Postagrogenic migrational-mycelial chernozems of abandoned fields of different ages in the southern forest-steppe of European Russia

The restoration of the properties and morphology of migrational-mycelial (typical) chernozems under the impact of natural vegetation successions on abandoned fields of different ages (from 1 to 60 years) was studied in the forest-steppe zone of the Russian Plain. The stages of the postagrogenic transformation of the chernozems were identified, the rates of restoration of the particular soil properties were determined, and the time required for the restoration of the properties of virgin chernozems was estimated.     

Dynamics of the agrochemical fertility parameters of arable soils in the southwestern region of Central Chernozemic zone of Russia

Data of the agrochemical survey of arable soils in Belgorod oblast during the period from 1964 to 2014 have been analyzed. The soil cover mainly consists of typical chernozems (Haplic Chernozems) and leached chernozems (Luvic Chernozems) in the forest-steppe zone and ordinary chernozems (Calcic Chernozems) in the steppe zone. Under long-term agricultural use (from 1964 to 2014), the content of mobile phosphorus in arable soils of the region under study has increased from 55 to 137 mg/kg, and the content of mobile potassium has increased from 105 to 147 mg/kg. During the period of 1976–2014, the share of acid soils has increased from 22.8 to 45.8%, including medium-acid soils from 1.5 to 12.6%. No significant changes in the weighted average content of soil organic matter are revealed for the period from 1985 to 2014. The value of this parameter is within the range of 4.8–5.0%. In the 2010–2014, 95.0% of arable soils belonged to the category of low supplied with mobile sulfur; 99.2, 96.9, 94.1, and 54.4% of soils were poorly supplied with zinc, copper, cobalt, and manganese, respectively. During the same period, the maximum average productivity of the crop area (3710 f. u./ha) was noted at the application of 4.8 t/ha organic fertilizers and 97.9 kg/ha organic fertilizers on the average. The maximum long-term yields of sugar beet (36.8 t/ha) and corn grain (4.97 t/ha) were obtained at the application of relatively low fertilizer rates.     

Soil cover in the southern forest-steppe of the Central Russian Upland against the background of centennial climate fluctuations

Special approaches and algorithms for studying the response of zonal soils and the soil cover of the forest-steppe zone to climate fluctuations were developed on the basis of data of repeated soil surveys. They made it possible to analyze the particular transformations of the soil cover as indicators of short-term climate fluctuations in the southern forest-steppe of the Central Russian Upland. Vector soil maps and related databases on soil polygons were developed using GIS technologies. Changes in the climatic conditions between two rounds of large-scale soil surveys in 1971 and 1991 reflecting the so-called Brückner cycles were identified. A characteristic feature of climate change during that period was the rise in the mean annual air temperature by 0.2°C and an increase in the mean annual precipitation by 83 mm. In response to this change, the area of leached chernozems (Luvic Chernozems) on the interfluves somewhat increased, whereas the area of typical chernozems (Haplic Chernozems) decreased.     

Agrogenic evolution of automorphic chernozems in the forest-steppe zone (Belgorod oblast)

Agrochronosequences of chernozems with different periods of their use in rainfed farming with application of traditional technologies have been studied in a typical forest-steppe area in Belgorod oblast. Certain stages in the development of these soils during more than two centuries of their agricultural use have been identified. These stages are related to changes in the intensity and direction of soil forming processes, such as soil compaction, soil aggregation, dehumification of the upper horizons, calcification of the soil profiles, argillization, etc. A significant impact on the soil changes during the agrogenic evolution of chernozems is exerted by the digging activity of burrowers, which is especially pronounced in the old-arable chernozems.     

Comparative assessment of the biological tolerance of chernozems in the south of Russia towards contamination with Cr, Cu, Ni, and Pb in a model experiment

The biological properties of chernozems in the south of Russia worsen under the impact of contamination with Cr, Cu, Ni, and Pb compounds. The tolerance of chernozems towards contamination decreases in the following sequence: ordinary chernozems > typical chernozems > southern chernozems > leached vertic chernozems. This sequence is specified by the soil reaction and the organic matter content. The high humus content determines the high buffer capacity of chernozems towards contamination with chromium, whereas the high pH values ensure the soil tolerance towards contamination with copper, nickel, and lead. With respect to their adverse effect on the biological properties of the chernozems, the studied heavy metals can be arranged into the following sequence: CrO₃ > CuO > PbO ≥ NiO.     

Soil loss tolerance in the central chernozemic region of the European part of Russia

To calculate the soil loss tolerance for chernozems of the central chernozemic region, a linear modification of Skidmore’s equation was used. The soil loss tolerance values were obtained with due account for the soil type, the degree of erodibility, and the crop rotation pattern. The maximum possible value (10 t/ha per year) was obtained for a typical noneroded chernozem in all the crop rotations. Close values were obtained for noneroded leached and typical chernozems (9.6–9.9 t/ha per year depending on the crop rotation pattern). The soil loss tolerance for the noneroded podzolized chernozem was somewhat lower: 9.1 t/ha per year in the grain-herb-intertilled crop rotation and 6.3 t/ha/year in the grain-intertilled crop rotation. With an increase in the degree of the soil erosion, the soil loss tolerance decreased in all the variants of the experiment with an especially abrupt decrease in the grain-intertilled crop rotation (from 9.9–10.0 to 0.3–2.0 t/ha per year in the, respectively, noneroded and slightly eroded ordinary and typical chernozems). In the grain-herb-intertilled crop rotation, these differences were much smaller: in the slightly eroded typical chernozem the soil loss tolerance was estimated at 9.7 t/ha per year, while, in the slightly eroded typical chernozem, at 8.1 t/ha per year. The moderately eroded chernozems without the addition of manure could only be used in the grain-herb-intertilled crop rotation; the soil loss tolerance was estimated at 9.0 t/ha per year for the typical chernozem and 4.3 t/ha per year for the ordinary chernozem.     

Soil cover patterns on flat interfluves in the Kamennaya Steppe

Three-component soil combinations developed on flat interfluves in the Kamennaya Steppe consist of the low-contrasting areas of typical, leached, and zooturbated chernozems. Against the background of this natural soil cover pattern, the low-contrasting combinations of agrochernozems and postagrogenic chernozems are formed under the impact of different land uses. Both random and regular patterns of the spatial variability in the morphometric soil characteristics can be distinguished. The latter are manifested by regular changes in the thickness of soil horizons predetermined by the spatial differentiation of local factors (the burrowing activity of animals and the redistribution of water by the elements of microtopography) affecting the soil development. On the flat interfluves, the morphometric parameters of the soils display weak statistical correlation with the parameters of the relief for the entire soil combination. However, they are closely correlated with the relief in the thalweg zones of local hollows occupied by leached chernozems. The specificity of the soil cover pattern in the Kamennaya Steppe should be taken into account upon the organization of soil monitoring studies; a detailed soil mapping of key plots is necessary.     

Soil development in anthropogenically disturbed forest-steppe landscapes

The results of long-term studies of chernozem development in anthropogenically disturbed landscapes of the forest-steppe zone are discussed. Parameters characterizing the formation of the humus horizon of chernozems and the rate of this process are presented. Critical points and characteristic times of the formation of humus horizons are determined. The regeneration of soil properties as dependent on the degree of anthropogenic disturbance of chernozems is estimated.     

Diversity of soil nematodes across a Mediterranean ecotone

As an indicator of ecological maturity, we have analyzed the nematode community of an erosion-prone Mediterranean macchia and a pine stand within it. Species richness, abundance, diversity and maturity indexes have been measured from a number of standardized soil samples taken along parallel transects laid across the boundary between the pine stand and the macchia. Results of multifactor analysis on these data show three distinct nematode communities of different species composition. The intermediate nematode community (ecotone) is not a mixture of elements of adjacent communities (pine stand and macchia), thus suggesting the existence of an ecotone-specific community beyond the expected boundary effect.     

Irrigation of steppe soils in the south of Russia: Problems and solutions (Analysis of Irrigation Practices in 1950–1990)

Experience in irrigation of chernozems in the steppe zone of Russia for a period from 1950 to 1990 is analyzed. By the end of this period and in the subsequent years, the areas under irrigation reduced considerably, and the soil productivity worsened. This was caused by the improper design of irrigation systems, on the one hand, and by the low tolerance of chernozems toward increased moistening upon irrigation, on the other hand. The analysis of the factors and regimes of soil formation under irrigation conditions shows that irrigation-induced changes in the soil hydrology also lead to changes in the soil physicochemical, biochemical, and other properties. In particular, changes in the composition of exchangeable cations lead to the development of solonetzic process. In many areas, irrigation of chernozems was accompanied by the appearance of solonetzic, vertic, saline, and eroded soils. The development of soil degradation processes is described. In general, the deterioration of irrigated chernozems was related to the absence of adequate experience in irrigation of steppe soils, unskilled personnel, improper regime of irrigation, and excessively high rates of watering. In some cases, the poor quality of irrigation water resulted in the development of soil salinization and alkalization. To improve the situation, the training of personnel is necessary; the strategy of continuous irrigation should be replaced by the strategy of supplementary irrigation in the critical periods of crop development.     

Specific features of water permeability in virgin and cultivated chernozems

The tendency and type of quantitative changes in the main characteristics of the water permeability of automorphic (typical and ordinary) chernozems in the central part of the Russian Plain have been studied in the system of virgin soil (long-term fallow), rainfed plowland, and irrigated plowland. It is shown that irrigation exerts the most pronounced adverse effect on the water permeability of chernozems. The revealed causes of unfavorable changes in the water permeability of chernozems in the region are related to their agricultural use.     

Normatives of changes in the physical properties of chernozems in the forest-steppe zone of European Russia under conditions of their intensive agricultural use

Normatives of changes in the physical properties of plowed typical and leached heavy loamy and light clayey chernozems under their intensive agricultural use are developed for two major provinces of the forest-steppe zone of European Russia. The limits of the optimal, permissible, and critical values of the physical properties of the plow layer for crop growth are determined. It is shown that the variation in the physical properties of the plow layer of chernozems is determined not only by the zonal-provincial features but also by the period and type of their use and the farming standards. In the plow layer, the natural differences in the physical properties of chernozems at the subtype level are significantly leveled by agrotechnical measures and the similar requirements of cultivated crops. Upon high farming standards, the physical properties of plowed chernozems on fields with high and moderate fertility levels remain close to the optimum or permissible values. The technogenic compaction of the plow layer of chernozems of different textures in the forest-steppe zone and the corresponding decrease in the yield of cereals are predicted on the basis of known models. The developed normatives of changes in the physical properties of cultivated chernozems can be applied to assess the modern state of the physical conditions of these soils and the tendencies of their alteration; they can serve as a basis for improving regional systems of land use.     

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.     

Humus status and distribution of the underground phytomass in eroded chernozems of the Cis-Salair region

It is shown that humus loss may reach 1.7 t/ha per year as a result of plowing of leached chernozems and erosion development. Distribution of underground phytomass in uneroded and eroded chernozems and slightly aggraded meadow-chernozemic soils of dissected areas in the Cis-Salair region is analyzed. It is shown that an increase in the degree of soil erosion is accompanied by a decrease in the total phytomass reserves, whereas the average depth of the root zone increases.     

Impact of weather anomalies in recent decades on the water regime of typical chernozems of the reserved steppe area in Kursk oblast

The analysis of long-term weather records and data on the water budget in a 3-m-deep layer of typical chernozems in the reserved steppe area has shown considerable changes in the soil hydrological regime under the impact of climatic fluctuations. In the past 34 years, the warm season has become more humid and the cold season has become warmer in comparison with the climatic norm. These changes have been accompanied by the settling of trees and shrubs on the reserved steppe territory; more frequent cases of water percolation throughout the entire profile of chernozems owing to the increased accumulation of water reserves in the fall, winter, and spring seasons; less active evapotranspiration of soil water during the growing season; and the smaller deficit of soil water in the fall. In general, the chernozems have become better moistened, which has led to certain changes in their genetic features.     

Fractional composition of humus in leached chernozems and gleyed podzolized chernozem-like soils of the northern forest-steppe zone

The composition of humus in leached chernozems differs from that in gleyed podzolized chernozem-like soils in the northern forest-steppe zone of European Russia. Leached chernozems have the fulvate-humate humus. Gleyed podzolized chernozem-like soils have the humate-fulvate humus. A more aggressive composition of humus in the latter soils is caused by their overwetting and the development of gley processes under conditions of a stagnant-percolative soil water regime.     

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.     

What Characteristics of Soil Fertility Can Improve in Mixed Stands of Scots Pine and European Beech Compared with Monospecific Stands?

According to the current trends in forest management, endeavors are made to adjust the species composition to the site conditions and to increase the biodiversity. Changes in the species composition of forest stands lead to modifications of soil properties and nutrients cycle. The objective of the study was to evaluate the effect of monocultures (beech and pine) and mixed-species stands (pine-beech) on soil properties, particularly accumulation of soil organic carbon. We aim to demonstrate how different vegetation types influence soil properties in surface horizons of soil. The study sites are located in Germany and Poland under different tree stands Pinus sylvestris L., Fagus sylvatica L., and mixed-species stand. Contents of organic carbon and nitrogen, pH, and soil texture were analyzed. The studies conducted confirmed the positive effect of beech and mixed-species stands on acidification of surface soil horizons. We ordered the stands tested according to acidification effect on soils: pine stand > mixed stand > beech stand, which is consistent with previous studies. The most beneficial impact on the accumulation of organic carbon was observed in mixed-species stands in which beech and pine were found. Lower carbon-to-nitrogen (C/N) ratios confirm the high rate of organic matter decomposition and lower C/N ratio was reported in soil under beech stand in comparison to pine stands.     

The soil cover on a gentle watershed slope under conditions of the recent seasonal soil overwetting in the Kamennaya Steppe area

The soil cover pattern on a gentle watershed slope at the Kamennaya Steppe Experimental Farm consists of the areas of typical chernozems, zooturbated chernozems, and leached chernozems evolving into chernozemic-meadow soils; they are oriented along the slope. This soil combination is complicated by the presence of slightly eroded and slightly saline soils. The seasonal overwetting and inundation of the soils are favored by the discharge of the groundwater above the local aquiclude represented by the layer of dark brown calcareous clay at the depth of 1.0–2.2 m from the soil surface and by the concentration of snowmelt runoff in the concave parts of the slope. Seasonal overwetting of the soils leads to the appearance of olive tints and small iron concretions (quasigley features) in the lower horizons; in some cases, proper gley features (bluish coatings) appear in the chernozems. The veinlets of powdery gypsum are formed in the middle-profile horizons of some soils. Salt efflorescence on the surface in some places is also the result of the seasonal overwetting of the soils followed by their intense drying upon the hot and droughty weather conditions.     

Temporal changes of eroded soils depending on their agricultural use in the southern Cis-Ural region

Temporal changes of eroded soils in the southern Cis-Ural region (Republic of Bashkortostan) depending on their agricultural use during the period from 1975 to 2011 were studied. In the northern foreststeppe zone, the development of erosion processes was retarded upon the use of soil-saving management practices and grain-fallow-grass crop rotations. In slightly eroded light gray forest soils (Eutric Retisols (Cutanic)), the thickness of humus-accumulative horizons and the content of humus increased; the conversion of cropland into permanent fallow was found to be the most efficient measure to control soil erosion. In podzolized chernozems (Luvic Greyzemic Chernic Phaeozems) and typical chernozems (Haplic Chernozems) of the Cis-Ural steppe, the content of humus in the plow layer under grain-row crop rotation and classical soil management decreased, especially in moderately eroded soils. The development of water and wind erosion on slopes depended on the slope shape: the texture of soils at different degrees of erosion on slopes with free runoff became coarser by one gradation after 35 years; in the presence of linear obstacles in the lower part of slopes, the content of fine fractions in moderately and strongly eroded soils increased.