characteristics. The authors systematized information on existing methods for stabilizing clay soils of the base and subgrade of the road. The results of experimental laboratory studies performed by the authors of the article on the influence of water repellents on the physical properties of clay soil are presented. According to laboratory studies, it can be concluded that with the optimal selection of hydrophobic materials, it is possible to increase the bearing capacity of soft soils, which in turn will lead to an increase in the technical and operational characteristics of the structure and an increase in turnaround times. The main conclusions are formulated based on the analysis of laboratory tests.

Impact of Silica Gel application under Different Irrigation Levels on Water Retention Characteristics and some Physical Properties of Clay Soil

Impact of Silica Gel application under Different Irrigation Levels on Water Retention Characteristics and some Physical Properties of Clay Soil

The effect of nano composite on phosphate adsorption in rich black soil

Industrial waste disposal is one of the major causes for the contamination of water bodies and soil. This leads to increase in the amount of elements like phosphorous in the water bodies. As a possible solution to this problem, we investigate the effect of introducing a nano sized coating of graphene on coastal sand in the adsorption of phosphate. In the present study we employ batch adsorption techniques to perform Phosphate adsorption (p-Adsorption) on rich black coastal sand and nano composite. This will help us in understanding the physical properties of clay soils, the effect of nanoscale coating on the adsorption of phosphate in soil and its dependence on contact time, concentration and ph values.

Assessment of Orange Peel Hydrochar as a Soil Amendment: Impact on Clay Soil Physical Properties and Potential Phytotoxicity

The main objectives of this work were the following: (1) to investigate the applicability of orange peel hydrochar as a soil amendment for improving the physical properties of a compacted, clay soil and (2) to study the growth of maize on substrates composed of clay soil and hydrochar and determine any potential phytotoxic effects. The effect on soil’s bulk density (BD), aeration, water holding capacity (WHC), and hydraulic conductivity were examined with hydrochar additions of 5, 10 and 15% (w/w) and determined by conventional laboratory methods. Potential phytotoxic effects were determined through the Zucconi germination index on fresh, diluted and 4-week old undiluted hydrochar extracts. The effect of hydrochar on maize growth was studied in clay soil (as reference), clay soil with 5% (w/w) fresh hydrochar, clay soil with 5% (w/w) of 4-week-old hydrochar and clay soil with 5% (w/w) biochar (for comparison). At an application rate of 5% (w/w) hydrochar, the bulk density was reduced from 1.35 to 1.22 g/cm3, the air-filled porosity was increased from 33 to 37% and the saturated hydraulic conductivity from 0.96 to 1.01 cm/h. The water holding capacity remained practically unchanged, however it was considerably reduced at higher application rates. The seed germination test indicated strong phytotoxicity of the fresh, undiluted hydrochar extract, which was reduced when the extract was diluted or the hydrochar allowed to mature for 4 weeks. The pot tests indicated that hydrochar did not improve the yield of maize, probably due to the presence of phytotoxic substances. This study demonstrated a new valorization pathway for a significant agricultural waste. Additionally, it proved the applicability of orange peel hydrochar for improving the physical properties of clay soil. However, due to phytotoxic effects, further work is required before a field application is considered.

Estudo Experimental do Efeito da Argilosidade Sobre as Propriedades Físicas de Solos

This final course work aimed to evaluate the effect of shaliness on the physical properties of clay soils, with emphasis on the properties of porous media. For this, we used a gas poropermeameter based on the pressure variation on confining chamber, in order to obtain values of absolute permeability and effective porosity on unconsolidated sediments (soils). The values for pore volume are obtained by Boyle Mariotte law, which relates the variation of pressure and volume of an ideal gas at constant temperature, while permeability values are obtained by Darcy’s law. It is also emphasized the development of a method for analysis of unconsolidated sediments with the equipment since it was designed to consolidated sediments. This includes sample enveloping and studies for determination of ideal pressures and flows to be used. Measured values for permeability and porosity were used in estimating other physical parameter of the sediments, the specific surface of the grains, through the Kozeny-Carman equation, whose constant was considered equal to 5, since this is the value recommended for flow in porous unconsolidated sediments. Results show that this equipment can be used successfully for measurements of physical pore properties of soils if samples are properly prepared.

Effect of Cropping System on Physical Properties of Clay Soil Under Intensive Rice Cultivation

AbstractCropping systems are thought to alter soil quality in paddy rice fields. This study was conducted to quantify the long‐term effects of continuous crop production under different cropping systems with different crop rotations on physical properties of alluvial clay soil in the Mekong Delta, Vietnam. Soil samples were collected from four treatments: (i) traditional intensive rice monoculture with three rice crops per year (R–R–R); (ii) rotation with two rice crops and maize (R–M–R); (iii) rotation with two rice crops and mung bean (R–Mb–R); and (iv) rotation with one rice and two upland crops, mung bean and maize (R–Mb–M). We hypothesized that cropping systems with rotations of upland crops and their temporary beds improve the physical quality of paddy rice soil; hence, they are better options towards sustainable agriculture. Results show an improvement of soil physical quality for systems with two rice crops and one upland crop (R–M–R and R–Mb–R) and those with one rice crop with two upland crops (R–Mb–M) compared with intensive rice monoculture (R–R–R). This was translated in decreased bulk density and soil strength, increased soil organic carbon and total porosity, and higher aggregate stability index, plant‐available water capacity, and Dexter's S index, especially at depths of 10–20 and 20–30 cm. The systems with different upland crops (maize or mung bean) showed similar high physical quality improvement. To maintain soil quality in future seasons, introducing a cropping system with at least one upland crop in rotation with rice is recommended. Copyright © 2014 John Wiley & Sons, Ltd.

A BATCH STUDY OF PHOSPHATE ADSORPTION CHARACTERISTICS ON CLAY SOIL

The research has been carried out on Phosphate (p-Adsorption) on clay soil through batch adsorption techniques. Main objectives of this study are to study the physical properties of clay soils, detection of Phosphate removal by adsor bent as a function of contact time, adsorbent dosage and p H , to study sorption kinetics. The results of this study shows the optimum contact time, dosage and p for adsorption of Phosphate on clay soil reaching the equilibrium condition after 60 minutes with remov al efficiency of 86% and 1400 mg as optimum dosage. Higher adsorption of Phosphat e was observed at p H 9.0. The rate of adsorption of Phosphate obeys fir st order rate equation. The obtained results of the batch ex periments are best fit to Langmuir and Freundlich a dsorption isotherms. From the experimental analysis it is concluded that clay soi l shows good removal efficiency and can be used as good adsorbents. st century are waste disposal from various industries, municipal dumping in the urban areas and increased use of chemical fertilize rs, pesticides and irrigation water. The residues of fe rtilizers, pesticides and irrigation water created adverse imp act on soil and water bodies. The pollutants such as sewage and fertilizers contain nutrients as phosphates and nitrates. If th e nutrients are in excess level they over stimulate the growth of aquatic plants and algae. These excessive growths of algae and aquatic plants clogs the water ways, use up dissolved oxyge n as they decompose and block light to deeper water affecting the respiration ability of fish and other invertebrates that reside inside the water. Lakes, rivers and other water bod ies undergo Eutrophication an aging process in natural conditio n that slowly fills in the water body with sediment and or ganic matter. These sediments when enter water bodies fis h respiration becomes impaired, plant productivity an d water depth becomes reduced and aquatic organisms and their environment becomes suffocated. When the levels of oxygen drops below two-five parts per million many types o f fish and bottom dwelling animals cannot survive. When this occurs it leads to the disruptions in the food chain by killi ng aquatic organisms in large numbers. Oxygen demanding materials such as nitrogen and phosphorous are high in animal wastes and they often harbor pathogenic organisms. Hence s ome special attention must be given for budgeting of fe rtilizers; Phosphorous in high doses may be susceptible to dra in freely in the soil immediately followed by heavy rainfall causes some phosphorous losses through volatilization and leaching process. Thus once the ecosystem are contaminated by these elements they become a potential threat for many ye ars. Therefore it is of crucial importance to study the mutual influence of the different minerals in soil retenti on process whose migration ability of particular component in ground water is explained by the retardation factor(R).Far mers extensively follow the irrigation process due to av ailability of water from various sources, where phosphate polluti on is caused by the use of fertilizers and pesticides. Th us the main objective of this work is to study the leaching and retention of phosphate in the clay soil available in the area us ed for agricultural process, determining the maximum amount of phosphate adsorbed and to evaluate the potentials o f phosphate migrating through the soil during ground water percolation by using a set of batch experiments who se results are fitted to the equations given by Langmuir and F reundlich isotherms.

The effect of stratigraphic heterogeneity on areal distribution of land subsidence at Taiyuan, northern China

Taiyuan city has experienced serious land subsidence since the 1950s, with the maximum accumulated subsidence of 2,960 mm and a total affected area of 585 km2 by 2003. Tectonic settlement was found to contribute about 1% and the major cause is over-exploitation of groundwater. The spatial–temporal relationship between the areal distribution of land subsidence and that of groundwater drawdown from 1956 to 2000 indicates that although land subsidence centers overall match groundwater depression cones, there are local deviations, and that although the time series curves are similar, land subsidence always lags behind groundwater level decline, with different lag time at different sites. The major findings of this work on the control of stratigraphic heterogeneity on the spatial pattern of land subsidence at Taiyuan include: (1) land subsidence centers shift from the corresponding groundwater depression cones to the sides with thicker accumulated clay layers; (2) under the same pumping rate, land subsidence at places with more clay interlayers and thinner individual interlayers is greater and the lag time shorter; and (3) land subsidence is closely related to the physical properties of clay soils. The Interbed Storage Package-1, a modular subroutine of MODFLOW was employed to simulate the areal distribution of individual layer compression. The modeling results show that compression of different clay layers has different contribution to land subsidence. Pumping groundwater from water-bearing zones close to the most compressible clay layers should therefore be carefully controlled.

Effects of shallow tillage on physical properties of clay soil and growth of spring cereals in dry and moist summers in southern Finland

Field experiments under Nordic conditions have shown that on clay and silty clay soils, shallow tillage gives higher yields than ploughing if the early summer is dry. A long-term field experiment was carried out with spring wheat ( Triticum aestivum L.) during 1986–1990 and with spring oats ( Avena sativa L.) during 1991–1995 on a clay soil (Vertic Cambisol) in southern Finland. The objective of the study was to clarify the factors making soil shallow-cultivated (6 cm) in spring (SH) more drought-resistant than soil conventionally ploughed (25 cm) in autumn and cultivated in spring (CN). Between treatments, the differences in the macropore (equivalent diam. > 30 and 300 μm) volumes of the 0–20 and 20–40 cm layers were slight. At a depth of 20 cm the SH tillage increased the biopore (diam. 0.2–1 and > 1 mm) number, associated with earthworms and made by roots and root density. Shallow tillage favoured the deep growth of root systems during the early summer. No clear differences were found between the SH and CN treatments in root clustering in the soil. Just after sowing, the soil was markedly moister under SH treatment than under CN treatment. Spring shallow cultivation may substantially increase the yields (1.9 Mg ha −1) and N uptake by grains (48 kg ha −1) if the early summer is dry.

Changes of some physical properties of a clay soil following passage of rubber- and metal-tracked tractors

The aim of this research was to evaluate the change in physical properties of an arable clay soil following passage of rubber- and metal-tracked tractors in view of increased use of tracked tractors for ploughing on clay soil in centre-south and insular Italy. Field tests were carried out on arable soil cropped to lucerne ( Medicago sativa L.) to compare two types of tracked tractors, one with rubber tracks (CAT Challenger Ch35) and one with metal tracks (FIAT FA 150) in order to establish the compacting effects resulting from one and four passes of the tractors on the same track. The following parameters were studied: soil penetration resistance, bulk density and its increment ratio, pressure distribution on soil along the length of the tracks, soil macroporosity and hydraulic conductivity. Multiple passes made by the two tractors induced very similar effects in the surface soil in regards to soil penetration resistance and dry bulk density. Mean values of penetration resistance (0 to 0.20 m depth), were 2425 kPa for rubber tracked tractor and 2415 kPa for metal-tracked tractor; dry bulk density values were 1.52 and 1.48 Mg m −3, respectively. The decrease in macroporosity, in particular that of elongated pores in the soil surface layer (0–0.10 m depth) was greater in treatments involving the rubber-tracked tractor (from 10.6% to 4.0%) than for the metal-tracked tractor (from 10.6% to 7.3%). Following traffic of the two tractors hydraulic conductivity decreased and the lowest values were found after one and four passes of the rubber-tracked tractor (1.5 and 0.08 mm h −1, respectively). A highly significant correlation between hydraulic conductivity and elongated pores and a significant correlation with total macroporosity were found. Significant exponential relationships between macroporosity and penetration resistance for one and four passes of both tractors were found in the surface soil. A significant difference was found between tractors and for correlations of penetration resistance values above control values. However, in the soil surface with respect to the higher degree of porosity, treatments involving the metal-tracked tractor showed better soil structure quality.

Estabilidad estructural, distribución de tamaño de poros y propiedades electroquímicas de suelos arcillosos de diferentes mineralogías y contenidos de materia orgánica

En un estudio para evaluar los efectos interactivos de la mineralogía y la materia orgánica sobre las propiedades químicas y físicas de los suelos arcillosos, se tomaron medidas a varias profundidades en cuatro perfiles de suelos de mineralogía oxídica, caolinítica, mixta y montmorilonítica, respectivamente. En cada perfil el contenido de materia orgánica varió con la profundidad; la mineralogía y la textura se mantuvieron constantes. Estas condiciones permitieron evaluar los efectos combinados de la mineralogía y la materia orgánica bajo condiciones de textura constante. Se encontró que la estabilidad de los agregados bajo el agua correlacionó principalmente con el contenido de carbono orgánico del suelo; se observó una influencia relativamente pequeña la mineralogía excepto en el suelo oxídico donde posiblemente hubo cementación por óxidos. Conjuntante con un aumento en la materia orgánica del suelo, se observó un aumento en la capacidad retención de agua del suelo en los intervalos de potencial matrical entre 0 y -0.33 bares (0 y -33 kPa) y -0.33 y -0.8 bares (-33 y -80 kPa). El efecto de la materia orgánica sobre la retención de agua en el último intervalo fue más notorio en los suelos de mineralogía oxídica y caolinítica. En todos los suelos y horizontes la distribución de tamaño de poros en la región entre 0 y -0.33 bares de potencial matrical era de tipo logarítmico-normal. Se observó prácticamente la misma media geométrica y la misma desviación estándar en cada suelo. Los datos implican una similitud entre suelos, en el sentido que el espacio poroso atribuible a los poros de un tamaño dado, en proporción a la porosidad total entre 0 y -0.33 bares de potencial matrical, siempre fue el mismo. La diferencia principal entre los suelos fue la porosidad total entre 0 y -0.33 bares, lo cual dependió en gran manera del contenido de materia orgánica del suelo. Concorde con otros estudios en la literatura, se observó un aumento en la capacidad efectiva de intercambio catiónico y una disminución del pH correspondiente al punto isoeléctrico, según aumentaba la materia orgánica y según la mineralogía cambiaba en la secuencia oxídica -> caolinítica -> mixta -> montmorilonítica. Los resultados de estudio destacan la importancia del manejo de la materia orgánica para optimizar las propiedades químicas y físicas de los suelos, particularmente en suelos altamente meteorizados.

On the use of organic manures for amendment of compacted clay soils: Effects of aerobic and anaerobic conditions

The effects of manures on soil fertility are often inconsistent and unpredictable. It is suggested that proper aeration conditions in the soil-manure mixture may be essential for improving physical properties of clay soils. Soil samples were mixed with compost or manure and incubated aerobically, anaerobically (under N 2 atmosphere) and under flooded conditions. Soil density and aggregate stability were both improved when the mixtures were incubated aerobically, with no effect when the incubation was under anaerobic conditions. Similarly, aerobic incubation led to increased formation of polysaccharides, polyuronides and humic acids, compared to a decrease with time of these components under anaerobic conditions.

Effect of moisture and freezing on some physical properties of clay soils from plough layer

The aim of this study was to elucidate the effects of freezing on some structural properties of clay soils. The laboratory analyses were based on field observations including measurements of soil temperature and frost depth. The daily temperatures showed remarkable variations on the very soil surface both in the autumn and spring, ranging from below zero at night-time to above 10°C at daytime. The depth of soil frost was deepest in the ploughed field, whilst the straw cowers on the soil surface not only strongly reduced its depth, but also slowed up the thawing. Eight clay soil samples were analyzed in the laboratory. At the potentials of —0.001 to —0.1 bar the water retention capability of soil was reduced by freezing. Disruption of the 5 —10 mm aggregates by freezing, analyzed with wet and dry sievings and waterdrop analysis was strongly dependent on the water potential, the Water potential of 1.0 bar or lower having in general no effect. The total pore volume of aggregates Was dependent on the water potential when it exceeded —15.0 bar. Freezing had a minor effect on the pore volume of the aggregates, if they were let to thaw before drying. The freeze-dried aggregates showed a clear increase of pore volume when the water potential at freezing exceeded —1.0 bar. The movement of water due to ice formation was studied with small and big soil cylinders. It showed a great effect on the structure, if total pore volume, determined with a mercury method, is considered the standard of judgement. Thus it was concluded that the water movement even at a short freezing period is one of the most essential factors determining the structural formation of ploughed clay soil.

Changes in some physical properties of clay soils induced by dextrans

Durch Dextrane hervorgerufene Veränderungen einiger physikalischer Eigenschaften von TonbödenVeränderungen in Wasserstabilitätsindex, Spezifischer Oberfläche und Mikroporengrößenverteilung nach Behandlung mit 3 Dextranen wurden an 1–2 mm großen Aggregaten von 3 italienischen Tonböden bestimmt.Das Molekulargewicht der ausgewählten Dextrane reichte von 10.300 bis 1.960.000, und eine Lösung jeden Polymers wurde so zu den Bodenproben gegeben, daß der Endgehalt 0,5 bis 2,5 Gew.‐% auf lufttrockener Basis betrug.Die durch Feuchtsiebung bestimmten Wasserstabilitätsindizes stiegen signifikant nach jeder Behandlung mit den beiden Dextranen höheren Molekulargewichtes, blieben jedoch praktisch unbeeinflußt durch das kleinste Polymer noch bei der höchsten der benutzten Konzentrationen.Die Spezifische Oberfläche, bestimmt durch Stickstoff‐Adsorption bei niedriger Temperatur, nahm in den behandelten Böden immer unabhängig von dem Molekulargewicht des benutzten Dextrans, und ausschließlich abhängig vom Anstieg des Polymergehaltes ab.Die Größenverteilung der Mikroporen der 3 Böden, berechnet aus der Desorptionskurve der Stickstoff‐Isothermen, zeigte ein Maximum für Poren von ungefähr 19 Å. Alle Dextrane durchdrangen nicht die zu diesem Maximum gehörenden Poren, sondern blockierten teilweise ihren Eingang. Auf diese Weise wurde der für den Stickstoff zugängliche Volumenanteil vermindert.

Relationship between pore size distributions and physical properties of clay soils

Pore size distributions using mercury injection and nitrogen sorption techniques were determined on a number of soils classified as clays on the basis of particle size analysis. Some of these soils exhibit markedly different consistencies during texturing and undergo changes in texture during prolonged manipulation, e.g. subplastic, superplastic and self-mulching soils. The pore size distributions for these soils do not differ significantly from those obtained for the normal labile clay soil in the pore size range 2 nm to 50 �m. The clay soils examined, with the exception of the krasnozem, have the majority of their pore volume within pores smaller than 10 nm with the predominant pore size centred around 3 nm plate separation. In the case of the krasnozem, the particle size analysis does not correspond to the texture assessment as a clay loam. Surface and subsoil samples of the krasnozem have high porosities and predominant plate separations of 6 nm. They consequently possess significantly different pore size distributions from the other clays. In the case of the surface sample, only a small proportion of its total pore volume is in pores smaller than 10 nm. These differences in pore structure observed between the krasnozem and the other soils examined may result from differences in mineralogy, and in particular from the high sesquioxide content of the krasnozem.

Influence of Exchangeable Ions on the Physical Properties of Clay-soils

Influence of Exchangeable Ions on the Physical Properties of Clay-soils

The physical properties of clay soils and some aspects of their mechanical behaviour

The physical properties of clay soils and some aspects of their mechanical behaviour