No 11 (2023)

The chronosequence of soils buried under constructions of different ages at the large (h – 3.5 m, d – 74 m) kurgan Shumny in the Krasnodar Region has been studied. The kurgan was built sequentially by the people of Catacomb (XXVIII–XXII centuries BC) and Srubnaya (XV–X centuries BC) cultures, and includes five constructions, that built from the material of local soils and anthropogenic material. Each of the subsequent construction overlapped the previous one and went beyond it, covering some an additional space which allow studying a consecutive series of buried under the constructions soils. During the kurgan building (XXVIII–X centuries BC), the morphological and physicochemical properties of the soils changed: the content of organic matter and magnetic susceptibility increased, whereas the mixing up of the upper horizons by burrowing animals, the content of carbonates, and the share of exchangeable sodium in the composition of exchangeable bases decreased. The directions of these properties change in the materials of kurgan constructions, from early to late, agree with that for the soils buried below them. For the building of uneven-aged constructions of the kurgan, local soils were used, which had different properties at the time of a particular construction. Those soils occupied a significantly larger area than the kurgan, which increases the certainty of the studies. The evolution of soil properties and earth materials allow to suggest climatic trend for the period during the mound construction - atmospheric moisture increased and the mean annual temperature decreased from the Early Catacomb to Srubnaya cultures. For buried soils was carried out a palynological analysis, which, regardless of paleosol data, confirms the conclusions about climate changes. According to micromorphological observations, the Early Catacomb time can be additionally characterized as arid, which led to soil cracking and accumulation of carbonates in the upper part of soil profiles. Based on the structure and properties of mounds it is possible to identify the technology of their construction, which included compacting earthen material in dry and wet form, coarse mixing, adding of river silt, coals and bones.

The purpose of the work is to recognize rocky, sandy and calcareous soils from the surface using a multi-zone satellite image in the south of the Volga Upland in the Volgograd oblast. The object of the study was the Volga-Don irrigation system, within the experimental station “Oroshayemaya”. The recognition was carried out by the spectral brightness of the space image of the bare soil surface in 4 bands. The most ranked values among them were marked in B1 band. Three catenae were studied, along which field information about soils was obtained. It was found that the greatest brightness (B1) is created by stones, rubble and sand scattered on the surface (970–1100 units). This is followed by: surface-effervescent soils with strongly rubbled rocks at a depth of about half a meter and sandy loam soils (710–830 units), with effervescence from the soil surface on mottled loams and sands of about half a meter (up to 700 units), and surface-calcareous soils, where mottled loams and sands occur deep (more than 70 cm), or with the absence of calcareous material in the surface horizons, with a brightness of 560–670 units. The use of this approach will enable more detailed recognition of soils on the basis of satellite imagery materials and separate surface-rocky and sandy soils from surface-calcareous soils, which are displayed in images with a similar spotty heterogeneity, but differ in spectral brightness.

In this study, a systematic review and meta-analysis of scientific researches devoted to the assessment of the soil organic carbon content using Vis-NIR spectroscopy approaches was carried out. The meta-analysis included 134 studies published between 1986 and 2022 with a total sample of 709 values of quantitative metrics. The articles were searched in databases of scientific periodicals: RSCI, Science Direct, Scopus, Google Scholar by the key words: “Vis-NIR spectroscopy AND soil organic carbon”. In the process of meta-analysis, using the nonparametric one-sided Kraskel-Wallis variance analysis in conjunction with the nonparametric pairwise method, the presence of a statistically significant difference between the median values of the accepted quantitative metrics of the predictive power of the models (coefficient of determination (R²_cv/val), root mean square error (RMSE) and the ratio of performance to deviation (RPD) comparisons. As a result, the best efficiency (from the point of view of comparing these metrics) was revealed for the method of preprocessing spectral curves, for various multidimensional data analysis approaches used, and the results of assessing the organic carbon content of soils were compared between spectroscopy in the laboratory and directly in the field.

Dynamics in soil CO₂ emission, temperature and moisture was observed during the vegetation season (from May to October) in 2021 and 2022 in the residential areas of Murmansk and Apatity cities (Murmansk region) in comparison with natural references. The average emissions from urban soils were 5–7 gC/(m² day) in summer and 1–2 gC/(m² day) in spring and autumn. Temperature was the main abiogenic factor that determined the seasonal dynamics of soil respiration (R² from 0.4 to 0.7, p < 0.05; temperature coefficient Q₁₀ up to 2.5), while excess moisture had a limiting effect, especially in the natural areas. The heterogeneity of hydrothermal conditions and the content of biophilic elements determined the differences in the average CO₂ emission between natural and urban soils. For the natural soils, the average temperature was lower and the humidity was higher than for urban areas, which determined the lowest emission values. Among urban sites, higher CO₂ emissions have been shown for tree and shrub vegetation sites.

The microbiological and some physico-chemical properties of illuvial-ferruginous soddy-podburs (Entic Rustic Podzols) soils in Scots pine forests and gray-humic typical light loamy soils (Umbrisols) in secondary birch forests of the central regions of the Zabaikal krai have been studied. Fires in soddy-podburs pine forests resulted in decrease in the total exchangeable basis, total nitrogen, mobile forms of potassium and phosphorus, and in increase in the proportion of C : N; while in birch forests, on the contrary, an increase of the mentioned indicators and a narrowing of the C : N proportion in the gray-humic typical soils were observed. The content of humus in the upper soil horizon decreases only in recently burned Scots pine forests after a high-severity fire, while in other sites it increases. A decrease in the soil acidity was observed at all burned sites. High-severity fires lead to a significant decrease in the content of microbial biomass and the intensity of basal respiration, as well as to a change in the structure of ecological and trophic groups of microorganisms in the soils up to a depth of 10 cm of the mineral horizon, while low-severity fires mainly affect the duff. The qCO₂ coefficient increased 2–5 times after fires in the duff and 1.5–2 times in the humus horizon only after high-severity fires. In recently burned Scots pine forests, the storage of microbial biomass and microbial production of carbon dioxide significantly decreased up to a depth of 10 cm of the mineral soil layer. In the steppe site formed after the impact of fires in the pine forest, and in the birch forest after a high-severity fire, in the humus horizon the carbon storage of microbial biomass decreased by 15–20%, and the microbial production of CO₂ increased by 10–20%, predetermining the predominance of mineralization processes. The considered post-fire transformation of the structural and functional parameters of soil microbiocenosis, as well as a 20–40% decrease in the total carbon storage of microbial biomass in the soils of all sites demonstrate a long recovery period of soils after fires in light coniferous and deciduous forests of the central regions of the Zabaikal krai.

A study of the uncertainty sources in the assessment of organic carbon stocks in a layer of 0–30 cm at the scale of the sampling area (100 × 100 m) laid on soddy-podzolic cultivated soil (Albic Glossic Retisol (Aric, Loamic, Ochric)) was carried out. In the experiment, two sampling methods were used – the classic 10-cm layers from profiles and with an auger to the depth of 0–30 cm. The soil bulk density was determined by the Kachinsky method, the carbon content was determined by the Tyurin method. Some of the samples were additionally analyzed at the Bryansk State Agrarian University. The uncertainties associated with natural variation, sample preparation and the proper analytical process are estimated. The analytical uncertainty of the bulk density under the conditions of the experiment did not depend on the sampling depth and amounted to about 6%. The analytical uncertainty of Tyurin’s method did not differ in two laboratories. Its contribution was 5–9% of the total variation of the soil organic carbon content in the area. The uncertainty of sample preparation determined from 11 to 26%, natural variation – from 49 to 68% of the total variance, respectively. Determination of the carbon content in the samples taken by the auger, when the sample is taken immediately at 0–30 cm, wins in reducing intermediate operations and gives comparable results compared to layer-by-layer sampling. The uncertainty of sample preparation determined from 11 to 26%, natural variation – from 49 to 68% of the total variance, respectively. Determination of carbon content in samples taken by auger, when the sample is taken immediately at 0–30 cm, wins in reducing intermediate operations and gives comparable results compared to layer-by-layer soil sampling.

Soils formed in treatment facilities of sugar beet factories in the forest-steppe zone of the Kursk region were studied. The technogenic factors of soil formation associated with the industrial sugar beet activity, and post-technogenic processes, acting during the abandonment of treatment facilities, are considered. The alternation of settling ponds and the earth walls separating them is the main factor determining the kind of “cellular” pattern of the soil cover. The mode of inflow and discharge of wastewaters, their composition, as well as the duration of the abandonment of settling ponds determine the specifics of the soils formed in the bottoms of the ponds. In operating settling ponds, under the periodic impact of sewage mixed with other wastes, dark-humus quasigleyic soils are developed (Calcaric Gleysol). When ponds are abandoned with previously removed calcareous sewage sludge (press mud), in the presence of perched water dark-humus quasigleyic soils (Gleyic Cambisol) are formed in 30 years; and in conditions of a variable-humid regime, quasigleyic zooturbated Chernozems are formed in 40 years. In settling ponds with preserved sewage sludge abandoned 20 years ago, soil formation has been noticeably active only in the upper 10–15 cm; below, the properties of the layered sediment are retained. Dark-humus technogenic arti-stratified soils are identified here (Spolic Technosols). On the earth walls, dark-humus typical soils (Eutric Cambisols (Organotransportic) are formed in 70 years; on the surfaces covered with calcareous sewage sludge, underdeveloped highly alkaline technogenic pelozems (Spolic Technosols (Transportic) are identified, in which the mixed material of technogenic sediments remains practically unchanged. All soils are alkaline and strongly alkaline, rich in organic matter, carbonates, phosphates, nutrients and some heavy metals from wastewater. According to the combination of properties and characteristics, the soils of the sugar industry treatment facilities have no direct natural analogues in the Central Chernozem region and are a vivid example of soils developing under ext-reme conditions of “resource excess”.