Ergeni Upland Research Articles

CONDITIONS OF THE OAK FORESTS GROWTH AND CULTIVATION ON THE TOP SURFACES AND SLOPES OF THE NEAR-VOLGA AND ERGENI UPLANDS AND THE PLAINS OF THE SAL-MANYCH INTERFLUVE

Planted oak forests in the south of European Russia are of great conservation and economic importance. The widespread practice of their creation in dry steppes and semideserts dates back to the 1950-1970s and allows to form oak (Quercus robur L.) plantations with longevity up to 40-60 years. The aim of the study is to investigate the growth features of oak trees under different soil-climatic and biocenotic conditions and to suggest methods to increase their longevity.The research was carried out in 2011-2016 in the south of the Near-Volga Upland, the northern part of the Ergeni Upland and lowland plains of the Sal-Manych interfluve at 28 temporary sample plots using common methods of forest inventory and regression data analysis.It has been established that the viability of oak is limited by unfavorable topographic position of plantations, increased climate dryness (HC 0,4-0,6), high content of soil carbonates and shallow-lying horizon of their accumulation, as well as the presence of shrub layer and other competitors for moisture. Under these conditions, afforestation of depressions on the plains and shady slopes with pure plantations of oak and other species without shrubs should gain advantage. The methods of their creation should be modified depending on the topographic position of particular forest area and the climate dryness.So, the main soil cultivation in depressions could last 1-2 years, applying the system of black fallow with plantation plowing. It is advisable to keep 3,5-4,0-meter row spacing, frequent tending, and intensive clearing of young tree stands. Maturer plantations need careful sanitary-selective cuttings, mainly the low-type ones, and preservation of high canopy density. Poor water availability and deterioration of plantations should be prevented by construction of dams.Reclamation plantations of low marketability are created on flat areas after 2-3 years of deeper basic tillage. The carbonate horizon should be loosened and a large moisture reserve is needed. Row spacing of 2,5-3,0 meters is reasonable, accelerating the canopy closure. The area of tree nutrition is expanded by low-intensive uniformly selective cuttings, forming more open stands. The longevity of oak in already existing plantations could be increased by eliminating its competitors, such as living ground cover, shrubs and associated species.

HYDROLOGICAL REGIME OF WATER STREAMS AND THE PROBLEMS OF PUBLIC WATER SUPPLY IN THE REPUBLIC OF KALMYKIA

The constant shortage of fresh water for drinking and municipal use in the Republic of Kalmykia has become critically acute recently. Both natural factors, i.e. increasing climate aridity, limited reserves of fresh surface and groundwater, lack of sufficiently long sections of large rivers with constant flow, and the deterioration of hydraulic structures are the reasons. The exploitation of groundwater in existing deposits has led to their depletion and deterioration, while large deposits of fresh and slightly brackish groundwater in the southern Caspian region cannot be used because the content of pollutants in them is rather high. Recovery of old and construction of new water pipelines from the Volga River requires permanent significant financial investments at the federal level. Therefore, recently a new way to increase the supply of fresh water suitable for drinking purposes, i.e. an artificial groundwater recharge (AGR), has been actively discussed. The article provides an actual assessment of water resources of the littlestudied surface runoff of the rivers of Kalmykia, considers the possibility and feasibility of creating infiltration basins to replenish groundwater reserves, and calculates the parameters and operating mode of five planned basins. The main source of fresh surface water in Kalmykia is the rivers of the Ergeni Upland. The average long-term flow from its eastern slope is estimated at 0,120 km3/year, from the western slope at 0,105 km3/year and from the southern slope at 0,045 km3/year. Trends in modern modification of the hydrological regime of rivers under the influence of climate change have been revealed, namely a decrease in annual runoff and its intra-annual redistribution with a reduction of spring floods, a slight increase in winter runoff and a leveling of summer low-water periods. Calculation of the operating mode of planned infiltration basins allowed us to draw the following conclusions: the maximum possible volume of total infiltration will be about 220 thousand m3/year, which is 36 times less than the presentday water intake from the Troitsk and Bayarninsky fields for public water supply; sufficiently efficient operation of pools is only possible with annual cleaning of accumulated silt deposits, otherwise the soil filtration coefficient will come down each year, resulting in the reduction of infiltration supply by dozens times. Thus, the AGR can only be a temporary measure to compensate for the subsidence of groundwater level until the reconstruction and construction of new water pipelines from the Volga River to supply the city of Elista and the surrounding area with drinking water of acceptable quality

The vitality of individuals and the vital structure of coenopopulations of Tulipa biebersteiniana Schult. et Schult. fil. (Liliaceae) on the Ergeni Upland

Vital spectra are one of the most biologically important population characteristics. Currently, the study of the vital signs of rare species, which include the object of study Tulipa biebersteiniana Schult. et Schult. fil. (Liliaceae), is becoming increasingly actual. This work is devoted to the study of the vitality of specimens and the vital structure of coenopopulations of T. biebersteiniana in different parts of the Ergeni Upland. The study was carried out during two growing seasons (2022‒2023) in five coenopopulations from different plant communities confined to light chestnut soils of varying degrees of salinity. The vitality of specimens in the studied coenopopulations of T. biebersteiniana, estimated by the IVI index, varied widely – from 0.448 to 1.686. At the same time, the difference between the maximum values of individual vitality of specimens in most coenopopulations was greater in the second year of the study. The vitality values of the studied T. biebersteiniana cenopopulations, expressed by the IVC index, ranged from 0.800 to 1.270, which is consistent with the data provided in the literature. The dynamics of the values of the vitality index of T. biebersteiniana coenopopulations revealed a clinal character, increasing from the northern to the southern part of the Ergeni Upland. The highest values of the vitality index in the coenopopulations of T. biebersteiniana in the southern part of the Ergeni indicate the most favorable conditions for realizing the potential of the species in this part of the upland. The conditions of the second year of research, which were wetter and with a higher temperature during the period of plant growth and development, contributed to an increase in the vitality of both specimens and coenopopulations of T. biebersteiniana. The studied coenopopulations of T. biebersteiniana belonged to the vital type “prosperous”.

Археологические памятники г. Элисты (по археологическим разведкам С. В. Арапова 1992 г.): современное состояние

Introduction. The earliest surveys of kurgans in the vicinity of Elista were conducted in 1929 . To date, this area of Kalmykia — southern part of the Ergeni Upland — remains a most underexplored one. Only burial sites from the Bronze, Iron and Middle Ages have been investigated here. However, there is still no consolidated list of existing archaeological sites located in the city district of Elista. Meanwhile, as the administrative center of the Republic, the city is continuously growing, residential areas and economic facilities are being rebuilt, once remote outskirts of the city are being actively developed. All these factors threaten the archaeological sites. Goals. The article aims to introduce the results of S. Arapov’s surveys and an updated description of kurgans identified in 1992 into scientific circulation. Results. Our insight into the 1992 field report of S. Arapov shows the document describes a total of 22 monuments (single mounds and kurgan groups) comprising 87 kurgans. These can be divided into four groups, namely: kurgans on a ridge south of the city, ones on northwestern city outskirts, ones in northeastern parts, and those on a ridge west of the airport. The 2022 efforts have localized 52 of the 87 mounds identified by S. Arapov in 1992, the remaining 35 mounds never to have been rediscovered. The main reason for this state of affairs is the lack of systematic work, some of the monuments had stayed unprotected by law only to be damaged or destroyed during construction and agricultural activities. To date, it is urgent to intensify work for the identification and preservation of archaeological sites in the vicinity of Elista. It is necessary to register archaeological monuments and list them as cultural heritage sites, this being the only way to protect them from potential destruction in the future.

Археологические памятники Калмыкии по современным картографическим источникам

Introduction. When it comes to contemporary maps of Kalmykia, one can mention those contain quite a number of symbols to denote kurgans / mounds. Goals. The study aims at examining informational values of contemporary cartographic sources it terms of localizing actual archaeological sites of the Republic. Results. The work reveals 7.860 objects strongly supposed to be kurgans, the bulk of them placed in the Ergeni Upland, Kuma-Manych Depression, and Sarpa Lowland, while a lower density observed in western parts of the region (northwest of the Stavropol Upland) with scarcest numbers delineated within the Caspian Depression. The distribution of archaeological objects on the map essentially aligns with the well-known fact that different natural and geographic zones of Kalmykia are characterized by varying densities of kurgans. Despite the maps contain not all kurgans, they do mention sizeable ones, and 1.580 of 7.860 objects have height indications. So, there is a review map with largest sites. As is known, immense kurgans are not that solitary and often serve to mark groups of smaller mounds. Conclusions. The examined cartographic materials are significant sources that may be instrumental in exploring archeological sites in future. The data obtained can be used in further expeditions and development of image interpreting methods. Such efforts shall make it possible to discover not only large monuments but also minor ones.

Geochemical partition of chemical elements in Kastanozems and Solonetz in a local catchment within a semiarid landscape of SW Russia

The vertical and lateral migrations of chemical elements (ChEs) under semiarid conditions were studied in a soil catena within the uppermost local catchment (2 ha) in the NE part of the Ergeni Upland (the NW Kalmykia, SW Russia). The data were interpreted using the key soil properties typically influencing the mobilisation and accumulation capacity of ChEs: pH, electrical conductivity and soil organic and inorganic carbon content as well as clay, silt and sand fractions. The patterns of the vertical distributions of ChEs were similar in all soils (Kastanozems and Solonetz) irrespective of their topographic location, but the depth of translocation was larger in the gully bottom. The content of mobile fractions of Ca, Mn and, to a lesser extent, P was higher than a residual fraction, which means that these elements have the highest potential mobility in soils (considering the sum of the three mobile fractions: weakly bound acid-soluble, bound with complexes and (hydr)oxides of Fe and Mn). In Kastanozems and Solonetz, weakly bound acid-soluble forms of the readily soluble ChEs (B, Ca, K, Na and Sr), and acid-soluble compounds (of Cd, Fe, K, Na and P) as well as both acid-soluble compounds and complexes for biogenic heavy metals (Co, Cu and Mn) are the major actors of geochemical migration. In the gully catchment, spatial differentiation is governed by the availability of water and the presence of readily soluble compounds of B, Cl, Li, Na and S. Within the topsoil of Kastanozems and Solonetz, the mobility of ChEs decreases in the following order: Mn, Ca > Pb, Co, Cu > V, Ba, Zn > Fe, Al > K, Cr > Si and Ti. In Kastanozems and Solonetz, mobile B, Ca, K, Na, Sr and, to a lesser extent, Mg (in the whole soil profiles) as well as Ba, Be, Mo and S (in subsoil and parent materials) are weakly bound by carbonate and exchangeable compounds. Mobile Co, Cu and Mn are held by soil organic and inorganic complexes. Mobile Cd and Fe occurred mostly within compounds extracted by 1 M nitric acid. The content of elements differed from the parent materials more strongly in the topsoil of Kastanozems due to the accumulation of substances at the biogeochemical barrier in the A-horizon and in the subsoil of Solonetz due to the accumulation of substances at the sorption barrier in the natric horizon. The ‘Solonetz at microhighs–Kastanozems at microdepressions’ is a translocation-solutional microcatena due to the migration of the most mobile chemicals in the soil solution in spring (downward movement) and the dry season (upward movement). Furthermore, the 'Kastanozems at the interfluve–Kastanozems at the gully bottom' is a leaching catena due to the downward movement of less mobile chemicals with melted snow and meteoric water.

Погребения периода Золотой Орды в волго-манычских степях

Goals. The article examines Golden Horde nomadic burials explored across the Volga-Manych steppe. Materials. The work analyzes materials from 90 burials dated to the 13th – 15th centuries AD. Results. The mentioned territory comprises three large geographical zones. The examined burials are located in different topographic areas but basically tend to cluster within Bronze Age mound groups. The study results in certain conclusions regarding the nomads’ ethnic history and their geographical distribution across the territory under consideration. So, the largest numbers of such monuments have been registered in the Ergeni Upland, in the Sarpa and Caspian Lowlands. The burials largely form groups, while single complexes are rare enough.

Элистинский курганный могильник: анализ соотношения курганов и погребений раннего и среднего бронзового века

Introduction. Elista grave field is a largest and most investigated one in the Ergeni Uplands, with the bulk of barrows and burials dated to the Bronze Age. Burial mound sites in the mentioned area are distinguished by linear positioning of tumuli — the most sizeable groups constitute chains of kurgans located transversally along watershed lines. Plateau-like ridges may comprise groups consisting of several parallel kurgan chains. Goals. The study aims at analyzing the correlation (ratio) between kurgans and burials of Early and Middle Bronze Age cultures within the grave field of Elista. Results. The work reveals some specific functions of under-kurgan rooms (space) in different cultures of the examined period. So, burial mounds of the Yamnaya culture contained one central burial each. In the Early Catacomb era, inlet burials were made only in ‘own’ barrows, while the arrived North Caucasian steppe culture gave rise to scattered cases of constructing inlet burials in culturally alien kurgans. Pit-catacomb burials were characterized by somewhat differing use of foreign culture barrows: one such construct virtually demolished the main burial in a Yamnaya kurgan; in another instance, the creation of an inlet burial was followed by heaping quite a plenty of soil which resulted in that the tumulus became several times as large. The distinctive feature is that all the monuments are arranged along the watershed without visible clustering. The largest group is that of kurgans and burials referred to as the East Manych Catacomb culture. Catacomb barrows were inserted into the existing chain, and dimensionally the bulk of them were virtually identical to previous monuments. Conclusions. The analysis shows research of Early and Middle Bronze Age burials should focus not only on quantitative properties in separate kurgans. When it comes to counting inlet burials it is critical to identify the cultural and chronological affiliation of the main burial. Moreover, it is important to obtain additional data, such whether the burial is located inside the tumulus or below the latter, whether there is any trace of later soil heaping, etc. This may be instrumental in discovering additional groups of inlet burials that vary from ‘common’ to ‘elite’ ones and could have been accompanied by several-fold enlargement of the initial (original) tumulus.

Changes in Soil Salinity at the Chervlenoe Irrigation Massive (Volgograd Oblast) in a Quarter of Century

Maps of soil salinity and toxic alkalinity in 2017–2018 were developed for the Chervlenoe irrigation massive of Svetloyarsk irrigation system. These maps were compared with the maps of soils in the virgin state and under irrigation in 1992 and 2006. The massive is located close to the Volga–Don Canal on the northern slopes of the Ergeni Upland (Volgograd oblast). Before irrigation, the soil cover was composed of associations (complexes) of loamy solonetzic light chestnut soils (Sodic Cambisols (Loamic, Ochric, Magnezic, Bathyprotosalilic)) and steppe solonetzes (Endosalic Solonetz (Albic, Loamic, Columnic, Cutanic, Differentic, Ochric, Magnezic)) developed from loesslike loam. The soil cover was strongly transformed by surface leveling during the irrigation system construction, and underwent secondary salinization in the 1970s–1990s because of excessive irrigation water supply. Changes in the soil salinity in the past 20–25 years are discussed. Both favorable (partial salt leaching) and negative (alkalization of topsoil horizons) processes are revealed.

Жертвенные комплексы в курганах бронзового века (по материалам могильников Ергенинской возвышенности)

Introduction. The article examines sacrificial complexes within Bronze Age mounds of the Ergeni Upland. The archaeological culture represented by the investigated mounds is characterized by cattle sacrifice where a cow’s head and limbs symbolized a whole carcass of the sacrificial animal. A majority of the complexes contained fragmented or whole incense pots. The goal of the research is to analyze the sacrificial complexes and reveal key features of theirs essential for the reconstruction of Early and Middle Bronze Age cattle sacrifice rites. Results. The paper investigates materials from seven mound groups located in the Ergeni Upland. It concludes that mounds equipped with sacrificial altars constitute 15 % of the total number of mounds (17 of 112) and identifies somewhat basic features of such altars that tend to cluster in two groups: group one is characterized by the use of cattle bones only, and group two adds incense pots to such bones. The work attempts to attribute the presence of sacrificial altars to certain burial patterns within each mound. So, it reveals that sacrificial complexes are most frequently associated with burials of men. Special attention is paid to the presence of cattle skins placed into burials, according to participants of excavations, with animal heads and limbs. Indirect indicators of the presence of cattle skins were traced in two sacrificial altars only. The paper compares outcomes of the research of the Ergeni Upland’s sacrificial complexes to studies of similar structures within East Manych mounds, draws ethnographic and historical evidence related to such sacrificial practices that might have stemmed from the worship of the ox / cow as the primal forefather / foremother, protector of sentient beings, also tied to the fertility cult.

Changes in the Ameliorative Status of Irrigated Soils of Volgograd Oblast in the 21st Century

The ameliorative status of irrigated soils was estimated on the basis of reclamation cadaster data for 2001 and 2016 on 17 state irrigation systems in three nature regions of Volgograd oblast: (1) the Khvalyn clayey plain and Volga sand ridge in the Caspian Lowland, (2) the Volga and Ergeni uplands, and (3) the Volga and Don river valleys. Significant changes took place in the ameliorative status of these systems during the studied period: the total irrigation area sharply decreased (–31%), especially under irrigation by the local runoff (‒44.5%); the groundwater level became lower, and the area with deep (>5 m) groundwater table increased to 77.3%; and the areas of saline and solonetzic soils decreased by 22.9% and 19.3%, respectively. In many cases, the differences in natural conditions determined the ameliorative status of irrigated soils and the intensity of their changes. The changes were the greatest on the initially saline slightly drained soils of the Khvalyn clayey plain and the smallest in the Volga River valley. During the entire period of irrigation, some areas were subjected to secondary salinization and abandoned. Our investigations at the Raigorodsk plot of the Svetloyarsk irrigation system within the Khvalyn clayey plain in 2016 demonstrated that the soils subjected to secondary salinization in the period of maximum irrigation intensity (in 1990) are now at the stage of gradual desalinization.

Археологические памятники Калмыкии, исследованные И. В. Синицыным и У. Э. Эрдниевым в 1961–1970 гг.: историографический обзор

Introduction. The article analyzes the results of archaeological excavations conducted by a joint expedition of the Kalmyk Research Institute of Language, Literature and History, Kalmyk Republican Ethnography Museum, and Saratov State University in the territory of Kalmykia between 1961 and 1970. The works were directed by Uryubdzhur E. Erdniev and Ivan V. Sinitsyn. The historiographic review deals with publications of results of archaeological excavations held within mound burial sites (Lola 1 and 2, Arkhara, Elista, East Manych, Kermen Tolga, and Gashunsky) and analytical papers based on data obtained during explorations of the mentioned monuments. Goals. The paper aims to analyze published works by I. Sinitsyn and U. Erdniev and gradually reintroduce the 1961–1970 studies into scientific discourse. Methods. The work applies both common scientific methods (typology, comparison, analogy) and specific history research ones (the comparative-historical and typological-historical methods). Results. The insight into results of I. Sinitsyn and U. Erdniev’s archeological surveys reveales that the bulk of the publications deal with monuments investigated between 1961 and 1970, and when it came to reconstruct elements of material and spiritual cultures data from archeological studies once held in adjacent territories were used. Certain parts of the works examine results of field excavations, namely, describe the mounds, burials, sacrificial sites, and discovered remains of the buried individuals and accompanying utensils. Some publications deal with outcomes of field excavations only, being released in the form of separate articles in a number of collections, while others are essentially analytical papers investigating monuments of certain cultures and periods that were published as articles conference reports. The publications consolidated results of the large scale archeological excavations, and were – then and there – unique ones to have described cultural and historical processes inherent to ancient and medieval communities that had inhabited Kalmykia and adjacent territories. It is also noteworthy that in the face of the then vigorous economic activities within the Ergeni Upland and Kuma-Manych Depression all the investigated monuments were threatened with complete destruction. And it was only due to U. Erdniev and I. Sinitsyn’s initiatives and efforts that the numerous monuments never disappeared but were preserved for science, and the results of those works were used in their reviews and reports, and are still applied by contemporary researchers.

Biogeochemical Processes in Steppe Landscapes of the Ergeni Upland in the Holocene

A soil catena was studied on the Ergeni Upland; the soils and plants were sampled in five dependent points. The contents of macro- and microelements in them were determined. It was found that the radial (vertical) geochemical migration predominates in the eluvial positions of the catena, and the lateral geochemical migration predominates in the transeluvial and transeluvial–accumulative positions. Plants of the Poa L. genus intensely accumulated elements within the eluvial part of the catena, whereas plants of the Artemisia genus were element accumulators within the trans-superaquatic position. Plants of the Artemisia genus were generally characterized by a higher coefficient of the biological uptake of elements in all parts of the catena, except for the eluvial position, where this parameter was higher for plants from the Poa L genus. A rise in the magnetic susceptibility of the soil profile relative to the parent material was the highest in the eluvial position and the lowest in the trans-superaquatic position. A comparative analysis of geochemical ratios for modern soils showed that they are determined by the topographic position of the given point. However, the gradient of variations for surface soils is much smaller in comparison with that for buried soils indicative of the climatic fluctuations. The obtained geochemical indicators can be used for comparative analysis of buried soils found not only on the divides but also in the subordinate landscape positions.

Variability of Microbial Biomass in Paleosols of Different-Age Burial Mounds of the Lower Volga Region in Relation to the Dynamics of Climate Humidity

The microbial biomass variability in buried chestnut and light chestnut soils of different ages under burial mounds and their modern background analogs in the Volga and Ergeni uplands were studied. It was shown that almost all microorganisms in chestnut paleosols of the Bronze Age are in the dormant state and provide no respiratory response to the addition of glucose. In the paleosol buried in the most arid period, an increase in the total microbial biomass and the abundance of colony-forming units was revealed. The maxi-mum values of active microbial biomass upon the minimum number of cells were found in soils buried in rel-atively humid periods. The increase in the total microbial biomass and the proportion of microbial cell carbon in the organic carbon of soils buried in extremely dry seasons at the turn of the III–II millennium BC may indicate the adaptation of microbial communities to unfavorable environmental conditions.

Population density and total biomass of microbial communities in chestnut soils and solonetzes of the dry steppe zone in the Lower Volga region

The population density and total biomass of microbial communities were determined in chestnut soils and solonetzes of the dry steppe zone in the Lower Volga region with the use of the methods of sequential fractionation of the soil and direct counting. The mean weighted values of the population density of the microbial communities in the soil profiles (A1 + B1 + B2 horizons) in the studied soils varied within 3.8–8.0 × 1011 cells/g of soil. The total microbial biomass in the soils of the Privolzhskaya Upland reached 0.9–2.4 mg C/g of soil; in the soils of the Ergeni Upland, it was 20 to 75% lower. The microbial cells in the soils of the Privolzhskaya Upland were larger than those in the soils of the Ergeni Upland. Sequential fractionation of the soil prior to direct counting contributed to the more complete assessment of the population density of the microbial communities.

Mineralogical and chemical compositions of the paleosols of different ages buried under kurgans in the southern Ergeni region and their paleoclimatic interpretation

The chemical and mineralogical compositions and the contents and properties of the organic matter were studied in the paleosols of different ages buried under the kurgan group “Kalmykia” in the southern part of the Ergeni Upland. The investigated sequence of soils included profiles developed on the given territory about 5100, 4410, 4260, 4120, 3960, and 600 yrs ago. The background light chestnut soil was also examined. The results of our study showed that the earlier established climate changes in this area during the second half of the Holocene are reflected in the chemical and mineralogical compositions of the soils. These characteristics can be used as indicators of the paleoclimatic conditions together with some petrophysical characteristics, such as the magnetic susceptibility of the soil samples. The study of the mineralogical composition of the clay fraction of the paleosols attests to the transformation of the smectitic phase, accumulation of illites, and destruction of chlorites manifested at different degrees. It is argued that the geochemical indices—CIA, Al2O3/(CaO + MgO + K2O + Na2O), Rb/Sr, and Ba/Sr—are sensitive to climate changes and reflect the transformation of the mineral soil mass and the soil genesis.

Anthropogenic transformation of soils in the northern Ergeni Upland (studies at the first experimental plot of the Arshan’-Zelmen Research Station)

The results of soil studies performed in 2005–2009 at the first experimental plot of the Arshan’-Zelmen Research Station of the Institute of Forest Science of the Russian Academy of Sciences are discussed. The post-reclamation state (about 55 years after reclamation) of the soils under forest shelterbelts and adjacent croplands in the rainfed agriculture was studied. The long-term efficiency of forest reclamation and crop-growing technologies developed in the 1950s by the Dokuchaev Soil Science Institute and the Institute of Forest to reclaim strongly saline solonetzic soils was proved. In 55 years, strongly saline sodic solonetzes with sulfate-chloride and chloride-sulfate composition of salts were replaced by agrogenic soils with new properties. Under forest shelterbelts, where deep (40–60 cm) plowing was performed, the soils were transformed into slightly saline solonetzic agrozems with slight soda salinization in the upper meter and with dealkalized plowed and turbated horizons (0–20(40) cm). Under the adjacent cropland subjected to the influence of the shelterbelts on the soil water regime, strongly saline solonetzes were transformed into solonchakous agrosolonetzes with slight soda salinization in the upper 50 cm. In the plow layer, the content of exchangeable sodium decreased to 4–12% of the sum of exchangeable cations. An increased alkalinity and the presence of soda were found in the middle-profile horizons of the anthropogenically transformed soils.

Dynamics of the properties of steppe paleosols of the Sarmatian time (2nd century BC-4th century AD) in relation to secular variations in climatic humidity

Paleosols buried under kurgans of the Early (2nd-1st centuries BC), Middle (1st-2nd centuries AD) and Late (2nd-IV centuries AD) Sarmatian epochs were studied in dry steppes and desert steppes of the Lower Volga region (the Privolzhskaya and Ergeni Uplands and the Caspian Lowland). It was found that temporal variations in the morphological, chemical, microbiological, and magnetic properties of the paleosols in the interval of 2200–1600 BP were characterized by the cyclic pattern related to secular dynamics of climatic humidity with changes in the mean annual precipitation of ±30–50 mm. These climate changes did not transform chestnut paleosols and paleosolonetzes at the type or subtype taxonomic levels. However, they led to certain changes in the humus, carbonate, and salt profiles of the soils; in the character of solonetzic horizon B1; and in the state of microbial communities. According to these data, the Sarmatian time was characterized by alternation of micropluvial and microarid stages lasting fro about 100–200 years. In particular, the stages of humidization were observed in the 1st century BC-1st century AD and in the 4th century AD; the most arid conditions were observed in the second half of the 2nd and the first half of the 3rd century AD.

Assessment of the microbial biomass using the content of phospholipids in soils of the dry steppe

Microbiological and biochemical investigations of chestnut soils and solonetzes were conducted in the dry steppe of the southern Privolzhskaya and northern Ergeni uplands. The living biomass of the microbial communities in the soils was estimated based on the content of phospholipids in the soils. Significant correlations were revealed between the contents of phospholipids and the main soil properties (the contents of humus, r = 0.66, P = 0.999; clay, r = −0.41, P = 0.95; physical clay, r = −0.57, P = 0.99; and pH, r = −0.59, P = 0.99). The content of phospholipids varied from 69 to 192 nmol/g of soil in the A1 horizons; with depth it decreased down to 36–135 in the B1 horizon and to 26–79 nmol/g of soil in the B2 horizon. The microbial biomass in the solonetzes was lower by 5 to 38% than that in the chestnut soils. A trend of the decreasing of the microbial biomass in the soils from the north to the south was revealed. Based on the content of phospholipids, the number of living microbial cells was assessed; the weighed averages of their number varied from 0.7–3.2 × 1010 to 7.5–13.6 × 1010.

Alkalinity of virgin solonetzes in northern Kalmykia (the Arshan-Zel’men Experimental Station)

The alkalinity of virgin solonetzes of the Ergeni Upland, Ergeni Plain, and Sarpinsk Lowland has been studied. These soils are characterized by the neutral salinization and the high alkalinity of the solonetzic and subsolonetzic horizons. The analysis of the soil water extracts demonstrated that the highest alkalinity is typical of the subsolonetzic horizons containing calcium carbonates (the B2 and BCca horizons). In the solonetzic horizons without CaCO3, the alkalinity is lower despite the high exchangeable sodium percentage (up to 42%). The alkalinity of the solonetzic and subsolonetzic horizons may be conditioned by two processes: (a) the hydrolysis of the exchange complex (EC) containing sodium (EC-Na + H2O ↔ EC-H + Na+ + OH−) and (b) the reaction of the ion exchange with the substitution of calcium for sodium in the exchange complex (EC-2Na + CaCO3 ↔ EC-Ca + 2Na+ + CO32−). Calculations performed on the basis of the thermodynamic equations of the physicochemical equilibria according to the LIBRA program indicate that soda is absent in the solonetzic horizons, whose alkalinity is related to the carbonatecalcium equilibria. The high alkalinity of the calcareous subsolonetzic horizons is related to the presence of soda in combination with CaCO3. The formation of soda in these horizons is due to the reaction of ion exchange described by Gedroits.