Subsurface Horizons Research Articles

Characterization, classification, and suitability evaluation of soils formed in fluvial deposits within eastern part of Kogi State in Nigeria for rice and maize production

The impact of rice and maize production on food security in Nigeria cannot be over-emphasized. The aim of this research was to characterize, classify and evaluate the suitability of soils formed in fluvial deposits within eastern part of Kogi State in Nigeria for rice and maize production. This was supported by the fact that the knowledge of the characteristics and soil groups of fluvial deposits in soils is an integral part in soil suitability evaluation as well as management. Four (4) soil profile pits were sunk within the research area. The pedonswere located within the 19a mapping unit of the soil map of Nigeria which has the fluvial deposits. Pedons were adequately described as soil samples were collected from pedogenic horizons, and preserved in well-labelled polyethylene bags, transported to the Laboratory for analyses. The findings revealed that the soils were characterized by dominant gray (10YR4/1) and dark reddish gray (10R4/1) in the surface soils and dominance of various shades of gray in the subsurface soils. Most of the soil structures were single-grained and subangular blocky at the surface and subsurface soils respectively. The soil texture was sandy clay loam and sandy loam in the A horizons. The soil reaction showed mean values of 6.1 and 5.5 at the surface and subsurface horizons with base saturation highest (91%) at C1 horizon of 19a3 pedon. The pedons were classified as inceptisols, and were currently not suitable (N1) for rice cultivation but marginally suitable (S3) for maize cultivation.

Characterization, classification, and suitability evaluation of some soils in the floodplains of River Niger, Kogi East, Nigeria for rice, maize, cassava, and oil palm production

This study was conducted to characterize, classify and evaluate four soils along River Niger in Kogi East for rice, maize, cassava and oil palm production. The soils developed predominantly from alluvium. The soils were located in four communities namely Ejule-Ojebe, Shintaku, Bagana and Kpata all in the floodplains of River Niger in Kogi East. The soils were investigated using a free survey technique. Four pedons representing four soils located at different sites in the floodplain were studied. The environs and the profiles of the soils were described according to standard field procedures. Soil samples were then taken from genetic horizons for laboratory analysis. The soils were also characterized and classified according to Soil Taxonomy and the World Reference Base for Soil Resources (WRB). The colour of the soils ranged from shades of brown to grey generally due to poor drainage. The soils also varied in depth and horizonation due to differences in profile development. Due to the relatively higher sand content of the soils, especially in the surface and subsurface horizons, the texture of the soils generally ranged from sand to clay loam. The pH (H2O) of the soils ranged from 4.8 to 7.3, strongly acidic to slightly alkaline, and tended to increase with depth. The soils containedmoderate amounts of organic carbon in the surface soils but lower levels in the lower horizons. Based on their properties, the soils were classified according to Soil Taxonomy as Alfisols (Ejule-Ojebe), Entisols (Shintaku), Inceptisols (Bagana) and Alfisols (Kpata) and according to WRB as Planosols, Arenosols, Gleysols and Planosols, respectively. The soils were found to be highly suitable for rice production but moderately suitable for maize, cassava and oil palm. Apart from rice cultivation, wetness of soil was found to be the major limiting factor for optimum rainfed cultivation of maize, cassava and oil palm.

Last Glacial Maximum active layer thickness in Western Europe, and the issue of ‘tundra gleys’ in loess sequences

AbstractLate Marine Isotope Stage (MIS) 3 and MIS 2 loess–palaeosol sequences in Western Europe comprise alternating loess layer and 3‐ to 30‐cm‐thick bleached soil horizons with Fe–Mn oxide precipitations, which are usually interpreted as waterlogged active layers and referred to as ‘tundra gleys’. Active layer thickness data derived from a regional climate model simulation and the fossils (shells, earthworm granules) found in ‘tundra gleys’ argue against such an assumption. Most of these horizons better correspond to Fe‐depleted, slightly humic topsoil horizons or subsurface eluvial horizons and should be referred to as (incipient) Ag or Eg horizons. They formed during climate ameliorations associated with vegetation (cryptogams, herbs) development, possibly limited by long‐lasting snow cover. Strong mixing usually occurred in these horizons due to the activity of anecic earthworms and frost activity.

Concurrent 9. Presentation for: Evaluating Australia’s energy commodity resources potential for a net-zero emission future

Presented on Wednesday 18 May: Session 9 Australia’s future energy production will increasingly be focused on developing clean energy resources to achieve the goal of net zero greenhouse gas emissions by 2050. To achieve this, an understanding of Australia’s natural gas resources and greenhouse gas storage potential is needed to facilitate the rapid implementation and expansion of low-emission technologies. While Australia continues to be a net gas exporter, additional volumes are needed to support future domestic manufacturing capabilities. These extra volumes can be produced from existing accumulations that are close to infrastructure or can be unlocked from highly prospective, yet underexplored regions. The coming decade will see a dramatic change in the energy mix that supports the Australian economy. A major driver will be the development of a hydrogen production industry, initially using fossil fuels with carbon capture and storage (CCS) until the cost of hydrogen production from renewable energy becomes more reliable and competitive. The expansion and projected lower costs of renewable energy generation via solar and wind will ultimately replace much of the non-renewable energies for hydrogen production. Geoscience Australia’s energy-related work program is focused on supporting Australia’s energy transformation assessments of untapped resource potential onshore include the evaluation of geologic hydrogen occurrences, the presence and suitability of subsurface salt horizons for hydrogen storage and the distribution of effective reservoir and seal fairways for underground carbon storage. While offshore, new data from Geoscience Australia’s sea-floor mapping project will improve the understanding of suitable areas for offshore wind farms. Results from these research activities are being made publicly available either through Geoscience Australia’s data portal and its data repository. To access the presentation click the link on the right. To read the full paper click here

Vertical distribution of DTPA-micronutrients content of some selected pedons in Hydromorphic soils of Khagaria district

An investigation was carried out to entitled on “Vertical distribution of DTPA-micronutrients content ofsome selected pedons in hydromorphic soils of Khagaria district”. The DTPA Fe content of selected pedonswas ranged from 9.56 to 13.55 and 3.15 to 14.20 mg kg-1 soil at surface and sub-surface horizon. The DTPAMn content varied from 5.24 to 10.55 mg kg-1 soil in surface layer and 4.23 to 11.11 mg kg-1 soil in the subsurface layer. However, the available DTPA-Mn content increases towards depth except lower depth in all selected pedons (P1 to P6). The overall results have been indicated that DTPA-micro nutrient (Fe, Mn, Cu and Zn) contents show sufficiency level, and placed above their critical limits, which shows the congenial environment favoured for available micronutrients cations based on their geographical setting and suitable plant growth especially of hydromorphic areas.

Морфологические, диагностические признаки и агрофизические свойства орошаемых лугово-сероземных почв в аридных земельно-климатических условиях (Азербайджан)

The article presents morphological, diagnostic features and agrophysical properties of meadow-sierozem soils irrigated in arid soil-climatic conditions of Azerbaijan. The research was carried out on lands in the territory of the village of Malbinasi, Yevlakh district, in the Arzu farm. The thickness of the humus horizon of irrigated meadow-sierozem soils of the object of study is 55-65 cm. Hardening is most often observed in the deep layers. Due to siltation, a cloddy-granular structure was formed in the subsurface horizon. With increasing depth, a sharp increase in soil density is observed.

Evaluating Australia’s energy commodity resources potential for a net-zero emission future

Australia’s future energy production will increasingly be focused on developing clean energy resources to achieve the goal of net zero greenhouse gas emissions by 2050. To achieve this, an understanding of Australia’s natural gas resources and greenhouse gas storage potential is needed to facilitate the rapid implementation and expansion of low-emission technologies. While Australia continues to be a net gas exporter, additional volumes are needed to support future domestic manufacturing capabilities. These extra volumes can be produced from existing accumulations that are close to infrastructure or can be unlocked from highly prospective, yet underexplored regions. The coming decade will see a dramatic change in the energy mix that supports the Australian economy. A major driver will be the development of a hydrogen production industry, initially using fossil fuels with carbon capture and storage (CCS) until the cost of hydrogen production from renewable energy becomes more reliable and competitive. The expansion and projected lower costs of renewable energy generation via solar and wind will ultimately replace much of the non-renewable energies for hydrogen production. Geoscience Australia’s energy-related work program is focused on supporting Australia’s energy transformation assessments of untapped resource potential onshore include the evaluation of geologic hydrogen occurrences, the presence and suitability of subsurface salt horizons for hydrogen storage and the distribution of effective reservoir and seal fairways for underground carbon storage. While offshore, new data from Geoscience Australia’s sea-floor mapping project will improve the understanding of suitable areas for offshore wind farms. Results from these research activities are being made publicly available either through Geoscience Australia’s data portal and its data repository.

Soil and climate effects on winter wine produced under the tropical environmental conditions of southeastern Brazil

Southeastern Brazil is an emergent region in terms of the production of high-quality fine wines. To contribute to typicity assessment, the soils (morphology, mineralogy, chemical and physical analyses), parent material (geologic maps and portable X-ray fluorescence spectrometry) and climate (temperature and precipitation) were characterized in seven vineyards located in the state of Minas Gerais and São Paulo, Brazil, by carrying out state-of-the-art terroir analysis and assessing the environmental variations of the study sites. A soil profile was described and sampled in the central part of each vineyard. Principal Component Analysis (PCA) biplots were used to analyze the relationships between these factors and the composition of wines (2016, 2017 and 2018 harvests) produced from Syrah in commercial vineyards in different municipalities of Três Corações (TC), Cordislândia (COR), Andradas (AND), São Sebastião do Paraíso (SSP), Três Pontas (TP), Espírito Santo do Pinhal (PIN) and Itobí (ITO). The vineyards were grouped according to soil and climate characteristics. Group A was composed of COR, AND and PIN vineyards, which exhibited the highest correlation with soil Al3+ content and accumulated rainfall. The group’s wines had the lowest ash alkalinity, total polyphenol index (TPI) and pH values and the highest fixed acidity. Group B consisted of the TP and TC vineyards, which had the highest soil organic matter and boron contents and the highest thermal amplitude with similar values (15.4 °C in TC and 15.2 °C in TP); their wines showed average composition. Group C comprised ITO alone, which was characterized by the shallowest and least developed soils. Its wine had the highest flavonol content and high dry extract, color intensity, TPI, alcohol content and sugar values. Group D contained the SSP vineyard, in which the soil subsurface horizons were correlated with the highest wine pH. Late harvest in this vineyard caused the most dehydration of grapes and consequent concentration of most wine compounds (human effect on terroir). The terroir information produced in this study adds substantial value to the wines produced under the tropical environmental conditions of southeastern Brazil, for which such studies are very rare. By characterizing the natural factors (soil, soil parent material and climate) and human factors (vineyard management and wine characteristics) related to terroir, this study can also provide historical information about the wine from this emergent region (the historical factors). In addition, its results can be used to guide producers in their choice of vineyard cultivation sites according to preference in wine composition.

Assessment of Physico-chemical Properties of Tada Shonga Irrigation Scheme Soil

This research was conducted to analyze the soil physico-chemical properties of Shonga Irrigation Scheme to ascertain its suitability for rice production. The study was carried out in the dry season of 2019. Disturbed soil samples were collected from the 0–15 and 15–30 cm soil layers in five identified areas in the irrigation scheme. The samples were sent to the Soil laboratory of the Lower Niger River Basin for physical and chemical analysis. Most of the soils were strongly acidic to moderately acidic with pH values ranging between 4.8 and 5.7. The organic carbon and organic matter ranged from 0.13 to 0.19% and 0.03 and 0.32%, respectively which implies low fertility. Calcium values ranged between 2.1 and 3.75 cmol/kg, with the low values related to the soil pH status. Magnesium values averaged 2.48 and 1.95 cmol/kg in the top and lower soil layers, respectively. Exchangeable Acidity (EA) values ranged between 0.20 and 3.40 cmol/kg in the surface horizon and between 0.2 and 5.4 cmol/kg in the sub-surface horizons. Available phosphorus had an average of 40.05 and 23.14 ppm in the surface and sub surface soil layers, respectively. Analysis of variance techniques was used for significant differences within chemical properties. For all tests, a threshold of P=.05 was used to define statistical significance. Soil pH and available phosphorus were within the recommended land suitability requirement for rice cultivation. Organic carbon, organic matter, calcium and magnesium were not within the recommended range for rice production. Organic carbon and organic matter can be supplied through the incorporation of organic manure.

Pedogenesis of soils with accumulation of organic carbon in the subsurface horizons in a saline lake in the Pantanal wetland of Nhecolândia, Brazil

The Nhecolândia region is formed by sandy sediments, coming mainly from the Taquari river basin, with soil sodification and the accumulation of organic matter in the subsurface being the main pedogenic processes observed in this environment. This research aimed to study the genesis of soils with spodic features in the subsurface horizons in an alkaline environment in the saline lagoons of the Pantanal of the State of Mato Grosso do Sul, Brazil. Three trenches were excavated, and the soils were morphologically described and classified according to Brazilian Soil of Classification System in Espodossolos and WRB in Arenosols. In addition, deformed samples from all soil horizons were sampled and used in physical, chemical, mineralogical and micromorphological analyses. In all profiles, the sandy texture predominates (sand ≥879 g kg−1) the colors vary from light olive-brown on the surface horizons to grayish-brown-very dark on the subsurface horizons, with hues ranging from 2.5Y to 5Y. In the profiles, the occurrence of the E horizon was observed, followed by the subsurface horizon with cementation, forming ortstein. The profiles showed high pH values (6.8–10.2), electrical conductivity (EC) > 4 dS m−1, and high saturation for Na+ (up to 60.6%), characterizing them as saline-sodic soils. In the soils around the saline lagoon, it was observed the accumulation of Fe (Fe2O3), Al (Al2O3) and dissolved organic carbon (DOC) in the horizons with spodic features. Among the humic substances, the humin fraction presented the highest levels, mainly in the B horizons, with variations from 0.1 to 6.2 g kg−1. In the thin sheets, coatings and fillings were observed, consisting of organo-ferruginous colloidal material of brown to opaque color with monomorphic characteristics, covering and binding the quartz grains. Alkaline soil conditions in saline lakes contribute to the dissolution of clay minerals and surface organic matter, and later, to the dispersion of dissolved organic compounds together with Al2O3, Fe2O3, and amorphous silica, forming subsurface horizons rich in organic matter, Al, neoformed clay minerals and ortstein cemented horizons.

Composted Sewage Sludge Application Reduces Mineral Fertilization Requirements and Improves Soil Fertility in Sugarcane Seedling Nurseries

Sugarcane demands large amounts of nutrients to reach a high level of productivity. Nutrients are generally supplied by mineral fertilizers, but their high costs and negative environmental impacts have generated interest in greater use of organic nutrient sources such as composted sewage sludge (CSS). In this study, we evaluated changes in soil chemical properties after the application of CSS or CSS/mineral fertilizer (MF) combinations to soil containing sugarcane seedlings under nursery conditions. Treatments included: T1: conventional mineral fertilization (MF) without application of CSS, T2: 100% of the recommended MF (06–30–24); T3: application of 2.5 Mg−1 CSS; T4: 5.0 Mg−1 CSS, T5: 7.5 Mg−1 CSS, T6: 2.5 Mg−1 CSS and 50% MF, T7: 5.0 Mg−1 CSS and 50% MF, T8: 7.5 Mg−1 CSS and 50% MF, T9: 2.5 Mg−1 CSS and 100% MF, T10: 5.0 Mg−1 CSS and 100% MF, T11: 7.5 Mg−1 CSS and 100% MF. Soil chemical properties were evaluated from the soil surface (0.0–0.25 m) and subsurface (0.25–0.50 m) horizons. The results showed that the increase in CSS application did not affect soil organic matter content at either depth, while Zn concentrations increased in the soil subsurface horizon. The application of CSS at 5.0 Mg ha−1 with or without 50% MF resulted in the highest pH values, sum of bases, cation-exchange capacity, P, K, Ca, Mg, Cu, and Zn in surface horizons. The use of CSS as an organic fertilizer in sugarcane nurseries improves soil fertility, reduces mineral fertilizer requirements, and, thus, facilitates the sustainable disposal of sewage sludge.

Characterization and Classification of High Density Apple Orchard Soils of North Kashmir

Jammu & Kashmir presents a benefit for the economy of India, since is the rich producer of fruits and vegetables and is the most important temperate fruit producing state. Apple is the oldest and commercially the most important temperate fruit and is the fourth among the most widely produced fruit. Basic needs of life can be fulfilled by maintaining high productivity of soil and having the rational use of soil as per its potentiality in order to maintain sustainability. At the same time, the sustainable use of soil resource requires extensive knowledge regarding its genesis, morphology and other properties. Despite the importance of the area for producing quality apples, high density apple were planted in 2002. However no systematic study was undertaken so far with respect to soil characterization and classification of apple orchard soils under high density plantation. Keeping all this in view, the present investigation entitled, “Characterization and classification of High Density Apple Orchard Soils of North Kashmir” was undertaken . current paper aims to contribute to the existing challenge in soil research in India. To this end 45 soil profiles were observed in orchards,- Based on homogeneous properties, e.g., age, topography, rootstock, variety only 12 profiles were selected from 45 observed profiles (purposive method of sampling). These twelve profiles were categorized into high, mid and low altitudes for detailed investigation of the soil profile properties and to classify soils of the district as per Keys to Soil Taxonomy (2015). The excavated soil profiles were exposed to a depth of 120 cm and more for studying morphological and physico-chemical characteristics. As per the results, profiles of the study area were classified from ‘ moderately deep’ to ‘very deep. A slight strong effervescence with diluted HCl was observed both in surface and sub-surface horizons profile P3, P7 and P10 located especially in mid and low altitude. The pH were ranging between 6.60 to 8.10 in the surface horizons whereas in the sub surface horizons it ranged from 6.84 to 8.50 and showed an increasing trend with depth. The EC in general showed increasing trend with depth as compared to surface horizons and was found to be in normal range in both horizons. On the basis of the U.S. Comprehensive System of Soil Classification as per Keys to Soil Taxonomy (Soil Survey Staff, 2014) and Soil Survey Manual (Soil Survey Staff, 2003), studied profiles were placed in the orders of Mollisols, Alfisols, Inceptisols and Entisols and the suborders Udolls, Udalfs, Orchrepts and Orthents. The great groups to which these soils were further classified are Argiudolls, Hapludalfs, Eutrochrepts and Udorthents respectively, on the basis of presence of the diagnostic surface and sub-surface horizons, profile development and the presence of particular moisture and temperature regime. However this study was first of its kind with an aim to evaluate the most probable path of plant nutrients added to soil. In this way, it can also support a better understanding of the soil genesis and the electro-chemical behavior. Besides, detailed study of clay mineralogy may provide a tool to classify the soils up to series level.

Occurrence of some rare earth elements in vineyard soils under semiarid Mediterranean environment

A comprehensive investigation has been carried out into the concentrations of a range of REEs (neodymium Nd, cerium Ce, lanthanum La, yttrium Y, scandium Sc) in soils of vineyards belonging to the protected denomination of origin (PDO) Valdepeñas (Central Spain). The mean concentrations (expressed in mg kg−1) are Ce 70.6, Nd 32.9, La 36.2, Y 21.6, and Sc 13.7 in surface horizons (Ap), while in subsurface horizons (Bt or Bw and some Ck), the values are Ce 67.6, Nd 31.8, La 34.4, Y 19.6, and Sc 13.9. The relative abundance in these soils is Ce > La > Nd > Y > Sc in both the surface and subsurface horizons. These values are close to, or slightly higher than, the regional levels but similar to national and global averages, although relatively high values have been detected at certain sampling points. Another aim was to explain the spatial variations in these elements within the territory under study. It was found that the spatial variations are due to the nature of the parent materials and the pedogenetic processes, although the sparse spatial distribution patterns with prominent anomalies are interpreted arising from anthropogenic sources (fertilization). However, these anomalies did not present any environmental risk in the studied zone.

Mineral Protection and Resource Limitations Combine to Explain Profile‐Scale Soil Carbon Persistence

AbstractThe fate of soil carbon (C) is largely controlled by microbial oxidation of organic matter (OM), which is constrained by a variety of mechanisms. OM association with soil minerals provides pronounced protection against microbial decomposition. However, factors such as climate, occlusion, and resource limitations also contribute to OM preservation. We explore the factors explaining C distribution and age within an upland rainforest soil in Hawaiʻi, a site with abundant preferential flow paths (PFPs) and high short‐range order (SRO) mineral content. We characterized lateral and vertical changes in ∆14C, SRO mineral content, C‐functional group chemistry, and microbial community composition to elucidate the contributions of multiple protection mechanisms to OM preservation. Consistent with our expectation, SRO mineral content and ∆14C were strongly correlated (R2 = 0.95), indicating strong mineral protection of OM throughout the profile. Surprisingly, distance from PFP was also a significant predictor of ∆14C and improved model fit, particularly in the shallow horizons (R2 = 0.97). Elevated C/N ratios, decreased microbial abundance, and greater SRO mineral content suggest nitrogen limitations and enhanced mineral protection constrain OM turnover with distance from PFPs in deep, subsurface mineral horizons. Steady microbial abundance, increasing putative anaerobe abundance, and changes in C‐functional group chemistry indicate oxygen limitations constrain OM turnover in the matrix of shallow mineral horizons. Given that oxygen and nutrient limitations contribute to OM preservation in this high SRO system—an exemplar of mineral protection—resource limitations may play an even more important role in OM preservation in other well‐structured soils.

Optical, morphological and Physico-chemical Properties For some soils in central and northern Iraq, using a digital camera

The study was conducted in three selected sites representing the soils of three governorates of central and northern Iraq (Salah al-Din, Kirkuk, and Erbil), to determine the effect of morphological, physical and chemical characteristics of some soil genetic horizons on their spectral reflectivity using digital camera as well as Knowing the degree of soil development and classification according to the Quantitative (American) system for classifying soils, Three pedons representing these soils were excavated, the horizons were morphologically diagnosed and samples were obtained from each horizon of each pedon from the soils of the study sites to conduct some laboratory tests for the physical and chemical properties. Pictures were taken that combine dry and wet samples; In order to calculate the spectral reflectivity and RGB values using ERDAS software. The results revealed a heterogeneity in the morphological characteristics represented by the dominant color class of each pedon, with the diagnosis of the morphological features of each of the surface diagnostic horizon Ochric with the subsurface diagnostic horizons Gypsic, Calcic and Argillic. The results also found that the spectral reflectivity values of RGB were high in dry soil and decreased in the wet condition, and the lowest value of the spectral reflectivity was for the surface horizons, as it reached 44.87% on the surface horizon of the second pedon, and the highest value of the reflectivity was on the horizon Cky1 of the pedon 1, where its ratio is 72.15% ,and the reflectivity values of the red color at the red band were high in pedon Erbil as a result of the effect of iron oxides. Show the spectral and hematological differences represented by the index of brightness (value), hue and index of iron oxides The results also found that the most influential traits in these spectral indices are the dominant soil color as well as the texture of the soil represented by the content of silt and clay with moisture content, as well as the effect of the content of organic matter, iron oxides, gypsum and lime content on the surface and subsurface diagnostic horizons.

Influence of the after effect of the main tillage methods on the water properties of the alluvial soil

The issue of tillage is one of the most important in agricultural farming since it directly affects the quality of crops. Therefore, this paper presents the materials of scientific research on the change in the parameters of the water properties of the alluvial soil depending on the influence of the aftereffect of the methods and the depth of the primary cultivation. The research was conducted at the production fields of the Teplichnoye JSC in the Oktyabrsky District (Republic of Mordovia, Russia) during 2018 to 2020. The main method of the study is a field one-factor experiment in triplicate. It was found that deep plowing in the second year of aftereffect improved the water properties of the subsurface soil horizon; namely, the total, capillary, and minimal moisture capacity had increased compared to traditional plowing. Subsoiling reduced the reserves of productive soil moisture before the growing season of spring wheat and increased its water consumption since in those variants the plants used moisture at a lower rate. The minimum water consumption was observed in the variants with moldboard plowing at depths of 26–28 and 32–34 cm, and the maximum water consumption was noted after subsoiling and plowing to a depth of 20–22 cm. Concerning the conditions of this region, the study has substantiated the most effective combination of depth and method of tillage and their influence on the water properties of the soil in the aftereffect. There is a lot of data on the influence of different cultivation methods on the hydrophysical properties of soils, but the preservation of their effect for subsequent years has practically not been studied.

Revisiting the Carbonate Chemistry of the Sea of Japan (East Sea): From Water Column to Sediment

In this study, we investigated the carbonate system in sediments and water columns from five stations in the Sea of Japan (East Sea) (JES) during the R/V Hakuho Maru KH-10-2 research cruise in the summer of 2010. The total alkalinity (TA) and pH were measured. Adopting a saturation degree of 91% and 80% for the lysocline depth and calcite compensation depth (CCD), respectively, we found that those depths corresponded to 1360 and 1980 m. A comparison of the calcite saturation depths, lysocline depths, and CCD depths obtained for 1999 and 2010 suggests that acidification of the interior of the JES occurred. Sediment cores were retrieved using a multi-corer. In the sediment cores, a sharp decrease in the pH by 0.3–0.4 pH units was observed in the subsurface horizons (0–10 cm) compared with the pH of the seawater from the bottom horizons. The TA in the porewaters was significantly higher than that in the overlying seawater. The anaerobic degradation of organic matter is probably the main cause for the increasing TA in the sediments. The porewaters were significantly undersaturated with calcite and aragonite, except in that from the shallowest station, where the sediments below 7.5 cm were saturated, and even supersaturated, with calcite and aragonite. A linear correlation between the dissolved inorganic carbon and the TA for sediments with a slope of 0.9993 was found, despite there being potentially different ways for the diagenesis of the organic matter to occur. The diagenesis of organic matter in the top sediments of the JES forms gradients of TA and CO2* concentrations on the interface of “bottom water–sediments”. Averaged fluxes of TA and dissolved inorganic carbon (DIC) from the sediments to the bottom waters estimated by means of Fickian diffusion were calculated as 44 and 89 mmol/(m2 year) for TA and DIC, respectively.

Importance of accessory minerals for the vertical distribution of uranium and thorium in soil profiles: A case study of durbachite from the Třebíč Pluton (Czech Republic)

The mineralogical character of a parent rock strongly affects the uranium (U) and thorium (Th) contents of soils. We have selected five representative soil profiles developed on amphibole–biotite to biotite durbachites in the Třebíč Pluton (eastern part of the Czech Republic) to characterize the radioactivity and variable-intensity weathering. The Endoskeletic Cambisols with a silt loam to loamy sand texture and a well-developed subsurface Bw horizon represented the most common product of the pedogenetic processes on durbachites. All studied soil profiles showed the evidence of pedogenetic alteration with intrasoil weathering. They were moderately deep (70–80 cm) with high rock-fragment concentrations within the B and C horizons. The predominant grain size fractions were silt (12% to 83%) or sand (8% to 87%), and the percentage of clay was up to 15%. A feldspar–quartz–vermiculite (biotite)–amphibole–kaolinite–Fe–Mn (oxy) hydroxide assemblage was typical for the most weathered parts of the profiles. Variation in the U and Th contents within the studied soil profiles resulted predominantly from the changes in the amounts of primary accessory minerals at different depth levels. Uraninite, monazite, thorite, allanite, zircon, thorogummite, REE-(Rare Earth Elements) fluorocarbonates, and minerals of the rhabdophane group were the main carriers of radioactive elements in the parent durbachite and overlying soil profiles. The gamma-ray spectrometry, geochemical and mineralogical analyses show that uraninite was stable only in the parent durbachite and disappeared at the rocks–C horizon interface. This process was followed by the gradual alteration of allanites, thorites, brabantites and secondary U- and Th-rich minerals (e.g., thorogummite, bastnäsite) toward the soil surface.

Enzymatic activity and functional diversity of soil microorganisms along the soil profile – A matter of soil depth and soil-forming processes

Most studies concerning soil microorganisms and enzymes are focused on the upper horizons of the soil profile even though they transform soil organic matter at every depth of the soil profile. The aim of this study was to determine how the soil microbial functional diversity and enzymatic activity changed as a function of depth across the soil profiles which developed on the same parent material (glacial till) but differed in their soil-forming processes thereby resulting in the formation of different reference soil groups (RSG) (Luvisols, Gleysols and Stagnosols). Four soil profiles were excavated at different sites that are located in two mesoregions of the South Baltic Lake District (central Poland) in fields with alfalfa (Medicago sativa L.) in the fourth year of its cultivation. Using the soil samples collected in June 2019, we assessed the oxidoreductase activity (DHA – dehydrogenases, POX – phenol oxidase, PER – peroxidase), the fluorescein diacetate hydrolysis (FDAH) rate, the microbial biomass carbon and nitrogen (MBC, MBN) content, the number of microbial groups and the related physico-chemical properties. The community-level physiological profiles of the soil microorganisms were evaluated using the Biolog EcoPlate™ method. In general, the highest level of enzymatic activity per soil mass unit was found in the Ap horizons, whereas the dehydrogenases activity and FDAH decreased gradually with depth, while the phenol oxidase and peroxidase activity revealed no consistent trends between the sub-surface horizons. The specific enzymatic activity, expressed per unit of soil TOC and MBC, was more variable in response to profile depth than the enzymatic activity, which was expressed per soil mass, and this did not allow for clear trends to be determined. Also, the specific activity was different with regard to the intracellular and extracellular enzymes. The DHA/MBC ratio was markedly higher in the Ap horizons (all profiles) and generally decreased with depth. The phenol oxidase and peroxidase activities, expressed in the terms of the MBC content, did not exhibit any clear trends in the studied profiles, however, they reached their highest levels in the deepest layers in all of them. The abundance of all of the microbial groups was generally highest in the Ap horizon and decreased sharply with depth. A greater abundance of microbial groups was found in the gleyic horizons of the Gleysols and Stagnosols as compared to the upper and lower horizons. The highest average well color development (AWCD) under aerobic conditions was observed in the Ap genetic horizons (with the exception of the Haplic Luvisol profile), while the highest values of AWCD in anaerobic conditions were found in the illuvial and gleyic horizons. In contrast to the AWCD, the Shannon diversity index (H) and Shannon evenness index (S) (equal usage of compounds) indices were more similar in the compared horizons. Our findings suggest that the studied microbial properties in the Ap horizons were primarily determined by the TOC content, while their activity in the sub-surface layers was also affected by factors associated with soil-forming processes.

Thermal properties of Cambisols in mountain regions under different vegetation covers

Soil thermal properties regulate the thermal and water balance and influence the soil temperature distribution. The aim of the current study is to present data on the changes in the thermal properties of Cambisols at different ratios between the water content and the air in the pore space under different vegetation covers in mountain regions. The undisturbed soil samples were taken from the surface soil layers under grassland, deciduous and coniferous forests in three experimental stations of the Forest Research Institute – Gabra in Lozen Mountain, Govedartsi in Rila Mountain and Igralishte in Maleshevska Mountain. The soil thermal conductivity (λ), the thermal diffusivity (α) and the volumetric heat capacity (C<sub>v</sub>) were measured with the SH-1 sensor of a KD2Pro device at different matric potentials in laboratory conditions. The thermal conductivity of the investigated soils was also measured with the TR-1 sensor of a KD2Pro device at the transitory soil moisture in field conditions. An increase in the thermal properties with the soil water content was best pronounced for λ and depended inversely on the total porosity. As the total porosity increased with the soil organic carbon content and decreased with the skeleton content, the lowest value of λ was established in the surface horizons of Dystric Cambisols (Humic) in the experimental station in Govedartsi. The soil thermal conductivity increased with the depth under the deciduous forest (Gabra and Igralishte) due to the lower soil organic carbon content (SOC) and the total porosity. There were no such changes in the subsurface horizon under the grassed associations. The increase in the heat capacity with the water content depended on the SOC to less extent. In the horizons with a SOC of less than 1.5%, the changes in the thermal diffusivity over the whole range of wetness were 1.7 times higher than those with a higher SOC.