Profiles Of Chernozems Research Articles

Sorption of humus and its distribution in the profile of chernozems depending on the granulometric composition

Particle-size composition is a fundamental characteristic that has a significant impact on many properties and regimes of soils, including sorption and fixation of humus by elementary soil particles (ESP). The main role in increasing the humus content of soils belongs to ESP with sizes <0.01 mm. We examined the structural features of humus profiles of leached chernozems formed on soil-forming rocks of different granulometric compositions. For this purpose, a large sample of data on the quantitative content of humus in chernozems of different granulometric compositions was analysed. The goal of the research was to identify the dependence of humus sorption on the granulometric composition of chernozems, and also to reveal the features of the profile distribution of humus in them. Objectives: conduct field research of chernozems of different granulometric composition; select soil samples and conduct a series of laboratory studies of these samples for the identification of the sorption properties of ESP in relation to humus; identify the features of humus distribution in soils of different granulometric compositions. It has been shown that with an increase in the granulometric composition of the content of ESP related to physical clay (<0.01 mm), the sorption capacity of the soil for humus increased. Thus, from sandy loam (ESP <0.01 mm=14-20%) to clayey varieties (ESP <0.01 mm = 61-64%) of chernozems, the humus content increased, respectively, from 3.88 to 7.09%. The thickness of the humus layer increased in the same direction from 22 to 100 cm. Therefore, soils of different granulometric compositions have their own structural features of the organoprofile, consisting in the nature of the humus distribution.

Soil cover structure and transformation of morphometric parameters of Haplic Chernozems under no-tillage

The results of the field experiment have been analyzed, it was set up on two experimental fields (with an area of 2.4 hectares each), where two different agricultural techniques – traditional and no-till – were applied. Diagnostics of morphometric parameters of typical chernozems such as: the thickness of the A1 horizon, A1 + AB horizons and the depth of carbonates reaction with 10% HCl, has shown that some changes in soils and soil cover had occurred in the fields over 8 years. The integral indicator of soil productivity is the thickness of the humus horizon, it demonstrated trends to decrease and increase in the soil cover structure of the experimental fields with different compositions of chernozem subtypes. The trends result from both climate change and periodic dry periods, which are not typical of the region, and from the change of traditional technology to no-till. The carbonates leaching from chernozem profiles in all variants of the experiment decreased, which correlates well with climatic indicators, changing with the seasons of the year. Chernozems with thin humus layaer and reacting with HCl close to the surface do not require liming. The revealed changes are not statistically significant, they reflect the resistance of chernozems to the variability of natural and anthropogenic factors of soil formation. Crop residues on the soil surface under no-tillage reduce physical evaporation, which contributes to moisture accumulation in the soil. The use of cover crops in winter also increases the moisture reserves, which are consumed by the plants during the summer growing season. Information on the transformation of morphometric parameters allows making temporal and spatial corrections in the applied agricultural practices (crop rotation, fertilization, the use of cover crops, herbicides and pesticides).

Short–Range Variation of Humus and Carbonate Profiles of Arable Chernozems (Key Site in Belgorod Region)

The short-range variation of soil properties is a particular expression of the spatial soil variability; it is non-directional short-periodic (in the range of a few meters) changes in soil-profile features. The short-range variation of soil properties is aimed to characterize the continuum nature of soil cover instead of the discrete (as in the soil cover pattern theory), thus the soil cover is presented by a continuum field of various soil properties, and the boundaries of the selected soil properties ranges may or may not coincide with the soil taxonomic boundaries. The study is based on soil data of three parallel transects (length 240 m) in the watershed, perpendicularly crossing the 60-year-old shelterbelt in their central part. The sampling step was 10 m on agricultural fields, 6 – under the shelterbelt; In total, the features of the humus (the content of organic carbon in the 0–20 cm layer, the thickness of the humus horizon and profile) and carbonate (the effervescence depth, the carbonate content in the effervescence layer and the horizon of maximum accumulation of carbonates) profiles were studied at 75 points. It was revealed that the parameters of the humus and carbonate profiles of soils have periodic changes with a step of 6–10 meters. The parameters of the humus profile are characterized by lower coefficients of variation (less than 30%) than the parameters of the carbonate profile of soils (more than 50%). The growth of trees on agrochernozems (Haplic Chernozem (Aric)) for 60 years led to the formation of new taxonomic components (postagrogenic agrochernozems (Haplic Chernozem)), characterized by a smaller lateral variation in soil properties compared to arable soils. In total, 3 types of soils are found within the studied area: agrochernozem (64 points; Haplic Chernozem (Aric, Loamic, Pachic)), clay-illuvial agrochernozem (7 points; Luvic Chernozem (Aric, Loamic, Pachic) and Luvic Chernic Phaeozem (Aric, Loamic, Pachic, Loamic, Pachic)) and agrochernozems, clay-illuvial quasigley (4 points; Luvic Stagnic Chernic Phaeozem (Aric, Loamic, Pachic)), including 8 subtypes.

Dynamics of summer moisture reserves in the profile of non-eroded and eroded chernozems in the southeast of West Siberia

The aim of the study. To identify the presence and causes of summer moisture deficit in the profile of non-eroded and eroded soils against the background of multi-year increase in moisture content in the southeast of West Siberia. Location and time of the study. The water regime of Protocalcic Chernozems (Siltic) of the Kuznetsk Basin (1968-1979), Calcic Chernozems (Siltic) of the Priobie (1984–1993), Protocalcic Chernozems (Siltic) of the Predsalairie (1995 and up to the present time) under virgin vegetation and water regime changes as a result of tillage and erosion processes is considered. Methods. Soil moisture content of each 10-cm layer to a depth of 150 cm was investigated. Under laboratory conditions, the thermostat-weight method was used to determine the moisture content of the samples. Data about the precipitation and warm period air temperature were obtained from climate reference books, Internet weather archives and authors’ observations at key study sites. Results. It was established that in early spring (April) moisture reserves in the 0-1,5-m of the virgin chernozem profile were 50 mm less than in the arable chernozem. This difference in moisture reserves was maintained during the entire summer. But by mid-October the difference in moisture reserves between the non-eroded chernozems disappeared. The replenishment of soil moisture reserves was negatively influenced by the surface runoff of storm water. Therefore, the profile of these chernozems was under-saturated with moisture. Its spring deficit in the 0–1,5 m of soil profiles located on the slope of southeastern and southwestern exposition was approximately the same (58 and 48 mm, respectively), and in June the profile of the arable weakly eroded chernozem located on the southeastern slope was more dried up (moisture deficit of 101 and 48 mm, respectively). Conclusions. The moisture deficit in the arable non-eroded chernozem profiles in spring, together with sparse precipitation in the first half of the warm period combined with high air temperature markedly decreases soil moisture, bringing its deficit by August during the dry and regular hydrological cycles. The last 10 years (2013–2022) saw the tendency of the non-leaching moisture regime type of the Cis-Salair chernozems being transformed into intermittently leaching type due to increased early autumn precipitation and air temperature.

Profile Soil Carbon and Nitrogen Dynamics in Typical Chernozem under Long-Term Tillage Use

For the first time in research literature, this report presents the seasonal changes of total organic carbon (TOC), total nitrogen (TN), and TOC:TN ratio in Chernozem solum (0–100 cm) as effected by 14 years of application of conventional tillage (CTu), deep reduced tillage (DRTu), and reduced tillage (RTu) under barley growing. During the season, TOC content drastically declined in the spring, increased in the summer, decreased in the middle of August, and recovered in October. TN content was gradually decreased during a crop growing season and renewed in the autumn. A trend of TOC:TN changes (vertical peak curve) in 0–30 cm soil layer varied from TOC (S-shaped curve) and TN (unsymmetrical decayed curve). The amplitude of seasonal TOC and TN changes in deeper layers was far fewer related to the upper horizons. The highest amplitude in 0–30, 30–60 and 60–100 cm layers was under: DRTu, CTu, DRTu—for TOC and DRTu, CTu, RTu—for TN correspondently. Tillage practices differently stratified the content of organic carbon and nitrogen in Chernozem profile. Minimum tillage benefited TOC sequestration in 0–5 and 5–10 cm layers: 24.83 ± 0.64- and 24.65 ± 0.57 g kg−1—under RTu, 24.49 ± 0.62- and 24.71 ± 0.47 g kg−1—under DRTu, while CT—deeper than 20 cm: 22.49–15.03 g kg−1. The vertical distribution of TN content repeated TOC trend. TOC:TN ratio upraised from 12.60 in 0–5 to 14.33 in 80–100 cm layer and was the highest in summertime. A total (0–100 cm) profile was much greater under RTu and DRTu—for TN, and CTu, DRTu—for TOC. The correlation coefficient (r) was almost negligible between TOC and: T (air temperature), P (precipitation) and W (soil moisture). The strong and very strong r was found for TN—W, and P—W pairs. The negative r was between: TOC–P, TN–P, TOC:TN-W, TOC:TN–T and P–W pairs.

The Evolution of the Chernozems in the Central Part of Russia and their Complex Analysis in Modern Conditions

An increasing anthropogenic impact on soils leads to qualitative and quantitative changes in chernozems, the richest soils on Earth. In this regard, the understanding of modern soil-forming processes is undoubtedly relevant because it will allow predicting the future state of not only soils, but also nature as a whole. The methodology for studying the evolution of chernozems is based on a process-factor analysis of genetically conjugated and agrogenic series of chernozems of different taxonomic levels. The objects of the study were system complexes of soil series, including subtypes of virgin, arable, and irrigated chernozems in the central regions of Russia. The data obtained made it possible to identify patterns of variation in the composition and properties of virgin chernozems in a genetically conjugated series at a subtype level and in the series virgin land – arable land – irrigated arable land; we also detected the processes and factors that determine the nature and direction of changes in the composition and properties of chernozems in the studied series and determined the direction of anthropogenic evolution of chernozems. The main provisions of the work conceptually develop the theory of the chernozem-forming process and serve as a theoretical basis for the development of models for the formation of the chernozem profile. Established quantitative and qualitative indicators of humus profiles of chernozems are important diagnostic features in the classification of these soils. The nature and direction of the chernozem evolution disclosed in the work can serve as the basis for long-term forecasting of the state of these soils and the development of a set of measures for their rational use and protection.’’

Specificity of genetic nature and classification characteristics of Zmiiny Island chernozem soils

Even the first researchers of the nature of the small (20.5 hectares) rocky Zmiiny Island in the northwestern Black Sea region visually diagnosed the soil there with black earth. Since 2003, the staff of the Department of Soil Science and Soil Geography of the Odessa National University named by I.U.Mechnikov ONU began the study of factors and processes of soil formation, soils and soil cover of Zmiiny Island territory. It was found out that on the inter-rocky areas of the island un- der the steppe grassy vegetation on the gravelly-stony eluvium or eluvium-deluvium of dense rocks formed unusually high humus (up to 14-18%) undeveloped and short-profile chernozem soils. However, the diagnostic and classification of these soils remains unclear. The purpose is to characterize the specificity of the genetic nature of the island soils and to determine their diagnostic and classification affiliation, including the World Reference Base for Soil Resources WRB.The materials presented in this article are obtained as a result of our extensive fieldwork and laboratory analysis, research and mapping of soils and soil cover of Zmiiny Island with the application of methodological principles of the process-genetic paradigm.Chernozem soils on the island are formed on a low-strength (25-40, up to 50 cm) rocky-gravelly crust of weathering of dense acidic rocks under the cover of almost virgin steppe herbaceous vegetation and year-round salting from the sea, mainly chlorides and Na sulfates. The soils are short-profile, typical chernozem humus-accumulative type with typical for the chernozem profile genetic horizons, gravel-stony, non-carbonate, almost non-structural, acidic, varyingly saline and solonetinous, but without solonets-ileuvial profile differentiation. The humus content in the upper horizons is very high (10-12, up to 15-18%), it is typical of the chernozem composition of the Chumic acid : Сfulvic acid (2,5-3,3), but with a sharp dominance of the HA-1 fraction (70% and more) and very low content (1-2, up to 3-4%) or lack of typical chernozem HA-2fraction. It is established that there is a tendency to an irreversible constant increase of the chernozem properties and characteristics in soils as the bioproductivity of herbal vegetation increases.For the first time their diagnostic and classification dependence on the system of both domestic and World WRB soil classifications has been determined. The WRB system proposes to refer these soils to the Phaeozem abstract group, with clarification of the classifiers Leptic and Skeletic. The work is practically significant in terms of the integration the Ukrainian soil science in the system of the current international standard of soil classification WRB.

ОСОБЕННОСТИ ВОДНОГО РЕЖИМА В ЧЕРНОЗЕМЕ ПОД НАСАЖДЕНИЯМИ БЕРЕЗЫ ТОПОЛЕЛИСТНОЙ И ЕГО РЕГУЛИРОВАНИЕ

Forest stands of the arboretum contribute to the preservation of ecological balance on the territory of Barnaul. It contains a large number of tree species, one of which is poplar birch (Betulapopulifolia). The article shows that over the years of research, the water regime in the Chernozem profile under birch stands remains tense for most of the growing season, so there is a need to use irrigation with different irrigation standards, depending on the emerging hydrological state.

Морфогенез чорнозему типового та ізогумусолю за довготривалого використання різних систем обробітку грунту

Chernozems involvement in agriculture influence some natural transformation processes in the soil profile leading to corresponding changes in the morphological features of genetic horizons and their properties. The aim of our research was to identify the morphological changes of typical chernozem and isohumusol under the long-term tillage influence. In the article were compared similar Mollisols, which were formed due to chernozemic process, Forest-Steppe region and loess, but under influence of different facial conditions. The study was conducted at a research station in Velyka Snitynka village, Fastiv district of Kyiv region (50°5′N, 30°2′E) and at the National Agroecosystem Research Station in Hailun, China (47°126′N, 126°38′E). There was used comparative geographical, morphological and statistical research methods during studying. Our findings have defined, that H and H + Hp horizons were deeper by 0.7-5.8 and 9.8-22.4 cm at isohumusol, H + Hp + Phk + P (h) k horizons - by 27.3-53,1 cm - at typical chernozem due to additional 38.4-42.3 cm horizon made of mole influenced loess enriched with humus incrustations. The upper H horizon was the deepest under plowing: 54.3 – at typical chernozem and 55.0 cm – at isohumusol and shortened under minimum till - 48.2 cm – at typical chernozem. Humus horizons had more brown colors: 10YR 3/2, 10YR5/2 - 10YR5/3 - at isohumusol and gray colors: 2,5Y 3/1 - 2,5Y 5/3, 10YR 4/2 - 10YR 5/2 - at typical chernozem. Conservation tillage effects on closer, to the soil surface, humus horizons placement, better aggregation of granular peds, the profile has higher amount of up and down oriented pores between aggregates, carbonates boil in the lower part of the upper transition horizon. Chernozem profile acquires some characteristics of their virgin analogues under conservation technologies use.

Wettability of soil surface as a property of solid phase studied for Chernozems of Kursk region

Soil surface wettability is the main physical property that defines organization of elementary soil particles into soil structure. Human impact affects the changing in properties of soils under arable land use. The objective of this research is to study this impact by the example of two profiles of Chernozems (Kursk region), located under the forest and at the arable field. For both profiles some soil solid phase properties (contact angle, aggregate composition, aggregate waterstability) were measured. There was a positive correlation between the content of organic matter and soil’s wettability in studied soils – a growth of contact angle with the increasing the content of organic matter. Under the forest the content of soil organic matter was changed from 6.41% on the surface to 1.9% at the depth of 100 cm. In the Chernozem under the arable land use the organic carbon content in arable horizon is almost two times less. The maximum of hydrophobicity (78.1°) was observed at the depth of 5 cm under the forest. In the profile at the arable field the contact angle value at the same depth was 50°. The results of the structure analysis showed a decrease in the content of agronomically valuable and water stable aggregates in the profile under arable land.

SALT AND CARBONATE REGIMES OF SOUTHERN C HERNOZEM IN THE DRIP IRRIGATION CONDITIONS

Problem Statement and Purpose. Drip irrigation is used more widely for cultivation of agricultural crops in the Steppe of Ukraine. Influence of this method of moisture supply on the southern chernozems and patterns of their salt and carbonate regimes in condition of drip irrigation by first class water stays insufficiently studied. Accordingly to this the purpose of the study is the estimate of influence of long-term drip irrigation on salt and carbonate regimes of southern chernozems, their essence and direction of change and fertility in irrigational conditions.Data&Methods. Physical and chemical analyses of soils and irrigational water were made in order to certified standard methods and mobile calcium was defined using Drueeno-Gale method. Research was conducted on the territory of agricultural firm “Dobra Gorodyna ”, Bilyayivka district of Odesa region.Results.Vue results of research of drip irrigation influence on the chemical composition and chernozems properties show that the applying of the drip irrigation method to vegetables led to certain degradation agio-meliorative condition in chernozems and high variability of their fertility indicators. The salt regime of southern chernozems in drip irrigation conditions is characterized with a tendency of increasing of salts in arable and sub-plow horizons. The greatest differences in chernozems salt content, which are irrigated in drip method, are noted till 70 cm depth and then they are leveled. The tendency to decrease of the relation of absorbed Ca2+: Na+ and increasing of relation Na++ K+ with the sum of absorbed cations are visible throughout the soil profile. The top part of chernozem profile is lixiviated because of calcium carbonates and their active forms during vegetative and irrigational period. The condition of chernozem does not restore under spring barley during two vegetative season without irrigation. The differences in salt composition of soil profile maintain without irrigation during two years under barley. In arable horizon of this chernozems the differences of salinity persists and the content of sulfates and sodium stays little more heightened. The level of possible irrigational salt content of arable layer stays on the verge of weak ones. Under the barley the profile allocation of active calcium restores to initial values whereas general carbonate content stays a little bit lower.

Distinct changes in composition of soil organic matter with length of cropping time in subsoils of a Phaeozem and Chernozem

SummaryDeeper soil horizons might provide an opportunity to enhance C sequestration because soil organic matter (SOM) at depth is assumed to be stable. However, it is unknown whether the stable composition of organic carbon in subsoils changes with the length of cropping time and the type of soil. The objectives of this study were to determine the effects on the chemical structures of SOM of cropping time after conversion from grassland to arable land under a Phaeozem and Chernozem in northeast China. Near‐quantitative multiple cross‐polarization (multiCP)13C nuclear magnetic resonance (NMR) spectroscopy was applied, and 11 types of carbon (C) functional groups were identified. Principal component analysis of these functional groups showed that the chemical composition of SOM was differentiated by soil type and depth. The Phaeozem and Chernozem profiles differed mainly in their relative proportions of aromatic C–C and (CH2)ngroups: the Phaeozem contained relatively more aromatic C–C, whereas the Chernozem contained relatively more (CH2)ngroups. The fused‐ring aromatic C–C carbon was probably derived from char‐like organic matter generated by burning of plant litter or from SOM humification, whereas the (CH2)ngroups were likely to be from plant‐ or microbially‐derived residues. The main differences between top‐ and sub‐soils were the occurrence of more protonated C in the topsoils and more non‐protonated C in the subsoils. With increasing length of cropping time, aromatic C–C and C–O groups and COO/N–C=O groups increased, but (CH2)ngroups decreased in the Phaeozem subsoils and increased in the Chernozem subsoils. Our findings suggested that leaching and soil moisture might influence the origin, redistribution and transformation of the recalcitrant components of SOM in the soil profile, resulting in changes in SOM composition under different climates and soil types.HighlightsCharacterization of chemical structures of soil organic matter (SOM) in soil profiles by solid‐state13C NMRSOM composition varied between a Phaeozem and Chernozem and to a larger extent in the subsoilsFused‐ring aromatics and (CH2)ngroups accumulated in subsoils of the Phaeozem and Chernozem, respectivelySOM composition of subsoil changed probably with precipitation‐controlled translocation or transformation

Distribution of prokaryotic communities throughout the Chernozem profiles under different land uses for over a century

Land use affects physical, chemical and biological properties and processes in soil. Long-term field experiments were employed to reveal changes of soil characteristics induced by land use. Using high-throughput 16S rRNA gene amplicon sequencing and quantitative PCR, comparative analyses were conducted on prokaryotic community structure in different soil diagnostic horizons of Chernozems under forest, fallow and arable land within a long-term field experiment established by V.V. Dokuchaev in 1892. Soil organic carbon (SOC) was a more sensitive and reliable indicator of changes than microbial diversity indexes. Verrucomicrobia changed most among different prokaryotic phyla. Long-term tillage did not result in detectable changes in α-diversity of Chernozem prokaryotic communities, except for that plow pan horizon that showed a pronounced decrease in microbial diversity. The differences in prokaryotic community structure between soil horizons were more contrasting than between land uses. Analysis of β-diversity indicated that soil microbial communities at different depths formed non-overlapping clusters of A and B horizons, while microbiomes of transitional AB horizons fall in between these two clusters. The sharp decline in α-diversity in the plow pan horizon, as well as significant differences between the communities of A and B horizons indicate that the soil microbiomes are horizon-specific.

Profile degradations of podzolic chernozem of the territory of Male Polissia

The article presents the results of the study of Male Polissia podzolic chernozems profile degradation. The causes and consequences of this dangerous natural and man-made phenomenon resulting in changes in the habitus of soils, losses of soil mass and humus, deterioration of general physical properties and structural and aggregate composition, decrease in soil fertility and agriculture unprofitability on the slopes have been analysed. In the study of the profile degradation of podzolic chernozems, the following methods have been used: comparative-geographical, comparative-profile, soil-catena, analytical, and statistical. Field studies were conducted after the vegetation period. According to the study results, the thickness of the profile of weakly eroded podzolic chernozems, in comparison with non-eroded types, decreased by 17.0–35.5% as compared to the standard, which corresponds to satisfactory and pre-crisis condition, in medium eroded soils - by 32.2–63.4%, the degree of degradation is estimated as pre-crisis, crisis and catastrophic. In the highly eroded types, the thickness of the soil layer decreased by 47.8–74.9%, which indicates a high and very high (crisis) level of profile degradation. Erosion soil loss compared to the standard in weakly eroded podzolic chernozems is 1245.0-3744.6 t/ha, in medium eroded soil – 6762.4-8321.0 t/ha, and in highly-eroded soil – 8874.0-11595.0 t/ha. It has been established that chernozems as a result of water erosion from one hectare of weakly eroded podzolic, on average 39.47–118.70 tons of humus was eroded, 214.36-237.98 tons was eroded from medium eroded ones, and 240.49-267.84 tons from highly eroded soils. The average annual loss of humus is from 0.23-0.68 t/ha in weakly eroded types to 1.37-1.53 t/ha in highly eroded podzolic chernozems. Erosion processes result in deterioration of physical properties of soils. The use of dense and low-humus plumage horizons for plowing causes compaction of soils and deterioration of structure. Minimization of podzolic chernozem profile degradation in Male Polissia is possible provided that the system of anti-erosion measures, especially the conservation of highly eroded soils, the introduction of soil protection methods for soil cultivation, optimization of the structure of crop areas, ban on cultivated crops on slopes more than 3° steep, consolidation of small areas in larger arrays are applied. It is also necessary to introduce a system of basic and crisis monitoring over the condition of eroded soils. Key words: Male Polissia, podzolic chernozems, profile degradation, water erosion, humus, soil conservation.

Human activity formed deep, dark topsoils around the Baltic Sea

Previous findings showed that the humus-rich topsoils designated as Chernozems around the Baltic Sea were influenced by the addition of pyrogenic organic matter linked with human activity. For a deeper insight into the human activities, we investigated the isotopic signatures of sulphur (δ34S) and the 14C age from nine soil profiles in order to clarify which kind of organic matter was added to the soils and to estimate the beginning of the Chernozem formation. The study area was expanded by two additional Baltic Chernozem profiles on the island of Fehmarn in which we also analyzed the portions of black carbon (BC) with the benzene polycarboxylic acids (BPCA) method and the SOM composition with the Pyrolysis-field ionization mass spectrometry (Py-FIMS). The compound classes from Py-FIMS and the BC portions were similar to all other Baltic Chernozems and Chernozems from European loess areas and indicated an input of combustion residues to the soils. The δ34S isotope signature of the SOM in the Axh-horizons (Median: δ34S=11.5‰) at the island of Poel and Sjaelland indicated an input of seaweed (δ34S=20‰) or other marine biomass. The AMS14C ages from the humin fraction, i.e. the oldest fraction of SOM, of the Axh-horizons and the settlement history implied that the formation of the Baltic Chernozems started in a time period between the Nordic Bronze Age (3800 to 2800BP) to the Roman Iron Age (2700 to 2000BP). In summary, the results provided a strong evidence for an input of combustion residues and marine biomass by anthropogenic activities and we conclude that the formation of the Baltic Chernozems reflects an anthropo-pedogenesis. Therefore, we propose to classify these soils as Anthrosols.

The influence of climate cycles on the water regime and carbonate profile in chernozems of Central European Russia and adjacent territories

The influence of long-term “dry” and “wet” climatic cycles on the water regime, hydrological parameters, and carbonate profiles of chernozems in Central European Russia and adjacent territories was studied. The hydrological and carbonate profiles were found to change during the wet cycle. However, the upper part of the hydrological profile is basically unchanging, whereas in its lower part, the number of hydrological horizons and contrast in their moistening decrease in the forest-steppe chernozems and increase in the steppe chernozems. The frequency of through wetting of chernozems increases during the wet cycles. The vertical lithological heterogeneity of the parent material affects the soil moisture status. In the wet climatic cycle, the moisture content above the lithological contact increases resulting in the development of the features of soil hydromorphism. In the carbonate profile, the character of pedofeatures is changing: some carbonate neoformations disappear, while the other ones develop. Possible variations of the periodically percolative water regime were revealed in chernozems. The classification of water regime proposed by A.A. Rode may be updated based on the data obtained during the dry climatic cycle. Rode’s hypothesis about cyclic variations in the soil water regime is confirmed.

Distribution of Metabolically Active Prokaryotes (Archaea and Bacteria) throughout the Profiles of Chernozem and Brown Semidesert Soil

The distribution of metabolically active cells of archaea and bacteria in the profiles of typical chernozems (Voronezh oblast) and brown semidesert soils (Astrakhan oblast) of natural and agricultural ecosystems was studied using the method of fluorescent in situ hybridization (FISH). The studied soils differed sharply in the microbial biomass and in the numbers of metabolically active cells of archaea and bacteria. The number of active bacterial cells was 3.5–7.0 times greater than that of archaea. In the arable chernozem, the numbers of active cells of archaea and bacteria were 2.6 and 1.5 times, respectively, lower than those in the chernozem under the shelterbelt. The agricultural use of the brown semidesert soil had little effect on the abundances of bacteria and archaea. The soil organic carbon content was the major factor controlling the numbers of metabolically active cells of both domains. However, the dependence of the abundance of bacteria on the organic matter content was more pronounced. The decrease in the organic carbon and total nitrogen contents down the soil profiles was accompanied by the decrease in the bacteria: archaea ratio attesting to a better adaptation of archaea to the permanent deficiency of carbon and nitrogen. The bacteria: archaea ratio can serve as an ecotrophic indicator of the state of soil microbial communities.

Magnetic properties as indicators of Chernozem soil development

A detailed magnetic study of four types of Chernozem profiles developed on the loess in the Homutovsky Steppe (Ukraine), Middle Poland and Moravia (Slovakia) was carried out. The magnetic methods were used to examine the subtle differences between four Chernozems, their pedogenic horizons and mechanism of soil formation. Loess of Ukrainian Chernozem (H2) revealed the greatest values of magnetic susceptibility (25 10−8m3kg−1) and frequency-dependence of susceptibility (6.5%), which indicates weathering processes responsible for loess alternation at the beginning of the soil formation. The advanced pedogenic processes in the mollic horizon resulted in the formation of superparamagnetic grains of pedogenic maghemite. The Chernozem from Middle Poland (MDZ) has the lowest values of all magnetic parameters but one of the highest intensities of pedogenesis expressed by the relative changes of frequency-dependence of susceptibility between top-soil and parent material. It could be the consequence of the short duration of pedogenic activity. The correlations between the organic matter content expressed by loss on ignition and magnetic parameters were found. For the mollic A-horizon the organic matter influences the magnetic enhancement (∆χ) and the production of SP grains through stimulation of pedogenesis. The correlation between mean annual rainfall – MAR and pedogenic component of susceptibility – magnetic enhancement gives the opportunity to look at the history of studied profiles. The data for studied Chernozems fit well with the relations between MAR and ∆χ for loessic soils from Russia, Ukraine and Europe.

Regional specificity of the climatic evolution of soils in the southern part of eastern Europe in the second half of the Holocene

The analysis of characteristic features of chernozems and chestnut soils of different ages that have been formed in the south of the East European Plain in the past 5000 years attests to the spatial and temporal heterogeneity of the rate and direction of pedogenetic processes, i.e., to the metachronous development of the soil cover. A linear zone of the retarded (before 3600–3200 years ago) and, then, enhanced development of the humus profiles of chernozems was found along the Voeikov climatic axis corresponding to the contact zone between cyclonic and anticyclonic weather conditions. It was concluded about the significant rise in the degree of atmospheric moistening of the territory took place at the end of the Subboreal–the beginning of the Subatlantic periods of the Holocene. This factor favored the more active growth of the humus profiles of chernozems in this zone in comparison with chernozems on adjacent territories.

Equivalent latitude for prediction of soil development in a complex mapunit

Whitson, I. R. 2015. Equivalent latitude for prediction of soil development in a complex mapunit. Can. J. Soil Sci. 95: 125–137. Soil pattern in the Hillwash complex mapunit from Saskatchewan is too variable to be resolved spatially with conventional mapping approaches. The equivalent latitude metric allows identification of an index based on gradient and aspect that ranks sites based on differences in direct radiant energy inputs. Effects on soil development with reference to surface horizon color and soil classification were investigated at three study areas in southern Saskatchewan. At the first, sites with equivalent latitude greater than local latitude (north group) had a higher frequency of darker soil colors than sites where equivalent latitude was less than local latitude (south group). Black Chernozemic profiles made up nine of 13 profiles from the north group compared with none in the south group or in local controls. Similar color and classification trends in a north sample group were found at a second study area. Results from a third study area more than 200 km away and in a drier ecoregion found similar differences albeit a different set of subgroups between north and south group soils at that location. The equivalent latitude metric could be used in a GIS context to better resolve soil characteristics within this complex mapunit, but only after additional work to include a climate parameter such as potential transpiration into the model.