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The paper presents an assessment of the rates of erosion and sedimentation in hollows of the Temeva Rechka small dry valley catchment, dominated by forest-steppe gray forest soils (Luvic Retic Greyzemic Phaeozems), over the past 55–60 years with the use of the radiocesium technique. This catchment is located in the Myosha River basin (Republic of Tatarstan, European Russia). The hollows have been grouped by the catchment's slope aspects, hollow length, hollow bottom gradient, and shape of the thalweg profile of the hollow bottoms; origin and age, as well as by the specifics of erosion/sedimentation processes. Short agrogenic hollows with a small catchment area on relatively steep western slopes of the Temeva Rechka small dry valley, probably formed after human deforestation, have been identified. The shape of their catchments contributes to the formation of surface runoff, sufficient for the erosion of a significant part of their bottoms at a rate of about 2–4 t/ha per year. Older, polygenetic, and relatively long hollows with a slightly sloping bottom and larger catchments serve as sediment transit zones between plowed areas and the Temeva Rechka small dry valley bottom. They are characterized by alternating areas of soil erosion and sediment accumulation. The average rate of soil erosion in these landforms is 0.8 t/ha per year. In some hollows, when several small tributaries (smaller hollows) flow into their lower parts, soil erosion loss increases to 3 t/ha per year. The average soil erosion loss is 6 t/ha per year on short slopes of the hollows; in their upper parts, it can reach 11 t/ha per year. There is a general decrease in the rates of soil erosion and accumulation of eroded material in recent decades due to changes in climate and land use. [ABSTRACT FROM AUTHOR]

The study presents a new scheme of zoning of modern gully erosion in a large region of the Russian Federation. Automated landscape zoning by means of artificial neural networks was carried out in order to determine the natural and anthropogenic conditions for the development of the gully network. Erosion zoning was implemented on the basis of large-scale geoinformation mapping of gullies with visual interpretation of high- and ultra-high-resolution satellite images for 2017–2021. The basins of small rivers (1314 in total) with an average area of 91 km2 were taken as operational territorial units. 22 688 gullies (including their lateral branches) were identified in the study area; their average length was 65 m, and the total length of the gully network was about 1500 km. The mean density of the gully network constituted 12 m/km2, and the maximum density reached 301 m/km2. This indicator indirectly reflects the intensity of gully formation and was used for the zoning of gully erosion. Most of the studied river basins (84%) had either no gully dissection or very weak and weak gully erosion. The main reasons for the widespread damping of gully erosion are related to changes in land use and in the climate system, as well as to an evolutionary factor—the transition of many gully forms to the balka stage of development. [ABSTRACT FROM AUTHOR]

Climate change is visible as climatic events like flood and drought. Floods have a major impact on soil properties by altering them through dilution, transporting and deposition of minerals. Kerala had a flood on August 2018 with a different duration or temporal variation from three to seven days due to heavy and unexpected rain from June to mid of August 2018, that triggered large landslides on that month. The current study was focussed on the impact of flood on soil chemical properties (pH, soil EC, organic carbon, available NPK) at Thrissur district of Kerala in forest, rubber, nutmeg (homegarden), coconut and open land use systems. Soil samples were collected from flood affected and adjacent non flood affected of these land use systems from 0–20 cm depth after six months of flood and analysed chemical properties according to standard methods. The result of soil pH analysis showed a greater significant decrease in coconut plantation (6.28 to 4.94) after flood. Forest, rubber and homegarden showed an increase in organic carbon (OC) (0.22, 0.77, 0.45% respectively), available P (36.85, 32.6, 38.42 kg/ha respectively). Forest showed a higher amount of available N (84 kg/ha) after flood while rubber, nutmeg and open land use systems showed a decrease in available nitrogen (201.6, 107.1, and 207.9 kg/ha decrease respectively. Forest (196.6 kg/ha), rubber plantation (299.4 kg/ha), nutmeg plantation (292 kg/ha), coconut plantation (421.4 kg/ha) and open condition (125.7 kg/ha) showed a decrease in available K content after flood. Tree based land use systems showed a remarkably better resilience or masked the ill effect of flood very quickly compared to other systems. Integration of shade tolerant species (Grewia robusta, Ailanthus triphysa and Vateria indica) in coconut plantation would help the plantation to adapt flood like situation from soil nutrient loss, also it would increase the productivity of land by maximum utilisation of land resources. [ABSTRACT FROM AUTHOR]

A soil organic carbon (SOC) map of high accuracy is the basis for taking mitigation measures against crises of food security and global climate change. Predicting SOC based on a limited number of soil samples can reduce the cost and time for laboratory analysis. This study aimed to assess the influence of sample size on the prediction of SOC and to identify the optimal sample size of SOC prediction for cropland in northern Jiangsu, China. A total of 1182 soil samples were randomly split into calibration and validation sets. Ten calibration subsets of samples between 108 and 1064 were selected by using a parent material-based stratified random resampling strategy. The random forest algorithm was used to develop 10 calibration models validated based on the same validation sample set. These 10 models were evaluated through the explained variance (EV) and the root mean square error (RMSE). The results showed that the calibration model based on 960 soil samples had the best performance in SOC prediction. Significantly biased predictions were produced by the calibration models based on more or less than 960 soil samples due to underrepresentation or overrepresentation. Relief and climate were demonstrated to be the predominant factors influencing SOC prediction in this study area. These results may provide theoretical support for studies relevant to SOC mapping. [ABSTRACT FROM AUTHOR]

We investigate the key predictors that influence the soil organic matter (SOM) content in higher altitude plantations. This is to study the potential of carbon sequestration for recapturing CO2 from the atmosphere, which is an important consideration in mitigating global climate change. This research applied distance-based linear models to evaluate and predict the influence of topography and types of land use on soil carbon storage in the tropical mountainous areas of Central Vietnam. Three predictors plantation, altitude, and slope together explained 73.8% of the SOM variation. We focused on four types of plantations including acacia, rubber tree, cassava plantations, and plantations with rotation system between acacia and cassava. We found that they had different carbon accumulation, which depended on various characteristics of the terrain. The acacia plantation forest stored the highest amount of SOM and was less sensitive to changes in altitude. The soil carbon content in cassava plantations was the lowest, and altered considerably with altitude. SOM content in rubber tree and acacia-cassava rotation plantations were similar to each other. Altitude was the most critical driver in affecting the capacity of soil carbon sequestration in each plantation. In higher elevation zones, soil carbon stock was greater, which was probably related to decreasing decomposability by microorganism, and increasing carbon content in foliage and leaf litter. The carbon retention tended to increase gradually over an elevation range of 133–300 m a.s.l. The effects of the terrain slope were observed, when considering certain types of land use, and ones with small altitude disparity. In the slope range of 0° to 20°, the carbon pool showed a tendency to increase its capacity. Higher slope gradients, however, could hinder carbon retention due to organic material loss through erosion. In particular, when the slope was above 30°, the soil organic matter content decreased substantially. [ABSTRACT FROM AUTHOR]

Development of carbon polygons for monitoring the emission and deposition of carbon compounds in terrestrial ecosystems is one of the priority tasks in the case of climate and biosphere conservation. Significant is the role of soils, which are not only the main source of greenhouse gas emissions into the Earth's atmosphere but also a long-term reservoir that stores significant amounts of organic carbon in the form of soil humus. The article discusses the organization of monitoring of greenhouse gases at carbon polygons, the methods of sampling soil horizons, and methodological approaches to determine the content and stocks of organic carbon in soils. The importance of information on the qualitative and quantitative composition of soil organic matter and humic substances, which is necessary for the operation of modern simulation models and calculation of carbon units for the economic assessment of the direct and reverse carbon footprint have been revealed. Russia faces a number of challenges related to carbon offset and a low-carbon economy. The necessary volumes of monitoring data, which must be obtained at carbon polygons for the use of the ROMUL and Efimod models are considered. The necessity for an adequate spatial coverage of the territory of Russia with a network of carbon polygons is emphasized. Particular attention should be paid to the arctic territories that contain significant amounts of organic matter in permafrost and can become precursors of the formation and emission of significant amounts of carbon dioxide and methane into the atmosphere. [ABSTRACT FROM AUTHOR]

On the basis of the conducted paleosol, updated data on the direction of climate changes in the second half of the Holocene in the territory of the Kuban–Azov Lowland were obtained. The Atlantic optimum of the Holocene was replaced at the beginning of the third millennium BC by a short period of aridization. The 27/26th–22/21st centuries BC were the period of climate humidization followed by a warm and dry period in the 22/21st–16th centuries BC. In the Early Iron Age, from the second half of the 2nd century BC to the beginning of the 2nd century AD, a sharp aridization of the climate was reconstructed, the peak of which occurred at the turn of the millennium. Paleosols of the second half of the third millennium BC are characterized by the high humus content, leaching of carbonates from the upper horizons, impregnation with carbonate pseudomycelium of the profile, the presence of calcareous veins, disintegration or absence of calcareous nodules, and zooturbation of the profile. These features attest to humid climatic conditions. At the turn of the era, with the increasing aridity of the climate, the chernozems acquired features of more southern subtypes, but there was no change in soil types and subtypes during this period. [ABSTRACT FROM AUTHOR]