Том 52, № 1 (2019)

Extreme environmental conditions that occur in Arctic, Antarctic, high mountains, extremely arid regions, as well as in toxic or nutrient-poor substrates, shallow waters, under intense anthropogenic impact, and in specific atmosphere or its absence in extraterrestrial systems, lead to the formation of soils and soloids (soil-like bodies) that cannot be adequately described, and their genesis and geography cannot be satisfactorily explained within the framework of the traditional Dokuchaev’s pedology. A new scientific direction is proposed—extreme pedology (genesis and geography of soils in extreme environments), which requires its own theory, conceptual apparatus, and methodological basis. It is based on the assumption that soils and soloids can develop in extreme conditions under the deficit or surplus of resources. In the first case, soloids are just few millimeters thick; in the second case, they have the profiles of multimeter scale. Various classes of soils and soloids extremeness are specified: factorial, regime-functional, and chorological (extra-areal). The behavior of extreme objects in time and the nature of their pedogenic records can have both specific and common features with normal soils. Morphological and analytical study of soils and soloids of extreme environments requires state-of-the-art methodological approaches and scientific equipment.

The current status of soil classification in Russia is considered: its usage; difference among variants of 1997, 2004, and 2008; and reasons, means, and methods for its updating. To reach harmonization of abundant information and maintenance of the system’s principles and structure is now the main problem. Starting from 2004–2006, many proposals have been forwarded; they concern mostly the introduction of new diagnostic horizons and genetic features and, hence, new soil types and subtypes, respectively, for tundra and taiga regions; gaps and mistakes in the system have been revealed. A considerable portion of new data serves as a basis for discussion and introduction of new genetic features providing most complete and adequate soil names in terms of taxonomy, as well as for improving the definitions of diagnostic horizons and genetic features. Moreover, to the definitions of horizons, the relationships with other diagnostic horizons having similar properties should be added, as well as some particular landscape characteristics. As for genetic features—qualifiers for subtypes—there are doubts, whether some of them should be transferred to a lower taxonomic level—that of genus, which seems underestimated in the current system. Identifying and classifying soils encounter some problems because of traditional standards for field description of soil profiles, which are insufficiently oriented on soil properties required for recognizing diagnostic horizons and genetic features.

The estimation of soil contamination with anthropogenic lead requires uncontaminated analogues of the recent soils for comparison. For this purpose, a paleosol buried under a 2-m high burial mound of the Bronze Age and protected by it from atmospheric deposition during 4500 years was studied. The content and isotopic composition of mobile and total lead in the buried and recent soils (roadside and remote from lead sources) were compared. Obvious signs of anthropogenic contamination were revealed in only the upper layer of the roadside soil within 10 m from a highway. These were an increase in the absolute content of all lead forms; a high relative content of mobile forms; high ratios of Pb relative to Ti, Zr, and Y; and the similarity between isotopic compositions of the soil lead and the lead from modern atmospheric aerosols and Russian gasoline. Interestingly, no significant difference was found in the total lead contents or in the isotopic compositions between the recent soil remote from roads and the buried soil. However, some signs of anthropogenic impact could be revealed by the analysis of mobile lead forms, which make up a small portion of the total content.

The development of tomographic studies of soil pore space in Russian soil science in 2011–2018 is discussed. In several years, these studies have evolved from the qualitative description of pores in some soils from the European part of Russia to the quantitative functional assessment of soil pore space on the bases of 3D tomographic models. Three stages of tomographic studies of soil pores can be distinguished: (1) qualitative analysis of pore space as a spatial-geometric characteristic of soil structure and as a component of the general analysis of soil morphology; (2) the obtaining of quantitative morphometric data on the shape, size, and orientation of soil pores and combined analysis of these tomographic data and data on the physical soil properties; and (3) the use of calculated tomographic parameters in the study of hydrological and physicomechanical properties of soils important for both theoretical and applied aspects of soil science. In recent years, the research has been focused on the assessment of the relationships between tomographic parameters of soil pore space and traditional soil hydrological constants, possibility of calculating the water retention curve and water conductivity function from the tomographic parameters of soil pore space, and on the quantitative assessment and prediction of soil degradation on the basis of tomographic data. The solution to these problems will make it possible to explain the physical phenomena controlling soil hydrological characteristics and to substantiate the use of tomographic data in applied soil science, soil hydrology, and agrophysics.

The influence of oil pollution caused by the accident of 1994 on the biological activity of Histic Cryosols is considered. Despite the use of complex mechanical (oil removal), physicochemical (washing on special devices), and agrotechnical (fertilization, plowing, grass sowing) reclamation techniques, the residual content of oil hydrocarbons in the soils can reach high values. The disturbance of the natural peat soil horizon during the reclamation procedures reduces the respiratory activity, as well as the potential rate of consuming the substrates, plant residues and water-soluble organic matter, which decreases the carbon cycle rate.

The quantitative and qualitative diversity of the clay fraction (<1 µm) from parent materials (BC and C horizons), albic (suprasolonetzic eluvial SEL) horizons, and clay-illuvial solonetzic (BSN) horizons of Solonetzes in different regions of the East European and West Siberian plains is described. The contents of smectitic phase (1.7 nm) (SM), illites (1.0 nm) (IL), and the sum of kaolinite and chlorite (0.7 nm) were calculated by the Biscaye method for all the samples. Overall, data on the mineralogical composition of 394 samples of soil horizons in 71 Solonetz soil profiles were summarized. The empirical statistical cumulative and differential distribution curves of clay minerals were obtained. The frequency of occurrence of different types of mineral distribution in the profile was assessed. It was found that Solonetzes do not have a single type of distribution of clay minerals in the profile because of the differences in the mineralogical composition of parent materials and soil forming conditions. The eluvial–illuvial distribution pattern of illites in the bulk soil mass (IL_SEL < IL_BSN > IL_BC) was the most frequent variant; its occurrence frequency varied from 25 to 65% in separate groups of Solonetzes and comprised 57% of the total data sample. Traditionally, the eluvial–illuvial distribution of smectitic phase (SM_SEL < SM_BSN > SM_BC) is considered to be typical of Solonetzes. However, its occurrence frequency varied from 10 to 30% in separate groups of Solonetzes and comprised just 20% of the total data sample.

Soil-biogeochemical aspects of the current state of arable land in the Russian Federation are discussed. Considerable transformation of Russian agriculture has led to structural changes in the agricultural land use, including arable farming. About forty million hectares of former arable land have been abandoned and converted into the category of abandoned lands subjected to overgrowing with meadow and woody vegetation. The restoration of natural vegetation in postagrogenic ecosystems is accompanied by changes in the biological productivity and composition of vegetation on agricultural land in general. The reduction of plowlands and their transformation to abandoned lands have changed the carbon budget. In the early 1990s, arable farming was the net source of C-CO₂. At present, the total arable land area in Russia is estimated at approximately 80 M ha. This area is a source of about 20 Mt C-CO₂/yr. Forty million hectares of former arable land have turned into the sink of C-CO₂ of about 40 Mt/yr in size. Thus, the entire agricultural land in Russia functions as the net sink for atmospheric CO₂ at the rate of 20 Tg C/yr. This fact can be considered a contribution of Russian agriculture to the goals of the “soil 4 per mille” international program assuming carbon sequestration in agricultural soils. Changes in the agricultural land use patterns together with a sharp decrease in the application of all kinds of fertilizers have led to prevalent biogeochemical flux of nutrients (N, P, K) from arable soils to urbanized areas. The deficient nutrient budget implies that the soil-climatic potential and the potentials of other factors increasing farming productivity (new varieties, plant-protective chemicals, etc.) are not fully realized in agricultural production. In 25 years (1992–2016), the uptake of nutrients by crops from arable land comprised 91, 33, and 90 Mt for N, P₂O₅, and K₂O, respectively. The amount of applied fertilizers in that period was only about 28 Mt for N, 10 Mt for P₂O₅, and 28 Mt for K₂O. The highly deficient budget of phosphorus is of special concern. Under these conditions, it is necessary to significantly restrict the export of apatite concentrate and phosphate fertilizers as strategic (nonrenewable) resources necessary for ensuring the food security of Russia for decades ahead.

Pavel Vladimirovich Ototsky was the founder and first editor of the Pochvovedenie journal. The article presents his biography and activity in science and organization of research.