The problem of salinization/spreading of saline soils is becoming more urgent in many regions of the world, especially in context of climate change. The monitoring of salt-affected soils’ properties is a necessary procedure in land management and irrigation planning and is aimed to obtain high crop harvest and reduce degradation processes. In this work, a machine learning method was applied for modeling of the spatial distribution of topsoil (0–20 cm) properties—in particular: soil organic carbon (SOC), pH, and salt content (dry residue). A random forest (RF) machine learning approach was used in combination with environmental variables to predict soil properties in a semi-arid area (Trans-Ural steppe zone). Soil, salinity, and texture maps; topography attributes; and remote sensing data (RSD) were used as predictors. The coefficient of determination (R²) and the root mean square error (RMSE) were used to estimate the performance of the RF model. The cross-validation result showed that the RF model achieved an R² of 0.59 and an RMSE of 0.68 for SOM; 0.36 and 0.65, respectively, for soil pH; and 0.78 and 1.21, respectively for dry residue prediction. The SOC content ranged from 0.8 to 2.8%, with an average value of 1.9%; soil pH ranged from 5.9 to 8.4, with an average of 7.2; dry residue varied greatly from 0.04 to 16.8%, with an average value of 1.3%. A variable importance analysis indicated that remote sensing variables (salinity indices and NDVI) were dominant in the spatial prediction of soil parameters. The importance of RSD for evaluating saline soils and their properties is explained by their absorption characteristics/reflectivity in the visible and near-infrared spectra. Solonchak soils are distinguished by a salt crust on the land surface and, as a result, reduced SOC contents and vegetation biomass. However, the change in saline and non-saline soils over a short distance with mosaic structure of soil cover requires high-resolution RSD or aerial images obtained from unmanned aerial vehicle/drones for successful digital mapping of soil parameters. The presented results provide an effective method to estimate soil properties in saline landscapes for further land management/reclamation planning of degraded soils in arid and semi-arid regions.

The possibility of using industrial and poultry wastes as an ameliorant/fertilizer for erosion-prone soils was investigated. We studied the impact of phosphogypsum (PG) and turkey litter (TL) application on the physicochemical properties of weakly eroded agrochernozem in conditions of a 5-year field experiment in the South Ural region, Russia. In particular, we examined the effect of treatments on the soil moisture reserves, soil structure, microaggregate composition and particle size distribution, aggregate stability (water resistance), organic carbon content (C_org), ammonium, nitrate and alkaline hydrolysable nitrogen, available phosphorus (P_av), exchange potassium (K_ex), and potato productivity/ecological quality. Treatments included the application of the PG at 5, 10, and 20 t ha^–1, the TL at 40 and 60 t ha^–1; and in mixes of PG and TL at ratios of 1:10, 1:5, and 1:2. The obtained results indicated that the introduction of PG and TL increased (compared to control) the moisture reserves (by 10–17%), resistance of soil aggregates to water (8–15%), the content of C_org (6–10%), available nitrogen (two orders of magnitude), P_av (3–6 times) and K_ex (2–3 times), and improved, as well, soil structure. In general, years factor had a significant effect on soil water-physical properties; its influence was 44–67%, while the effect of treatments was 21–30%. The agrochemical properties (C_org and P_av) were dependent on treatments factor (77 and 95%, respectively), while the content of all forms of nitrogen depended on the year factor (34–57%). The obtained results suggest the application of PG and TL to improve agrochernozem fertility status and minimize its erodibility without soil and plant contamination.

Modern technologies make it possible to obtain a lot of diverse information about the soil properties using satellite images, but field studies are also required to create or refine digital soil maps. To create a digital soil map scaled 1:25 000 in 2016, a classical field study was conducted with the laying of soil sections in places with the same coordinates as in the mapping of 1982. It allowed to carry out retrospective monitoring of transformation of morphogenetic and agrochemical properties of soils of the southern forest-steppe of the Republic of Bashkortostan (Russia) for the 34-year period of farm use. Thus, the correction and digitization of the soil map allowed to establish that arable land occupies 69.792 ha (67.9%) in the structure of agricultural land (102 811 ha). The monitoring showed deterioration of the main characteristics of arable soil fertility: the diminishing of humus-accumulative horizons, significant decrease of humus content (p ≤ 0.05), a small but reliable acidification of the medium reaction and reducing labile phosphorus. Losses of organic matter occurred mainly in the most fertile soils; their proportion decreased from 55.9% of the total area of agricultural land to 12.4%.

Global climate change is a fact that affects all components of the environment. The main aim of this research was to conduct the retrospective monitoring of soils in the Trans-Ural Steppe Zone (Russia) and the analysis in changing of key climatic parameters for the periods 1937–1982 and 1982–2019. We investigated average temperatures and precipitation (monthly and annual) using archived data from a nearby weather station, as well as data from NASA and weather forecast websites. We identified a decrease of soil fertility and an increase in alkalinisation processes over the past 37 years for the studied area. Comparison of these periods showed an increasing the average monthly and annual air temperatures (on 1.4°C) and a decrease in the amount of precipitation in the summer (on 4.4 mm) period. We found that a more arid climate accelerates the rate of soil salinization due to the active evaporation of groundwater. Nevertheless, in some areas there were found the soil desalinization due to the change in the hydrologic regime and lowering of the groundwater level. In general, the climate changing in the studied region is consistent with global warming trend. Increased average annual temperature and reduced precipitation in summer period contribute to aridization of the region. Such conditions will more restrict soil fertility due to development of salinization and desertification processes.

   Aim. Data collection and analysis of the composition and productivity of vegetation and assessment of carbon sequestration by vegetation and soil in meadow steppe at a fallow site in the Bashkir Cis‐Urals, Russia.   Material and Methods. The work is based on a survey of vegetation and soils of meadow steppe located in fallow areas, where post‐agrogenic restoration succession has been going on for more than 20 years.   Results. The plant cover of the area studied is close to natural rich‐forb meadow steppes but differs in lower indicators of species richness and saturation, as well as the presence of weedy segetal species. The total plant biomass on the plot studied was estimated at 11.35 t/ha (including live aboveground biomass 2.98 t/ha, mortmass 3.11 t/ha, root weight 5.25 t/ha). The average stock of carbon in the plant biomass is 427.6 g/m², and the total carbon stock in plant matter within the site is 36.88 tons. The soil cover of the area studied is Chernozem Calcic. The average levels of carbon stocks in short‐thickness soil at the 0–90 cm layer is 308 t/ha, while in medium‐thick soil it is 378 t/ha.   Conclusions. A feature of the communities surveyed is a poor floristic composition, low productivity and low proportion of roots (47 % of the total plant biomass), which is caused by incomplete recovering of steppe vegetation and low thickness of the humus horizon. The soils of the site are close to virgin steppe lands in terms of carbon content and reserves.

Purpose of the study was to analyze soil organic carbon (SOC) content and stocks in the abandoned lands of the Southern Cis-Ural, which are used as hayfields and pastures or are under spontaneous forest revegetation. Location and time of the study. Russian Federation, Republic of Bashkortostan, Mishkinsky district, «Eurasian carbon polygon», May-October 2023. Methods. Soil samples were taken layer by layer (every 10 cm to a depth of 60 cm) from the abandoned (for 20–25 yrs) lands of the carbon polygon occupied by birch forests, hayfields and pastures. The samples were used to determine the content of organic carbon, alkali-hydrolyzable nitrogen, mobile phosphorus and exchangeable potassium, as well as pH (water) and salts. Main results. The SOC content both under forest and grasslands in the 0–30 cm layer in gray forest soil was 3.2%, (in the 30–60 cm layer – 1.9%); SOC stock was estimated as 94–102 t/ha (in a layer of 0–60 cm – 162–179 t/ha). The SOM content in the dark-gray forest soil under a birch forest was 8.8% in the 0–30 cm layer (6.4% in the 30–60 cm layer), and its stocks were 257 t/ha (492 t/ha in the 0–60 cm layer). The SOC content in the 0–30 cm layer of grasslands used as hayfields and pastures was 5.1–5.7% in the 0–30 cm layer and 3.9–4.3% in the 30–60 cm layer. The respective SOC stock was estimated as 167–187 t/ha in the 0–30 cm layer and 319–343 t/ha in the 0–60 cm layer. Conclusion. The SOC content and stock in the gray forest soil under communities of herbs and grasses were 1.6–1.9 times less than in the dark-gray birch forest soil, where the content and SOC stock were 50–70% higher than in hayfields and pastures. Thus abandonment of the arable lands in the forest-steppe in the southern Cis-Urals region decreased the excessive percentage of ploughed land, stopped the low-profitable agricultural production and started spontaneous restoration of ecosystems and their soils in the direction of adjacent virgin ones, decreasing erosion hazards. The SOC and its stock values of the abandoned soils being between the respective ones for the arable and virgin soil, suggest that further on with course of time these properties may significantly increase.