Humus Profiles Research Articles

Formation of soil humus profile under long-derivative forests on the Vasyugan Plain (West Siberia, Russia)

Humus profile formation in southern Vasyugan plain is closely related to its parent rocks ranging from carbonaceous clays and heavy loams. Carbonates ensure slowing down of restoration cycles of the indigenous vegetation at the stage of grass deciduous forests (for more than one generation), because well developed grass cover dominated by bunch grasses impedes restoration of dark coniferous species. This gives an insular pattern to some features of climatic zonality due to different soil-vegetation relationship between zonal and successional derivative communities. Plant and soil cover determine local conditions for soil drainage and leaching. In contrast to zonal forest communities with tree storey composed of dark conifers, growing  on sod podsolic soils with residual humus horizons, under revegetating deciduous forests soil formation takes place under higher soil biological activity due to differing quantity and quality of plant matter input. The well drained areas under aspen and birch forest with understorey dominated by herbs and grasses (the most abundant species being  Betula pubescens, Populus tremula, Carex macroura, Aegopodium podagraria, Calamagrostis obtusata, Equisetum pratense, Rubus saxatilis) are occupied by organic matter accumulating soddy podzolized soils with carbonate-containing layers close to the surface. In semihydromorphic and hydromorphic biotopes under smallreed aspen-birch forests (the most abundant species being Betula pubescens, Populus tremula, Calamagrostis phragmitoides Carex globularis, Equisetum sylvaticum, Filipendula ulmaria) organic matter accumulating soils with varying thickness of the humus/peat horizons are common. The species composition of such plant communities corresponds to the one typical for the southern taiga, but their production characteristics are closer to those common for the more southern communities of the northern forest-steppe with 3–5 t/ha (dry mass) of phytomass. Phytomass mineralization rate is higher, and leaves and grass decomposition products are less acidic as compared with zonal forests, where plant litter is rich in needles and mosses. As a result, organic matter accumulating soils under such communities developed some features, more common for their southern counterparts, distinguishing them from the soddy podzolic soils and making them more like the humus-accumulating soils in the northern forest-steppe. These soils have weak granulometric differentiation and well developed structure of the humus horizon. Humus content in quite high, reaching in the southernmost part of the soil area 6–8% in humus accumulating horizons (AU) 50 cm thick. The northernmost parts of the area see the decreased thickness of the dark humus horizon where the latter is substituted with brownish-gray (AY) horizon common for the taiga soils with 4–6% humus content. Organic matter accumulating soil profiles were found to be contrasting in pH(H2O), as the latter increased from 5.5–6.0 in layers immediately below the litter to the neutral values of 6.0-7.0 in humus horizons and 7.0–7.5 in subsoil horizons. High location of carbonates and solonetz properties of parent rock results in high (75-95%) saturation of soil absorbing complex with basic elements, also preventing drastic degradation of humus profile, as only the topmost part of the humus horizon was found to be affected by acidic products of forest litter decomposition. The relic part of the soil profile can be seen in all studied soils. The radiocarbon age of the relic horizons, as determined by humic acids, ranged 4,000–6,000 years. Humus quality reflects differences in humus horizon genesis. Contemporary horizon of soddy podzolised soils is formed due to climatic conditions of the southern taiga zone and has humic to fulvic acids ratio of 1.2–1.4 and low content of Ca-bound acids, while residual humus horizons were found to have increased humic acid content, decreased fulvic acids content of aggressive 1 and 1a fractions, the highest ratio of humic to fulvic acid carbon of 1.8–2.1 and increased content of their Ca-bound fractions. These features, as well as a very low boundary of humus horizon indicate relic humus formation under more southern, i.e. forest-steppe, environmental conditions. The microbiomorph fraction of humus horizons was found to be dominated by plant detritus and phytoliths. The phytoliths assemblages of the contemporary and relic humus horizons were quite similar with notable absence of coniferous phytoliths. All these suggest that organic matter accumulating soils formation under different climatic conditions in late Holocene was related to phytocenoses similar to grassy deciduous forests. The study revealed that both contemporary humus accumulation and relic humus preservation are negatively correlated with eluvial process rate. So successional dynamics of forest communities determines the pendulum nature of soil evolution. The stage of native dark coniferous forests is characterized by humus horizon degradation under acidic forest litter. The restoration stage of grassy birch forests accelerates humus accumulation and partial restoration of both contemporary and relic humus profiles, which is more explicit with the longer duration of this successional stage.

Classification of humus forms in Caspian Hyrcanian mixed forests ecoregion (Iran): Comparison between two classification methods

Temperate forest productivity and functioning may be explained by complex interactions among tree canopy composition, topographic conditions, climate, morphogenetic identification and classification of humus forms. In this study, we report the main morphological feature of humus profiles classified according to both American (AHCM) and European (EHCM) classifications under the six most common forest stands in northern Iran, i.e., Alnus subcordata (AS), Acer velutinum (AV), Fagus orientalis-Carpinus betulus (FO-CB), Carpinus betulus (CB), Fagus orientalis (FO), and Fagus orientalis-Carpinus betulus-Parrotia persica (FO-CB-PP). Organic and organic-mineral layers samples were collected in 61 permanent plots (20 × 20 m) within a 30 × 30 cm metal frame, for identification. Our result showed that Mull was the dominant humus system according to both classifications, whereas Mor (AHCM) and Amphi (EHCM) were the less frequent humus systems in the study area. Mull and Amphi (EHCM) were dominant at the lowest slope and altitude under AS canopy cover; Moder was usually present at intermediate slope and altitude under FO-CB and FO-CB-PP; while Mor was the dominant form at intermediate slopes and highest altitudes under FO and FO-CB. Due to the temperature changes and litter decomposition, altitude seems to be the best predictor of humus type and litter thickness. Our findings also indicate that EHCM could be preferred in the identification and classification of humus forms in temperate deciduous forests in Iran.

Humus conditions of the Pre-Dnisterian Podolia Haplic Chernozems

The humus state of chernozems typical of Pre-Dnisterian Podolia is investigated. It has been established that for the content of humus the chernozems typical of the Pre-Dnisterian Podolia are low humus (2.78–3.98 %). With depth, the content of humus decreases gradually, indicating a uniformly accumulative type of distribution of organic matter in the soil profile. It is determined that in typical chernozems the phenomenon of moderate migration of humic acids is observed, thus forming a deep humus profile. Humic content to the depth of 90–100 cm is dominated by humic acids (Cga:Cfais 1.12–1.78). The general tendency of relative “pluralisation” of the arable lay eras a result of its agronomic exhaustion has been observed. In relation to the Cga to the general organic C, the chernozems soil of the study area is characterized by a high and very high degree of humification of organic matter. It is proved that the intensity of the migration processes of humic acids decreases in the direction of strengthening the hardness of the GTK territory, due to the tightening of calcium carbonates closer to the surface of the soil. Its middle and lower parts were formed, to a large extent, by infiltration of humic acids, moreover, mainly due to the calcium humates. In the case of the use of chernozems without the use of organic fertilizers, the processes of mineralization of plant residues and humus are more active, and the balance of humus is scarce. However, when applying a setoff measures, you cannot only prevent loss of humus but also increased their content. Such a complex should include the following measures: soil replenishment with organic substances, in particular, the planting of perennial grasses and sown crops, the abandonment of a higher grain of grain; minimizing cultivation; creation of optimal ratios of crops in crop rotation to reduce humus losses; the application of meliorants, which would ensure the strengthening of soil fixation of newly formed humus substances. Key words: Pre-Dnisterian Podolia, Haplic Chernozems, humus, humic acids, fulvic acids.

Specific features of accumulation of humus in technozems under poplar plantations in the conditions of the Western Donbass

Specific features of accumulation of humus in technozems under poplar plantations in the conditions of the Western Donbass

Humus forms pathways in low-elevation cold scree slopes: Tangel or Mor?

Low-elevation cold scree slopes are characterized by a remarkable abiotic phenomenon: an internal air circulation, the chimney effect, which leads to a strong negative anomaly of temperature in their lower part, potentially resulting in the formation of underlying permafrost lenses at very low altitude (<1500m in the Alps). The aim of this study was to better understand humus forms of the five cold screes known in the Isère department (French Alps). We tested two alternative hypothesizes: (i) despite an atypical abiotic context, the humus forms of the cold screes are following the two theoretical pathways under colder conditions, leading to Mor humus forms (acidic context) or scarcely known Tangel (calcareous context). (ii) The micro-scale varying vegetation type within the coldest area of the scree may induce some differences in humus profile and soil organic matter. Surprisingly, we did not find any significant vegetation influence either on humus profile or organic matter throughout the OF-OH-A (H) layers. Moreover, among the four pedogenesis we observed, three were unusual (intermediate Tangel/Mor humus in calcareous context, plus peculiar Tangel and Histomor humus), while only one was fully consistent with its usual pathway (Mor humus in acidic context). Our results suggest that the underlying abiotic conditions (bedrock, soil temperature and moisture) of the cold scree slopes outweigh vegetation and atmospheric climate as dominant drivers of the ecosystem functioning. This remarkable context may impact the complex abyssal environment within cold screes, leading to divergences from regular ecological pathways.

Matching Estonian humus cover types’ (pro humus forms’) and soils’ classifications

For characterization of soil cover influence on formation and functioning of ecosystems, the special attention should be paid to its biologically active superficial part i.e. to the humus cover (HC). The used by us term ‘HC type’ corresponds well to the internationally recognized term ‘humus form’. The fabric of the HC is characterized by the humus profile, which consists of the organic matter-rich soil horizons (forest floor, humus, organo-mineral and peat horizons). For the basis of comparative analysis, the classification schemas, elaborated separately for natural area HCs and soils, were used. In both schemas, the classification units are arranged according to soils moisture conditions and genesis. A good coincidence of HCs’ and soils’ types was obtained in relation to moisture scalar. The four first stages of moisture conditions enfold soils, in which the leading role belongs to the mineral components of the soil. The fifth column enfolds the transitional HC types between mineral and peat soils, whereas the typical peat soils are located in the 6th column. The genetic-lithic scalar shows that the calci-mull HCs have formed on soils rich in free calcium carbonate; forest-mull on calcareous pebble and leached soils; moder-mull on slightly eluviated endocalcareoussoils; moder types - on glossic and sod-podzolic soils; moder-mor on transitional podzols (between sod-podzolic and typical podzols) and mor type HCs on typical podzols. HCs in the 1st column (drought-timid soils) are divided according to their calcareousness and acidity, but those in the 5th and 6th columns (peaty and peat soils) - according to the content of nutrition elements in the feeding water, into 3 types. The matching of classification units of HCs and soils are analysed as well on the basis of the soils matrix table.

Use of micromorphology for humus characterization and classification in some mediterranean calcareous soils

A micromorphological approach is potentially useful in the classification of humus systems. However, the systematic description of organic material found in thin sections of humus profiles is poorly developed in comparison to already existing guides for mineral soils. This study presents the use of thin section microscopical analyses combined with digital images in order to set the highly detailed method of qualitative description and classification of some Mediterranean humus forms. Three forests and one meadow were selected for topsoil sampling in the Catalan Pre-Pyrenean mountain region. Fourteen thin sections were prepared, scanned and analyzed using the petrographic microscope. This resulted in the description of seven micromorphological fabric units based on their amount, shape, color, size, distribution and degree of decomposition. Digital images from thin section scans helped to classify three Amphi (Pachy-, Eumacro-, Eumesoamphi), and two Mull (Oligo-, Eumull) humus forms.

Morphology and Genesis of Humus Profiles under Chaparral Shrubs in Southern California

Core Ideas Litter layers of chaparral soils differ dramatically under different plant species. The rate of litterfall, balanced by the rate of decomposition, influences the type of litter layers that develop. Macrofauna, such as earthworms, are inhibited by dry conditions and have minimal effects on litter layer characteristics. Chaparral is the predominant wildland ecosystem adjoining many urban areas of California. The litter layers under this dense shrub cover are important because they modify soil climate, support soil fauna, provide nutrients, and protect against soil erosion. The objectives of this study were: (i) to understand how the morphology of chaparral litter layers changes with depth under different shrub species, and (ii) to determine the influence of shrub species and associated macrofauna on the genesis of humus profiles. Research was conducted within mature chaparral stands (38 yr after fire) on the San Dimas Experimental Forest under four common chaparral species: chamise (Adenostoma fasiculatum H. &amp; A.), hoaryleaf ceanothus (Ceanothus crassifolius Torr.), bigberry manzanita (Arctostaphylos glauca Lindl.), and scrub oak (Quercus dumosa Nutt.). Increased litter decomposition with depth was expressed as decreasing C/N ratios, proliferation of fungal hyphae, and degradation of characteristic leaf features. Mineral matter content also increased with depth in the humus profiles, resulting from mixing by soil fauna. Earthworm densities were low throughout the chaparral, caused by seasonal moisture limitations, and were insufficient to consume manzanita leaf litter effectively, leading to thicker humus profiles and the development of Mor‐type humus. Moder‐type humus forms, with thinner litter layers, were found under scrub oak and ceanothus. Chamise litter was classified as a Rhizomull because of minimal litter accumulation, resulting from low and roughly equivalent litterfall and decomposition rates. Unique characteristics of the chaparral species led to different humus profiles and humus forms but macrofauna were not an overriding genetic influence.

Evolution of forest pedogenesis in the south of the forest-steppe of the Central Russian Upland in the Late Holocene

The Late Holocene stage of forest pedogenesis has been studied on the interfluves along river valleys in the forest-steppe zone of the Central Russian Upland. The development of gray forest soils from the former chernozems as a result of the Late Holocene advance of forest vegetation over steppes is discussed. It is argued that the climatic conditions of the Subatlantic period were unstable, so that multiple alternation of forest and steppe vegetation communities took place. This specified a complex character of soil evolution upon contrasting substitution of forest pedogenesis for steppe pedogenesis. On the interfluves near the natural drainage network (balkas, ravines, and steep slopes of river valleys), the climate-driven dynamics of forest and steppe vegetation with corresponding changes in the character of pedogenesis could take place during the entire Holocene, which is reflected in a lower thickness of humus profiles and deeper leaching of carbonates from chernozems of the Early Iron Age in comparison with their analogues formed under steppe cenoses in central parts of the interfluves. Two variants of the evolution of gray forest soils can be suggested: the pulsating evolution typical of balkas and interfluves near river valleys and the continuous progressive evolution typical of automorphic (plakor) positions in central parts of the interfluves.

Гумусовий стан чорноземів типових терсових місцевостей Західного Бугу та Стиру

Volyn Upland Haplic Chernozems are distributed mainly on the terrace landscapes of the Western Bug and the Styr and their tributaries (Chornohuzka, Luha, Lypa). Most of these soils are old ploughlands that have experienced various types of degradation. Haplic Chernozems are low-humus soils and they have low storages of humus substance in the 20 cm arable layer and middle storages of humus in 100 cm soil thickness. There is correlation of C humic acids to C fulvic acids within 1.2–3.3 in the humus profile. Among the various fractions of humic substances the 2nd fraction associated to Calcium dominates. A content of “free” humic acids (1rst fraction) is very low and the amount of humin is low. The optical density of humic acids ( 0,001% НА Е1 cm, 465 nm ) are high and very high. The organic matter of Volyn Upland Haplic Chernozems has some regional peculiarities. First, it caused by topographical conditions of its formation and evolution in the Holocene. Chernozems of the 1st terrace of the River Western Bug are extremely deep. They have progressive-accumulative type of humus distribution in profile, humate type of humus in upper 100 cm layer, a very high degree of organic matter humification and the same content of humic fraction associated to Calcium and lowmiddle content of 3rd fraction associated to clay minerals. The molecules of humic acids in the humus horizon of Chernozems of the 1rst terrace are better structured that indicates the older age of humus in these soils. Chernozems of the 2nd terrace above the floodplain of the River Styr are middle-deep soils. They are characterised by the regressive-accumulative type of humus distribution in profile, humate-fulvate type of humus and very high degree of organic matter humification only in 25–50 cm layer. The content of fractions associated to Calcium and clay minerals is predominantly high. Key words: Haplic Chernozems, humus, humic acids, fulvic acids, optical density, humus condition.

Micromorphology of organic matter and humus in Mediterranean mountain soils

Humus classification is one of the most useful approaches when studying the dynamics of SOM in an ecosystem. Until now, soil micromorphology has seldom been applied to the determination of humus types, in spite of the close relationship between soil organic matter and soil structure. Micromorphological techniques were applied to the study of humus soils under forest and pasture in the Catalan Pre-Pyrenean region in order to characterize particulate organic matter, its degree of decomposition and its relationship with the physico-chemical and biotic properties of topsoil. Fourteen thin sections were studied from the humus profiles of 5 soils (2 Typic Ustifluvent, 2 Typic Calciustept and 1 Typic Ustorthent). Nine fabric units related to organic matter were identified and counted through a petrographic microscope and in scanned images of the thin sections. The results helped to classify two humus forms (Amphi and Mull) that had statistically different qualities and quantities of micromorphological features and assemblages. Amphi humus forms were characterized by a laminated fabric in the OL horizon and by a loose dropping fabric in the OF and OH horizons; with droppings of mesofauna (enchytraeids, springtails and mites), and fungal elements (sclerotia, hyphae). Mull humus forms had larger amounts of earthworm casts and feces of Isopods/Arthropods/Diptera together with faunal pores. The use of scanned thin sections proved to be useful for the general determination of the humus forms, although for a detailed organic matter study the use of the optical microscope is essential.

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.

Reaction of Graw Forest Soils on the Agricultural Management in different Climatic Conditions of Forest-Steppe

Study of agrochronosequences of automorphic graw forest soils on the territory of Central Russian Upland (Belgorod and Tula oblast) and North-East of Central Plains of USA (Iowa) shows of trend direction of transformation of these soils into Chernozem. Increasing thickness of humus profiles during their plowing up is considered a general specific feature for three examined region.

The evolution of podzolized and regraded chernozems in Eastern Upland Wooded Steppe of Ukraine and the ways of their development

It is indicated that podzolized and regarded chernozems in moderately humid and arid zones of Left-bank Wooded steppe with HTC 1,2–1,0 (within the valleys of the Sula and Oskil rivers) occur in high watersheds along right bedrock banks of the valleys, adjoining or being included into wooded refugiums. Being formed by the grove biogeocenosis, they have high rates of fertility. The morphological research of natural podzolized chernozems profiles showed, that the upper humus slightly-eluviated horizon, densely interweaved by roots, has coarse agronomically valuable structure, loose composition, dark-grey colour, that indicates high content of humus. It is mostly favoured by the biologically active, rich in calcium ground litter and the pristinity of soil texture. The general capacity of the humus profile is not less than 100 cm. While brining natural soils into tillage some changes of soil development conditions arise. They are: hydrothermic conditions, secondary carbonate enrichment (regradation), loosening of illuvial horizon. Under mechanical tillage the granular structure changes into a pulverescent and cloddy one, the topsoil becomes lighter because of humus loss, though the humus profile becomes 10–20 cm deeper. The analytical results indicate the sufficient differences in physicochemical and agrochemical characteristics between forest podzolized chernozems and their regradated analogs in tillage. Natural soils contain 5,7–6,5 % of humus in upper 0–35 cm layer, and up to 10,0 % in 0–15 cm layer. They also have considerable resources of hydrolyzable nitrogen. In agrogenic soils the humus content is up to 3,6 %. The humus is of a humate type both in podzolized and regarded soils. The smallest proportion of Сh.a./Сf.a is in the lower layer of humus eluviated horizon of forest soils. The level of humus loss by agrogenic soils in humus slightly-eluviated layer fluctuates from 37 % to 44 %. Dark-grey and grey forest soils lose more than half of humus content, typical chernozems – nearly 30 %, ordinary chernozems – 20 %. Regraded analogs are inferior according to the hydrolyzable nitrogen content. Positive evolutional changes in tillage, such as acidity reduction, bases saturation growth, illuvium destruction, didn’t yield expected results – resistance to degradation processes. For the development of agrogenic soils it is necessary to implement flexible complex systems of husbandry with minimal intensity of tillage, adapted to the landscape, bringing the culture of husbandry closer to natural conditions. Promising is the implementation of soil protection technologies with the maximum use of freak produce of plant growing. The integrity of soil composition and biologically active layer of mulch create the conditions, close to virgin ones, that lead to the transition of soil to natural non-degradation conditions without losing its productive functions.

Chemical characterization of soil organic profiles for assessing the European morphogenetic reference base of humus forms in Mediterranean environments

In the Castelporziano Reserved Area (Tyrrhenian coast near Rome, Italy), the organic horizons of 14 forest sites were chemically characterized to assess the European reference base of humus classification in Mediterranean ecosystems and evaluate the impacts of typical ecological disturbances on humification processes. Soils were sampled in three diagnostic horizons OL (litter), OF (fulvic) and OH (humic), and the biological type of humus were investigated on a morpho-functional basis and assigned to the taxonomic levels Mull, Amphi and Moder. For each diagnostic horizon, the total organic carbon (TOC%), the C/N ratio, the extractable carbon (TEC%), the humic and fulvic acids carbon (CHA%, CFA%), the degree (DH%) and the index of humification were determined. All data were statistically analyzed (ANOVA, post hoc HSD Tukey’s). In the OF horizon of some OL/OF sites, the CHA values were found very high, indicating the presence of a not-detected OH horizon. Conversely, part of the sites sampled with a complete humus profile, did not show differences between OF and OH, which should thus be grouped into a single diagnostic horizon. The humification parameters showed a fairly good correlation with the humus forms, limited to the first taxonomic level and the OF horizon. Overall, several discrepancies were found between humus classification and the chemical fingerprint of the humic profiles. In this regard, the use of screening analytical methods, i.e., the chemical characterization of OM, may provide a powerful support in modeling the morpho-functional references of humus forms on the peculiar features of Mediterranean forest environments.

Genetic Characteristics of Brown Forest Soils on the Middle Urals

Feature of mountain soil formation is that the soils on the mountain slopes are formed in different bioclimatic and orogeomorfological conditions. The purpose of research is to study genetic properties of the brown forest soils in the Middle Urals. Features of the morphological structure: truncated profile (35-75 cm), weakly expressed in the differentiation of the soil profile into individual Horizons, detritus (20-65%), loamy fine earth, the signs of podzolization in the soil profile is not found. Feature granulometric size distribution of the soil - a gradual increase in weight on the profile into Sandy Loam to Silty Clay and Clay, the dominant factions are either big Silt or Sand. Soils are characterized by a very acidic environment and high hydrolytic acidity. The soils are enriched in organic matter and humus profile characterized by prolixity. Group composition humus shows mobility, high degree of humification of organic substances to fulvic acids. Gross composition shows that the processes of soil formation on Mount, North Basegi aren’t leading to a distinctly different profile. Coefficients of geochemical accumulation, subsurface weathering, eluviation, oxidation calculated and helped define the features of the gross composition of soils. Character of distribution in profile and correlation of forms of iron help to diagnose physical processes of weathering and soil formation (burozemic pedogenesis et al.); signs Podzolization not revealed. Weathering and soil formation processes that occur with varying intensity, creating a diversity of soil cover and the spatial heterogeneity of soils, even within the same type. Thus, in the mountains of the Middle Urals brown forest soils form a number of subtypes: raw organic (900 m) - ferruginized (655 m) - metamorphosed (590 m) - clay-illuvial (577 m) - eluvial (565 m) - clay-illuvial (315 m).

Evolution of Chernozems in the southern forest-steppe of the Central Russian upland under long-term cultivation examined in the agro-chronosequences

Chernozems are the major component of soil cover in the forest-steppe of the Central Russian Upland. They underwent the most significant anthropogenic transformation in terms of duration and scale of development in profiles, due to ploughing. Despite the long list of experimental works, the obtained conclusions are often contradictory. From our point of view, the best way to observe the effect of ploughing on Chernozems is the examination of soils with different durations of cultivation based on an agrochronosequence approach which was used in this study.The most appreciable changes occurred in the arable Chernozems for the first period after the beginning of cultivation. In the soils with 16 and <100 years duration of cultivation, the following changes are observed: 5–7 to 9 cm decreasing of the humus profile, compacting of the plough-layer and its initial enrichment by clay, 15–30% decreasing of the soil organic carbon (SOC) content and stocks in the 0–30 and 0–50 cm depths, about 40 cm uplift of carbonate accumulation, and increasing of soil inorganic carbon (SIC) content and stocks in the 0–100 and 0–200 cm depths. These changes occurred due to abrupt decreasing of the plant residues in agriculture, influence of machinery treatment resulting in destruction of the plough-layer structure and this layer compaction, and changes of water regime. In the arable soils with 100–150 and 150–200 years of cultivation, the further compaction of soil mass, loss of SOC and uplifting of carbonates are not observed. There is backfilling of the SOC along the cracks in the middle part of a profile, high activity of burrowing animals, and continuing redistribution of clay fraction in the deeper horizons. These processes resulted in stabilization of SOC stocks in the profile of the arable soils on the “new” reduced level and shifting of carbonates back to the initial (before cultivation) or even lower level of location, concentrations, and stocks in a profile. After 220–240 years of cultivation, high instability of the studied indicators of the humus and carbonate status can be emphasized. Relatively rapid changes occur in Chernozem properties after the beginning of ploughing, with subsequent slowing. The activity of burrowing animals introduces an ambiguity in the trends of development of the long-ploughed Chernozems in the agrochronosequences we studied. This factor was previously underestimated.

Specific features of organic matter in urban soils of Rostov-on-Don

Data on the fractional and group composition of humus in urban soils of Rostov-on-Don are discussed. We have compared the humus profiles of chernozems under tree plantations and those buried under anthropogenic deposits (including sealed chernozems under asphalt). It is shown that the type of humus in these soils remains stable despite a decrease in its total content after the long-term burial under asphalt. Under the impact of the trees, the organic matter of the chernozems acquired some features typical of gray forest soils, i.e., the humate-fulvate type of humus in the humus horizon and the sharp drop in the humus content down the soil profile.

Change in the morphological properties of chernozems in an agrosilvicultural landscape

A change in the thickness of humus profiles and the depth of effervescence with chernozems involvement in the plowing and subsequent replacement of arable land by windbreaks was studied. A divergence of the anthropogenic evolution of chernozems in different types of their use in an agrosilvicultural landscape was established.

The formation of the agrogenic typical chernozem profile in the Ukrainian forest-steppe after plowing virgin steppe and fallow soils

The data on the changes in the physicochemical, biological, and agrochemical properties of a loamy-clayey typical chernozem after plowing a 40-year-old Fallow (for six cycles of a cereal-beet rotation) and a sandy-loamy typical chernozem (for eighteen cycles of a five-course rotation) under different intensities of their use are presented. The major role of the mineral and organic fertilizers and the methods of their application have been revealed in the formation of the humus profile, the acid-base characteristics, and the agrophysical and agrochemical properties.