A comparison of soil-geographical units of the Unified State Register of Soils of Russia with a database on the disappearance of woody forest vegetation for the period from 2000 to 2021, built on Landsat satellite data, made it possible to identify soil areas in the country that were affected by forest fires. The greatest impact on the soil cover is noted for the Asian part of the Russian Federation within the cryolithozone, where the pyrogenesis zone mainly includes the most common here thin rubble soils of mountain taiga forests: podburs, podzols, rzhavozems, cryohomogeneous peat-cryozems, soils of the organo-accumulative section, (carbo)lithozems, petrozems, i.e. soils most susceptible to erosion processes, as well as ice-frozen fine-earth soils of medium-heavy granulometric composition: pale yellow, pale solodized, gleyzems, cryozems, in which the processes of paludification, cryosolifluction, thermokarst are activated. The probability of activation of post-pyrogenic soil degradation processes as a result of forest loss in the period from 2000 to 2021 exists on approximately 16 % of the territory of Russia. These are water (10 %) and wind (8 %) erosion, paludification (about 15 %) and cryogenic processes of solifluction (10 %) and thermokarst (7 %). Areas with a potential for increased post-fire water erosion are located in the Central Siberian Plateau, Transbaikalia, North-Eastern Yakutia, the south of the Far East; deflation – in Yakutia, northern Baikal and Transbaikalia, paludification – in the Central Yakut lake-alluvial plain, in the intermountain basins of Transbaikalia and North-Eastern Yakutia, in Western Siberia, cryosolifluction and thermokarst – in Central and Northern Yakutia, Krasnoyarsk Krai, Magadan Oblast, and in the north of Amur Oblast.

Modern soil physical models traditionally consider the pore space as static; however, new visualization techniques, such as X-ray tomography, have revealed structural dynamics that can intensively change under the influence of moisture and temperature. The aim of this study is to investigate the structure of the pore space using pore network models (PNMs) and to compare them with the method of the water retention curve (WRC). The study was based on the laboratory experiment involving the wetting and drying of samples of Haplic Chernozem from the Kursk region, with measurements of WRC and registration of the soil structure state using X-ray computed tomography (XCT). From the 3D soil images, PNMs were extracted, for which hydrophysical properties were calculated, including modeling of the WRC and the water conductivity. The comparison of pore sizes and volumes shows a significant excess of the pore volume calculated based on WRC measurements, compared to direct geometry measurements by XCT. The difference in the representation of the pore space is expressed through significant differences in modeling of water conductivity based on PNMs in the regions of low and high capillar pressure (large and small pore sizes, respectively) compared to the approach based on WRC modeling using the van Genuchten and van Genuchten-Mualem equations. However, the curves of relative unsaturated hydraulic conductivity measured using PNMs and based on WRC show a high degree of similarity. Based on the results of the study, it was demonstrated that modeling soil hydrophysical properties using PNMs is a highly promising approach and has the potential to be a more reliable tool for modeling water dynamics than the approach based on describing WRC using the van Genuchten equation. Nevertheless, the fundamental differences between the methods leave several questions open that require answers before the widespread use of PNMs for calculation of soil hydrophysical properties.

The world has accumulated quite a lot of experience in remote assessment of organic carbon content in soils. But, except for rather schematic global approaches, monitoring at the detailed level is still localized, and the constructed models cannot be extrapolated to other territories. The aim of the study was to develop a strategy for unified remote sensing monitoring of organic carbon content in arable soil horizons for the whole territory of Russia and to test it. The strategy is based on the analysis of Landsat 8-9 OLI satellite data archives. Regression models (linear or exponential) of the relationship between the reflectance of the open surface of soils in the near infrared range and the content of organic carbon in arable soil horizons are built on the basis of literature data and their parameters are selected individually for each unit of the country regionalization, which is the geometric part of the Unified State Register of Soil Resources of Russia. On the basis of models, a base map of carbon content in arable soil horizons for a period of five years was constructed. After that, a map of carbon content at the end of the current year was built on the basis of the same methodological approaches. Comparison of the maps allows estimation of changes in the current year relative to the base period. Demonstration of the use of this approach was carried out for two contrasting regionalization units in the Tver and Tula regions of Russia. The approach showed low, but comparable to analogs, accuracy for detecting small changes in carbon content (prediction error was 0.8–1.0%), but allowed to confidently identify areas with abrupt changes. It is assumed that the accuracy of modeling will increase annually with the accumulation of field data on carbon content in the arable horizon of soils, as well as with the refinement of models in each regionalization unit. Such an approach can be used to organize annual remote sensing monitoring of carbon content changes in arable soils within the framework of climate projects of the country.

Conversion of natural forests into conventional agricultural lands may lead to significant soil organic carbon losses. Soil organic carbon stock assessment for such land use changes is very crucial for appropriate land use management, soil fertility improvement, ecosystem restoration and climate-change mitigation measures. However, information on the status of soil organic carbon stocks for such land use types is limited in Eritrea and in the Horn of Africa. Thus, the study aimed to assess soil organic carbon stocks for natural forests, continuous cropping, shifting cultivation, and grazing land use types. Fifty-one surface soil samples were collected from these four types of land use around Adi Hakin, Laelay Gash, Eritrea, and analysed. One-way analysis of variance (ANOVA) test results showed that land use changes had highly significant effect on soil organic carbon stock (p < 0.001). The natural forest and continuous cropping land use types recorded the highest (51.69 Mg·ha^-1) and lowest (21.23 Mg·ha^-1) mean soil organic carbon stocks, respectively. Grazing and shifting cultivation had 22.74 and 23.57 Mg·ha^-1 soil organic carbon stocks, respectively. Conversion of natural forest into continuous cropping, grazing, and shifting cultivation in the study area in the long run resulted in losing 58.93, 56.00 and 54.40% of soil organic carbon stocks, and emitting 111.79, 106.25 and 103.20 Mg·CO₂ ha^-1, respectively, to the atmosphere. Thus, the study concludes that conventional agriculture contributes to the atmospheric CO₂ concentration through soil carbon emission. On the contrary, conservation of natural forests is crucial for soil carbon sequestration and atmospheric CO₂ mitigation endeavors.

The chemical structure of organic matter (OM) pools within water-stable free microaggregates, isolated from air-dry aggregates (2–1 mm) in arable horizons of non-eroded, eroded and deposited agrochernozems has been studied by solid-state ¹³C-NMR spectroscopy. An assessment is made of the alteration of their chemical structure in the denudative-accumulative landscape. It was revealed that the overwhelming majority of water-stable free microaggregates in erosion zone are the fragments of destroyed macroaggregates, mainly newly formed due to the dynamic replacement of OM in situ. This is clearly evidenced by the integral indicators of the chemical structure of all OM pools in free microaggregates of eroded agrochernozem compared to those of the non-eroded one: reduced OM decomposition index (DI), OM aromaticity index (ARI) and OM hydrophobicity index (HI). Analytical data indicate the predominant transport from the erosion zone of microaggregates, represented by fragments of destroyed and mainly newly formed macroaggregates. During the transport phase, the previously physically protected occluded OM of free microaggregates undergoes partial mineralization. Predominantly its most labile part (hydrolysable) is mineralized, and its stable part remains little/non-changed. Mineral-associated OM (Clay and Residue) changes little, maintaining relative freshness.

Sustainable functioning of fruit agrocenoses and obtaining ecologically clean products are impossible without assessing the microelement content in soils. The paper presents the results of studying the content and distribution of copper, manganese, zinc, iron and nickel in calcic chernozem under cherry (Prunus avium L.) cultivated in the southern horticultural zone of the Rostov region. Soil samples were collected from the following layers: 0– 20, 20–40, 40–60, 60–80, 80–100 cm. The accumulative type of profile distribution with the greatest concentration in the humus-accumulative horizon 0–40 cm was established for all the elements under consideration. The stocks of trace elements in the metre layer of soil were determined. According to content levels Cu, Mn, Zn, Fe and Ni can be arranged in the following decreasing series: gross content – Fe > Mn > Zn > Ni > Cu, mobile forms – Mn > Fe > Cu > Ni > Zn. The share of mobile Cu, Zn, Ni, Fe from their total content in all layers of calcic chernozem is very low and vary from 0.02 to 0.45%, for Mn – from 1.67 to 2.04%. It was revealed that the carbonate content is one of the key factors determining the mobility of trace elements in calcic chernozem. An inverse correlation has been established between the studied mobile compounds of trace elements and the amount of carbonates (for Cu r = –0.88, for Mn r = –0.85, for Zn r = –0.74, for Ni r = –0.85 and for Fe r = –0.84 at p < 0.05). The amount of copper, manganese, zinc, iron and nickel in calcic chernozem in fruit agrocenosis corresponds to regional norms and does not exceed the maximum permissible concentrations.

The article presents the possibilities of detailed analysis of the spatial distribution of soil acidity to reduce liming costs and optimise land use in five working areas of the experimental farm “Gutko S.”. Based on variogram analysis, the patterns of acidity distribution in key areas are determined. Regression analysis showed a significant and high polynomial dependence between the NDVI index and soil acidity (the correlation ratio is 0.60–0.75 at sites No. 2–4) and a significant direct linear relationship at site No. 1. Geostatistical analysis revealed an average spatial dependence (residual variance of 29.9%) at site No. 3. Based on the strong relationship between the average values of the NDVI index for the summer months over 3 years (9 images) and soil acidity, it was proposed to use NDVI as a predictor for optimising the sampling grid using stochastic modelling. It was found that the relationship with NDVI is more pronounced in areas where the relief is less fragmented. Based on calculations of costs for liming, the advantage of detailed acidity accounting over the classical methods of agrochemical survey used in the Republic of Belarus was substantiated. The profit per rotation was about 1,200 US dollars from an area of 184.5 ha. Based on the results of the analysis of acidity distribution, the NDVI index and field history, a more detailed scheme of elementary plots with crop rotations that take into account soil acidity was proposed. The limitations of the available agricultural equipment prevented a more detailed division of the plots.

 The influence of long-term use of organic, mineral and organomineral fertilizer systems leveled by nutrients (control – without fertilizer application; cattle manure 10 and 20 t/ha per year; NPK equivalent to 10 and 20 t of manure; manure 5, 10 and 20 t + NPK equivalent to 5, 10 and 20 tons of manure) on the exchangeable (pH_KCL), hydrolytic acidity (Ac_tot), the sum of exchangeable bases (S) and the degree of soil saturation with bases (V) is considered. The field experiment was performed in 1969–1970 at the Perm Research Institute of Agriculture, on soddy slightly podzolic heavy loam soil. Field crop rotation included 8 fields. Data are presented for each cycle of crop rotation (1969–2017) in the arable soil layer and at the end of rotation VI (2016–2017) in the meter layer. The effect of fertilizers on soil properties was studied against the background of liming (at a dose of 1.0 Ac_tot), which was carried out in the first rotation. The greatest efficiency of liming was observed in the first two rotations; a gradual deterioration in pH_KCL, Ac_tot, S and V was noted from the third rotation in all variants of the experiment; the degree of changes differed significantly depending on the fertilizer system used. Application of cattle manure at the rate of 10 t/ha per year restrained the deterioration of the acid-base properties of the soil (relative to the control variant); application of 20 t/ha per year ensured in III–VI rotations at least the maintenance of the studied soil properties at the initial level (before liming) or contributed to their improvement. The positive effect of manure on pH_KCL, Ac_tot and V indicators was observed mainly in the soil layer of 0–40 cm. The use of a mineral fertilizer system led to acidification of the soil and a decrease in V. The pH_KCL, Ac_tot and V indicators in the “NPK eq. 20 t/ha of manure” in V–VI rotations were significantly lower than the initial level (pH_KCL before liming – 5.5, II rotation – 5.9, V–VI rotation – 4.5–4.6; Ac_tot – 3.1, 2.5 and 3.7–4.4 cmol(eq)/kg; V – 84, 90, 80–82%, respectively). The adverse effect of mineral fertilizers on pH_KCL, Ac_tot and V after application of NPK eq. 20 t/ha of manure (N₇₀P₅₀K₁₀₀ per year) was observed in a meter layer, NPK eq. 10 t/ha of manure (N₃₅P₂₅K₅₀ per year) – in the arable layer. The organomineral fertilizer system occupied an intermediate position between mineral and organic ones in terms of its effect on pH_KCL, Ac_tot, S and V; processes of soil acidification were observed, but they were less pronounced.

The structure of the soil cover of the Northern Caspian region includes the interdepression solonetz complex, soils of depressions and estuaries. Permanent elements of the microrelief of the estuary bottom are closed rounded microdepressions up to 9 m in diameter. The soil combination of microdepressions is represented by meadow-steppe solods with different thickness of the solodized horizon, the largest on the periphery and the smallest in the bottom. Two soil profiles were studied: in the bottom of the microdepression – medium-thick solod, and on the flat part of the estuary bottom on the edge of the microdepression – deep solod. Less solodization thickness in the bottom of the microdepression is accompanied by a higher content of silt particles with the same thickness of textural and accumulative-carbonate horizons. In both soils, the same type of qualitative composition of clay and clastogenic minerals was established. A uniform differentiation was revealed by the profiles of clastogenic minerals, but the degree of their expression is not the same. The more contrasting differentiation was established in the solod of the microdepression. The content of feldspars increases in the lower horizons and quartz, on the contrary, in the upper horizons. Differentiation of clay minerals also occurs. Illite accumulates in the upper horizons, and the content of chlorite increases in the lower horizons. In the textural horizons of the profiles, an increase in mixed-layer mica-smectite formations is noted and insignificant kaolinite minerals are fixed in a superdispersed state. A decrease in the role of the smectite phase in the upper horizons is associated with its illitization in both solods. In the solod of the microdepression, superdispersion is associated with the reverse transformation of illite into smectite layers, which is ensured by a periodically stagnant water regime of atmospheric nutrition, in which the products of chemical weathering are mobilized within the soil profile in the form of various mixed-layer formations.

Soil salinity is a serious disaster in many arid and agricultural regions, especially in Central Asia. The extensive economic impact of soil salinization on the national economy of Central Asian countries is significant. To solve the above problem, three systems are of great importance: drainage system, high-quality land leveling (planning) and salt washing activities. The aim of this study to review published articles on the issue of the term of soil salinity regions in Central Asia from 2000 to 2022. Aligning with this aim, we have collected, reviewed, and analyzed 661 publications, met the selection criteria in the Scopus database during 2000–2022. Bibliometric analysis showed that all articles were published in English, with the highest publication numbers coming from the Uzbekistan, Kazakhstan, Germany, China, the Russian Federation and the United States. The bibliometric analysis showed that international research on soil salinity and importance of drainage system is needed to expand the scientific exchange on this topic, as well as long-term, continuous research and sustainable development of soil salinization concepts for future agriculture and soil salinity management integration will be useful.