Postagrogenic transformation of organic matter in soddy-podzolic soils

In the chronological sequence of postagrogenic soils, the restoration of the original differentiation of the soil profile and its horizons proceeded with different rates depending on the fallow age and the horizon depth. The layer sampling (at 5-cm intervals) showed that the plow horizon began to differentiate into a system of subhorizons in all the fallow soils. The zonal pedogenesis showed clear signs of manifestation already in the 15-year-old fallow. The upper part of the former plow horizon in the 15- and 60-year-old fallows under herbaceous plants was transformed into a soddy horizon, while a postagrogenic soil 90 years old already developed under a zonal type of vegetation and approached the control soil in its morphological features. The content and reserve of carbon in the soils showed a stable tendency of increasing (especially in the upper part of the plow horizon) during the entire postagrogenic period under study. The water permeability of the soils gradually increased and approached that of the virgin soil. However, the compacted subsurface horizon (the plow pan) disappeared only after 90 years. The assessment of the physicochemical properties of the soils and the structural and functional parameters of the humic acids indicated the expansion of the layer differentiation primarily within the homogeneous plow horizon. From the elemental analysis and 13C NMR spectroscopy data, the degree of aromaticity in the molecular structure of the humic acids gradually decreased, and the aliphatic part developed with the age of the fallow.     

Soil evolution on the low terraces of Lake Nero

The soil evolution in the depression of Lake Nero was driven by climate changes in the Holocene and by the history of the relief’s development in this region. In the Alleröd period, dark-colored soils were formed; in the Late Dryas period, they were cryoturbated and covered by colluvial deposits from the adjacent slopes. These specific paleosols are found on relatively high ancient surfaces. In the Early and Middle Holocene (10000–3700 BP), dark-colored horizons of soils with high stability of the organic matter were formed. The properties of humus in these soils are close to the properties of humus in forest-steppe soils. In the past 3500–3700 years, under conditions of some cooling and humidization of the climate with the development of taiga pedogenesis, these soils have evolved into soddy-podzolic soils. Their dark-colored horizons have degraded, though their lower parts are partly preserved in many places as the second humus horizons, the most distinctive feature of the soil polygenesis in the studied region. The soils of the low terrace (100–103 m a.s.l.) are younger than the soils of the higher and more ancient surfaces. Their evolution followed the same stages, though the Alleröd paleosols have not been found on this surface. In the coastal zone, at the heights below 97 m a.s.l., the soil formation began later, about 7000 years ago. Afterwards, the soils of this surface were subjected to the influence of fluctuations in the lake’s level. During the regression phase (7000–3500 BP), which corresponded to the dark-colored pedogenesis, these soils and the habitation deposits of the Bronze Age were formed on the dried bottom of the lake below its modern lake level of 93.2 m a.s.l. In the Late Holocene, these soils in the coastal zone were subjected to waterlogging rather than to podzolization due to the rise in the lake’s level; they have evolved into the soddy gley soils.     

Ecological-hydrothermal assessment of pyrogenic soils of cutover peatlands

The morphology, physical and chemical properties, distribution and composition of mesofauna, hydrothermal regime, dynamics of the aeration porosity, and fertility of pyrogenically modified and soddy-pyrogenic soils of worked-out peat deposits were studied in years with different precipitation. The ash and carbonized horizons were constituents of the pyrogenic profiles of these soils. The surface ash horizons contain grains of quartz sand, ferruginous formations, and carbonates and have an alkaline reaction. The lower lying carbonized horizon is represented by thermally transformed organic matter, and it has an acid reaction and a low water-holding capacity. The studies of the hydrological regime have revealed the differences between the pyrogenically modified and soddy-pyrogenic soils and the necessity of their additional moistening. The moisture reserves in the soddy-pyrogenic-sandy soils were much lower than their optimal amount during the whole growing period, whereas, in the pyrogenically modified peat soils, they were optimal. However, the air humidity in the years when the investigations were performed did not exert any significant influence on the hydrological regime of the soils. The analysis of the temperature regime showed that spontaneous burning of the peat soils studied was impossible. Within 2–3 years after the fire, the fertility of the pyrogenically modified and soddy-pyrogenic soils was found to be somewhat higher than that of the soils long used for grass growing due to the enrichment of the organic matter with ash. Some measures are recommended for the optimization of the fertility of the pyrogenic soils.     

Soil mixing and genesis as affected by tree uprooting in three temperate forests

The purpose of this study was to identify general patterns of pedoturbation by tree uprooting in three different, forested landscapes and to quantify post‐disturbance pedogenesis. Specifically, our study illustrates how the effects of ‘tree‐throw’ on soils gradually become diminished over time by post‐uprooting pedogenesis. We studied soil development within 46 pit‐mounds in two regions of the Czech Republic, one on Haplic Cambisols and one on Entic Podzols. A third study site was in Michigan, USA, on Albic Podzols. Uprooting events were dated by using tree censuses, dendrochronology and radiometry. These dates provided information on several chronosequences of pedogenesis in the post‐uprooting pits and mounds, dating back to 1816 AD (dendrochronological dating, Haplic Cambisols), 322 AD (median of calibration age, ¹⁴C age = 1720 ± 35 BP, Entic Podzols) and 4077 BC (¹⁴C age = 5260 ± 30 BP, Albic Podzols). Post‐uprooting pedogenesis was most rapid in pits and slowest on mounds. Linear chronofunction models were the most applicable for pedogenesis, regardless of whether the soils were in pit or mound microsites. These models allowed us to estimate the time required for horizons in such disturbed sites to obtain the equivalent thicknesses of those in undisturbed sites. These ranged from 5 (O horizon in pits on the Haplic Cambisols) to > 16 000 years (E horizon on mounds on the Albic Podzols). On the Albic Podzols, development of eluvial and spodic horizon thicknesses suggested that pathways involving divergent pedogenesis may occur at these small and localized spatial scales.     

Postpyrogenic Polycyclic Soils in the Forests of Yakutia and Transbaikal region

Periodical forest fires are typical natural events under the environmental and climatic conditions of central and southern Yakutia and Transbaikal region of Russia. Strong surface fires activate exogenous geomorphological processes. As a result, soils with polycyclic profiles are developed in the trans-accumulative landscape positions. These soils are specified by the presence of two–three buried humus horizons with abundant charcoal under the modern humus horizon. This indicates that these soils have been subjected to two–three cycles of zonal pedogenesis during their development. The buried pyrogenic humus horizons accumulate are enriched in humus; nitrogen; total and oxalate-extractable iron; exchangeable bases (Са⁺² and Mg⁺²); and the fractions of coarse silt, physical clay (<0.01 mm), and clay (<0.001 mm) particles in comparison with the neighboring mineral horizons of the soil profile. The humus of buried pyrogenic horizons is characterized by the increased content of humic acids, particularly, those bound with mobile sesquioxides (HA-1) and calcium (HA-2) and by certain changes in the type of humus.     

Soils of sea terraces and bedrock slopes of fiords in Western Spitsbergen

The genetic characteristics of soils on the main geomorphic elements of Western Spitsbergen are compared with those of soils on similar rocks of the Kola Peninsula. Soils of the same type—gray-humus (soddy) soils with an O-AY-C profile—are developed from the rocks of different geneses and textures. These soils have a weakly differentiated profile. The accumulation of humus takes place under the litter horizon, and the soddy gray-humus (AY) horizon is formed. It has a diffuse boundary with the C horizon. The analytical data indicate that the bulk contents of iron and aluminum, as well as the contents of their oxalatesoluble compounds, are similar in the soils developed in different geomorphic positions and from different rocks. In all the soils, the bulk elemental composition and the oxalate-soluble sesquioxides are not differentiated in the profiles.     

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.     

Soil formation in the quarries for limestone and clay production in the Ukhta region

The soils forming on the overgrowing technogenic dumps of quarries for limestone and clay production were investigated in the northern taiga (the Ukhta region). The soils are formed under sparse herbaceous plant communities. In the soils on calcareous technogenic eluvium and clay dumps, the processes of humus formation and accumulation predominate. In the soils of the clay dumps, the leaching of carbonates is expressed to a greater extent than in the soils of the limestone quarries. The nitrogen content of organic matter is low in the soils on the technogenic lime substrates and very low on the clay ones. Fulvic acids predominate in the humus composition. At the stages of the soil restoration studied, the zonal trend of pedogenesis is manifested only in the humus accumulation. The calcareous technogenic eluvium is found to be more favorable for the development of microbial communities as compared to the clay substrates with their small microbial biomass. However, there are no features pointing to the development of zonal soil profiles. This fact attests that, in the first 20–30 years, the soil-forming potential in the northern taiga is insufficient for the initiation of the zonal processes.     

Palevye (pale) soils of Central Yakutia: Genetic specificity,properties, and classification

Permafrost-affected palevye (pale) soils of Central Yakutia are developed from mantle calcareous deposits of different textures and are characterized by the common mica-chloritic association of clay minerals with a higher content of chlorite in comparison with the soils developed from mantle loams and loess-like loams in the European part of Russia. In the pale soils, the distribution of clay minerals in the profile has an even pattern in the loamy variants and a differentiated pattern typical of podzols in the loamy sandy variants. Data on the chemical extracts and Mössbauer spectroscopy indicate that the iron in the pale soils is mainly fixed in silicate minerals. The content of nonsilicate iron represented by the amorphous and weakly crystallized compounds in the pale soils is relatively low. The humus-accumulative horizon in these soils is close to the gray-humus (soddy) AY horizon according to its acid-base characteristics (the soil pH and the degree of base saturation) despite the presence of exchangeable sodium and the shallow occurrence of the calcareous horizon.     

Carbon dioxide emission as affected by the properties of arable soils polluted with fluorides

Adverse changes in the physical and chemical properties of arable gray forest and soddy meadow soils (forest-steppe zone, Lake Baikal region) polluted with fluorides emitted by an aluminum smelter in Irkutsk are shown. The field experiments of the long-term (1997–2005) monitoring and laboratory incubation experiments revealed that the CO₂ emission from the gray forest soil was higher than from the soddy meadow soil. Its intensity depended on the soil properties and buffering capacity of the soils to fluorides, as well as on the content of water-soluble fluorides and the hydrothermal factors.     

Ecological assessment of soils in high-mountain landscapes of northeastern part of the Greater Caucasus (Azerbaijan)

The current state of soils and bioproductivity of high-mountain pastures and hayfields in the northeastern part of Great Caucasus within Azerbaijan were studied, and the quality assessment of soils was performed. The ecological evaluation of soils was based on special assessment scales and soil bonitet scores. The soils suitable for the development of meadow vegetation were identified. The highest score (89 points) was given to mountainous meadow chernozemlike soils (Eutric Mollic Leptosols); these soils are most suitable for pasturing. Mountainous meadow soddy soils (Dystric Umbric Leptosols) ranked second (76 points). Mountainous meadow-steppe soils (Eutric Mollic Leptosols) were estimated at 72 points; these soils are suitable for plant communities of subalpine meadows. Mountainous meadow soddy–peaty soils (Brunic Umbric Leptosols) had the lowest score of 68 points mostly because of the excessive precipitation against the background of relatively low mean annual temperature limiting the biological productivity of alpine meadows.     

Complex pedogenesis of ferrallitic savanna soils in South Sudan

Complex pedogenesis in ferrallitic savanna soils is demonstrated by means of three typical profiles. The information provided includes relative age relationship of soils on the polycyclic pediment slopes, macro- and micromorphological characteristics, some chemical and complete mineralogical data. The authors compare the operation of basic processes of saprolitization (kaolinization, primary mottling) and pedogenesis (homogenization, local, vertical and lateral redistribution of iron) in forest soils formed on deep saprolite, and savanna soils on generally much shallower saprolite. Complex pedogenesis in the latter results from intermittent erosional impact, changes of climate and the stepwise downward weathering and deepening of the solum. All of these factors cause (homo- or heterogenetic) changes of internal hydrological conditions in the whole or parts of the solum. By means of detailed differentiation of ferruginous precipitates in regard to their crystal form (hematite and goethite) and their successive formation and alteration, the authors attempt to elucidate the history of soil formation.     

Crop yields and soil fertility as affected by dryland rotations in Southern Alberta

Abstract

Six of seven nonfertilized dryland crop rotations, consisting of combinations of fallow, wheat, alfalfa, and grass, have depleted several major plant nutrients in the soil in 20 years. The average contents of organic matter, total N, and exchangeable K were decreased by 14.5, 10.1, and 26.7%, respectively, in the 0‐ to 15‐cm soil horizon and by 24.1, 13.3, and 25.7% in the 15‐ to 30‐cm horizon. Total P content of the soils changed very little during 20 years of cropping. The amount of NaHC03‐extractable P decreased by 38.3% in the 0‐ to 15‐cm horizon of all soils except those in a manured fallow‐wheat‐wheat rotation, where a 30.6% increase occurred. Although soils were generally depleted, plant nutrients have not yet reached critically low levels, and therefore crop yields have been maintained at a fairly uniform level by using improved cereal varieties, timely tillage, good seedbed preparation, suitable seeding methods, and adequate in‐crop weed control. However, further depletion of plant nutrients from the soils will probably restrict crop production in the future. The results indicate that applications of adequate amounts of N, P, and K fertilizers, as determined by soil tests and correlative field tests, must be made to these and similar soils to ensure continued productivity.     

Soils of the Lena-Angara Plateau in the area of the Kovykta gas condensate field

It is shown that soil-forming rocks—red calcareous silicate Lower Ordovician and Upper Cambrian deposits—play the leading role in the formation of unique long lastingly frozen mountainous taiga soils of Central Siberia. The functional role of the litter horizon forming under dark coniferous forests is analyzed. This horizon is sensitive to the bioclimatic factor. The genetic specificity of the predominating prepodzolic soils, podburs, soddy burozems, and soddy-calcareous soils and of the locally forming shallow pink-colored podzols is shown.     

Changes in the properties and biological activity of crusty solonetzes in the Baraba Lowland under the long-term impact of gypsum

A single application of gypsum to crusty hydromorphic low- and high-sodium solonetzes led to the destruction of the columnar structure and the formation of a valuable crumb-granular structure after 25 years. The surface crust disappeared from the reclaimed solonetzes, whereas its thickness in the control soils was about 10 cm. The long-term impact of gypsum also resulted in lower bulk density values in the upper soil meter, especially in the high-sodium solonetz. The number of microorganisms accumulating available nitrogen- and carbon-bearing compounds increased, and the urease and proteolytic activities of the soil became more pronounced. In the upper 20 cm of the reclaimed solonetzes, the microbiological transformation of the plant remains into the soil organic matter became more intensive, thus attesting to the development of the soddy process. The favorable effects of gypsum increased with an increase in the rate of its application.     

Soils developed from alluvial and proluvial deposits in the Gr?ndalselva River valley in West Spitsbergen

The genetic characterization of soils developed from alluvial and proluvial deposits in the Gr?ndalselva River valley (West Spitsbergen) is presented. These soils are compared with analogous soils formed on marine terraces along the coasts of Isfjord and Gr?nfjord. Gray-humus (soddy) soils with an O-AY-C profile have been described on parent materials of different origins, including alluvial and proluvial sediments. The texture of the soils in the Gr?ndalselva River valley varies from medium to heavy loam and differs from the texture of the soils on other geomorphic positions in the higher content of fine particles. The soils developed from the alluvial deposits are characterized by their richer mineralogical and chemical composition in comparison with the soils developed from proluvial deposits, marine deposits, and bedrocks. All the deposits are impoverished in CaO. No differentiation of the chemical composition of the soils along the soil profiles has been found in the soils of the coastal areas and the river valley. Some accumulation of oxalate-soluble Al and Fe compounds takes place in the uppermost mineral horizon. The soils of all the geomorphic positions have a high humus content and a high exchange capacity.     

Modeling of the evolution of steppe chernozems and development of the method of pedogenetic chronology

Geoarchaeological methods were used to study chronosequences of surface soils in the steppe zone and to trace soil evolution during the Late Holocene in northwestern Crimea. It was found that the morphological and functional “maturity” of the humus horizons in steppe chernozems of the Late Holocene was reached in about 1600–1800 yrs. After this, their development decelerated irreversibly. The maximum concentration of trace elements accumulated in these horizons in the course of pedogenesis was reached in 1400 yrs. A new method of pedogenetic chronology based on the model chronofunction of the development of irreversible results of pedogenesis over time is suggested. Original pedochronological data and growth functions—the most suitable models for simulating pedogenesis over the past three thousand years—suggest that the development of morphological features of soil as an organomineral natural body follows growth patterns established for biological systems.     

Nature of an overlapped paleosol and its significance in pedogenesis and paleogeography in North Huai region, China

An overlapped paleosol (albic Paleudalf) in North Huai region was studied by means of sand and clay mineralogy, elemental geochemistry, particle size distribution, observation of quartz sand surface structure under SEM, micromorphology, pollen analysis as well as soil dating. These albic soils are very extensive on uplands in this region and the profiles have developed on two individual formations rather than being differentiated by the homogenous eluvium of gneiss. It was also indicated that the soil evolution in this region proceeded from dessication and kaolinization during the middle Pleistocene to accumulation of bases and predominance of fragmental minerals in the early Holocene. The pedogenesis was further related to climate-landscape events in this region during the Quaternary. This study advocated that awareness of soil-landscape evolution was necessary in advance of pedogenesis research and a single soil-forming process could not account perfectly for soil formation with delicate evolution history.     

Soddy-Podzolic Soils with a Complex Organic Profile in the Right-Bank Part of the Lower Vyatka River Basin

Data on soddy-podzolic soils with the second humus horizon in the southwestern part of Kirov oblast are discussed. These soils were first studied by the authors on mantle calcareous loams of the Yarano- Kokshagskaya Plain in the eastern part of the Central Russian southern-taiga province of medium-humus soddy-podzolic soils of European Russia. The aim of this study is to reconstruct the history of the development of soil properties and soil cover in automorphic landscapes of this region. Morphology, substantive properties of mineral and organic components, soil genesis and evolution are analyzed using a set of physical, chemical, physicochemical, biochemical, and geochronological methods. The results of our study attest to the relict character of second the humus horizon and polygenetic nature of the studied soils. These soils have passed through two essentially different evolutionary stages in the Holocene: the accumulative stage in the first half of the Holocene and the accumulative-eluvial stage of erasing evolution with preservation of some inherited features in the second half of the Holocene. According to their properties, the studied soils are analogous to the earlier studied southern-taiga Vyatka–Kama province of high-humus soddy-podzolic soils of the northeast. At present, plowing of these soils leads to a partial or complete destruction of the second humus horizon; thus, spontaneous degradation processes are complemented by the human-induced soil degradation. A tendency for a gradual disappearance of these soils from the soil cover under the influence of natural and anthropogenic factors has been noted. The materials presented in this paper may be useful for organization of specially protected soil areas in the southwestern part of the Vyatka River basin.     

Organic phosphorus speciation and pedogenesis: analysis by solution 31P nuclear magnetic resonance spectroscopy

Changes in phosphorus (P) during soil development are central to the understanding of labile P for plant productivity and soil P management. We used NaOH‐EDTA extraction with ³¹P nuclear magnetic resonance spectroscopy (³¹P NMR), sequential P fractionation, and general soil chemical characterization to better our understanding of P dynamics within two chronosequences (Manawatu and Reefton) and one Basalt maturity sequence under original native vegetation. With time, orthophosphate and orthophosphate monoesters tended to increase with organic C to a maximum of about two‐thirds of NaOH‐EDTA‐extractable P in young soils (16 000 years in the Reefton chronosequence), but gradually declined thereafter to about one‐third of NaOH‐EDTA‐extractable P in the oldest soils (130 000 years old). This coincided with a depletion of P from primary minerals (e.g. apatite) and readily available P for plant production. This depletion of inorganic P resulted in a greater reliance on organic P cycling via mineralization, hence the depletion of the normally recalcitrant monoester‐P pool. Concomitantly, the build‐up of labile P species (diesters and pyrophosphate) and scyllo‐ over myo‐inositol hexakisphosphate occurred as soils developed, and might be attributed to microbial activity, including scavenging for P. This work highlights the importance of organic P cycling during pedogenesis.