Gleyed soils of depressions under agrocenoses in the Letka River basin of the Komi Republic

Depressions that are subjected to overmoistening in the spring and to heavy rains in the summer are widespread on the Russian Plain, including arable lands. Excessive moistening results in the development of gley features throughout the soil profile. These soils differ from the adjacent slightly gleyed soils by their lower thickness of the humus horizon and the eluvial layer, their lower contents of humus and adsorbed bases, and their higher contents of clay and sesquioxides in the deeper soil layers.     

Solods of the Baraba Lowland and the Priobskoe Plateau: Their properties and genesis and the methods of their diagnostics

The properties, hydrological features, and genesis of the solods occurring in the Baraba Lowland and Priobskoe Plateau were studied. Methods for determining the hydromorphism degree are considered; the features of the similarity and differences between the solods and other soils with textural profile differentiation are shown. Depending on the reasons for the waterlogging, the solods should be divided into two groups: the solods of groundwater waterlogging and the solods of surface waterlogging. Criteria for their discrimination are suggested: the ratio between the contents of the clay fraction in the parent rock (or in the B2 horizon) and that in the A2 horizon, the changes in the pH values along the soil profiles, and the content of nonsilicate iron compounds. The solods studied are shown to be formed under the conditions of a stagnant-percolative regime and gleying. This circumstance is an obligatory and sufficient reason for the formation of the light-colored acid eluvial (A2) horizons. According to some basic properties of the soil solid phase (the acidity, the total chemical composition, and the clay pattern in the eluvial part), the gleyed solods are close or identical to the gleyed soddy-podzolic and gleyed chernozem-like podzolic soils. At the same time, the solods differ from the gleyed chernozem-like podzolic soils by their thicker A1 (or Ap) horizon and their higher humus content (5–7%).     

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.     

Genesis and classification position of automorphic soils developed from mantle loams in the northern taiga of European Russia

Automorphic loamy soils of the northern taiga and forest-tundra zones in the northeastern part of European Russia are characterized. These soils are diagnosed by the presence of a paragenetic system of the podzolic (often, with gley features) and iron-illuvial horizons combined with a specific cryometamorphic CRM horizon. The podzolic horizon is considerably impoverished in the total and oxalate-extractable iron and slightly impoverished in aluminum and clay in comparison with the iron-illuvial horizon. A distinctive feature of the cryometamorphic horizon is its fine angular blocky, ooidal, or granulated structure in the dry state and curdled cryogenic structure in the wet state. The soil profile is relatively weakly differentiated with respect to the contents of clay and sesquioxides. The genesis of these soils is related to a combination of the gley-Al-Fe-humus mobilization, migration, and illuvial accumulation of substances and the cryogenic structuring. According to the new Classification and Diagnostic System of Russian Soils, these soils fit the criteria of iron-illuvial svetlozems in the order of cryometamorphic soils. In the studied area, these soils are found together with texture-differentiated gley-podzolic soils having the Bt horizon and belonging to the order of texture-differentiated soils.     

Base-buffering properties of native and agrogenically transformed dark-humus gley soils of the Primor’e region

The base-buffering properties of native and agrogenically transformed dark-humus gley soils of the Khanka Valley were studied using the method of equilibrium potentiometric titration. The major buffering systems of the soils under study were characterized. The highest base-buffering capacity was observed in the humus horizon of the dark-humus gley soil, where correlations between the buffer intensity, the exchangeable and total acidities, and the carbon content were revealed. In the agrogenically transformed soil, the base-buffering capacity decreased by an order of magnitude.     

Soils of northern spurs of the Cherskii Ridge in the area of the northern pole of cold: Morphology,properties, and classification

The soils in the area of the northern pole of cold located on the interfluve between the Yana and Adycha rivers within the spurs of Kisilyakh Ridge included in the mountain system of Cherskii Ridge have been studied for the first time. The profile-genetic approach has been applied to describe the soils and determine their classification position. It is found that the major soil types in this region are the soils of the postlithogenic trunk belonging to the orders of lithozems (Cryic Leptosols), gley soils (Gleyic Skeletic Cryosols), and Al–Fe-humus soils (Spodic Skeletic Cryosols). The ecological ranges of altitudinal zones— the taiga zone with various types of lithozems below 630–700 m a.s.l. and the tundra zone with combinations of gley and nongley cryogenic soils above these heights—have been established. The development of gley or nongley soils is specified by the local orogenic and lithological conditions and slope aspect, which, in turn, control the degree of drainage and the presence and character of permafrost. In the profile of mountainous gley soils (gleyzems) with shallow ice-rich permafrost, cryogenic processes and features typical of the analogues of these soils on plains—cryogenic cracking, cryoturbation, solifluction, thixotropy, oxiaquic features above permafrost, saturation of the soil profile with mobile humus, etc.—are typical.     

Gley morphology and soil water regimes in some soils in south-central england

A good correlation was observed between the development of gley morphology and period of saturation at a depth of 38 cm in 44 soil profiles from south-central England. Gley morphology in the surface horizon (13 cm depth) was a less reliable indicator of waterlogging. Drainage class assignment based on morphological evidence produced effective separation of soils based on their water regimes, characterised by the period of saturation at 38 cm. Although the relationships observed are probably restricted to soils developed on similar parent materials, the subjective identification and assessment of gley morphology may be an alternative to the absolute colour criteria currently used in many soil classification schemes.     

Differences in silica release from soils of two Scottish associations as assessed by trimethylsilylation

The amounts of monomeric silica released on trimethylsilylation of a range of Soil Groups of the Darleith Soil Association, developed on glacial till derived from Carboniferous age lavas of basic and intermediate composition, is significantly higher than the amounts released from corresponding Soil Groups of the Lauder Soil Association, developed on glacial till derived from Devonian age conglomerates and sandstone. Monoremic silica release values for the leached soils within an association are, in general, higher than those of the gley soils. For all soil profiles the eluvial horizon released the smallest amount of monomeric silica with the maximum amount being released, in most instances, from the illuvial horizon. Ferromagnesian minerals and crystalline clay minerals, in particular vermiculite and chlorite in the Darleith Association soils, release monomeric silica under acid conditions. For both the Darleith and Lauder Association soils the principal source of monosilicic acid is thought to be aluminosilica gel of low Si:A1 ratio.     

DISTRIBUTION OF PYROPHOSPHATE-EXTRACTABLE IRON AND ORGANIC CARBON IN SOILS OF VARIOUS GROUPS

Potassium pyrophosphate (0.1m ) removes very little Fe from crystalline Fe oxides at pH 10, but peptizes finely divided hydrous amorphous oxides and organic matter in soils. Fe and C contents of extracts from each horizon of twenty-six British soil profiles show distinctive patterns, independent of the residual dithionite-soluble Fe. Thus extracts of humus Fe podzols have maximum Fe and C in the B horizon, peaty gley podzol has maximum Fe in the B horizon but maximum C in the surface. These groups are differentiated from non-podzols which have maximum pyrophosphate extractable Fe and C in the surface horizon, decreasing with depth. Intermediate patterns help to quantify differences in soils of classes having properties of more than one soil group.     

Zu Eigenschaften,Horizontaufbau und Gliederung der „Haftnässepseudogleye”︁

Properties, horizons and classification of the “Haftnässepseudogleye” (Stagnosols periodically waterlogged with capillary water) The term “Haftnässe” (soil wetness due to capillary moisture) can be used in describing soils with Sg-horizons in which long-term waterlogging and anaerobic conditions occur in the absence of gravitational water. “Haftnässe” is caused by water held in pores with an equivalent diameter of 0.2–50 μm by soil-water tension (pF) between 1.8 and 4.2, when the air capacity of the horizons is very low. “Haftnässe” moves primarily by capillary forces and is available to plants (available water). In some soils, the horizon below the Sg-horizon contains large pores, is well aerated and tends to impede the movement of capillary water. This type of horizon is often wetter than the overlying and underlying horizons, due to the presence of capillary water in the immediately overlying Sg-horizon. The symbol “So” is proposed for such horizons. In these soils, in the Sg-horizon reduced iron compounds are oxidized and precipitated, forming rusty mottles. The sequence of horizons developed in the “Haft(nässepseudo)-gleye” (Stagnosols periodically waterlogged with capillary water) typically affects the continuity of the pathways along which capillary water normally moves. The “Haft(nässepseudo)gleye” are divided into two subtypes on the basis of the sequence of horizons in the soil profile:

• Typical “Haft(nässepseudo)gley” (Shn) exhibits a sequence Ah/Sg/(II)So and shows transitions to Luvisol and Glossisol,
• Thick “Haft(nässepseudo)gley” (Shm) exhibits a sequence Ah/Sg and shows transitions to “Stau(wasserpseudo)gley” (Gleysol periodically waterlogged due to perched water), Gleysol, Fluvisol and tidal marsh soil.

     

Microbial communities of alluvial soils in the Volga River delta

The number and biomass of the microbial community in the upper humus horizon (0–20 cm) were determined in the main types of alluvial soils (mucky gley, desertified soddy calcareous, hydrometamorphic dark-humus soils) in the Volga River delta. Fungal mycelium and alga cells predominate in the biomass of the microorganisms (35–50% and 30–47%, respectively). The proportion of prokaryotes in the microbial biomass of the alluvial soils amounts to 2–6%. No significant seasonal dynamics in the number and biomass of microorganisms were revealed in the alluvial soils. The share of carbon of the microbial biomass in the total carbon content of the soil organic matter is 1.4–2.3% in the spring. High coefficients of microbial mineralization and oligotrophy characterize the processes of organic matter decomposition in the alluvial soils of the mucky gley, desertified soddy calcareous, and hydrometamorphic dark humus soil types.     

Water and oxygen regimes of four soil types at Newcastleton Forest, south Scotland

The water and oxygen status of four upland soils under Sitka spruce plantations was studied for 2 years. In a brown earth, waterlogging only occurred ephemerally in the subsoil and oxgen concentrations were generally high. In contrast, waterlogged and near-anaerobic conditions persisted for much of the year in stagnogley and stagnohumic gley soils. In a peaty stagnopodzol moist conditions occurred above and below the thin ironpan, but while high oxygen concentrations generally persisted in the subsoil, low concentrations were common in the soil above. In the brown earth, healthy roots of Sitka spruce were present at a depth of 85 cm, but in the gley soils rooting was mainly limited to 25 cm and many roots were dead. In the peaty stagnopodzol, roots penetrated the ironpan and grew in the subsoil to 75 cm depth.     

Al,Fe, and Si compounds in Tamm and Mehra-Jackson extracts from mucky-peaty-podzolic gley soil: Contents,reserves, and profile and particle-size distributions

Equal or comparable contents of Fe and Al extractable by Tamm and Mehra-Jackson solutions have been revealed in all the horizons of a loamy mucky-peaty-podzolic gley soil on binary deposits. The content of Si extractable by the Mehra-Jackson solution has exceeded that of oxalate-soluble Si by an order of magnitude. The distributions of Al in the Tamm solutions from the entire soil and its fractions of 1–5 and >5 μm are of accumulative type with a maximum in the mucky H horizon and a gradual decrease of the content with depth in relation with the analogous distribution of Al-organic complexes. The maximum content of oxalate-soluble Al in the clay fraction has been found in the eluvial ELg horizon, which can be due to the partial dissolution of Al hydroxide interlayers in soil chlorites. The distribution of Fe in the entire soil has two maximums, in the H horizon due to the accumulation of Fe-organic complexes and in the concretion-rich ELnn,g horizon due to the accumulation of Fe hydroxides. Depletion of oxalate-soluble Fe in the eluvial ELg horizon has been observed in all the fractions, which can be related to its mobilization and removal under strongly acidic conditions and the development of reductive processes, as well as the enrichment of the concretion-rich horizon with these compounds because of an increase in pH and the development of conditions favorable for water stagnation and Fe segregation.     

Manganese, iron, and phosphorus in nodules of chernozem-like soils on the northern Tambov Plain and their importance for the diagnostics of gley intensity

Nodules (nodules) forming in the chernozem-like soils of flat-bottomed closed depressions on the northern part of the Tambov Plain differ in their morphology and chemical composition as related to the degree of hydromorphism of these soils. The highest are the coefficients of Mn, P, and Fe accumulation in the nodules from these soils. The Fe to Mn ratio grows with the increasing degree of hydromorphism. Under surface moistening, the maximal amounts of mobile Mn and Fe compounds were extracted from the nodules of the most hydromorphic podzolic chernozem-like soils; under the ground moistening, their greatest amounts were extracted from the least hydromorphic soil—the weakly gley soil. In the first case, the content of organic phosphates in concretions amounted to 30–50%; in the second one, 2–3% of their total content. Under surface moistening, the proportion of active mineral phosphates becomes higher with the increasing hydromorphism: from 30 (podzolized soil) to 70% (gleyic podzolic soil). Under ground moistening, on the contrary, their proportion decreases from 70–89% in the weakly gley soil to 40–50% in the gley chernozem-like soil. The possibility to determine the degree of hydromorphism of chernozem-like soils based on the coefficients of bogging is shown. The expediency of using Schvertmann’s criterion in these studies is assessed.     

The morphology and genesis of eight surface-water gley soils developed in till in England and Wales

The morphology is described of eight surface-water gley soils developed in til in Wales and central and northern England. Physical and chemical analyses as well as micromorphological observations are used to investigate processes affecting the genesis of the soils. The characteristic property of surface-water gley soils, namely slowly permeable subsurface horizons, causes a degree of periodie waterlogging within the profile. Effects of gleying and shrink/swell processes are described. Three main aspects of weathering are shown to be operating: decalcification in two of the three calcareous profiles, the breakdown of coarse into finer particles and the alteration of the clay fraction, chiefly the formation of mixed-layer minerals from mica. Argillic B horizons are present in some soils. In profiles developed in calcareous till the degree of decalcification relates strongly to the amounts of recognizable clay concentrations as seen in thin section. Of the other five profiles three clearly have argillic B horizons. Problems associated with the identification of argillic B horizons in surface-water gley soils in till are discussed.     

Distributions of Heavy Metals and Benzo[<Emphasis Type="Italic">a</Emphasis>]pyrene in Oligotrophic Peat Soils and Peat Gleyzems of Northeastern Sakhalin

The contents and profile distributions of Cr, Ni, Cu, Zn, Cd, Hg, Pb, and benzo[a]pyrene in oligotrophic peat soils, oligotrophic peat gley soils (Dystric Fibric Histosols), humus-impregnated peat gleyzems (Dystric Histic Gleysols), and mucky gleyzems (Dystric Gleysols) have been analyzed with consideration for their degree of oligotrophicity and anthropogenic loads. Horizons with the accumulation (O, Tpyr, TT) and removal (Ghi,e) of heavy metals have been revealed. The increase in the content of heavy metals and benzo[a]pyrene in the upper layer of oligotrophic peat soils under technogenic fallouts in the impact zone of flare and motor transport has been considered. Statistical parameters of the spatial variation of parameters in organic and gley horizons have been calculated. The variation coefficients of pollutant elements (Pb and Zn) in the surface horizons of soils increase to 100–125%. Positive correlations revealed between the content of some heavy metals in litter indicate their bioaccumulation and possible joint input with aerotechnogenic fallouts. No correlations are found between the contents of benzo[a]pyrene and heavy metals, but a reliable negative correlation with the ash content is noted in the peat horizon.     

Transformation of peat horizon in swampy southern taiga forests under the impact of surface drainage

The results of stationary studies of swampy southern taiga forests in Yaroslavl oblast are presented. Estimates of changes in the thickness of peat horizon in peat podzolic gley soils (Folic Albeluvisols) of forests subjected to clearcutting and further intensive forest management in the past 30 years are given. The mean annual precipitation in these three decades has been 116 mm higher than that during the preceding three decades, which has led to a progressive swamping of spruce stands on heavy loamy soils within virtually flat (with slopes up to 0.0035) surfaces and an increase in the organic matter storage in the peat soil horizon with the mean annual rate of 22–68 g/m². On more pronounced slopes (0.0050), no swamping of spruce and pine stands growing on sandy soils has taken place. Surface drainage of swampy forests through the network of shallow ditches has led to an increase in the productivity of forests; in most cases, the pool of organic matter in the peat horizon has been decreasing with the mean annual rate of 32–46 g/m². This attests to the reversible character of swamping in dependence on climatic fluctuations and forestry measures. Changes in the carbon pool of swampy soils during short (several years) excessively wet or excessively dry periods may be significantly higher than the average values for 30 years in different types of forests. This allows us to consider swampy forests as the source of significant errors in the estimates of the current contribution of biota to the carbon cycle, because their role (as well as the role of other forests) is assessed without taking into account considerable short-term fluctuations in the carbon pool of their soils.     

Surface-water gley soils in Bangladesh: Genesis

Extensive areas of periodically wet, acid soils in Bangladesh have a seasonally fluctuating pH of the surface horizon and evidence for net clay loss. Morphological, chemical, mineralogical and other data mainly on a typical profile of these surface-water gley soils indicate a clay loss of some 1.5 kg/dm' ; alteration of smectite to a soil chlorite, interlayered material with trapped ferrous iron; the consequent drop in C.E.C. of the clay fraction; and the presence of amorphous silica. The data were used to reconstruct a sequence of three soil forming processes: Vertisol formation, then argilluviation, followed by ferrolysis.Ferrolysis involves, in the wet season: reduction producing ferrous iron, which displaces part of the exchangeable basic cations and aluminium; leaching of bases and part of the aluminium; and interlayer formation by the remaining aluminium while some exchangeable ferrous iron is trapped in the interlayers. In the dry season, oxidation of exchangeable ferrous iron produces exchangeable hydrogen, part of which attacks the clay minerals and is neutralized by liberation of Al, Mg and other ions from the clay structure. Part of the silica remaining from the clay structure is leached out in the next wet season, part accumulates in amorphous form. In soils long used for paddy cultivation, man has concentrated the ferrolysis process in the ploughed layer by the formation of a slowly permeable ploughpan causing strong reduction only in the surface horizon.The hydromorphic albic horizon over more clayey material is indicative of the dominant process in surface-water gley soils. This sequum could usefully have a more important place in soil classification than it has at present, e.g. at great group level.     

A concept of Gleyization and its role in the pedogenesis

Three simple factors ‐ excessive moistening, anaerobic microflora and organic matter, are indispensable and sufficient conditions for gley formation. This process is always characterised by a non‐silicate iron loss from the soil fine earth or soil plasma. Gley formation takes place under conditions of stagnant or stagnant‐percolative water regimes.

In the second case gley formation induces a drastic acidification of the mineral soil part, lessivage, removal of iron, aluminium, calcium, magnesium, bleaching of the soil fine earth, and it appears the features of soil with eluvial, acid, bleached horizons. Therefore soils with such horizons should be regarded as manifestations of gley formation in conditions stagnant ‐percolative water regime on acid, neutral or leached parent material. Under influence of stagnant water regimes Fe of mineral substrat is removed and unconsiderable eluviation of Ca and Mg takes place. pH of parent material does not change or has the trend to increase. In this case does not arise a soil with bleached horizons.     

Acid-base buffering of soils in transitional and transitional-accumulative positions of undisturbed southern-taiga landscapes

The method of continuous potentiometric titration (CPT) of soil water suspensions was used to evaluate the acid-base buffering of samples from the major genetic horizons of podzolic soils on a slope and soddy gley soils on the adjacent floodplain of a rivulet. In the soils of the slope, the buffering to acid upon titration from the pH of the initial titration point (ITP) to pH 3 in all the horizons was 1.5?C2.0 times lower than that in the podzolic soils of the leveled interfluve, which could be due to the active leaching of exchangeable bases and oxalate-soluble aluminum and iron compounds with the later soil flows. In the soddy gley soils, the buffering to acid in the mineral horizons was 2?C10 times higher than that in the podzolic soils. A direct dependence of the soil buffering to acid on the total content of exchangeable bases and on the content of oxalate-soluble aluminum compounds was found. A direct dependence of the buffering to basic upon titration from the ITP to pH 10 on the contents of the oxalate-soluble aluminum and organic matter was observed in the mineral horizons of all the studied soils. The soil treatment with Tamm??s reagent resulted in the decrease of the buffering to acid in the soddy gley soils of the floodplain, as well as in the decrease of the buffering to basic in the soils on the slopes and in the soddy gley soils. It was also found that the redistribution of the mobile aluminum compounds between the eluvial, transitional, and transitional-accumulative positions in the undisturbed southern taiga landscapes leads to significant spatial differentiation of the acid-base buffering of the mineral soil horizons with a considerable increase in the buffer capacity of the soils within the transitional-accumulative terrain positions.