1.5.19. Почвоведение

In a model experiment, the decomposition of white poplar leaf litter in the humus-accumulative horizon of Calcic Chernozem was studied. Experimental choice included artificial contamination with a zinc sulfate solution, as well as watering with water with a humic solution. The duration of the experiment is 1 month. After this period, soil and decaying litter were taken. The total content of zinc in the soil was determined by X-ray fluorescence method and the amount of mobile zinc compounds in the acetate-ammonia extract was determined using atomic absorption spectroscopy, as well as the state of structural units by dry and wet sieving. In an aqueous extract from decaying leaf litter, the content of carbon and nitrogen was determined. It was found that watering with water containing a humic solution promotes the acceleration of the decomposition and humification of leaf litter: the concentration of carbon in the extract from the decomposing litter increases, as well as the value of the chromaticity coefficient. The addition of zinc sulfate with irrigation water led to a high degree of soil degradation, and this reduced the rate of decomposition of plant residues. The combined addition of zinc sulfate and the humic solution accelerates the decomposition of plant litter, practically eliminating the negative effect of zinc pollution on this process. When humic fertilization is applied to the soil, there is a significant increase in the percentage of agronomically valuable aggregates and a convincing increase in the value of the structural coefficient. Zinc contamination practically does not affect the results of dry sieving, but it sharply increases the water resistance of the aggregates to the destructive action of water.

Due to significant differences in environmental and genetic properties, soils of the Black Sea coast of the Caucasus vary significantly in resistance to anthropogenic effects. The purpose of this work is to investigate the change in catalase activity in the main types and subtypes of soils of the Black Sea coast of the Caucasus during contamination with heavy metals (TM) and oil. Oil and TM (Cr, Cu, Ni, Pb) were chosen as pollutants, it was they that largely contaminated soils in southern Russia. Catalase activity was determined by Galstyan 30 days after contamination. As a result of the model experiments, it was found that soil contamination with TM and oil, as a rule, reduces the activity of soil catalase of the Black Sea coast of the Caucasus. By the degree of negative influence on the soil catalase activity of the Black Sea coast of the Caucasus, TM oxides form the following series: Cr > Cu ≥ Pb ≥ Ni. Soil rows of the Black Sea coast of the Caucasus were obtained in terms of the degree of decrease in catalase activity during TM pollution (soils are located as their stability decreases): yellow soil ≥ sod-carbonate typical ≥ brown typical ≥ brown carbonate = sod-carbonate leached ≥ brown forest acidic ≥ brown leached ≥ brown forest acidic, and when contaminated with oil: brown carbonate  > brown typical > sod-carbonate leached > brown forest acidic dormant ≥ sod-carbonate typical ≥ yellowish ≥ brown forest acidic.

The studies were carried out in the steep-growing areas of the «Step Priazovskaya» nature reserve, located in the educational and experimental farm «Nedvigovka» of the Southern Federal University in the Myasnikovsky district of the Rostov region. Physical (soil density and its structural state) and chemical (humus content and composition) properties were studied in soils formed on deposits of different ages (3, 4, 5, 15, and more than 60 years), the comparison option was the chernozem of the arable area, directly adjacent to the steppe land. Soil density was determined by the cutting ring method. The state of the structure (dry and wet sieving) was studied by the Savvinov method. Organic carbon content was determined by oxidation with a chromium mixture (I.V. Tyurin’s method in the Orlov-Grindel modification) with a spectrometric ending. The fractional-group composition of humus was determined according to Ponomareva-Plotnikova. The object of the study is migration-segregation chernozem (Calcic Chernozem according to WRB, 2014). According to the soil classification of the USSR, it was called ordinary carbonate chernozem, even earlier known as Severo-Azov chernozem. The steppe formation of chernozem, expressed in the change of succession stages from rhizome-cereal to fescue, with a predominance of dense sod grasses, is accompanied by a change in soil properties. An increase in the bulk density in the first years of abandoning the fallow plots was established, followed by a gradual decrease in the value of this indicator. The structural state is improving: as the steppe increases, the structural and water resistance coefficients of the aggregates increase. The humus content increases in the row arable land – 3–4 years – 5 years – 10 years – 60 years of fallow in the samples of autumn samping, and differs little during the period of active vegetation of plants. The qualitative composition of humus also changes due to an increase in the content of fulvic acids and a decrease in the non-hydrolyzable residue.

Identification of soil type taxonomic units in the new Russian Soil Classification is based on combinations of diagnostic horizons, and the topsoils in all chernozems are qualified as dark-humus (AU) diagnostic horizon in “virgin”soils, and agrodark-humus (PU) one in arable soils. However, the dark-humus horizon occurs in other soils, and its properties are somewhat different there. For a more adequate diagnostic of chernozems, which is required for solving either pedogenetic, or applied problems (including the ecological issues), it is proposed to introduce in the updated version of the Russian Soil Classification system a new diagnostic horizon – black-humus (AN) horizon specifying chernozems among other soils. The AN horizon differs of the AU horizon by its monochromic color, high pedality with strong structure, quality of humus, physical properties, fertility and resilience to human impacts. This pair of horizons resembles chernic and mollic horizons in WRB. It is also discussed whether it is feasible to introduce the arable derivate of the black-humus horizon (PN), since its properties have much in common with those of the dark-humus horizon.  

Methodical principles for determination and data interpretation of the investigation of soil bulk density have considered at the article. Necessity of introduction for soil science two terms for the characteristic of bulk density such as «bulk density at maximum shrinkage of soil» and «bulk density at the maximum swelling of soil» has proved. In addition, amendments for the calculation method for the soil substances stock have offered.

A method for assessing the natural resource potential (PRP) of agricultural landscapes in Russia is proposed. Evaluation PRP is carried out for soils used in agriculture. Agro-climatic indicators that determine the productivity of agricultural crops are taken into account: the sum of temperatures above 10°C and the annual amount of precipitation. All soils and agro-climatic parameters are ranked in points from 5 to 100. It is proposed to use information and logical analysis to calculate the final PRP of the agricultural landscape. In the equations, the estimated indicators are arranged as the impact on the crop decreases. Agricultural landscapes are evaluated taking into account soil properties and two important agro-climatic parameters that characterize the conditions of heat and moisture supply. These formulas are "open", which allows you to enter other informative, estimated indicators in them.  

In the nineteenth century, V. V. Dokuchaev argued that soils are formed according to the action of 5 factors of soil formation. In the 21st century, the sixth factor, anthropogenic impact, is increasingly manifesting itself. In places of mining, anthropogenesis manifests itself to the highest degree. It will never be possible to restore the original appearance of the territory, since according to the laws of genetic soil science, if at least one soil formation factor is changed, soils will be different. Morphological properties, as the most indicative, give an idea of the quality of soils formed in landscapes exposed to the sixth factor of soil formation. The article reflects the features of the formation of soil cover, which morphologically differs sharply from background soils - leached chernozems. Embryozems of anthropogenic landscapes of the Gorlovsky coal basin should be considered as azonal soil formations. The azonality of embryozems leads to the emergence of new ecological systems with a number of distinctive features from zonal ones, the main of which is the formation of soils with a small set of soil functions. As a result of the study, an unsatisfactory soil and ecological assessment of the territory that underwent anthropogenesis is given, because after 35 years from the initial phase of anthropogenesis, embryozems of the primary stages of soil formation are determined in the soil cover - initial and organo-accumulative and there are no embryozems of the late stages of soil formation - soddy, the more humus-accumulative. Trends in the direction of soil development in a disturbed ecosystem are determined: the formation of azonal dry-steppe soils and various subtypes of organo-accumulative embryozems is assumed as part of the soil cover. Ways are suggested to restore the landscape transformed by man, namely, to form technozems with a high set of soil and environmental functions.  

The article presents the results of research to determine the influence of different methods of basic soil treatment and the predecessor of winter wheat on the water quality of ordinary chernozems and productivity in conditions of erosion-dangerous slope. It was found that the use of chisel as the main soil treatment had a positive effect on the structure of erosion-dangerous black earth soils, increasing not only the water strength of aggregates, but also the water strength coefficient, which contributed to an increase in soil resistance to water erosion. The highest coefficient of soil water quality was observed when chiseling pure steam from the precursor. When sowing, it was 3.71, during the renewal of the spring growing season it increased to 4.26, and when harvesting, it increased to 4.65. The highest yield of winter wheat of 3.99 t / ha was formed with the chisel method of soil treatment according to the precursor pure steam.  

Since the beginning of the 90s, arable soils have ceased to be cultivated, arable land has gradually transferred to fallow lands, and the fertility of fallow lands has deteriorated. Gradually, on fallow soils, weed vegetation began to grow. The soils of these areas have degraded. The soils of fallow areas have not been surveyed for a long time. The aim of the study was to study the effect of organic-mineral fertilizers on the fertility and productivity of the granary. The subjects of research are dark chestnut soils. The classification of 1977 is still in effect in Kazakhstan; in Russian Federation, a new classification of soils has been adopted, where these soils are called texture-carbonate chernozems. Alkaline hydrolyzable nitrogen characterizes potential soil fertility. The alkaline hydrolyzable nitrogen in 0—20cm layer contents 77—105 mg/kg of soil. In a layer of 20-40 cm is from 70 to 98 mg / kg of soil. That is, both in the 0—20 layer and in the 20—40 cm layer, the content of alkaline hydrolyzable nitrogen is high. According to the content of labile phosphorus, fallow soil is characterized by a low and medium degree of availability. It is provided with medium potassium. The studied soils are characterized by low natural fertility; the humus content in the surface soil layer does not exceed 3,85 %. As a result of the processing of fallow soils, the introduction of organomineral fertilizers and wheat grass crops, the soil fertility was improved.  

The aim of the research was to study the diagnostic features of the meadow-brown soils (irrigated meadow-brown merged, meadow-brown cultivated, meadow-brown carbonate) of the southern slope of the Greater Caucasus and give the name to these soils in accordance with the International Classification Soils on the Reference Base (WRB) in 2015. The objects of research are meadow-brown soils of the southern slope of the Greater Caucasus. Field experiments and analyzes on soil samples were carried out by standard methods. The paper deals with the main features of meadow-brown soils of the southern slope of the Greater Caucasus, their distribution, relief, climate, vegetation, morphological description, basic genetic signs (content of humus, exchange nitrogen, ratio of C:N, pH, cation exchange capacity, granulometric composition) and soil classification. For the first time, an attempt was made to give the name meadow-brown soils (irrigated meadow-brown merged, meadow-brown carbonate) according to the international classification of soils based on the Reference Base (WRB). With the different principal and supplementary qualifiers all soils were classified as Cambisols.  

The soil cover of urbanized areas, regardless of the degree of anthropogenic influence, can be subjected to significant pressure. The article is devoted to establishing the features of the distribution of the activity concentration of natural radionuclides and artificial 137Cs in the upper soil layer of some towns and villages of the Rostov region. The activity concentration of radionuclides in soils was determined by the instrumental gamma spectrometric method of radionuclide analysis. The arithmetic mean activity concentration of radionuclides in the soils of the urbanized territories of the Rostov region was 13.3 Bq/kg, 21.4 Bq/kg, 27.3 Bq/kg and 435.9 Bq/kg for 137Cs, 226Ra, 232Th and 40K, respectively. The size, status and degree of urbanization do not affect the average concentrations of radionuclides in the topsoil. In this case, territories contaminated with various pollutants, for example, oil products, can be recorded and, as a result, contain rather high concentrations of natural radionuclides.