Journal articles on the topic 'Podzol'

Abstract. Equatorial podzols are soils characterized by thick sandy horizons overlying more clayey horizons. Organic matter produced in the topsoil is transferred in depth through the sandy horizons and accumulate at the transition, at a depth varying from 1 to more than 3 m, forming deep horizons rich in organic matter (Bh horizons). Although they cover great surfaces in the equatorial zone, these soils are still poorly known. Studying podzols from Amazonia, we found out that the deep Bh horizons in poorly drained podzol areas have a thickness higher than 1 m and store unexpected amounts of carbon. The average for the studied area was 66.7 ± 5.8 kgC m−2 for the deep Bh and 86.8 ± 7.1 kgC m−2 for the whole profile. Extrapolating to the podzol areas of the whole Amazonian basin has been possible thanks to digital maps, giving an order of magnitude around 13.6 ± 1.1 PgC, at least 12.3 PgC higher than previous estimates. This assessment should be refined by additional investigations, not only in Amazonia but in all equatorial areas where podzols have been identified. Because of the lack of knowledge on the quality and behaviour of the podzol organic matter, the question of the feedback between the climate and the equatorial podzol carbon cycle is open.

Abstract. Equatorial podzols are soils characterized by thick sandy horizons overlying more clayey horizons. Organic matter produced in the topsoil is transferred in depth through the sandy horizons and accumulate at the transition, at a depth varying from 1 to more than 3 m, forming deep horizons rich in organic matter (Bh horizons). Although they cover great surfaces in the equatorial zone, these soils are still poorly known. Studying podzols from Amazonia, we found out that the deep Bh horizons in poorly drained podzol areas have a thickness higher than 1 m and store unexpected amounts of carbon. The average for the studied area was 66.7 ± 5.8 kg C m−2 for the deep Bh and 86.8 ± 7.1 kg C m−2 for the whole profile. Extrapolating to the podzol areas of the whole Amazonian Basin has been possible thanks to digital maps, giving an order of magnitude around 13.6 ± 1.1 Pg C, at least 12.3 Pg C higher than previous estimates. This assessment should be refined by additional investigations, not only in Amazonia but in all equatorial areas where podzols have been identified. Because of the lack of knowledge on the quality and behaviour of the podzol organic matter, the question of the feedback between the climate and the equatorial podzol carbon cycle is open.

Abstract. Hydromorphic Podzol soils in the Amazon Basin generally support low-stature forests with some of the lowest amounts of aboveground net primary production (NPP) in the region. However, they can also exhibit large values of belowground NPP that can contribute significantly to the total annual inputs of organic matter into the soil. These hydromorphic Podzol soils also exhibit a horizon rich in organic matter at around 1–2 m depth, presumably as a result of eluviation of dissolved organic matter and sesquioxides of Fe and Al. Therefore, it is likely that these ecosystems store large quantities of carbon by (1) large amounts of C inputs to soils dominated by their high levels of fine-root production, (2) stabilization of organic matter in an illuviation horizon due to significant vertical transfers of C. To assess these ideas we studied soil carbon dynamics using radiocarbon in two adjacent Amazon forests growing on contrasting soils: a hydromorphic Podzol and a well-drained Alisol supporting a high-stature terra firme forest. Our measurements showed similar concentrations of C and radiocarbon in the litter layer and the first 5 cm of the mineral soil for both sites. This result is consistent with the idea that the hydromorphic Podzol soil has similar soil C storage and cycling rates compared to the well-drained Alisol that supports a more opulent vegetation. However, we found important differences in carbon dynamics and transfers along the vertical profile. At both soils, we found similar radiocarbon concentrations in the subsoil, but the carbon released after incubating soil samples presented radiocarbon concentrations of recent origin in the Alisol, but not in the Podzol. There were no indications of incorporation of C fixed after 1950 in the illuvial horizon of the Podzol. With the aid of a simulation model, we predicted that only a minor fraction (1.7%) of the labile carbon decomposed in the topsoil is transferred to the subsoil of the Podzol, while this proportional transfer is about 30% in the Alisol. Furthermore, our estimates were 8 times lower than previous estimations of vertical C transfers in Amazon Podzols, and question the validity of these previous estimations for all Podzols within the Amazon Basin. Our results also challenge our previous ideas about the genesis of these particular soils and suggest that either they are not true Podzols or the podzolization processes had already stopped.

Abstract. Hydromorphic podzol soils in the Amazon Basin generally support low-stature forests with some of the lowest amounts of aboveground net primary production (NPP) in the region. However, they can also exhibit large values of belowground NPP that can contribute significantly to the total annual inputs of organic matter into the soil. These hydromorphic podzol soils also exhibit a horizon rich in organic matter at around 1 m depth, presumably as a result of elluviation of dissolved organic matter and sesquioxides of Fe and Al. Therefore, it is likely that these ecosystems store large quantities of carbon by (1) large amounts of C inputs to soils dominated by their high levels of fine-root production, (2) stabilization of organic matter in an illuviation horizon due to significant vertical transfers of C. To assess these ideas we studied soil carbon dynamics using radiocarbon in two adjacent Amazon forests growing on contrasting soils, a hydromorphic podzol and a well-drained alisol supporting a high-stature terra firme forest. Our measurements showed similar concentrations of C and radiocarbon in the litter layer and the first 5 cm of the mineral soil for both sites. This result is consistent with the idea that the hydromorphic podzol soil has similar soil C storage and cycling rates compared to the well-drained alisol that supports a more opulent vegetation. However, we found important differences in carbon dynamics and transfers along the vertical profile. At both soils, we found similar radiocarbon concentrations in the subsoil, but the carbon released after incubating soil samples presented radiocarbon concentrations of recent origin in the alisol, but not in the podzol. There were no indications of incorporation of C fixed after 1950 in the illuvial horizon of the podzol. With the aid of a simulation model, we predicted that only a minor fraction (1.7%) of the labile carbon decomposed in the topsoil is transferred to the subsoil of the podzol, while this proportional transfer is about 90% in the alisol. Furthermore, our estimates were 8 times lower than previous estimations of vertical C transfers in Amazon podzols, and question the validity of these previous estimations for all podzols within the Amazon Basin. Our results also challenge previous ideas about the genesis of these soils and suggest that either these soils are not true podzols or the podzolization processes had already stopped.

Abstract Atotal of 212 soil profiles were described and assessed for physical and chemical properties during July 2006 as part of an Ecological Land Classification study along the Churchill River in central Labrador. Two major soil types were found in the study area along the Churchill River: Podzols and Organic soils. Podzolic soils covered approximately 60% and Organic soils occurred in 24% of the study area. Approximately 15% of the study area was classified as rock and other unconsolidated material. Summary results and a sub−set of the following soil units (from 10 soil profiles) are presented here and were distin− guished according to the Canadian System of Soil Classification (CSSC) (Soil Classifica− tion Working Group 1998): Orthic Humo−Ferric Podzol, Placic Ferro−Humic Podzol, Gleyed Humo−Ferric Podzol, Sombric Humo−Ferric Podzol, Gleyed Regosol and Orthic Luvic Gleysol. The basic properties of the soil units identified above included: (i) morpho− logical descriptions of soil profiles with differentiated horizons; (ii) field−texture tests were used to determine classes and physical properties of sands, silts, loams and occurrence of mottles; and (iii) a range of soil chemical composition of different horizons (e.g., pH, total organic carbon [TOC] and select metal concentrations) which indicated no anthropogenic contamination above background concentrations in the area.

In recent years, the number and intensity of forest fires has increased and thus more attention is paid to studying the pyrogenic soils. Parameters under study include, the post-fire return of phosphorus, alkali and alkaline earth metals, etc. from burnt plants and forest floor to the soil, but the related dynamics of iron and aluminum compounds has been poorly studied. However, these two elements are crucial for soil-forming processes and the productivity of many soils, in particular of the podzols under the most fire-hazardous pine forests in dry habitats. The present analysis comparative geographic is based on literature and original data related to podzols on quartz sand, in which the eluvial-illuvial distribution of sesquioxide compounds along its profile is one of important diagnostic features. An increase in the frequency of forest fires disrupts the bio-pedogenic accumulation of R2O3 in podzol profile. It is suggested that sorption on charcoal and detritus does not compensate for the removal of iron and aluminum from the podzol profile. The problems of taxonomy of post-pyrogenic soils are discussed.

Mountainous areas represent regions with specific soil cover pattern that is naturally given by an altitudinal gradient. The objective of our study was to describe the soil cover development on the altitudinal gradient under changed environment given by man-planted vegetation and acidification. The studied area is characterized by spruce monoculture planting that replaced the original broadleaf natural vegetation and high load of anthropic acidification. The common hypothesis considering the sequence of Dystric Cambisol-Entic Podzol-Haplic Podzol with increasing altitude was not proved. The results of our study indicate that the influence of spruce vegetation causes the occurrence of Haplic Podzols at low altitudes where the natural soil formation does not induce their development. Results showed that the vegetation type can overrule other altitude-related soil-forming factors. The conversion of natural broadleaf and mixed forests to spruce monocultures leads to the expansion of podzolization process to lower altitudes.

Soil solutions from an Orthic Ferro-Humic Podzol and a Typic Humisol were extracted using a soil to solution ratio of 1:10 by the batch and column procedures. The aluminum speciation in the extracts was determined by measuring three forms of dissolved aluminum (uncomplexed monomeric, total monomeric and total reactive). The two methods of extraction gave different results. For most of the mineral horizons and the moderately to well-decomposed organic horizons the batch method tended to extract more dissolved aluminum, particularly in uncomplexed monomeric form. The greatest differences between the two methods were for the lowest bulk density materials, the L and F horizons of the Podzol and the Of of the Humisol. The variations were due to channelling in the column and the inability of the shaker to assure good mixing between the soil and solution. It is concluded that the batch method is best suited for routine laboratory analyses. Key words: Soil solution chemistry, Podzols, Humisols

Modern researches of genetic nature of sod-podzol soils with underling carbonates are considered in the article. They are erected to evolutional row from rendzina to sod-podzol soils and forming soils on the layer of water-glacial with were put on carbonates rocks. Key words: genesis, evolution, sod-podzol, soils, carbonic rocks.

Abstract. Podzol-ferralsol soil systems cover great areas in Amazonia and in other equatorial regions, they are an end-member of old equatorial landscape evolution, are frequently associated with kaolin deposits and store and export large amounts of carbon. Their biogeochemistry was usually inferred from soil mineralogy and from spring or river water properties. This paper presents a database for groundwaters sampled in situ in a typical podzol-ferralsol soil catena from the Alto Rio Negro region, Brazil; the sampling periods allowed to sample under high- and low-level water-table conditions. The compositions of the groundwaters percolating the soil system are consistent with the currently observed mineral and organic paragenesis. The acidity and the site density of the dissolved organic matter (DOM) produced and circulating in the podzol white sand horizons are similar to what was observed in acid podzolic temperate zone. The aggressiveness of the white sand groundwater with regard to secondary minerals favours the podzol development at the expense of the ferralsolic or kaolin material. Some DOM is able to percolate in depth through clayey material with concentrations up to 9.7 mgC l−1 (4.0 on average). This DOM is characterized by high site densities indicating a large proportion of small carboxylic acids. In the deep kaolin and in the ferralsolic horizons, the Si and Al content of the groundwater is controlled by gibbsite and kaolinite precipitation/dissolution and by quartz dissolution. The mobility of Fe, mainly transported as Fe2+, is sensitive to small variations in EH. The bleaching of the deep kaolin at the upper part of the slopes is favoured by the high content of small carboxylic compounds and by the redox conditions of the solutions issuing from the podzolic horizons. The transfer of Al and Fe result in the precipitation of Al-nodules in slope horizons and of Fe-oxides in the upper downslope horizon. It can be inferred that thick bleached kaolin are likely everywhere presently active giant podzols are close to a slope gradient sufficient to allow deep percolation of groundwater.

This paper is the first of a series reporting studies in the genesis of podzols and humus podzols on coastal dunes in a chronosequence that spans >700K yrs. It is concerned mainly with temporal changes in profile morphology across a podzol chronosequence and with brief descriptions of sites chosen for genetic studies. It summarizes the geology, geomorphology and general mineralogy of dune systems at Cooloola and North Stradbroke Island and briefly discusses the effects of parent material, geomorphic component, climate, dune denudation and vegetation on soil development. Its purpose is to provide a field and morphological framework for other papers in the series dealing essentially with laboratory investigations and interpretations of the chemistry, mineralogy and genesis of these subtropical soils.

AbstractTwo soils, a haplic Podzol and a dystric Cambisol, developed from post-glacial tills, were studied with respect to their soil chemistry and clay mineralogy. Although the state factors (age, geology, topography, climate) of soil formation were almost identical, two different types developed. The E horizon of the Podzol contained more smectite, characterized by a montmorillonite-beidellitemixed phase. The neoformation of smectite could be traced back to the weathering of mica and chlorite. The Podzol had less hydroxy-interlayered smectite (HIS) in the surface horizons than the Cambisol. A larger amount of chelating compounds in the E horizon of the Podzol either transformed HIS into smectites or inhibited the formation of HIS and favoured the formation of smectites. The physical structure of the soil material is believed to be the most important factor in the different modes of soil evolution. The greater abundance of coarse pores in the topsoil at the Podzol site probably led to a faster eluviation of base cations, a different vegetation at ground level, and, consequently, to a faster soil evolution with the formation of spodic horizons.

Abstract. The podzol-ferralsol soil systems, which cover great areas of Amazonia and other equatorial regions, are frequently associated with kaolin deposits and store and export large amounts of carbon. Although natural organic matter (NOM) plays a key role in their dynamics, little is known about their biogeochemistry. In order to assess the specific role of dissolved organic matter (DOM) on NOM storage in deep horizons and to determine possible relationships between kaolin formation and DOM properties, we studied the groundwater composition of a typical podzol-ferralsol soil catena from the Alto Rio Negro region, Brazil. Groundwater was sampled using tension-free lysimeters placed according to soil morphology. DOC, EH, pH, and dissolved Si, Al3+, Fe2+, and Fe3+ were analyzed for all samples and values are given in a database. Quantification of other dissolved ions, small carboxylic acids and SUVA254 index and acid-base microtitration was achieved on selected samples. Part of the DOM produced by the hydromorphic podzols is directly exported to the blackwater streams; another part percolates at greater depth, and more than 90% of it adsorbs in the Bh-Bhs horizons, allowing carbon storage at depth. Humic substances are preferentially adsorbed with regard to small carboxylic compounds. With regard to kaolin genesis, kaolinite precipitation is favored by Al release from NOM mineralization within the Bh-Bhs and kaolin bleaching is ensured by iron reduction due to acidity and relatively low EH. Fe2+ mobility can be related to small EH variations and enhanced by the significant concentration of small carboxylic acids. The long-term result of these processes is the thickening of the kaolin, and it can be inferred that kaolin is likely to occur where active, giant podzols are close to a slope gradient sufficient enough to lower the deep water table.

AbstractThe studies on quartz silt surface microstructures using scanning electron microscopy (SEM) were performed in Brunic Arenosol and Gleyic Ortsteinic Podzol, as major components of soil cover of the lower supra-flood terrace of the Słupia River, N Poland. Brunic Arenosols have developed from coarse- and medium-grained fluvioglacial sands, whereas Podzols from aeolian sands of mid-Holocene age, which in some places were covered with younger aeolian deposits. A group of at least 100 randomly selected grains from each soil horizon have been analyzed. The grains were classified into one of the following groups: fresh (type A), grains with the features of chemical weathering (type B), grains coated with scaly-grain incrustations (type C), grains coated with bulbous incrustations (type D), and cracked grains (type E). Parent materials of the investigated soils did not differ significantly in terms of contribution of grain types and type C predominated in both soils. Significant differences were noted in soil solums. Grains covered by scaly-grained incrustations predominated in Brunic Arenosol, which constituted 62–89%. In the profile of Gleyic Ortsteinic Podzol grains type B predominated in AE and E horizons (65–82%), whereas in the remaining horizons grains type C (54–77%).

Urbanization in the Arctic results in considerable and still poorly known environmental consequences. The effect of urbanization on soil microbiome—an ecosystem component highly sensitive to anthropogenic disturbance—remains overlooked for the Arctic region. The research compared chemical and microbial properties of the natural Podzol soils and urban soils of Murmansk—the largest Arctic city. Particular attention was given to the profile distribution, which is almost completely ignored by most microbial studies. Soil microbiome was investigated by the quantitative indicators based on fluorescence microscopy (microbial biomass) and PCR real-time methods (amount of rRNA genes copies of archaea, bacteria, and fungi). The principal changes in urban soils’ properties compared to the natural references included a shift in pH and an increase in C and nutrients’ contents, especially remarkable for the subsoil. The numbers of rRNA genes copies of archaea, bacteria, and fungi in urban topsoils (106–1010, 109–1010, and 107–109, respectively) were lower than in Podzol; however, the opposite pattern was shown for the subsoil. Similarly, the total microbial biomass in urban topsoils (0.55–0.75 mg g−1) was lower compared to the 1.02 mg g−1 in Podzols, while urban subsoil microbial biomass was 2–2.5 times higher than in the natural conditions. Both for urban and natural soils and throughout the profiles, fungi were dominated by mycelium forms; however, the ratios of mycelium–spores were lower, and the amount of thin mycelium was higher in urban soils than in natural Podzols. Urbanization in the Arctic altered soil morphological and chemical properties and created a new niche for microbial development in urban subsoils; its contribution to biodiversity and nutrient cycling promises to become increasingly important under projected climate change.

Integrating soil and relief contribute to the understanding of the evolution of landscapes and subsidize the planning of use and occupation of lands, mainly in places under urban sprawl, as Northeast Coast of Bahia. This work looked for understand the factors that promoted the podzolization and how part of the Coastal Tablelands’ relief may had evolved. To reach those goals, analysis of images of the study area were made, followed by fieldwork, elaboration of two catenas, classification of soils and physical and chemical laboratory analysis. Despite being located under similar climate conditions and present common podzolization processes, both slopes present very distinct pedogeomorphological conformations, resulted of depositional, geochemical and topographical dynamics. Therefore, the slope “A” presents in its summit a Arenosol, a soil constituted by white sand that is possibly the result of the eolian rework of Pleistocene-age alluvial fans or fluvial deposition of Pojuca river, being succeeded by a Podzol, in the back slope, and by a Cambisol, in the foot slope, arising from sediments of the Grupo Barreiras. In the slope “B” was identified a pedological transformation system from Ferralsol to Podzol. Thus, in the summit is present a Ferralsol, succeeded by a Podzol, which is succeeded by a Podzol again. This work demonstrates that the study area shows a current pedogeomorphological set resulted of neotectonic reactivation and podzolization.

AbstractThe aim of this research was to assess the relationships between exchangeable and water-soluble cations in forest soil types. Three dominant soil types were distinguished on studied plots: Haplic Podzol, Dystric Arenosol and Dystric Cambisol. Ca, Mg, K, Na and Al in soil sorption complex and soil water extracts were determined. The differentiation of the ionic composition of soil sorption complex and soil water extracts within a soil type and amongst soil types was presented. The sum of cations in the soil and water extracts was the highest in Dystric Cambisol and the lowest in Haplic Podzol. Ca is a dominant cation in soil and soil water extracts in organic horizon, whilst Al is dominant in mineral soil horizons. The Ca/Al and the base cations to Al (BC/Al) molar ratios increased in the sequence of soils: Haplic Podzol < Dystric Arenosol < Dystric Cambisol. The parent material, soil-forming processes and vegetation cover affected the Ca/Al and BC/Al ratios.

Sanborn, P., Lamontagne, L. and Hendershot, W. 2011. Podzolic soils of Canada : Genesis, distribution, and classification. Can. J. Soil Sci. 91: 843–880. Podzolic soils occupy 14.3% of the Canadian landmass, and occur in two widely separated areas, eastern Canada (northern Ontario, Quebec, Maritimes) and British Columbia, usually under coniferous forest and on non-calcareous parent materials. Broad climatic control of Podzol distribution and properties is evident at the national scale, with higher organic matter concentrations (Ferro-Humic Podzols) in wetter climates, in contrast to Humo-Ferric Podzols predominating in drier boreal forest regions. Humic Podzols are least abundant and are restricted to the wettest landscape positions. International and Canadian research suggests that a more diverse range of processes is involved in podzolization than was envisioned in the 1960s, and proposed mechanisms must account for observed patterns of organic matter distribution and a diverse array of inorganic amorphous constituents in profiles. Taxonomic concepts of Podzolic soils in the Canadian System of Soil Classification have remained consistent since the late 1970s, and the higher-level criteria defining the order and its great groups have proved to be meaningful in new applications, such as delineating soil carbon stocks across Canadian landscapes. Canadian contributions to pedological research on Podzols declined dramatically after 1990, coincident with shifting research priorities in soil science and diminished activity in soil survey.

Abstract. Soil studies commonly comprise the uppermost meter for tracing, e.g., soil development. However, the maximum rooting depth of various plants significantly exceeds this depth. We hypothesized that deeper parts of the soil, soil parent material and especially paleosols provide beneficial conditions in terms of, e.g., nutrient contents, thus supporting their utilization and exploitation by deep roots. We aimed to decipher the different phases of soil formation in Dutch drift sands and cover sands. The study site is located at Bedafse Bergen (southeastern Netherlands) in a 200-year-old oak stand. A recent Podzol developed on drift sand covering a Plaggic Anthrosol that was piled up on a relict Podzol on Late Glacial eolian cover sand. Root-free soil and sediment samples, collected in 10–15 cm depth increments, were subjected to a multi-proxy physical and geochemical approach. The Plaggic Anthrosol revealed low bulk density and high phosphorous and organic carbon contents, whereas the relict Podzol was characterized by high iron and aluminum contents. Frequencies of fine (diameter ≤ 2 mm) and medium roots (2–5 mm) were determined on horizontal levels and the profile wall for a detailed pseudo-three-dimensional insight. On horizontal levels, living roots were most abundant in the uppermost part of the relict Podzol with ca. 4450 and 220 m−2, significantly exceeding topsoil root abundances. Roots of oak trees thus benefited from the favorable growth conditions in the nutrient-rich Plaggic Anthrosol, whereas increased compactness and high aluminum contents of the relict Podzol caused a strong decrease of roots. The approach demonstrated the benefit of comprehensive root investigation to support interpretation of soil profiles, as fine roots can be significantly underestimated when quantified at the profile wall. The possible rooting of soil parent material and paleosols long after their burial confirmed recent studies on the potential influence of rooting to overprint sediment–(paleo)soil sequences of various ages, sedimentary and climatic settings. Potential consequences of deep rooting for terrestrial deep carbon stocks, located to a relevant part in paleosols, remain largely unknown and require further investigation.

Abstract. Soil studies commonly comprise the uppermost meter for tracing e.g. soil development. However, the maximum rooting depth of various plants significantly exceeds this depth. We hypothesized that deeper parts of the soil, soil parent material and especially paleosols provide beneficial conditions in terms of e.g. nutrient contents, thus supporting their utilization and exploitation by deep roots. We aimed to decipher the different phases of soil formation in Dutch drift- and coversands. The study site is located at Bedafse Bergen (SE Netherlands) in a 200 year old oak stand. A recent Podzol developed on driftsand covering a Plaggic Anthrosol that established in a relict Podzol on Late Glacial eolian coversand. Root-free soil and sediment samples, collected in 10–15 cm depth increments, were subjected to a multi-proxy physical and geochemical approach. The Plaggic Anthrosol revealed low bulk density and high phosphorous and organic carbon contents, whereas the relict Podzol was characterized by high iron and aluminum contents. Frequencies of fine (≤ 2 mm) and medium roots (2–5 mm) were determined on horizontal levels and the profile wall for a detailed pseudo-three-dimensional insight. On horizontal levels, living roots maximized in the uppermost part of the relict Podzol with ca. 4450 and 220 m-2, significantly exceeding topsoil root abundances. Roots of oak trees thus benefited from the favorable growth conditions in the nutrient-rich Plaggic Anthrosol, whereas increased compactness and high aluminum contents of the relict Podzol caused a strong decrease of roots. The approach demonstrated the benefit of comprehensive root investigation to support and explain pedogenic investigations of soil profiles, as fine roots can be significantly underestimated when quantified at the profile wall. The possible rooting of soil parent material and paleosols long after their burial confirmed recent studies on the potential influence of rooting to overprint sediment-(paleo)soil sequences of various ages, sedimentary and climatic settings. Potential consequences of deep rooting for terrestrial deep carbon stocks, located to a relevant part in paleosols, remain largely unknown and require further investigation.

The geochemically conjugate series of soils (Albic Podzol – Albic Podzol Gleyc – Hystosol) formed on an undulating glaciolacustrine plain in the middle taiga of Karelia was investigated. Surveys for redox conditions showed them to vary from oxidizing in automorphic soils to reducing in soils occupying accumulation-favoring locations. The geochemical coefficients descriptive of the features of accumulation and directions of migration in the studied soils were calculated and analyzed. The distribution of silicic acid and a majority of sesquioxides inside the profile of the studied soils is typical of podzols. The podzolic horizons of the soils occupying interstitial positions have a faster outmigration of elements than in automorphic soils, while their Al-Fe-humic horizons accumulate aluminum, iron, titanium and phosphorus. All the soils are deficient in a majority of microelements as compared to their background levels; very low concentrations were determined for nickel, cobalt and manganese. The content of copper and sometimes zinc is at the background level. The distribution of the studied elements across the soil profile follows the accumulation-eluviation-illuviation pattern, but the scope of variation in the migration of elements varies among topographic positions. In well-drained locations microelements are quite monotonously distributed through the lower part of the soil profile, while soils in transitional landscapes have a higher differentiation of microelements. The differentiation of the catena through lateral migration is of the transient eluviation type, i.e. soils in lower-lying positions are poorer in the studied elements than soils in automorphic positions. This pattern is due to the natural characteristics of the area: low surface slope, homogeneous sandy parent material, low humus content in soil.

Eleven pedons in an agricultural landscape at elevations 80-130 m above sea level in Jokioinen, south-western Finland were investigated and classified according to Soil Taxonomy, the FAO-Unesco system (FAO), and the World Reference Base for Soil Resources system (WRB). The soils were related to geomorphology of the landscape which is characterized by clayey fields and forested bedrock high areas covered with glacial till. A Spodosol/Podzol was found in a coarse-sandy soil in an esker while the sandy loam in a bedrock high area soils did not have an E horizon. A man-made mollic epipedon was found in a cultivated soil which had a sandy plow layer while clayey plow layers were ochric epipedons. Cambic horizons, identified by structure and redox concentrations, were common in cultivated soils. In a heavy clay soil, small slickensides and wedge-shaped aggregates, i.e., vertic characteristics, were found. Histosols occurred in local topographic depressions irrespective of the absolute elevation. According to the three classification systems, the following catenas are recognized: Haplocryods - Dystro/Eutrocryepts -Haplocryolls - Cryaquepts - Cryosaprists (Soil Taxonomy), Podzols - Regosols - Cambisols - Histosols (FAO-Unesco), and Podzols - Cambisols - Phaeozems - Gleysols - Histosols (WRB).;

Very sandy and sometimes seasonally inundated humus podzols of the Bassendean soil association in southwest Australia experience severe leaching of fertiliser P with consequent eutrophication of waterways. P sorption by these soils is mostly minimal and is primarily due to the podzol Bh horizon. The consequence of seasonal drying of profiles under the prevailing Mediterranean climate on the P sorption capacity of these B horizon materials is not known. The effects of air-drying on P sorption were studied for 3 sandy podzols using samples from entire soil profiles collected in winter (wet) and summer (dry). Results confirm that the surface and near surface horizons (i.e. A and E horizons) of these soils have very low P sorption capacities. Only some B horizon materials exhibit substantial P sorption and this is mostly due to allophane, with minor contributions from extractable Fe forms, organic carbon, and clay. Air-drying during summer and in the laboratory increased P sorption of B horizon materials by up to 120% compared with field-moist samples. The difference in P sorption between air-dried samples and the field-moist samples decreased for long reaction times.

More than 30 years have passed after the collapse of the Soviet Union, and huge areas of soil were left in a fallow state. The study of the microbiological status of fallow soils is an extremely urgent task because fallow soils represent the “hidden” food basket of Eurasia. In this context, we studied the influence of land use type (pasture, vegetable garden, hayfield, or secondary afforestation) on key agrochemical parameters and parameters of soil microbial biodiversity. All anthropogenically transformed soils included in the analysis showed increased humus content and pH shift to a more neutral side compared to the mature soil; the same seemed to be the case for all nutrient elements. It was established that the key factor regulating soil microbiome composition shift was the duration and degree of irreversibility of an agrogenic impact. The key phyla of soil microorganisms were Pseudomonadota, Acidobacteriota, Verrucomicrobiota, Bacteroidota, and Actinobacteriota. The proportion of other phyla was quite variative in soils of different land use. At the same time, all the 30-year-old abandoned soils were more similar to each other than to mature reference soil and 130-year-old soils of monoculture vegetable gardens. Thus, the first factor, regulating soil microbiome composition, is a continuation of soil agrogenic transformation. The second factor is the type of land use if the soil age was equal for fallow territory in the case of one initial podzol soil and one type of landscape. Thus, 30-year-old abandoned soils are intermediate in terms of microbial biodiversity between pristine natural podzols and plaggic podzol. It could be suggested that in the case of secondary involvement of soils in agriculture, the composition of the microbiome may turn to mature soil or to plaggic soil under intensive amelioration.

Today the rate of anthropogenic transformations of the soil cover significantly exceeds the rate of its natural restoration. According to a modern digital soil map at a scale of 1 : 200,000 in the Leningrad Region anthropogenically modified subtypes of natural soils, which were formed as a result of human economic activity, predominate. The article considers anthropogenic changes in soils and soil cover of the territory of the high-voltage power line. The study area of 100×500 meters is located in the Tikhvinsky district between the settlements of Kalivets and Novaya Ust-Kapsha. The landscape of the territory belongs to the lake-glacial plain, the soil-forming rocks are lake-glacial sands and sandy loam. Natural soils that are not affected by technological works are found only in the forest, outside the clearing laid during the construction of the power line. These are Albic Podzol, Entic Podzol, Histic Albic Podzol, Histic Entic Podzol and Histic Gleysol. It was revealed that in the study area, the horizons of the original natural soils are partially or completely cut off, turbated, compacted, which led to the formation of their anthropogenically transformed subtypes: over-compacted, abraded, turbid and stratified. Sometimes soil material is exposed to the surface and moved over the study area by tens of meters. After the construction of the high-voltage line, new formations appeared in the soil cover, such as Podzol Nudispodic, buried soils and several types of non-soil formations. It is revealed that each technological operation (logging, installation of power transmission line supports, organization of places for technological operations and the creation of temporary roads) is characterized by its own special disturbances in the soil cover. Thus, after the construction of the power line, there were no natural soils with an undisturbed structure in the soil cover. In addition to the fundamental transformation of the soil cover at the site, natural vegetation was reduced, the mesorelief was partially disrupted and the microrelief was almost completely changed. All these anthropogenic transformations will affect the quality of the ecological functions of the soil cover. During the further operation of power transmission lines, such as clearing a cut-out clearing, updating fire-prevention mineralized strips, maintaining the power grid, disturbances of the soil cover will be periodically repeated, preventing the ecosystem from returning to its original state.

Calcareous sands (Fluvisols/Regosols) and Podzol soils of at least seven different ages (0, 2500, 3000, 5000, 5800, 6200 and 6500 calendar years) form a soil chronosequence in the prograded beach-ridge plain near Moruya Heads, on the south coast of New South Wales. Ages of the soils were determined by radiocarbon dating of marine shell deposited with the sediment. The soils range from undifferentiated quartz sand mixed with marine shell debris at the youngest site, to well developed podzols with pronounced AI, A2 and iron-humus B horizons at the oldest sites. Age trends are evident in a range of physical and chemical soil properties, the most significant of which are: an increase in the thickness of the A2 and B horizons with a concomitant decrease in C horizon thickness; a decrease in Munsell colour chroma in the A1 and A2 horizons and an increase in B horizon chroma; a fall in the pH of all horizons (particularly in the younger soils); an increase in depth to the leaching front of marine shell carbonate; the progressive leaching of HC1-extractable manganese, calcium, magnesium and sodium from the soil profiles; and the progressive development of the A2 and B horizons in terms of HC1-extractable iron and aluminium.

Foram estudadas duas toposseqüências na planície litorânea no rio Guaratuba (SP), definindo seqüência de evolução pedológica e de deposição/acumulação, utilizando a análise macromorfológica de solos por meio de tradagens. A primeira seqüência ilustra a transformação de Espodossolo Ferrocárbico (Podzol) sobre sedimentos arenosos marinhos para Organossolo (solo orgânico), enquanto a outra mostra a relação entre Gleissolo Háplico (solo glei pouco húmico) sobre sedimentos continentais e Espodossolo Ferrocárbico (Podzol) em sedimentos areno-quartzosos marinhos. A sedimentação marinha é representada por feixes de restinga arenosos, com zonas embaciadas, propiciando o desenvolvimento de Espodossolos nas partes altas e Organossolos nas partes baixas. Morros isolados inferiores à planície funcionaram como antigas zonas de balizamento desses feixes, que limitaram o sistema deposicional continental, definindo o material marinho como anterior ao continental, onde ocorreu um encaixamento da drenagem próximo ao contato.

Four Bf and one Bhf Podzol horizon samples from the Precambrian Shield, Ontario, Canada were leached with pH 3 solutions in three different experiments to determine which soil aluminum fraction was primarily responsible for the aluminum leached into solution. For the Bf horizons, it was primarily the oxalate-extractable aluminum fraction (corrected for pyrophosphate, Alo–Alp); for the Bhf horizon it was equally the pyrophosphate (Alp) and Alo–Alp. A comparison with other studies suggests that when the ratio (Alo–Alp)/Alp is above 0.3–0.7, the oxalate-extractable fraction will be most important, and at lower ratios the pyrophosphate fraction becomes most important. The pattern of fluoride leaching in these experiments suggests that F was concentrated primarily on the surface of the amorphous aluminum fraction. Key words: Aluminum, silica, fluoride, Podzol, acid deposition

The establishment of a network of monitoring sites (term in Russian—«carbon polygons») for monitoring climatic processes as well as the emission and deposition of carbon compounds in various ecosystems is one of the priority tasks in the field of climate and biosphere conservation in the world. This paper presents the results of the study of the soil sections of the «Ladoga» carbon monitoring site. Folic Podzol (Arenic) and Fibric Histosol were considered. These soils are widely represented in the southern taiga subzone and can be used as benchmark monitoring soil sections. As a result of the analysis of chemical parameters, it was revealed that Fibric Histosol and Folic Podzol (Arenic) are characterized by an acidic reaction of pH, pronounced podsolization, and peat accumulation. Fibric Histosol stores a significant amount of soil organic matter (SOM) up to 42.95 kgC/m2. In the analysis of the molecular composition of humic acids (HAs) extracted from the studied soils, it was found that HAs from Fibric Histosol were characterized by a relatively high content of aromatic structural fragments (27–41%), while in Folic Podzol (Arenic), aliphatic structural fragments prevailed (up to 70%). The increase of aromatic structural fragments in the HAs composition indicates the stabilization and conservation of SOM. The creation of a monitoring network will make it possible to identify the main trends of SOM accumulation, determine the conditions under which accumulation occurs, and calculate its contribution to climate change on the planet.

A chronosequence of sandy soils was investigated on four terraces near Lake Michigan to assess rates of podzolization and changes in soil properties with age. The terraces ranged in age from 3000 to 10 000 BP. Each surface was systematically sampled to determine the modal profile, which was then described and sampled. Quantities of OC, Fe, and Al in the B horizons of modal soils increased with soil age. Silt content of surface horizons also increased with age, possibly due to eolian input or physical weathering. For weighted profile and B horizon Al and Fe averages and a variety of soil development indices, a single logarithmic model generally gave the highest statistical significance of the three chronofunction models used. All pedons sampled failed to classify as Podzols, but the oldest two met the criteria for the Spodosol order. Thus, more than 4000, but less than 10 000, years are required for the development of a spodic horizon in Michigan. Key words: Soil chronosequence, Podzol development, soil genesis, modal profile

Pine-green moss forests on Podzols exhibit high susceptibility to fire. Subsequent to wildfire, soot and charcoal enter the soil profile and accumulate in the upper part of the podzolic horizon (E). This process results in the development of a greying pyrogenic podzol horizon (Epyr). The maximum concentration of pyrogenic components accumulates in the surface layer of Epyr, which is 1 to 4 cm thick and the darkest in colour. The comprehensive soil descriptions showed the existence of a fine pyrogenic layer between the forest floor and mineral horizon. This layer was not analysed. The current shift in science towards assessing the environmental aspects of soil organic matter dynamics requires a more detailed study of the soil profile. We suggest distinguishing the pyrogenic organic mineral sub-horizon of the Eopyr as the upper Epyr layer. Our results show this sub-horizon contains sand, humus, detritus, and charcoal. It forms around 6%–22% of the entire organic matter pools in the biologically active part of the soil (0–30 cm). Further research is needed to obtain reliable qualitative and quantitative data on Eopyr.

This paper aimed to characterize urbostratozems (Urbic Technosol, WRB) of Saint Petersburg located in industrial (“Electrodepo” railway station) and residential (region Polish Garden) zones. These soils were also compared with background (natural) soddy podzol soil (Umbric Albic Gleic Podzol, WRB) sampled in recreational zone (suburban park “Oranienbaum”). Soil samples were collected from soil horizons for chemical analysis and from top of soils for microbialogical analysis in June of 2012. Chemical properties (pH, total organic carbon, mobile forms of K and P) and content of heavy metals (Pb, Cu, Zn, Ni) in soils were determined. Culturable forms of microorganisms (bacteria and fungi) were studied. Assessment of the enzymatic activity of the soil was carried out by culturing of microorganisms-producers of protease, amylase, cellulase and lipase on special media. Biotesting using cress (Lepidium sativum L.) seeds had been carried out for assessment of soil phytotoxicity. It was found that chemical properties of urban and natural soils differ greatly. Heavy metal pollution was evident in both urban soils, but maximum concentrations of heavy metals were found in the soil of the industrial zone. Phytotoxocity had been also most pronouncend in the soil of the industrial zone. The natural soil exhibited significantly higher respiration activity than urbostratozems. The greatest difference in the structure of the bacterial and fungal communities was observed between the natural soil of the recreational zone and the urbostratozem of the industrial zone. Algae had been present in the urban soils of the residential zone that was not observed in the natural podzol. The minimum number of producers of all enzymes, except for cellulase, was observed in the soddy podzol in the recreational zone. The maximum number of protease and amylase producers was found in the soil of the industrial zone. Lipolytic activity was almost the same in all samples. It was found that more sensitive biological methods are needed for environmental assessment of urban soils. The results of the article can be used by soil scientists and environmental engineers for a comprehensive environmental assessment of the condition of urban soils and for creating new urban green spaces.

Boreal agriculture struggles with soils of lower agronomic value, most of which are sandy with a low water holding capacity (WHC) and prone to nutrient leaching. Biochar amendments are associated with positive effects on soil hydraulic properties and enhanced nutrient retention. However, these effects are strongly related to feedstock type and pyrolysis parameters and depend on biochar application rates and soil types. While biochar could increase the productivity of boreal agriculture by improving water and nutrient use efficiency, little is known about its effects on hydraulic processes in podzol. In this study, we investigated the effects of biochar rates (10, 20, 40, 80 Mg carbon ha−1) and maturity on soil hydrology for an agriculturally used Podzol in Labrador, Canada. The in-situ soil water content (SWC) and weather data over an entire growing season were analysed. Hydrus 1D simulations were used to estimate changes in water fluxes. SWC showed clear differentiation among storage parameters (i.e., initial, peak and final SWC) and kinetic parameters (i.e., rate of SWC change). Storage parameters and soil wetting and drying rates were significantly affected by biochar rates and its maturity. The magnitude of the changes in SWC after either wetting or drying events was statistically not affected by the biochar rate. This confirms that biochar mostly affected the WHC. Nevertheless, reductions in cumulative lower boundary fluxes were directly related to biochar incorporation rates. Overall, biochar had positive effects on hydrological properties. The biochar rate of 40 Mg C ha−1 was the most beneficial to agriculturally relevant hydraulic conditions for the tested Podzol.

An ancient sand-dune system located in the Myall Lakes National Park, N.S.W. (32�28'S., 152�30' E.) supports an open eucalypt forest with Eucalyptus pilularis as one of the co-dominant tree species. Profile development of the sand mass is typical of a light humic podzol. The relative pool sizes of available nutrients contained by the acidic podzol were such that phosphorus was the most limiting for the growth of E. pilularis seedlings. The bulk of seedling phosphorus was assimilated from the A, horizon of this podzol. Soil from the A, horizon was characterized by a low total level of phosphorus (= 30 �g P g-1 soil). Approximately 90% of this phosphorus was 0.1 M H2SO4 insoluble and probably organic in nature. In addition, 30% of the total phosphorus was associated with compounds containing aluminium and iron. The concentration of soluble phosphorus in the soil solution (CaCl2, extractable) was 0.36 �g P g-1 soil. Although this value is comparable to those reported for fertile soils, the amount of readily exchangeable phosphorus was found to be very low (1.43 �g P g-1 soil). Anion exchange resin studies indicated that after this pool was exhausted, release of phosphorus from slowly available sources was extremely limited (0.013 �g P g-1 soil h-1). Studies showed that transfer of phosphorus to seedling roots in A, horizon soil was predominantly a diffusive process. Moreover, the effective diffusion coefficient for phosphate (10.81 x 10-8 cm2 s-1) indicated that this process was comparatively fast.

Distribution of total elemental C, Al, Si, Fe, Mn, P, Ti and Zr in a chronosequence of podzols spanning some 7x105 years is presented. Considerable variation in elemental composition occurred down each profile due to translocation and nonuniform banding of heavy mineral concentrations. The mobility and fate of these elements and Cr were determined by extractions with sodium pyrophosphate, ammonium oxalate (pH 3.0), dithionitelcitrate and dilute HCl. In some cases, pyrophosphate extractions gave higher values than expected when considering the ammonium oxalate values, confirming that peptization can occur with the former. Extraction data demonstrate that all elements with the exception of Mn and Zr have been mobilized from the A horizon and accumulated in the B horizon. Mn is lost from the A horizons but there is no evidence for accumulation elsewhere in the profiles, while there is no evidence for the movement or accumulation of Zr. As the profiles develop and the thickness of the A horizons increases, Al accumulates as Al-organic matter complexes in the Bh and Bhs horizons and as proto-imogolite allophane, determined by 29Si n.m.r. spectroscopy, in the Bhs and Bs horizons. Selective dissolution by using oxalate and dithionitelcitrate demonstrates accumulation of proto-imogolite in the Bhs and Bs horizons with age, and also suggests that its nature may vary within profiles. In most profiles, only a small proportion of P is extracted by oxalate or dithionitelcitrate and appears to be in the form of monazite and gorceixite. Across the chronosequence, P accumulates in the lower B horizons and is associated with Al-organic matter complexes and proto-imogolite. Iron accumulates in B horizons and, as the later stages of podzol development, such as the giant pipey podzols, are reached, many of the lower horizons contain >90% of Fe as secondary Fe oxyhydroxides. Most of the secondary Fe in the Bh and Bhs horizons is present as Al substituted goethite while, in the Bs horizons and below, ferrihydrite is the dominant mineral. There is little evidence for significant concentrations of Fe-organic matter complexes. Fe maxima occur above the Al maxima in the younger profiles and below it in the older ones. Fe is progressively lost during profile development and is depleted from humus podzols which are often the final stage of podzol genesis. Titanium is the most abundant element after Si. Extraction data strongly suggest that Ti is largely present in primary minerals such as ilmenite, rutilelanatase and pseudorutile. Evidence is presented for the presence of Ti-organic matter complexes in A horizons and Ti mobilized in this form appears to result in the formation of pedogenic anatase or rutile in the upper B horizons. The selective dissolution data for Ti and Fe suggest possible Ti-substitution for iron in goethites which appears to be common in B horizons of the freely drained profiles, although little Ti is associated with ferrihydrite.

Abstract Context. - Many ferralsols and podzols from central Amazon were developed by a long-time pedogenesis over a sandy-clay Cretaceous sediment which mainly consists of kaolinite and quartz [Lucas et al., 1996]. The soils progressively range from clayey microaggregate ferralsols on the plateaux associated with tropical forests, to podzols at the bottom of thalwegs and in some small declivities of the largest plateaux associated with forests of smaller trees or open savannahs [Chauvel et al., 1987; Bravard, 1988; Lucas, 1989; Cornu, 1995]. Their moisture properties are different from those of temperate soils [Arruda et al., 1987; van den Berg et al., 1997; Tomasella et al., 2000]. Methods. - To quantify the moisture properties, mercury injection porosimetry (MIP) seems to be an adequate method [Vachier et al., 1979]. It is easy to use and enables accurate investigation of the major part of the porosity spectrum. We used a Carlo-Erba 2000 which enabled 12 to 20 measurements for pore entry radii from 4 nm to 0.1 mm. It requires dried (here, air-then oven-drying), centimetre-sized samples. The drying of the sample, the large pressures of Hg used, the different surface properties of soil components in presence of water or Hg, may induce discrepancies between MIP data and water desorption measurements, particularly if the organic matter (OM) is abundant. We compared MIP and water desorption data, and established pedotransfer functions to estimate the water desorption curve from MIP data and OM content. Water desorption was performed with a pressure membrane equipment, which allows us to investigate pores with entry radii from 0.1 μm to 0.5 mm [AFNOR, 1996a], on decimetric samples. We also used water desorption data obtained in situ in other studies from similar sites [Tomasella and Hodnett, 1996]. For some depths, drying under controlled atmosphere [AFNOR, 1996a] enabled us to investigate pores with entry radii down to 1.5 nm. The total pore volume was determined on the same dry or humid sample (volume 100 cm3) by cylinder measurement or using the paraffin method [AFNOR, 1996b], in order to determine the volume of large pores. Organic carbon mass ratio (C) data are from Bravard [1988] and Cornu [1995]; a C value of 1 % corresponds to a volume ratio of organic matter to solid soil of 4.8 to 6 %. Notations. - We classified each pore class from its pore size (r), deduced from pressure data with the Laplace law (r is the entry radius for cylindrical pore model or the entry width for slit-shaped pore model): - nanopores (r &lt; 4 nm) and cryptopores (4 nm &lt; r &lt; 0.1 μm) are residual pores, containing residual water that roots cannot extract. It moves by evaporation in dry conditions; - micropores (0.1 μm &lt; r &lt; 10 μm) contain bioavailable water; - mesopores (10 μm &lt; r &lt; 0.1 mm) and macropores (0.1 mm &lt; r) are determinant for hydraulic conductivity, from which water drain in some hours (mesopores) or seconds (macropores) after the rain. We described their abundance in terms of volume, in order to better quantify their geometrical structure, and took as a reference the volume of dry solid matter in the soil, because the total soil volume is not constant (it depends on moisture content). Then we used the partial void ratio (u) for MIP, the water ratio (n) or the air ratio (a) for water desorption, and the fluid ratio (e) for total porosity: \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \[\mathit{u}=\frac{\mathit{V}_{\mathit{viod}}}{\mathit{V}_{\mathit{solid}}},\ \mathit{n}=\ \frac{\mathit{V}_{\mathit{w}}}{\mathit{V_{solid}}},\mathit{a}=\frac{\mathit{V_{air}}}{\mathit{V_{solid}}},\mathit{e_{humid}}=\ \frac{\mathit{V_{w}}+\mathit{V_{air}}}{\mathit{V_{solid}}}\ and\ \mathit{e_{dry}}=\ \frac{\mathit{V_{air}}}{\mathit{V_{solid}}}=\ \frac{\mathit{V_{void}}\ +\ \mathit{V_{Hg}}}{\mathit{V_{solid}}}\] \end{document} MIP and water desorption give directly the values of ucrypto, umicro, umeso, nres, nmicro, nmeso. Total pore volume measurements give ehumid and edry. We must be aware that the maximum water content remains below the fluid content, because of residual air: air bubbles trapped during wetting (we tried to minimize this effect by a progressive, two-week-long wetting), air linked to hydrophobic soil organic surfaces, and air in non-connected pores (not here). Residual air can thus be neglected for MIP, and for the water desorption of samples without organic matter. By subtraction, we obtain: \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \begin{eqnarray*}&&(\mathit{n_{macro}}\ +\ \mathit{a_{res}})\ =\ \mathit{e_{humide}}\ {-}\ \mathit{n_{res}}\ {-}\ \mathit{n_{micro}}\ {-}\ \mathit{n_{meso}}{\ }{\ }and\\&&(\mathit{u_{macro}}\ +\ \mathit{u_{nano}})\ =\ \mathit{e_{dry}}\ {-}\ \mathit{u_{crypto}}\ {-}\ \mathit{y_{micro}}\ {-}\ \mathit{u_{meso}}.\end{eqnarray*} \end{document} We can extrapolate the ratio of dry nanopores (unano) with reasonable accuracy because its value is anyway very low. For the ferralsols between 1.1 and 1.7 m depth, (umacro + unano) ≤0.03. We added a small triangle to the left of the porosity spectrum, in order to have unano = 0.01 at 1.4 m depth for the ferralsol. Then unano ranges from 0.002 for the podzol to 0.02 for the ferralsol above 0.7 m depth. All the porosity spectra we obtained had very few small micropores. Two porosity domains can thus be defined: textural porosity below 0.25 μm pore size, and structural porosity above. We described these two domains using their logarithmic average pore entry radii (rtext or rstruct) and their lobe width λ,. These parameters were defined by fitting an Ahuja and Schwartzendruber curve [1972] (often named a symmetric, m = 1, van Genuchten curve [van Genuchten, 1980]): \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathit{u}\ =\ \frac{\mathit{u_{text}}}{1+(\mathit{r_{text}}/\mathit{r})^{{\nu}_{\mathit{text}}}}\) \end{document} then \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathit{u}=\ \mathit{u_{text}}+\frac{\mathit{u_{struct}}}{1+(\mathit{r_{struct}}/\mathit{r})^{{\nu}_{\mathit{struct}}}}\) \end{document} and it is the same for n. [Log(rtext) − λtext;Log(rtext)+ λtext] is the interval gathering half of textural porosity, with λtext = Log3/νtext and it is the same for structural porosity. We set ustruct from e measurements, to give it a physical meaning, and introduced it as a value of associated with the 1mm pore size during the fitting, so that all curves approach their asymptotic value for about the same pore size. Results on porosity spectra. - The carbon content declines with depth, with a local maximum in the Bh horizon for the podzols (fig. 4). Ferralsols have a high residual porosity and average meso- and macroporosities (fig. 2 and 5), podzols have basically high meso- and macroporosities (figs 3 and 6), and transition soils are intermediate. For ferralsols and transition soils, named clayey soils here, all porosity classes have typical variations with depth: maximum at the surface; local minimum at a compacted horizon at 0.13 to 0.3 m (ferralsol) or 0.4 to 0.6 m (transition soil); local maximum for meso- and macroporosity, at the « termites’ horizon » at 0.4–0.6 m (ferralsol) or 0.8–1.2 m (transition soil); constant values for residual porosity below a depth of 1.2 m, and decreasing values for the other porosity classes. The average textural pore size increases vertically from the surface to the depth, with a local minimum at the compacted level, and laterally from ferralsols to podzols (fig. 7 and 10). Interpretation. - Residual porosity is correlated to clay content and textural pore size is correlated to the kaolinite particle size (unpublished work). The compacted level, named biological plough pan [Chauvel et al., 1987], may be due to a gravitational accumulation of the finest kaolinites from the above horizons, at the foot of the highly pedoturbated level. Low microporosity is linked to a very low silt and fine sand content, typical of tropical soils. Meso-and macroporosities are due to a clay microaggregation for clayey soils, and to the coarse sand fabric for the podzol. Microaggregation of clay is enhanced near the surface by root or ant pedoturbation, and at depth by termit pedoturbation, and maybe lateral water flows on the slope. Dispersion. - The dispersion of the values is low for a depth between 0.7 and 1.5 m, which is due to a homogeneous kaolinitic plasma. The dispersion increases with pore size, surface proximity for depth 0.7 m, or the increasing depth below 1.5 m. Near the topsoil, this is due to the heterogeneous biological activity, giving an heterogeneous soil structure. In horizons below 1.5 m, the causes are micronodules, localised water flows, and insufficient root pedoturbation. Therefore, we took more samples near the surface, we quantified soil shrinkage from the same sample before and after drying, we gave a higher statistical weight to data from 0.7 to 1.5 m depth in regressions, and smoothed values with depth (table IV). Comparison of results on dry or humid samples Total poral volume. - The shrinkage of the ferralsols samples decreases with depth. On the contrary, the shrinkage of podzol samples increases with depth (fig 5, 6 and table I). Residual porosity and microporosity. - OM presence is correlated to a decrease in the residual and micro- porosity given by MIP, compared to water desorption data. For soil samples with a low organic matter content, MIP gives a lower residual porosity especially for fine clays and a higher microporosity (table I). We could establish one pedotransfer function for all the soils studied here by taking into account the average textural pore size (table II and fig- 8). Meso- and macroporosity. — Through drying, mesoporosity increases for clayey soils and shrinks for podzol. These changes are more important for deep than for shallow horizons. Through drying, macroporosity increases, except for deep horizons of clayey soils (fig. 5,6; tables I, III). Textural porosity of ferralsols and transition soils. - The progressive vertical and lateral variation of MIP data gives reliability to a comparison with the two points where the textural porosity of humid samples was measured. MIP gives a higher pore size (roughly doubled, see table II) and a lower textural lobe width (roughly halved), compared to water desorption data. Structural porosity. - Our measurements on dry samples, compared to water desorption data, give simultaneous variations of three parameters, average structural pore size, structural lobe width, and macropores/mesopores volume ratio: an increase for the upper horizons of clayey soils or the deep horizons of podzol, a low change for the upper podzol horizons, and a decrease for the deeper horizons of clayey soils (fig. 9 and 10). However, the dispersion on these parameters is too high to predict them for humid samples from our data on dry samples. In order to parameterise the water desorption curve, we propose to apply equations of table I to subdivisions of micro- and mesoporosity, sharing out the organic matter influence between these subdivisions to get a precise water desorption curve, that can then be parameterised [Bastet, 1999]. Interpretation. - Hysteresis and pore geometry effects could not explain differences between water desorption and MIP, as in both cases the non-wetting fluid (air or Hg) enters pore space, and the same pore geometrical model was applied. The contact angle used in the Laplace law may change with the soil composition, especially with OM content for water desorption (hydrophobicity). Then we may have overestimated humid pore sizes at shallow horizons. Correcting this would enhance the discrepancies observed here. Some phenomena are not taken into account in the Laplace law: compression of porosity during MIP [Penumadu and Dean, 2000], or water physiosorption on mineral surfaces during water desorption [Tuller et al, 1999]. The first phenomenon causes the Laplace law to overestimate dry pore sizes (for r &lt; 2 μm), the second causes it to overestimate humid nanoporosity. Both explain that MIP gives a higher microporosity, a higher textural pore size, a lower residual porosity. The drying of samples causes porosity shrinkage, diminishing pore volumes and pore sizes. Then some macropores of clayey soils could turn into mesopores. However, the shrinkage at a given scale may cause the opening of the porosity at a higher scale, with cracking. Thus, the shrinkage of residual porosity can explain the increase of microporosity for all horizons, the increase of mesoporosity for clayey horizons, and the increase of macroporosity (eye-visible cracks), for shallow clayey horizons. The shrinkage of podzol mesoporosity can explain the increase of its macroporosity as well. The amount of shrinkage due to drying, or compression during MIP depends on soil OM content and type, soil structure and soil texture. Soil texture could explain a smaller shrinkage of total porosity for podzol than ferralsol, for shallow horizons: the lentil-shaped kaolinites, depending on their relative positions, are more likely to occupy a variable volume than the quartz grains, round-shaped with cavities. Soil structure is determined by its pedogenesis: eluviation/illuviation, pedoturbation. The unexpected large shrinkage for deep podzol seems to be due to a loose structure, inherited from eluviation of clay. Pedoturbation, together with OM presence, may either create porosity, or seal or compact porosity [Sokolowska and Sokolowski, 1998 ; Chauvel et al., 1999]. They may create a new porosity likely to shrink in clayey soils and on the contrary they may consolidate the loose structure of podzols. Conclusion. - We established pedotransfer functions to define the water desorption curve from MIP, organic carbon content, and bulk density (table I and II). These functions can be used for soils with the following characteristics, thus for most tropical soils: - negligible fine clay (&lt; 0.2 μm) content, in order to enable the extrapolation of nanopore volume from MIP, without needing nitrogen desorption [Bruand and Prost, 1987]; - soils mainly composed of kaolinite and quartz. The organic carbon content has little influence on the humic podzol studied here, so the equations established here are pertinent for other podzols. These pedotransfer functions give information on the structure of these soils : - residual and micro- porosities modify between MIP and water desorption, according to the organic carbon content and the texture of clay (given by the average textural pore size), with the same law for all soils; - mesoporosity changes according to two different types of structure : (1) clay microaggregates for clayey soils, (2) sandy fabric for podzol, loose at depth due to eluviation of parent clay, consolidated near the surface by pedoturbation; - total porosity follows, with an attenuation, the changes in the MO-linked porosity and in the porosity linked to soil structuring particles, that is the residual porosity for clayey soils, and the mesoporosity for podzols; - macroporosity, in reality as in the equations, compensates for the difference. This method could be tested on soils with other granulometry, mineralogy, or higher OM content. This work was supported by IRD and the PEGI and PROSE programs, we thank Max Sarrazin for his technical collaboration and the reviewers for their critical reading.

The soil microbiome is composed of various communities that play an important role in the existence of ecosystem services and the sustainable functioning of ecosystems under high anthropogenic loads. The transition of soils to a fallow state and their subsequent transformation lead to a notable alteration in the taxonomic composition of the soil microbiome, impacting the biochemical processes within the soil and its fertility levels. The object of this study comprised different-aged fallow soils of the southern taiga in the vicinity of Ban’kovo village, Leningrad region. The method comprising the high-throughput sequencing of 16S rRNA gene fragments using an Illumina MiSEQ sequencer was used to analyze the microbial community. The general processing of sequences was carried out with the dada2 (v1.14.1) package. It was found that the morphological organization of fallow soils has significant differences from the native podzol. In fallow soils, there are signs of leaching expressed in the accumulation of leached mineral particles, which indicates the degradation of the fallow–arable horizon. At the same time, there is a decrease in the content of P2O5 and K2O and an increase in the content of N-NH4 and N-NO3 in fallow soil. The analysis of alpha diversity index values showed that the highest level of alpha diversity in the microbial community is characteristic of 40-year-old soil, the alpha diversity index decreased with the increasing time of the fallow state, and the lowest alpha diversity index was observed in the native podzol. According to the values of the beta diversity index, a high correlation between the soil microbiome and the physicochemical characteristics of the soil was revealed, which indicates the formation of functional specialization in the studied microbial communities. As a result of the study of the taxonomic composition of microbial communities in fallow soils, it was found that the most represented microbial communities in fallow soils belong to Nitrosomonadaceae (Pseudomonadota), Mycobacterium (Actinobacteria), Nitrospira (Nitrospirota), and Luteolibacter (Verrucomicrobiota). The duration of post-agrogenic transformation is the leading factor influencing the changes in microbial communities; so, with an increase in the time that soils were in a fallow state, an increase in the oligotrophic microbial community was observed.

The organic matter in the A, Bh, Bhs and Bs horizons from a number of profiles from a chronosequence of podzols spanning some 7x105 years was studied using solid state 13C n.m.r. spectroscopy. Organic matter was effectively concentrated without chemicals using a Spex mixer and sedimentation. Acid dithionite treatment of samples containing appreciable amounts of iron significantly improved the signal to noise ratio. Acid oxalate treatment had a lesser effect. The organic matter from the A horizon was highly aromatic but was low in carboxylic acids. In the B horizons, aromaticity decreased in the order Bh-Bhs-Bs and increased with the degree of profile development. Only in the Bh horizons of the older highly developed profiles did aromatic carbon exceed alkyl carbon. The 'core' structure of these materials appeared to be aromatic rings heavily substituted (>90%) with alkyl and carboxylic acid groups. The Bhs and Bs horizons contained substantial amounts of carboxylic acid substituted alkyls with structures similar to the polymaleic or hydroxy acid models. Sixty per cent of the organic matter removed with iron on dithionite treatment was found to be alkyl. The aromatic and alkyl dominated horizons can exist in close proximity, occurring less than 10 cm apart in the case of the giant pipey podzols. None of the current theories on podzol genesis can adequately explain the arrangement of organic and inorganic components found in these profiles and a revised model based on existing theories is proposed.

Características morfológicas, físicas, químicas e mineralógicas foram determinadas em 5 perfis ao longo de uma topossequência numa depressão fechada de Latossolo Amarelo até Podzol em tabuleiro a 60 km de Maceió, Estado de Alagoas, no sentido de elucidar os principais processos envolvidos na formação dos solos. A formação dos solos está diretamente relacionada às condições de drenagem devido as posições que eles ocupam no relevo. O Latossolo Amarelo ocupa a posição de transição tabuleiro-encosta, o que permite uma boa drenagem e intenso intemperismo, enquanto que no outro extremo menos intemperizado ocorre o Podzol, ocupando posições de depressão no relevo, de drenagem imperfeita. Os solos Podzólico Amarelo Latossólico, Podzólico Amarelo com fragipãs e Podzólico Acinzentado, ocupam posições intermediárias no relevo com mineralogia essencialmente caulinítica. As formações especiais, fragipã, duripã e lamelas de concentração de ferro são também relevo (drenagem) dependente, aumentando seu desenvolvimento a medida que a drenagem tende a ficar mais imperfeita.

Pedons were described, sampled and classified at 5-m intervals along a 130-m transect in an area typical of the southern Laurentian Highlands in order to assess short-range soil variability. Orthic Ferro-Humic Podzol was the dominant subgroup (25 of 27 sites). Differences in depth to bedrock and in soil water regime resulted in four soil families; bedrock was exposed at one site. At 21 of the 27 sites, however, the pedons were classified in one family: Orthic Ferro-Humic Podzol, coarse loamy, cold, humid. Differences in thicknesses and sequences of horizons resulted in a total of at least nine soil series. At scales of 1:20 000 or somewhat smaller, the soils of map units in the area would be most appropriately indicated as slope phases (10–40% slopes) of families. The dominant family would be the one indicated above with inclusions of shallow to extremely shallow phases and bedrock outcrops. Key words: Soil variability, Podzolic soils, classification of pedons

Illuviated mineral horizons (Bf) from a Podzol on the Precambrian Shield, Ontario, Canada were collected, placed in columns and treated with distilled water, cation amended water, acidified water or cation and acid amended water over a 4-mo period. While the cation treatment had little effect relative to the control, the acid treatment removed large quantities of Al, Si and base cations. The source of the leached Al was primarily (~ 70%) dithionite–citrate–bicarbonate (DCB) extractable Al, apparently some form of amorphous gibbsite. Organic Al (pyrophosphate extractable) contributed only about 20%. However, even more pronounced was a major within-column migration of oxalate extractable Al–Si, perhaps allophane or imogolite, which was leached from the top of the acidified columns and precipitated below. The weathering of primary minerals and possibly interlayer Al in vermiculite contributed little to the leaching of Al from the acidified columns. Key words: Acid, weathering, Podzol, aluminum, silica

Thirty-nine species of scleractinian corals have been recovered from under a high dune on the western (mainland) side of North Stradbroke Island, eastern Australia. The corals are associated with thin intertidal sediments and their good condition implies burial in situ and preservation in a saturated zone. Most likely this occurred as the coast prograded and a large dune advanced into the littoral zone, burying intertidal sediments and coral. The species assemblage indicates a sheltered environment but one open to the ocean without wide fluctuations in salinity. Three species yielded a mean 230Th/234U age of 105,000 yr B.P. which is significantly younger than the nearest Pleistocene corals at Evans Head, New South Wales. The corals provide evidence of a sea stand near present sea level during isotope Stage 5c, which is considerably higher than previously suggested for this period. Their good condition implies that the overlying parabolic dune is of comparable age and formed during that high stand of sea level. Also, the isotope age provides a maximum period for the development of giant podzols in the podzol chronosequences on coastal dunes in southern Queensland.

Observations of a Humo-Ferric Podzol within a mixed deciduous forest in central Ontario showed vertical penetration of the parent C horizon by a tonguing Bf layer to depths greater than 2.5 m, in numerous localized areas of the soil. The tonguings were possibly initiated as white pine root casts formed by windthrow or in situ decay of undisturbed taproots. The role of these tonguings in the movement of water and solutes through the soil was assessed by comparing the physical and chemical properties of tonguing (Bf) and parent C2 horizons. In terms of the physical properties, there are only two distinct layers in the profile (the A + B and the BC + C1), while for CEC, organic matter and soil pH, there are four horizons (A, B, BC, and C1). The data suggest that tonguings are major conduits for water and solutes moving through the soil, and that processes such as nutrient cycling are concentrated within the tonguings, with little activity in adjacent C horizons. Key words: Podzol, tonguing, acidification