Properties of soils and soil-like bodies in the Vorkuta area

The specific features of the formation of soils and soil-like bodies on technogenic substrates in Vorkuta—a polar city specializing in coal mining—are characterized. According to the new Russian soil classification system, these soils are classified as urbanozems (urban soils) and constructozems (soil-like bodies constructed by humans); the latter are subdivided into recreazems (soil-like bodies of recreation zones) and replantozems (soil-like bodies of reclaimed urban areas with planted vegetation). They are characterized by the increased content of heavy metals and by some alkalization of the upper soil horizons in comparison with the natural background soils. The benz(a)pyrene content in most of the soil samples exceeds the maximum permissible concentration (MPC). The maximum levels of the soil contamination with benz(a)pyrene reach 80 MPCs. According to the total contamination index calculated relative to the background concentrations of the major contaminants, the upper horizons of the investigated soils and soil-like bodies are qualified as ecologically hazardous and extremely hazardous bodies.     

Inclusion of soils and soil-like bodies of urban territories into the Russian soil classification system

The results of the Internet discussion on the classification of urban soils aimed at evaluating their possible inclusion into the modern Russian soil classification system adopted by a wide range of specialists are presented. The first step was to address the urban diagnostic horizons as the basis for identifying soil types according to the rules of the Russian soil classification. New diagnostic horizons were proposed for urban soils: urbic (UR), filled compost-mineral (RAT), and filled peat (RT). The combination of these horizons with other diagnostic horizons and layers of technogenic materials correspond to different soil types. At the subtype level, the diagnostic properties (qualifiers) that may reflect both natural phenomena (gley, alkalinity) and technogenic impacts on the soils (urbistratified; phosphatic; or poorly expressed urban—ur, rat, rt) are used. Some corrections were proposed for the system of parent materials in urban environments. Urban soils formerly described in another nomenclature—urbanozems, urbiquasizems, and culturozems—are correlated with the taxa in all the trunks of the system. The proposals accepted can be used for the next updated version of the new Russian soil classification system.     

Microbial biomass and biological activity of soils and soil-like bodies in coastal oases of Antarctica

The method of luminescent microscopy has been applied to study the structure of the microbial biomass of soils and soil-like bodies in East (the Thala Hills and Larsemann Hills oases) and West (Cape Burks, Hobbs coast) Antarctica. According to Soil Taxonomy, the studied soils mainly belong to the subgroups of Aquic Haploturbels, Typic Haploturbels, Typic Haplorthels, and Lithic Haplorthels. The major contribution to their microbial biomass belongs to fungi. The highest fungal biomass (up to 790 μg C/g soil) has been found in the soils with surface organic horizons in the form of thin moss/lichen litters, in which the development of fungal mycelium is most active. A larger part of fungal biomass (70–98%) is represented by spores. For the soils without vegetation cover, the accumulation of bacterial and fungal biomass takes place in the horizons under surface desert pavements. In the upper parts of the soils without vegetation cover and in the organic soil horizons, the major part (>60%) of fungal mycelium contains protective melanin pigments. Among bacteria, the high portion (up to 50%) of small filtering forms is observed. A considerable increase (up to 290.2 ± 27 μg C/g soil) in the fungal biomass owing to the development of yeasts has been shown for gley soils (gleyzems) developing from sapropel sediments under subaquatic conditions and for the algal–bacterial mat on the bottom of the lake (920.7 ± 46 μg C/g soil). The production of carbon dioxide by the soils varies from 0.47 to 2.34 μg C–CO₂/(g day). The intensity of nitrogen fixation in the studied samples is generally low: from 0.08 to 55.85 ng С₂Н₄/(g day). The intensity of denitrification varies from 0.09 to 19.28 μg N–N₂O/(g day).     

Plant-available water capacity of soils at a regional scale: Analysis of fixed and dynamic field capacities

Estimation of the plant-available water capacity (PAWC) of soils at a regional scale helps in adopting better land use planning, developing suitable irrigation schedules for crops, and optimizing the use of scarce water resources. In the current study, 72 soil profiles were sampled from the Barossa region of South Australia to estimate pedo-transfer functions deduced from easily estimated soil properties. These functions were then used to estimate the fixed (10 and 33 kPa) and dynamic pressure head (h_fc) water contents at field capacity (FC) for minimum drainage flux (0.01 and 0.001 cm d^-1), which serves as the upper boundary for plant-available water in soils. The estimated residual water content was corrected for subsoil constraints, especially the exchangeable sodium percentage (ESP). The results showed that the mean values of h_fc in sand-dominated light and medium textured soils (i.e., sand, loamy sand, sandy loam, and loam) varied in a narrow range (15.8–18.2 kPa), whereas those in the clay-dominated heavy textured soils (i.e., clay loam) showed a wide range (11.3–49.3 kPa). There were large differences in PAWC for dynamic FC (PAWC_fc) and fixed FC at 10 kPa (PAWC₁₀), 33 kPa (PAWC₃₃), and a mix of 10 and 33 kPa (PAWC_10,33) pressure heads depending on soil texture. Normally, the difference between PAWC at 10 kPa and h_fc (∆PAWC₁₀) was positive, whereas that between 33 kPa and h_fc (∆PAWC₃₃) was negative across all sites. Nevertheless, the estimation of PAWC assuming a fixed FC at 10 and 33 kPa pressures (i.e., PAWC_10,33) for sandy, clay, and silty soils reduced the difference between fixed and dynamic pressure PAWCs to < 10% across the region. The estimation of PAWC was improved by incorporating the impact of subsoil constraints, such as high ESP, which was more pronounced for clay and silty soils. These findings demonstrate the inherent inconsistencies between static pressure and flux-based dynamic FC estimations in soils. Soil heterogeneity, intra-texture variability, subsoil constraints, and swell-shrink clays can have great impacts on the water retention capacity in response to dynamic and fixed pressure FC values.     

Communities of microorganisms and invertebrates in soil-like bodies of soccer fields in Moscow oblast

Artificially created soil-like technogenic formations (STFs) of soccer fields are developed under combined action of intense technogenic and natural factors and processes, which cannot but affect the structure and biological activity of their microbial communities and mesofauna. The microflora of the STFs is very similar to the microflora of the background soddy-podzolic soils of Moscow oblast with respect to the composition of the physiological groups of microorganisms. However, they are drastically different in their quantitative characteristics. The numbers of all the trophic groups of microorganisms, except for the microscopic fungi, in the STFs are much higher than those in the zonal soils. An increased biological activity of the STFs is due to regular watering, heating, application of sand and mineral fertilizers, and technogenic turbation processes. The mesofauna of the STFs is represented by several ecological groups of earthworms, including soildwelling (endogeic) earthworms (Aporrectodea caliginosa), epigeic earthworms dwelling at the soil-litter interface (Lumbricus rubellus), and litter-dwelling earthworms (Eisenia foetida).     

Investigation of water retention functions of artificial soil-like substrates for a range of mixing ratios of two components

Journal of Soils and Sediments - Urban greening is politically fostered as an adaptation strategy to climate change. Therefore, the demand for fertile planting substrates increases. Such substrates...     

Retention capacities of immiscible chemicals in unsaturated soils

Retention capacities were measured in the laboratory for n-hexane and tetrachloroethylene (PCE) in three soils at varying soil water contents. Two experimental techniques were used; 1) saturation/drainage experiments where the soil columns were saturated with the chemical and allowed to drain freely for 24 h, and 2) spill simulations where a known amount of chemical was spilled on the surface of the soil column and allowed to infiltrate for one hour. Results show that the retention capacities on a volume basis were independent of chemical type. However, the retention capacities did decrease with decreasing porosity and increasing soil water content. The decrease of retention capacity with respect to soil water content was significant, with the decreases ranging from 38% to 94%. The implication of this decrease is rapid chemical penetration into the subsurface. Retention capacities obtained from spill simulations were consistently lower than those obtained by the saturation/drainage experiments due to hysteresis.     

Dynamics of water, temperature, and salts in typical aridic soils after artificial rainstorms

In order to learn more about soil genesis, and ecology in the extremely dry desert of southwestern Egypt, we carried out irrigation experiments at four sites representing four typical (Solonchak and Yermosol) types of soil occurrence in this region. The irrigations simulated the rare episodic rainstorms. We measured water content, temperature, and salt content at various depths in the soil profiles for several weeks, at first hourly, then daily; we also observed changes in soil morphology. Thus, we obtained the rates of evaporation, water penetration, and salt migration at these sites. We speculate on the meaning of these data regarding soil genesis, and ecology in hyperarid deserts.     

华北旱地土壤硫施用量指标

Fifteen upland soils collected from the major arable areas in North China were used to assess the availability of soil sulfur (S) to plants in a pot experiment. Soils were extracted with various reagents and the extractable S was determined using turbidimetric method or inductively coupled plasma atomic emission spectrometry (ICP-AES), respectively. In addition, mineralizable organic S, organic S, N/S ratio, sulfur availability index (SAI) and available sulfur correction value (ASC) in soils were also determined. The S amount extracted by 1.5 g L^-1 CaCl₂ was nearly equivalent to that by 0.25 mol L^-1 KCl (40 ℃), and both of them were slightly smaller than that by 0.01 mol L^-1 Ca(H₂PO₄)₂ solution, as measured by turbidimetric method or ICP-AES. The extractable S measured by turbidimetric method was consistently smaller than that by ICP-AES. All methods tested except that for organic S and N/S ratio produced satisfactory results in the regression analyses of the relationships between the amounts of S extracted and plant dry matter weight and S uptake in the pot experiment. In general, 0.01 mol L^-1 Ca(H₂PO₄)₂-extracted S determined by ICP-AES or turbidimetric method and 0.25 mol L^-1 KCl (40 ℃)-extracted S determined by ICP-AES appeared to be the best indicators for evaluation of soil available S.     

Artificial soil-like bodies of a river valley and their evolution in an urban environment (Based on the example of the Moscow River valley)

Technogenic soil-like bodies and raw soils on technogenic sediments in the valley of the Moscow River in the city territory were investigated. Soil destruction and the accumulation of techogenic sediments, as well as their remediation, result in the formation of soil-like bodies called replantozems. Spontaneous overgrowth and the formation of raw soils that gradually evolve into mature urban soils result in soils called urbanozems. It is shown that the best foundation for replantozems in river valleys is in situ alluvium with relatively favorable physical and physical-chemical properties.     

Buried soils of the Nedvigovskoe ancient settlement and the role of the ancient anthropogenic factor in chernozem formation

Soils of the Tanais archaeological reserve (the Nedvigovskoe ancient settlement) were studied. These are the buried meadow-chernozemic paleosol and the modern ordinary calcareous chernozem formed above the ancient road to the settlement. The morphological, chemical, and physical properties of the soils and their specific genetic features were characterized. The results of this study prove that a soil body in the steppe zone is formed not only under the impact of the pedogenic transformation of the parent material but also under the impact of continuous sedimentation of dust particles onto the soil surface with their assimilation by the soil.     

Calculation of the field volumetric water content of cracking clay soils from measurements of gravimetric water content and bulk density

Uncertainty in estimating water use in shrinking soils from changes in gravimetric water content arises from the difficulty in ensuring that samples are taken from comparable depths at different sampling times, and of identifying the correct bulk density for the conversion to volumetric water content. Equations which express the amount of water held by the same mass of soil solid matter during soil drying and shrinking are derived for two models. In one the soil properties vary continuously with depth and in the other the values are averages for layers. The models are applied to field water content measurements made in the Sudan Gezira. Systematic errors (biases) are examined and their magnitudes calculated. The maximum overestimate of gravimetric water content arising from ignoring vertical shrinkage on drying was 2.3%. The maximum overestimate of volumetric water content from ignoring volumetric contraction was 24%; this was corrected by using for all sampling times bulk densities of layers before contraction.     

Simulation of water flow and solute transport in free-drainage lysimeters and field soils with heterogeneous structures

Lysimeters are valuable for studying the fate and transport of chemicals in soil. Large‐scale field lysimeters are used to assess pesticide behaviour and radionuclide transport, and are assumed to represent natural field conditions better than laboratory columns. Field lysimeters are usually characterized by a free‐draining lower boundary. As a result, the hydraulic gradient is disrupted, and leachate cannot be collected until the bottom of the lysimeter becomes saturated. We compared heterogeneously structured, free‐drainage lysimeters and field soils with respect to water flow and solute transport. Numerical simulations were carried out in a two‐dimensional heterogeneous sandy soil under unsaturated water flow conditions with the CHAIN_2D code. Three different soil structures (isotropic, horizontal, and vertical) were generated, and Miller–Miller similitude was used to scale the hydraulic properties of the soil. The results showed that ponding occurs at the bottom of the lysimeter for the three soil structures and that it occurred faster and was more pronounced with the vertical structure (preferential flow effect). Breakthrough curves of a conservative solute (bromide) showed that solutes are moving faster in the field than in the lysimeters. Fewer differences between lysimeters and field soils were found with the horizontal soil structure than with the isotropic and vertical structures.     

Crust formation on sandy soils in the Sahel II. Tillage and its effect on the water balance

The water balance for millet fields and for permanently crusted natural pastures is described, with special emphasis on the role of the crust in governing infiltration and runoff. Tillage destroys the crust and increases the surface storage for rainwater. The crust-breaking effect will last for only a few rainshowers, but the increase of surface storage is more permanent. The effect of a tillage system on the water balance of a millet crop is calculated.Tied ridges, giving a surface storage of 20–30 mm, could prevent runoff (which is about 50% under the conventional system) completely. It is expected that this would allow earlier sowing and thus prolong the vegetative growth by as much as 20 days, which might increase the average millet yield (500 kg ha^?1) by 40%.     

Cation exchange capacities of organo-mineral particle-size fractions in soils from long-term experiments

Soils with and without organic manuring from 10 long-term manurial experiments in East Germany were fractionated into organo-mineral particle-size separates by ultrasonic disaggregation and sedimentation/decantation. The cation exchange capacities (CECs) buffered at pH 8.1 were determined for the size fractions fine+medium clay, coarse clay, fine, medium and coarse silt, sand, and for the total soil samples. In the samples from nine field experiments the CECs decreased with increased equivalent diameters (fine+medium clay: 489–8 13 mmol_c kg^?1, coarse clay: 367–749 mmol_c kg^?1, fine silt: 202–587 mmol_c kg^?1. medium silt: 63–345 mmol_c kg^?1, coarse silt: 12–128 mmol_c kg^?1 and sand: 10–156 mmol_c kg^?1. The CECs varied with genetic soil type, mineralogical composition of the <6.3-μm particles, and the C and N contents of the size fractions. In a pot experiment examining the role of various organic materials in the early stages of soil formation, the clay-size fractions had the largest CECs (85–392 mmol_c kg^?1), followed by the medium-silt (1 9-222 mmol_c kg^?1) and fine-silt fractions (23–192 mmol_c kg^?1). The effect of organic amendments on CEC was in general: compost>fresh farmyard manure = straw + mineral fertilizer = mineral fertilizer.     

土壤大孔隙及其研究方法

  目的  土壤大孔隙是土壤水气迁移交换的主要通道,研究土壤大孔隙与水分入渗特征对探究水文连通时空变化强烈的山丘区坡地有重要意义,可为红壤丘陵区土地高效利用提供参考。  方法  研究通过电子计算机断层扫描技术和双水头渗透计法,定量研究了粤北红壤丘陵区不同土地利用方式土壤大孔隙与水分入渗特征。  结果  不同土地利用方式的土壤理化性质存在明显差异。林地为砂质黏壤土,园地为黏土,耕地为黏壤土,土壤容重随着土层深度的增加而变大,土壤有机质含量随土层深度的增加而减小。土壤大孔隙度、大孔隙总体积和总表面积表现为：林地 > 园地 > 耕地,大孔隙数量则表现为：园地 > 林地 > 耕地,随着土层深度的增加,土壤大孔隙度和大孔隙数量呈减少趋势;土壤大孔隙平均直径表现为：林地 > 耕地 > 园地,不同土地利用方式的土壤大孔隙直径都主要集中在0 ~ 3 mm。土壤大孔隙度与土壤容重呈显著负相关,与有机质和砂粒含量呈显著正相关性。土壤饱和导水率表现为：园地 > 林地 > 耕地,土壤饱和导水率除受容重影响外,还与有机质含量、大孔隙长度相关。  结论  不同土地利用方式会使大孔隙和饱和导水率等土壤理化性质产生显著差异。林地的大孔隙度和大孔隙总表面积最大,而园地的大孔隙数量和饱和导水率最大。     

Transformations of layered silicates in soils of the boreal and subboreal zones: Literature review

The transformation mechanisms of layered silicates during the formation of vermiculite (vermiculitization), smectite (smectization), illite-like minerals (illitization), and soil chlorites (chloritization) have been considered. The mechanism of olivization has also been discussed. The manifestation features of these processes in different soils and horizons have been analyzed. It has been shown that the rate, direction, and depth of the transformations depend on the climatic conditions; the mineral composition; the acid-base, redox, and hydrological conditions; and the soil solution’s composition. The amount of the accumulated solid-phase products of the transformations depends on the rate of the given transformation stage and (or) the rate ratio between the given and the next transformation stages.     

Numerical analysis of soil water dynamics in a soil column with an artificial capillary barrier growing leaf vegetables

An artificial capillary barrier (CB ), which consists of two layers of gravel and coarse sand, was used to improve the soil water retention capacity of the root zone of sandy soil for the cultivation of Japanese spinach (Brassica rapa var. perviridis ). The performance of a CB under specific conditions can be evaluated using numerical simulations. However, there have been relatively few numerical studies analyzing soil water dynamics in CB systems during crop growth. The objectives of this study were (i) to evaluate the performance of a CB during the cultivation of Japanese spinach irrigated at different rates and (ii) to investigate the effect of the irrigation schedule on root water uptake. Numerical analysis was performed using HYDRUS ‐1D after the soil hydraulic properties of the CB materials were determined. In most cases, the HYDRUS ‐1D results agreed well with the experimental soil water content data without any calibration when the dual‐porosity model describing soil hydraulic properties was used for gravel and coarse sand. We found that the dual‐porosity model was able to attenuate the unrealistically steep reduction in the unsaturated hydraulic conductivity predicted by the single‐porosity model. The numerical simulations also showed that the CB played an important role in maintaining plant‐available water in the root zone while maximizing the water use efficiency. The numerical simulations revealed that the irrigation frequency could be reduced by half during the early growth stage, and the water use efficiency could be greatly improved with the CB layer installed.     

淡水渔业与水体气候的关系

以生态观点简述了淡水渔业中水体气候的若干问题：研究鱼类的生长环境应以水体的生态气候因子为可靠依据；我国淡水鱼类依温度生态型的差异有不同适宜生长分布区；各地水体因光、热判别产生不同的浮游植物气候生产力；淡水鱼业气候区划主要应以水体气候资源特征及其对鱼类分布、生长和对水体初级和平力的影响为依据。