Effect of NaCl-induced saline sodicity on the interpretation of soil potassium dynamics

Excess of exchangeable sodium (Na) in salt-affected soils causes ion toxicity and decrease in nutrient uptake by plants, particularly potassium (K). A number of studies have been conducted to investigate the effect of K-fertilization on plant growth under sodic and saline-sodic conditions but the results are much diverse to process for concrete recommendations. To explore the possible reasons, it was hypothesized that Na applied as NaCl to produce salinity/sodicity in the soil may release non-exchangeable K, minimizing the effect of K-fertilization. Incubation studies were conducted for 2, 4 and 6 days in the light (sandy loam) and heavy (clay loam) textured soils producing two saline/sodic levels, i.e. 20 and 30 sodium adsorption ratio (SAR) along with control (SAR 3). Potassium fertilizer applied was calculated according to 40 (general recommendations based on soil-nutrient status), 80 and 160 kg K ha^?1. Interestingly, it was observed that addition of NaCl possibly released non-exchangeable K from the soil minerals and increased the K concentration in soil solution. Total K release was more in heavy textured soil but initial release was more in light textured soil. This release may eliminate the effect of K-fertilization applied under salt stress induced by NaCl. Therefore, it is suggested that while studying Na–K interaction in salt-affected soils, NaCl should be avoided to produce salinity, and naturally occurring saline-sodic soils may be used. Soil Na–K interaction studies including ameliorating effect of K under sodic or saline-sodic conditions should be conducted carefully considering the above-stated argument.     

CLAY MINERAL DISTRIBUTION AND ORIGIN IN THE SOIL TYPES OF ISRAEL

The mineralogical composition of clays (< 2μm) in representative profiles of all soil types of Israel was investigated. The soils were classified according to their clay mineral assemblages into three groups. I. Montmorillonitic soils. Montmorillonite is the dominant mineral and exceeds 65 per cent of the total minerals found; each of the other minerals comprises less than 15 per cent. 2. Montmorillonitic-kaolinitic soils. The soil clay fractions contain 50-60 per cent montmorillonite and 15-25 per cent kaolinite, generally adding up to more than 75 per cent of the clay fraction. 3. Montmorillonitic-calcitic soils. The clays contain more than 10 per cent calcite. Montmorillonite is the dominant clay mineral (except for one soil type, mountain rendzina, where calcite is dominant). The first and second assemblages are typical of the soils of the Mediterranean zone, whereas the soils of the desert zone are characterized by the third assemblage. The origin of montmorillonite, kaolinite, and illite, the three main clay minerals, was found to be detritic, as was the origin of palygorskite which was mainly found in the calcite rich soils of the desert zone. The cation exchange capacity of montmorillonite seems to be higher under higher precipitation. Montmorillonite content and cation exchange capacity of the clays were found to be highly correlated. The carbonate content of the clay fraction and the amount of carbonate in the soil were also highly correlated.     

Hydraulic conductivity of calcareous soils as affected by salinity and sodicity. I. effect of concentration and composition of leaching solution and type and amount of clay minerals of tested soils

Abstract

Although there is generally no physical problem with salt‐affected soils when irrigated with saline and sodic waters, physical deterioration of the soils often results when leached with good quality (low salt and low sodium) irrigation water or by rain. Two major mechanisms of swelling and dispersion of clay particles have been proposed to be responsible for reduction in hydraulic conductivity (HC). The type and amount of clay minerals are major factors influencing the swelling and dispersion properties of soil in the presence of saline‐sodic solutions. The study was initiated to improve the understanding of swelling and dispersion processes in response to saline‐sodic conditions, particularly the role of the type and amount of clay minerals of the tested soils and the concentration of the leaching solutions. The study was conducted in a series of two leaching experiments. In the first experimental soil samples were leached with solutions of different combinations of 100 meq (NaCl+CaCl₂)L^‐1 and sodium adsorption ratio (SARs) 5, 10, 15, and 20. In the second, 8 samples of them selected to be leached with solutions of the same SARs of 5, 10, 15, and 20, but the higher concentration of 1000 meq (NaCl+CaCl₂)L^‐1. The changes in the HCs were determined through the concept of “the Sensitivity Index‐SI values”;. In general, solutions with lower concentrations and higher SAR resulted in greater reductions in the soil HC (i.e, SI value), and the SI values and SAR level showed a negative linear relationship. With respect to the regression equations between the SI values and the swelling/dispersion processes, and the relatively coarse texture as well as the mineralogical composition of the tested soils which shows the dominant clay minerals in almost all tested soils is non‐expanding dispersive quartz, illite and chlorite, it may be concluded that the slaking of the soil structure is responsible for blockage of the conducting pores and reduction in the HCs of the tested soils.     

THE INFLUENCE OF MAGNESIUM AND OF EASILY WEATHERED MINERALS ON HYDRAULIC CONDUCTIVITY CHANGES IN A SODIC SOIL

Exchangeable Mg appears to have no specific effect on soil hydraulic conductivity of A and C horizons of a sodic sandy loam soil (montmorillonite and kaolinite clay minerals) leached with solutions which cause clay swelling to be the dominant mechanism reducing conductivity (SAR < 20, electrolyte concentration 10 meq per litre). There is some evidence of a specific effect when these soils are subsequently leached with water which causes clay dispersion to become important. Fresh loess in the A horizon dissolves in percolating rainwater, causing difficulties in the replication of experiments. It seems to give a small degree of ‘self protection’ to soil structure, a property likely to be operating in other soils affected by recent loess deposits.     

Fine silt and clay mineralogical changes of a soil chronosequence in the Langtang valley (Central Nepal)

Chemical and mineralogical properties of a soil chronosequence in the high mountain zone between 3857 m and 4120 m a.s.l. in Central Nepal (Langtang valley) are presented. The soils have been developed in moraine deposits which consist of acid gneisses. They were classified as Entisols, and Spodosols. XRD analyses of the clay and fine silt fraction show increasing changes with distance from the recent Lirung glacier, depending on the time of deposition, resp. soil age. Alteration of illite to interstratified minerals and to hydroxy-Al interlayered minerals or pedogenic chlorite with increasing soil development could be observed. The interstratified minerals could be identified as random and regular illite-interlayered vermiculite mixed-layer minerals. Intensification of the X-ray signals of the fine silt fraction is given compared to the clay. With increasing soil development differences between the clay and fine silt fraction seem to increase. Indications are given of interstratification of the mica-pedogenic chlorite and chloriteinterlayered vermiculite type in the more intensively weathered soils.     

解钾细菌与黏土矿物协同促进玉米生长提高土壤养分有效性

为了揭示解钾细菌在西北矿区浅埋古河道土壤中对植物生长和土壤养分利用的影响,通过日光温室短期盆栽的方式,以不同黏土矿物配比的人工培土为基质模拟古河道不同质地土壤,以西北地区常见农作物玉米为宿主,研究解钾细菌在人工培土基质中的微生物数量变化规律,以及二者协同作用对玉米生长和矿质养分吸收的影响。结果表明:1)土壤黏土矿物含量增大有利于提高土壤解钾细菌数量,促进微生物活性。当黏土矿物质量分数为68%,速效钾质量分数约170 mg/kg时,解钾细菌数量最大;2)玉米地上部分干质量、根冠比、根系活力随黏土矿物含量增大而增大,以解钾细菌作用下黏土矿物质量分数68%的玉米生长效果最佳;3)在解钾细菌作用下,植物氮磷钾积累量和土壤养分利用的最佳土壤黏土矿物质量分数为45%、68%和75%,土壤钾素、氮素和磷素最大利用率分别达到65%、53%和17%;4)解钾细菌在土壤钾素含量低时促进土壤磷素吸收,土壤钾素过量时,促进土壤氮磷钾的吸收,提高土壤养分利用率。因此,土壤黏土矿物与解钾细菌相互作用,而且积极影响植物生长和土壤养分的吸收利用,这对进一步探寻适合矿区浅埋古河道土壤的微生物复垦技术,深入改良和开发矿区退化土壤具有重要意义。     

The effect of lime on the response of soils to sodic conditions

The role of CaC0₃ in preventing clay dispersion and losses in hydraulic conductivity (HC) of sodic soils was determined directly by mixing two lime-free soils with 0.5 and 2.0 per cent CaCO₃. Whereas the HC of the lime-free soils dropped sharply when 0.01 n solutions of SAR 20 were displaced with distilled water, mixing the soils with powdered lime prevented both HC losses and clay dispersion. The response of a sandy soil mixed with lime was similar to that of a calcareous sandy soil. The beneficial effect ofCaC0₃ was not so pronounced in soils equilibrated with solutions of SAR 30. The increase in electrolyte concentration, due to CaCO₃ dissolution, was suggested as the mechanism responsible for the beneficial effect of lime.     

Effect of soil salinity and sodicity on Matricaria chamomilla,L. Growth

Abstract

Growth response of Matricaria chamomilla, L. was investigated on a range of soil salinity and sodicity levels using fine and coarse‐textured soil types. Twenty treatments including 4 levels of salinity and 4 levels of sodicity on each soil type were examined in addition to control. On the coarse‐textured soils, chamomile responded best under relatively low saline and sodic conditions. Plant growth decreased with increase in salinity and sodicity. On the fine‐textured soils, plants endured saline conditions up to 13 ECe and grew better under sodic conditions. The best growth of plants was achieved on fine‐textured soils with sodicity level of 31.8 Esp.     

Transformation of clay minerals in nanoparticles of several zonal soils in China

Purpose

Clay minerals significantly affect the physical, chemical, and biological processes of soils. They undergo spontaneous modification and transformation depending to the climatic conditions. Information concerning the compositions and transformation of clay minerals in nanoparticle colloids (NPs) (25–100 nm) is severely lacking. Studying clay mineral transformation is important approach to understand soil formation. This study was conducted to determine the transformation sequence of clay minerals in several zonal soil NPs.

Materials and methods

Four soils (Haplustalf, Alf-1; Hapludalf, Alf-2; Hapludults, Ult-1 and Ult-2) were collected from B horizons developed under three different climatic zones of China. Alf-1 (36° 05′ N and 117° 24′ E) was located under a warm temperate zone and Alf-2 (30° 38′ N and 115° 26′ E), Ult-1 (29° 13′ N and 113° 46′ E), and Ult-2 (19° 27′ N and 109° 17′ E) under a subtropical zone. The clay particles (<?2000 nm) (CPs) and nanoparticles (25–100 nm) (NPs) of tested soils were separated. The element composition of CPs and NPs was identified by microwave digestion method. The mineralogy and chemical bonding of clay minerals were studied by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR).

Results and discussion

With decreasing latitude, NPs and CPs showed that the molar ratio of SiO₂ to Al₂O₃ trends to diminish, indicating the phenomenon of desilication and allitization in the tested soils. XRD analysis revealed that the main clay mineral of Alf-1 NPs was illite, followed by vermiculite, kaolinite, and kaolinite interstratified minerals (KIMs). The clay minerals of Alf-2, Ult-1, and Ult-2 NPs were dominated by kaolinite (and KIMs), followed by illite, with a little content of hydroxyl-interlayered vermiculite (HIV) in Ult-1 NPs and trace content of gibbsite in Ult-2 NPs. With decreasing latitude, vermiculite and HIV decreased in NPs. When compared to CPs, smectite as well as illite-vermiculite mix-layer mineral (I-V) and illite-HIV mix-layer mineral (I-HIV) were not detected in NPs. The analysis of d060 region by XRD showed that with decreasing latitude, the main clay minerals in NPs were dioctahedral minerals (e.g., illite or kaolinite). These clay minerals resulted from the transformation of trioctahedral minerals in CPs. The disappearance of 2:1 swelling minerals and trioctahedral minerals showed that the NPs were more susceptible to weathering than CPs.

Conclusions

With decreasing latitude, the transformation of clay minerals followed the sequence of illite?→?HIV?→?kaolinite?→?gibbsite in tested NPs.

     

Effect of Organic matter application on the fate of 15N-labeled ammonium fertilizer in an upland soil

Abstract

The clay mineral composition of two “terra roxa estruturada” (TRE) soils occurring in the tropical rain forest and tropical forest/savannah transition zone, and a reddish brunizem in the savannah/semi-arid transition zone was studied comparatively in the southeast Amazon region.

Kaolin minerals were dominant in these soils, and hematite and goethite were found in the clay fraction. A small amount of 2 : 1-type clay minerals was found in two soils. The mineral composition of the clay fraction in the TRE soils was hardly influenced by the difference of the meteorological factor or their water condition in this region, and this factor should not control the influence of parent materials derived from basic rocks. The TRE soils were developed under the condition of laterite genesis, and were regarded claymineralogically as a kind of the lateritic soils.     

Interactions of clay minerals with Arthrobacter crystallopoietes: starvation, survival and 2-hydroxypyridine catabolism

For bacterial inoculants to be effective in soil remediation, the bacterial strain must be capable of overcoming any negative effects of soil minerals on cellular processes. One class of minerals commonly encountered by soil bacteria is clays. Thus, the effect of commonly occurring clay minerals in soils on starvation, survival and 2-hydroxypyridine catabolism by Arthrobacter crystallopoietes was evaluated. Stationary phase A. crystallopoietes cells were suspended in 0.03M, pH7.0, phosphate buffer containing no clay or amended with 0.2% (wt/vol) montmorillonite, sodium montmorillonite or kaolinite. Marked effects of clay minerals on both survival rates and catabolic rates of 2-hydroxypyridine were noted. For example, after 14 weeks starvation, 4.6% of the initial cell population was viable with no clay present, compared to 0.8% (montmorillonite), 22.1% (kaolinite) and 54.1% (sodium montmorillonite) in the presence of the clay minerals. Acclimated and nonacclimated cell populations were used to evaluate 2-hydroxypyridine catabolism. Induction of 2-hydroxypyridine metabolism occurred in the unacclimated cells following starvation. Differential impact of the clay minerals on unacclimated cells was detected. Montmorillonite enhanced the capacity for induction of 2-hydroxypyridine catabolism and its decomposition rate after 0–3 days starvation. For acclimated cells, clay did not affect the metabolic activity prior to starvation, but the presence of clay resulted in increased activity during starvation. For example, after 3 days starvation, a nearly two fold increase in metabolism was detected in the presence of clay minerals. These data suggest that some clay minerals in soil alter the survival time and metabolic activity of soil-amended bacteria, thereby affecting the potential for bioremediation success. Received: 1 March 1996     

Use of langbeinite to reclaim sodic and saline sodic soils

Abstract

Langbeinite is a soluble potassium‐magnesium sulfate mineral (K₂SO₄2MgSO₄) found as an evaporite in many regions of the world. Langbeinite was used as a reclaiming material in a fine textured (clay loam) saline sodic soil (Grabe Series). This amendment can be dissolved and directly into the irrigation water, displacing sodium (Na) quickly with minimal water use. This amendment was superior over gypsum as a reclaiming material for a saline sodic soil in batch, column, and greenhouse studies. Langbeinite required 50% less irrigation water than gypsum to displace and leach exchangeable Na from soils. Langbeinite improved the infiltration rates of saline sodic soils, but not as effectively as gypsum. Significant increases in germination percent dry matter production mass of lima bean (Phaseolus lunatus L.) plants were observed when using langbeinite over the gypsum soil amendment.     

Origin of the effect of ph on the saturated hydraulic conductivity of non‐sodic soils

Abstract

The effect of pH on the saturated hydraulic conductivity (K) of repacked columns of two non‐sodic soils (Healaugh and Fagaga soils) was examined. The K value was greater for the Fagaga soil than for the Healaugh soil which is attributed to the difference in the amount of free iron oxides between the soils. The K values reached a maximum when the pH was close to the point of zero net charge (PZNC) (3.7 and 4.8 for the Healaugh and the Fagaga soil, respectively) and decreased on either side of these pH values. The effect of pH on K was related to its effect on surface charge. As the pH of variable‐charge soils approaches the PZNC, the net surface charge decreases resulting in flocculation and maintenance of a high K. Conversely, as the pH deviates from the PZNC, the net surface charge increases, resulting in dispersion and a decrease in K. There was a negative relationship between the amount of dispersed clay and the K values, suggesting that clay dispersion and the resulting clogging of pores decreases K in these soils.     

Amorphous clay materials of towada ando soils

Towada Ando soils consisted of five soils—Towada-a (1,000 years old), Towada-b (2,000 years old), Chuseri (4,000 years old), Nanbu (8,600 years old), and Ninokura soils (10,000 years Amorphous clay materials of these soils taken at different localities were studied by the combined use of selective dissolution and differential infrared spectroscopy, X-ray analysis, electron microscopy, etc.

The main clay minerals of Towada-a soils, present-day soils, were montmorillonite-vermic-ulite chloritic intergrades and opaline silica, or these minerals and allophane in the humus horizons, and allophane in the non-humus ones. Towada-b soils overlain by the Towada-a soils showed the clay mineralogical constituents similar to those of Towada-a soils. However, allophane was one of the main clay minerals in all the humus horizons as well as non-humus ones. The main clay minerals of Chuseri soils were allophane and layer silicates consisting chiefly of chloritic intergrades and chlorite in the humus horizons, and allophane in the non-humus ones. Opaline silica was present in minor amounts in the humus horizons of Chuseri soils, but nearly absent in Nanbu and Ninokura soils.

There were remarkable differences in the clay mineralogical composition of Nanbu and Ninokura soils with differences of their environmental conditions. Allophane and imogolite Were dominant in the clay fractions of both humus and non-humus horizons of very shallowly buried Nanbu soil which was subjected to the strong leaching process. Allophane was the main clay mineral of deeply buried Nanbu and Ninokura soils which showed the absence of notable accumulation of bases and silica. On the contrary, halloysite with a small amount of siliceous amorphous material appeared in very deeply buried Nanbu and Ninokura soils where bases and silica were distinctly accumulated. The amounts of halloysite in the clay fractions were larger in the humus horizons than non-humus ones, and in Ninokura soil than Nanbu soil.

Soil age, soil organic matter, and depositional overburden of tephras were observed to be conspicuous among various factors relating to the weathering of amorphous clay materials in Towada Ando soils.     

Non-exchangeable potassium release and its removal in foot-hill soils of North-west Himalayas

In the present investigation, soils representing ten locations and three agro-climatic zones of foot-hills of north-west Himalayas were studied to assess Non-exchangeable Potassium (NEK) reserves, its release and influence of K-fixing capacity and clay minerals on NEK release. Maximum release of non-exchangeable K was obtained in temperate zone soils (295 mg kg^− 1) followed by intermediate zone (227 mg kg^− 1) and sub-tropical zone soils (106 mg kg^− 1), having relative soil quality index (RSQI) values of 85, 80 and 65, respectively. The quantitative analysis of clay minerals, through XRD technique, revealed that the temperate soils have more illite (averaging 62%) which holds well as a reason for high NEK reserves of 1556 mg kg^− 1 in these soils in comparison to intermediate (having illite averaging 53%) and sub-tropical (having illite averaging to 49%) soils having NEK amounting to 1022 and 918 mg kg^− 1, respectively. In order to study the NEK removal from the soils under investigation, maize was grown as a test crop and potassium was applied through four treatments having four levels of K (0, 15, 30 and 60 mg kg^− 1) applied as KCl. The crop demonstrated significant response in terms of dry matter yield up to 30 mg kg^− 1 in sub-tropical and intermediate soils while no such response was obtained in temperate soils. The percent NEK removed by maize crop from NEK reserves was 14, 25 and 20% in sub-tropical, intermediate and temperate soils, respectively. The information about NEK release, its removal as well as its relationship with K fixing capacity, clay minerals and RSQI can be used for understanding the K buffering potential of soils especially under adverse soil and climatic conditions that prevail in southwest India. Besides, the regression equations developed can be used for predicting NEK release on the basis of K fixing capacity and clay mineralogical composition.     

Chemical properties of soils where palm trees grow in Venezuela

Abstract

A study of soil chemical properties of eleven soils present in different geographycal locations where palm trees (Copernicia tectorum) grow in Venezuela gave the following relevant results: 1) ten soils have at least one layer with exchangeable Mg higher than exchangeable Ca (Mg/Ca>1.00; magnesic layer); 2) eight soils have at least one layer with more than 15% exchangeable Na (sodic layer); 3) ten soils have layers with predominance of Na+Mg in the exchangeable complex (Na + Mg >50%, sodic‐magnesic layers); 4) very acid soil pH values (3.75 to 5.00) on the soil surface layers increasing markedly (even to alkaline values) with depth; and 5) all profiles have very low available P values. The common occurrence of these rather unusual chemical properties, especially the first three ones on most of these soils were considered as evidence of their role as fundamental edaphic factors on palm tree adaptation and distribution. These results also indicate that, besides the already described soil physical (high clay content, slow permeability) and environmental conditions (seasonal flooding and drought, and yearly burning), unusual soil chemical properties seem to be also involved with the ecological conditions associated with the presence of palm trees.     

Differential leaching of cations and sulfate in gypsum amended soils

Abstract

An adequate supply of available Ca in the soil solution of the pegging zone during fruit development is required for production of high yields of high quality peanuts (Arachis hypogaea L.). On low Ca soils, application of gypsum during early bloom is recommended in order to ascertain adequate availability of Ca. Reaction of gypsum in soils under leaching conditions vary considerably and play an important role in fruit development and yield of peanuts. A laboratory study was conducted in leaching soil columns to investigate the effects of one gypsum amendment on leaching of Ca, K, Mg, and SO₄ to a depth of 8 cm (fruiting zone of peanut). Six soils of varying physical and chemical properties representative of major peanut growing soils in Georgia were utilized. Following leaching with 15 cm water through gypsum‐amended soil columns, 50% to 56% and 74% to 77% of applied Ca and SO₄, respectively, were leached below 8 cm in the sandy‐Carnegie, Dothan, Fuquay and Tifton soils. The respective values for the sandy clay loam‐Greenville and Faceville soils were 28% to 36% and 58% to 69%. Lower initial Ca status and greater leaching of Ca from the applied gypsum in the sandy soils as compared to sandy clay loam soils suggest greater beneficial effects of supplemental gypsum application for peanut production in the former soils than in the latter soils. Leaching of K or Mg (as percentage of Mehlich 1 extractable K or Mg) in gypsum‐amended treatment was considerably greater in sandy soils than that in the sandy clay loam soils. In view of the reported adverse effects of high concentrations of soil K and Mg in the fruiting zone on the yield and quality of peanuts, greater leaching of K and Mg from the fruiting zone in gypsum amended sandy soils enable them to maintain a favorable cation balance for the production of high yields of quality peanuts.     

The solonetzic process in surface soils and buried paleosols and its reflection in the mineralogical soil memory

The development of the solonetzic process in paleosols buried under kurgans and in the modern surface soils has been studied on the basis of the analysis of the clay (<1 μm) fraction. The revealed changes in the textural differentiation of the soils and the mineralogical composition of the clay fraction during 4500 years are assessed from the viewpoint of the “memory“ of the solid-phase soil components. The mineralogical characteristics show that the solonetzic process in the modern background soil is more developed. The mineralogical approach allows us to reveal the long-term changes in the soil status; it is less useful for studying the effect of short-term bioclimatic fluctuations. In the latter case, more labile soil characteristics should be used. The mineralogical method, combined with other methods, becomes more informative upon the study of soil chronosequences. Our studies have shown that the data on the clay minerals in the buried paleosols may contain specific information useful for paleoreconstructions that is not provided by other methods.     

Impact of Varying Ca/Mg Waters on Ionic Balance,Dispersion, and Clay Flocculation of Salt-Affected Soils

Inceptisols and Vertisols are two dominant soil orders that support major agricultural production in India. These soils often exist in semi-arid and arid regions. Low precipitation and high evaporation demand leads to salt accumulation in these areas. The problem of salt accumulation is further compounded by the presence of saline/alkaline groundwaters. We evaluated the effect of modified Ca/Mg waters on ionic composition, dispersion, and clay flocculation of sodic Inceptisols, saline-sodic Inceptisols, and normal Vertisols from different parts of India. A completely randomized factorial design with three replications of individual soils were sequentially leached with five pore volumes of deionized, saline water of 60 and 120 me L^?1 total electrolyte concentration (TEC) at a fixed SAR of 5.0 mmol^1/2 L^?1/2 and Ca:Mg ratio of 2:1, 1:1 and 1:2. Application of saline waters decreased pH and increased EC of the soil leachates after leaching five pore volumes of three Ca/Mg ratios of 60 and 120 me L^?1 solutions in sodic Inceptisols and normal Vertisols. In saline-sodic Inceptisols, application of saline waters decreased both pH and electrical conductivity (EC) of the soil leachates. Preferential Ca²⁺ holding in soil was only noticed in sodic Inceptisols when leaching process was performed with independent saline waters, but Mg²⁺ has a tendency to hold in soil upon application of independent saline waters for all soils except sodic Inceptisols. Periodic application of deionized water could increase soil dispersion and decreased flocculation of clay particles. Mg²⁺ ion had less flocculating vis-à-vis high-dispersion effect on soil clays than the Ca²⁺ ion.     

Clay materials in the soils of the Baraba Steppe and the Priobskoe Plateau

The composition and the regularities of the profile distribution of the clay minerals in the solods of the Baraba Steppe (ground moistening) and the Priobskoe Plateau (atmospheric moistening) were studied. The two profiles have the distinct eluvial-illuvial distribution of the clay fraction. The composition of the clay fraction in the eluvial layer is dominated by illite. The content of chlorite and labile minerals of the montmorillonite group increases downwards in the profile. The revealed regularities in the profile distribution of the clay fraction and some groups of clay minerals are explained by the joint influence of the mineral dissolution under the influence of the gleying and alkaline hydrolysis, as well as the processes of illitization and lessivage. The major differences in the content and distribution of the clay minerals between the solods and the podzolic soils are the following. The solods have a clear illuvial layer in the clay, while the majority of podzolic soil profiles have the eluvial distribution of the silty fraction. The solods in the eluvial part of the profile and sometimes in even the bottom layers have an unusually high content of the illite minerals in the clay fraction due to illitization. The podzolic layers of the solods do not contain soil chlorites common for the eluvial layers of the podzolic soils, which is due here to a less acidic medium that can not provide the proper conditions of aluminum mobilization and migration needed for the development of chloritization.