Volume 50, Nº 5 (2017)

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.

Detailed study of a peat plateau near the southern boundary of the East European permafrost zone has been performed. The botanical and palynological compositions of the peat to the depth of 10 m, its radiocarbon dates (the AMS method), and its physical and chemical characteristics have been determined. The accumulation of peat in this area began about 8300 years ago at the end of the Boreal period. In the middle of the Atlantic period, the rate of peat accumulation reached 1.44 mm/yr. During the warming phase in the Middle Subboreal period, the peat plateau was subjected to active thermal erosion; part of the peat was eroded. The processes of thermal erosion are also active at present and destroy the edges of peat mounds. At the same time, the gradual accumulation of peat on the plateau continues. An increase in the degree of peat mineralization is expected upon the establishment of aerobic conditions against the background degradation of the permafrost. Peat plateaus and large peat mounds have been the sinks of atmospheric carbon for a larger part of their history. In this context, we do not expect their significant negative influence on the climate in the future.

Concentrations of carbon and nitrogen extractable by 0.05 M K₂SO₄ (C_ext and N_ext, respectively) in 14 soils of different ecosystems vary from 16 to 205 and from 4 to 53 mg/kg, respectively. The portion of C_ext in soil organic matter is 0.06 to 0.38% of total carbon, and the portion of N_ext is 0.12–1.05% of total nitrogen. The storage of samples and their preparation to analysis differently affect the extractability of elements. The concentration of C_ext is less variable than the concentration of N_ext. An increase in C extractability (by 1.4–6.7 times) is a common feature of all soils under drying; at the following incubation of dried soils, the extractability of C decreases by 28–56%. The extractability of N increases not only under drying (by 1.5–7.1 times) and the following incubation of samples (by 25–60% to 2–3 times), but also under freezing of most soils and at the incubation of fresh and defrozen samples. A close direct correlation is observed between the initial water content of soil and the relative increase in C extractability under drying and N extractability under freezing and drying.

A collection of yeasts isolated from soils of different types (soddy-podzolic, gray forest, and chernozems) in European Russia was analyzed. Soil yeasts were found to accelerate the development of seeds of common crops (wheat, barley, and rye). Cultures of yeasts from different taxa (representatives of the Rhodotorula, Cystofilobasidium, Sporobolomyces, Metschnikowia, Saccharomyces, Aureobasidium, Debaryomyces, Cryptococcus genera) are shown to stimulate the seed germination. The impact of soil yeasts (and preparations made on their basis) on seed germination is determined by their penetration to seed endosperm (endophytic microflora) followed by the isolation of amylolytic enzymes and physiologically active substances stimulating seed germination. The method of seed treatment is shown to affect greatly the direction of the preparations’ action. When soaking seeds in solutions with the preparation, microorganisms multiply on the seed surface, and when treating seeds using a semi-dry method, seeds themselves and endophytic microorganisms inside them begin to develop. This study can be considered one of the new directions of soil microbiology related to studying the participation of soil microorganisms in the formation of endophytic communities and their role in the germination of vascular plant seeds.

Parameters of biological activity (humus and microbial biomass reserves, potential intensity of the CO₂ emission, and enzyme activity) have been determined in arable and natural chernozems on the plains of Kabardino-Balkaria as a part of the system for the ecological assessment of the state of the soil cover. Integral parameters of the eco-biological state of studied soils have been calculated on the basis of obtained data, and the level of changes in their total biological activity has been determined. A statistically significant decrease of the values of all the considered biological properties under the impact of tillage has been found. The data of two-way ANOVA suggest a stronger influence of agricultural management in comparison with genetic features of chernozems at the level of subtype. Differential approach is insufficient for evaluating the total level of soil biological activity, because there are many biological properties of soil, and the degrees of their changes in agrogenic soils are different. An integral approach has been used; it integrates the obtained data into a single integral assessment parameter. In arable soils, this integral parameter decreases by 39–46% and makes it possible to assess the degree of disturbance of the ecological functions of soils and their capacity for self-restoration.

Hyperspectral images provide rich spectral and spatially continuous information that can be used for soil mineralogy discrimination. This paper proposes a method to evaluate the feasibility of Hyperion image in the rapid prediction of soil mineralogy. Four areas in Egypt were chosen for the current study. Preprocessing of the Hyperion data was done before applying the atmospheric correction. The minimum noise fraction transformation was used to segregate noise in the data. Various techniques were applied to the studied areas in which mixture tune matched filtering gave good results in a prediction of the end-members. Then, it employed to predict soil minerals in each cell using a spectral unmixing method. Illite, chlorite, calcite, dolomite, kaolinite, smectite, quartz, hematite, goethite, vermiculite, palygorskite and some feldspar were identified. In addition, sand and limestone, calcite and dolomite, and sand surface from similarly bright clouds can be distinguished easily based on the proposed method. The soil minerals obtained from X-ray diffraction analysis of the soil samples are in conformity with spectrally dominant mineralogy from Hyperion data. Different minerals can be identified using this method without any knowledge of field spectra or any a priori field data, thus configuring a “true” remote sensing method.

Results of a long-term field experiment on the remediation of agrosoddy-podzolic soils (Retisols) contaminated with cadmium have been analyzed. The solidification/stabilization method (S/S technology) has been used for the development of remediation technology. Different rates of ameliorants and fertilizers (limestone and phosphorite meals, superphosphate, sodium sulfide, peat, and zeolite) have been studied as ameliorating additives. It has been shown that the efficiency of ameliorating additives in decreasing the mobility of cadmium in the soil depends on their type (the dissolution of ameliorant in water and solubility products of the resulting Cd compounds), application rate, and the time elapsed since the application. In the first year of the experiment, the highest efficiency has been observed for water-soluble forms of ameliorating additives: sodium sulfide and superphosphate. Limestone meal and zeolite have showed the longest aftereffect. The application of all ameliorating additives under study has increased the yield of agricultural crops and reduced their cadmium content down to below the MPC level in most cases, which makes this agronomic practice promising for the remediation of agricultural lands with an elevated content of cadmium.