Water Erosion Research Articles

Soil Erosion Characteristics of the Agricultural Terrace Induced by Heavy Rainfalls on Chinese Loess Plateau: A Case Study

Terrace erosion has become increasingly pronounced due to the rising incidence of heavy rainfalls resulting from global climate change; however, the processes and mechanisms governing erosion of loess terraces during such events remain poorly understood. A field investigation was performed following a heavy rainfall event in the Tangjiahe Basin to examine the soil erosion characteristics of loess terraces subjected to heavy rainfall events. The results show that various types of erosion occurred on the terraced fields, including rill, gully, and scour hole in water erosion, and sink hole, collapse, and shallow landslide in gravity erosion. Rill erosion and shallow landslide erosion exhibited the highest frequency of occurrence on the new and old terraces, respectively. The erosion moduli of the gully, scour hole, and sink hole on the new terraces were 171.0%, 119.5%, and 308.7% greater than those on the old terraces, respectively. In contrast, lower moduli of collapse and landslide were observed on the new terraces in comparison to the old terraces, reflecting reductions of 34.2% and 23.4%, respectively. Furthermore, the modulus of water erosion (32,102 t/km2) was 4.5 times that of gravity erosion on the new terraces. Conversely, on the old terrace, the modulus of gravity erosion (8804.1 t/km2) exceeded that of water erosion by 14.5%. Gully erosion and collapse dominated the erosion processes, contributing 67.8% and 9.4% to soil erosion on the new terraces and 38.7% and 34.0%, respectively, on the old terraces. In the study area, the new terraces experienced significantly greater erosion (39,252 t/km2) compared to the old terraces (16,491 t/km2). Plastic film mulching, loose and bare ridges and walls, inclined terrace platforms, and high terrace walls, as well as the developing flow paths, might be the key factors promoting the severe erosion of the terraces during heavy rainfall. Improvements in terrace design, construction technologies, temporary protective measures, agricultural techniques, and management strategies could enhance the prevention of soil erosion on terraces during heavy rainfall events.

Enhancing the Humidity Stability of Perovskite Films through Interfacial Modification with Differentiated Hydrophilic Organics.

Preparing high-quality perovskite films is a decisive step toward realizing highly efficient and stable perovskite solar cells (Pero-SCs). Water is a key factor affecting the stability of the Pero-SCs. Here, the widely used water adsorbents chitosan, sorbitol, and sodium hyaluronate (NaHA) were used as hydrophilic layers on the upper interface of the perovskite to form a barrier against water. The water adsorbents also passivated defects on the surface of the perovskite active layer due to their -OH and -COOH functional groups. The NaHA-modified devices showed the best power conversion efficiency (PCE) (PCE = 21.74%). Although the NaHA-modified Pero-SCs showed optimal photovoltaic performance, the stability of the modified devices decreased due to the strong water adsorption ability of NaHA, while with moderate water adsorption ability sorbitol-modified devices exhibited good stability and PCE. The devices were tested in the dark and room temperature at different humidity levels for 800 h. At low humidity (25% ± 5% RH), the PCEs of the sorbitol- and NaHA-modified devices were maintained at 80% and 71% of the initial values, respectively. At high humidity (75% ± 5% RH), the PCE was maintained at 64% and 23% of the initial values, respectively. This work provides an avenue to select adsorbents with suitable water absorption ability as the interface modification layer, thus reducing the water erosion of perovskite films and obtaining highly stable inverted Pero-SCs.

Study of cracks in the last-stage rotor blade of a steam turbine and the corrosion fatigue properties of its materials

In this study, to clarify the failure mechanism of the last-stage rotor blade in the low-pressure cylinder of a steam turbine, the peculiarities of crack initiation and propagation on the inlet side of the last-stage rotor blade at a distance of 125–165 mm were analyzed, along with the corrosion fatigue properties of its materials. The results showed that crack initiation occurred at the tip of the pit due to a combination of factors: stress concentration at the tip of the pit, corrosion of the Cr-poor area near the prior austenite grain boundary, centrifugal tensile stress, and steam bending stress. The crack propagation could be divided into the initial intergranular and late transgranular propagation stages. The main reason for the initial intergranular propagation was stress corrosion, and the main reason for the later transgranular propagation was corrosion fatigue. High-frequency induction quenching technology can improve the microhardness of the blade's surface material and enhance the blade's resistance to water erosion, but it may also reduce the corrosion fatigue resistance of the blade material. The rotary bending corrosion fatigue test can effectively simulate the crack propagation process of the blade. These results are of great significance for the safe operation of the last-stage rotor blade in the low-pressure cylinder of a steam turbine.

Irrigation technologies and management and their environmental consequences: Empirical evidence from Ethiopia

The main objective of this study is to understand the interlinkages between different irrigation technologies and management systems and environmental outcomes. We use a unique and comprehensive household and plot-level dataset covering ten districts of Ethiopia complemented with remotely sensed data and qualitative information collected from the study sites. The econometric results show that compared to open-access plots equipped with pump irrigation, other irrigated configurations, and especially private groundwater-based systems, have higher vegetation cover and show less susceptibility to the most common environmental concerns mentioned in the survey regions: water logging, soil salinity, and erosion externalities.

Firing the wall: A novel way to protect earth buildings

It is widely recognized that external earthen renders are susceptible to accelerated degradation caused by environmental factors. Therefore, chemical stabilization has become a common approach to address this issue. This study focuses on the stabilization of earth renders by heat treatment, considering criteria such as energy efficiency and the judicious use of resources. Different earth rendering mortars with additives such as wheat paste and horse dung were investigated. These were subjected to surface heat treatment at 400 °C for one minute. Changes in mechanical properties, including shear strength, adhesion and water erosion resistance were examined. The results showed that surface heat treatment at 400 °C improved water erosion resistance but negatively affected shear strength and adhesion to the adobe substrate. Interestingly, the mortar containing wheat paste showed the least reduction in shear strength and adhesion, with a 16 % decrease, while it experienced a water erosion resistance. The phenomenon was observed in all specimens and is attributed to the microstructural changes induced by the irreversible processes of dehydration and dehydroxylation, which alter the clay components on the surface of the earthen render. Overall, heat treatment shows promise for improving the durability of earthen renders against environmental degradation.

Empirical and physical modelling of soil erosion in agricultural hillslopes

Abstract Soil erosion is a complex and highly heterogeneous process with a wide range of environmental and economic impacts. Its estimation is particularly challenging and modelling is typically used for erosion estimation over large areas. The aim of this study was to compare the two leading empirical and physical erosion estimation models, i.e. the Revised Universal Soil Loss Equation (RUSLE) and the Water Erosion Prediction Project (WEPP). The models were calibrated and validated using data collected from field experiments conducted in agricultural lands of Mexico. The simulated rainfall experiments involved measuring erosion from field plots subjected to four tillage systems (No crop, Conventional tillage, Conventional tillage + residues, and Handspike) under two antecedent soil moisture conditions (dry and wet). Different calibration approaches based on the factors K and C for RUSLE, and interrill erodibility and hydraulic conductivity in WEPP were tested. The best-performing methods in RUSLE involved measuring the K factor and adopting the recommended C factor by the National Forestry Commission of Mexico. In WEPP, the best results were obtained when interrill erodibility was estimated from experimental measurements. Overall, RUSLE outperformed WEPP in most of the treatments except for CT under WAMC.

Microtopographic response of tilled loess slopes during stages of water erosion development

The tilled slopes in the loess region are characterized by artificial management practices that result in variations in microtopography, which serve as both the site of water erosion and a significant factor contributing to further slope erosion development. However, the response of microtopography during the process of erosion development on tilled loess slopes is unclear. In this study, artificial rainfall simulations were conducted to simulate the development of water erosion (splash erosion (SpE), sheet erosion (ShE), and rill erosion (RE)) under three slope gradients (5°, 10°, and 20°) and three tillage practices (artificial backhoe (AB), artificial digging (AD), and contour tillage (CT)) at a rainfall intensity of 60 mm h−1. The spatial correlation and heterogeneity of the microtopography were analysed using semivariogram functions and fractal dimensions. The response characteristics of microtopography during the water erosion development process on tilled loess slopes were analysed from three perspectives: microtopography factors, erosion equilibrium areas, and slope strips M-ΔDEM. The results indicated that the microtopography process data exhibited moderate to high spatial autocorrelation. There is a positive correlation between microtopographic factors and the slope gradient. Tilled slopes exhibit erosion equilibrium effects during the processes of splash erosion, sheet erosion, and rill erosion. These equilibrium effects are located in the longitudinal ranges of 700 to 1200 mm, 700 to 1300 mm, and 800 to 1100 mm, respectively. Soil erosion and deposition primarily occur in the middle and lower parts of the slope, with 70 % of the slope’s elevation changing within 10 mm, while the remaining changes can reach 25 mm. Among the three tillage practices, AB is the most susceptible to slope influences, which can lead to soil loss, and an optimal slope gradient exists for implementing AB measures. In the case of CT at a slope of 20°, ridge breaking is more likely to occur, but considering the combined effects of soil loss suppression and the difficulty in forming rills, it is recommended to prioritize CT as the preferred tillage practice among the three practices. This study can provide a theoretical foundation for understanding the mechanisms through which microtopography influences water erosion. Additionally, it can serve as a theoretical basis for calibrating parameters in soil erosion models for sloping cultivated lands.

A thermal infrared imaging observation system for the measurement of overland flow velocities under controlled laboratory conditions

Flow velocity is an important physical parameter in characterizing the hydraulics of water flow. The accurate measurement of overland flow velocities has great significance for understanding and modeling sediment transport and soil erosion. In this study, a Thermal Infrared Imaging Observation System (TIIOS) based on thermal infrared imaging techniques and computer vision recognition technology was established to measure overland flow velocities under controlled laboratory conditions. TIIOS has three subsystems including thermal tracer control, image acquisition and transmission, and image storage and processing. It can be used to dynamically monitor changes in shallow flow velocity by means of automatic control of thermal tracer, instantaneous image acquisition, image correction, noise removal and centroid determination. The observation precision was high with a standard deviation of 0.004 m·s−1 for flow velocity, a temporal resolution of 1/9th s, and a spatial resolution of 2 mm. The new system achieved higher accuracy compared to the traditional dye tracing and salt tracing techniques in observing the dynamic transport process of thermal tracer movement. The relative errors of the centroid velocity measured by the TIIOS ranged from −9.83 % to 6.40 %; whereas the relative errors of centroid velocity measured by salt tracer ranged from −21.36 % to 17.22 %. Measurements by the established TIIOS under different hydraulic conditions demonstrate that the relative errors of the centroid velocity are all smaller than those of the leading-edge velocity. This observational system provided a reliable way to measure shallow flow velocity for better understanding the mechanisms of water erosion processes and showed its potential to be used in field experiments under natural conditions.

Integrating policy, data and technology in pursuing effective management of ecosystem services

With the growing concerns about the protection of ecosystem functions and services, governments have developed public policies and organizations have produced an awesome volume of digital data freely available through their websites. On the other hand, advances in data acquisition through remote sensed sources and processing through geographic information systems (GIS) and statistical tools, allowed an unprecedent capacity to manage ecosystems efficiently. However, the real-world scenario in that regard remains paradoxically challenging. The reasons can be many and diverse, but a strong candidate relates with the limited engagement among the interest parties that hampers bringing all these assets into action. The aim of the study is to demonstrate that management of ecosystem services can be significantly improved by integrating existing environmental policies with environmental big data and low-cost GIS and data processing tools. Using the Upper Rio das Velhas hydrographic basin located in the state of Minas Gerais (Brazil) as example, the study demonstrated how Principal Components Analysis based on a diversity of environmental variables assembled sub-basins into urban, agriculture, mining and heterogeneous profiles, directing management of ecosystem services to the most appropriate officially established conservation plans. The use of GIS tools, on the other hand, allowed narrowing the implementation of each plan to specific sub-basins. This optimized allocation of preferential management plans to priority areas was discussed for a number of conservation plans. A paradigmatic example was the so-called Conservation Use Potential (CUP) devoted to the protection of aquifer recharge (provision service) and control of water erosion (regulation service), as well as to the allocation of uses as function of soil capability (support service). In all cases, the efficiency gains in readiness for plans’ implementation and economy of resources were prognosed as noteworthy.

Soil erosion risk assessment of the Lakhmess watershed (northwestern Tunisia) via the SEAGIS model: Inferred prioritization of risky sub-watersheds

Water erosion in Tunisian semi-arid regions causes harmful effects by silting reservoirs and reducing agricultural lands and soil fertility. Several factors are involved in the erosion process: rain erosivity, soil fragility, and degraded land cover on steep slopes associated with the intensification of inappropriate human practices. Thus, identifying erosion vulnerable sub-watersheds based on the assessed soil loss rate is very important to apply suitable conservation measures. The current research aimed to prioritize risky areas in the Lakhmess watershed, north-west Tunisia via the Soil Erosion Assessment using Geographical Information System (SEAGIS) model. To prioritize sub-watersheds vulnerable to soil erosion and sediment yield, the Lakhmess watershed, covering an area of 162 km2, was divided into 16 sub-watersheds (L1–L16), according to the hydrographic network. Then, the mean annual soil erosion rate and the mean annual sediment yield in the watershed were estimated by integrating the Revised Universal Soil Loss Equation (RUSLE) and the Sediment Delivery Ratio (SDR) in the SEAGIS model and their spatial distribution was determined. The obtained results indicate that the estimated average annual soil erosion rate is 4.2 t/ha/y and the annual sediment yield is 2.6 t/ha/y. Maner's SDR model was selected as the best model for estimating SY, with standard error, standard deviation, and coefficient of variation values of 0.75%, 0.01, and 0.45%, respectively. The prioritization of the Lakhmess sub-watersheds based on the estimated soil loss rate reveals that among the 16 sub-watersheds, three sub-watersheds (L10, L12, and L15) were identified as being in a very high priority soil erosion class. The high soil erosion rate and sediment yield in these sub-watersheds is explained by the steep slope and a high rainfall erosivity factor. Six sub-watersheds (L2, L4, L5, L6, L7, and L16) were found to belong to a very low priority soil erosion class, as they are characterized by a very gentle slope, which appears to be an extremely determining factor. These findings constitute a basis for decision makers to plan effective conservation measures to conserve agricultural lands, soil, and water resources in northwestern Tunisia.

Transport of nitrogen in grassed watersheds accounting for the combined influence of grazing and climate

A comprehensive modeling framework utilizing MIKE-SHE to investigate the feasibility of enhancing livestock production while concurrently mitigating the impact of grassland ecosystems on surface water quality is presented. In this study, a modeling framework that simulates nitrogen transport was developed using a physically based distributed hydrologic model, MIKE SHE. The model was calibrated and validated using observed overland flow and water quality data from El Reno, Oklahoma's Water Resources and Erosion Unit watersheds. Different scenarios involving variations in timing, duration, and frequency of grazing activities, stocking rates, and climate conditions were simulated using the calibrated MIKE-SHE model. The goal was to explore the extent of the influence of these aspects of grazing on water quality through these scenario simulations. The results provided valuable insights into the key factors for developing an intelligent grazing decision tool to delineate targeted grazing windows that optimally balance heightened livestock production with environmental sustainability. The study's findings showed that the observed variability in existing literature originates mainly from climatic differences, with precipitation being the primary driver of nutrient loss, while evapotranspiration and soil moisture conditions are secondary factors. The simulations revealed that the impact of grazing on nitrogen loss in the pasture is evident only when grazing activities, irrespective of the stocking rate, duration, and frequency, occur under weather conditions conducive to nutrient loss in the pasture. These intertwined processes suggest that the impact of grazing on nitrogen loss can only be generalized within the context of the prevailing weather conditions in the pasture. Hence, strategically matching grazing activities with prevailing weather patterns can increase livestock production while promoting environmental sustainability in pasture management.

Potential Reduction of Spatiotemporal Patterns of Water and Wind Erosion with Conservation Tillage in Northeast China

Conservational tillage (NT) is widely recognized globally for its efficacy in mitigating soil loss due to wind and water erosion. However, a systematic large-scale estimate of NT’s impact on soil loss reduction in Northeast, China’s primary granary, remains absent. This study aimed to investigate the spatial and temporal variability of soil erosion under NT compared to conventional tillage (CT) in the black soil region and to analyze the underlying mechanisms driving these erosions. The Revised Universal Soil Loss Equation (RUSLE) and the Revised Wind Erosion Equation (RWEQ) models were employed, incorporating previously published plot/watershed data to estimate the potential reduction of water and wind erosion by NT in this region. Results indicated that under CT practices, water- and wind-induced soil losses were widely distributed in the arable land of Northeast China, with intensities of 2603 t km−2 a−1 and 34 t km−2 a−1, respectively. Furthermore, the erosive processes of water and wind erosion were significantly reduced by 56.4% and 91.8%, respectively, under NT practices compared to CT. The highest efficiency in soil conservation using NT was observed in the mountainous regions such as the Changbai Mountains and Greater Khingan Mountains, where water erosion was primarily driven by cropland slopes and wind erosion was driven by the wind speed. Conversely, the largest areas of severe erosion were observed in the Songnen Plain, primarily due to the significant proportion of arable land in this region. In the plain regions, water-induced soil loss was primarily influenced by precipitation, with light and higher levels of erosion occurring more frequently on long gentle slopes (0–3°) than on higher slope areas (3–5°). In the temporal dimension, soil loss induced by water and wind erosion ceased during the winter under both tillage systems due to snow cover and water freezing in the soil combined with the extremely cold climate. Substantial reductions were observed under NT from spring to autumn compared to CT. Ultimately, the temporal and spatial variations of soil loss under CT and NT practices were established from 2010 to 2018 and then projected onto a cropland map of Northeast China. Based on this analysis, NT is recommended as most suitable practice in the southern regions of Northeast China for maintaining soil health and crop yield production, while its suitability decreases in the northern and eastern regions.

Influence of erosion control afforestation on some soil parameters in two watersheds in Southwest Bulgaria

Soil is limited resource with vital role in maintenance of variety ecosystems. One of the greatest treat for soils is soil erosion. This natural hazard is widely spread in the terrestrial world, and the territory of Bulgaria is also affected.  Important role for soil protection has a forest vegetation and afforestation is widely used for erosion control activity. The main benefits of afforestation are reduction of water runoff, erosion and sedimentation year-round, which is important for the areas located around the reservoirs and their basins. They also decrease the migration of vital substances for soils and sedimentation yield.  The main goal of the study is to establish the influence of erosion control afforestation to the main soil characteristics in the territory of two watershed situated in Southwest Bulgaria. Soil samples and dead leaf cover were analyzed as well as some characteristics of afforestation and topographic charac-teristics. It was established high water resistance of the soil aggregates under the planted forests and low resistance in the controls. The amounts of content of org. carbon and total nitrogen varying with slope and exposure. The differences between parameters of soils under afforestation and in control samples is established which shows an important influence of forest to the soil characteristics.

The function of phytogenic mounds in the accumulation and conservation of soil seed banks in semiarid areas with water erosion

BackgroundPhytogenic mounds are a type of microtopography formed under perennial plants canopies in water erosion areas. However, the function of phytogenic mounds in seed assemblages and their ecological consequences remain poorly understood in semiarid areas with water erosion. Thus, understanding the characteristics of seed banks on mounds is crucial for ecosystem conservation and management in water-eroded areas.MethodsWe compared the quantity and composition of soil seed banks on the upslope and downslope parts of mounds and intercanopy surfaces along four slope gradients. We also explored the relationships among the soil seed bank, aboveground vegetation, and environmental factors. Furthermore, the species similarity between the soil seed bank and aboveground vegetation was analyzed to clarify the important ecological consequences of phytogenic mounds for plant community construction in serious soil erosion area.ResultsFor slopes with α ≤ 46.6%, the intercanopy surfaces had greater soil seed bank species composition, density, and diversity than did the phytogenic mounds, and these characteristics showed no significant differences between the upslope and downslope parts of the mounds. As the slope increased, the soil seed bank density and species composition increased on the upslope part of the mound, and reached a maximum for slopes with α > 70%, while the downslope part of the mound negatively effected on seed aggregation. The sediment accumulation rate, soil moisture, particle size distribution, pH, organic matter carbon, and hardness were significantly correlated with the soil seed bank density and diversity in the study area. For slopes with 0 < α ≤ 26.8%, the species similarity coefficient between the soil seed bank and aboveground vegetation was the highest for the intercanopy surface. This species similarity on the upslope part of the mound showed an increasing trend with increasing slope gradient, while the downslope part of the mound had the opposite trend. For slopes with α > 70%, the upslope part of the mound did not only have more species in the soil seed bank but also had more species in aboveground vegetation than did the downslope part of the mound and intercanopy surface.ConclusionFor slopes with α ≤ 46.6%, phytogenic mounds had barely impact soil seed bank accumulation and conservation in semiarid and eroded areas. For slopes with α > 46.6%, the mounds (particularly on the upslope part of the mound) showed seed assemblage functions, which are coupled with improving edaphic conditions and decreasing microhabitat stress; thus, phytogenic mounds, or areas of microtopography, can be used to promote restoration success in semiarid eroded areas.

Quantifying impacts of livestock production on ecosystem services: Insights into grazing management under vegetation restoration

Recent decades, vegetation restoration initiatives and land institutional reforms have profoundly altered practices of livestock husbandry in China. However, the understanding of how livestock production affects restoration effectiveness remains limited, impeding the advancement of sustainable grazing management. Taking the Loess Plateau as a case area, this study aims to examine the impacts of livestock production on key ecosystem services (ESs) under the Grain-to-Green Program (GTGP). Based on an improved estimation of available biomass for livestock, grazing intensity across the study area in 2015 was quantified. Then, by linking grazing intensity with associated livestock economies, a comprehensive framework reflecting livestock production was constructed to analyze its overall impacts on three ESs (water yield, erosion control, and forage provision). Finally, spatial effects of each component within livestock production on the ESs were discussed to inform grazing managements under the GTGP. The results indicated that the three ESs still suffered widespread negative impacts from grazing intensity, with 9.82% of the region experiencing high-level grazing in 2015. Although grazing had potential to mitigate water consumption due to vegetation growth, livestock density of most areas has exceeded its threshold (0.52 sheep or goat per ha, or 0.30 cattle per ha) for maintaining available water resource. Livestock economies demonstrated positive effects on the ESs to varying degrees. Nevertheless, as the positive externalities from ecological compensation are on the wane, challenges in livestock management have surfaced in both poverty-stricken and large livestock-intensive regions. This study offers insights into assessing regional grazing intensity, and enriches understanding of impacts of livestock production under vegetation restoration.

Assessing Water Erosion Improvement in Beach Sand Treated with Bioslurry Using a Surface Percolation Technique

Assessing Water Erosion Improvement in Beach Sand Treated with Bioslurry Using a Surface Percolation Technique

Modeling and Mapping Water Erosion Risk via GIS, Remote Sensing, and the PAP/RAC Model - Case of Tamdrost Watershed, Morocco

Water erosion remains the main form of land degradation globally, with a particularly high sensitivity in Morocco. This study aims to assess and map areas at risk of water erosion in the Tamdroust watershed (Settat Plateau, Morocco) using the PAP/RAC model combined with Geographic Information Systems (GIS) and remote sensing. This comprehensive approach integrates several factors influencing erosion, such as topography, lithology, vegetation density, and land use, to identify erosion-prone areas. The methodology comprises three phases.The first, "predictive" phase generates a synthesized map illustrating the distribution of erosion states. The second phase spatializes different forms of erosion. Finally, the third phase integrates the results of the first two phases. The first phase reveals an abundance of moderate erosion covering 52% of the area, with significant erosion observed in about 7% of the watershed, indicating a trend towards increased erosion without intervention. The subsequent phases identified several forms of erosion such as sheet erosion, gully erosion, solifluction, and Badlands, mainly in areas with steep slopes and low vegetation cover. These results underline the need for interventions to prevent further deterioration of the Tamdroust watershed, highlighting the importance of sustainable land and water resource management in the region.

From forest to forest or where is the bare rocky Karst?

The natural vegetation on the Kras (Karst) Plateau is forest. Anthropogenic pressure on this region has been present since the prehistoric times. Because of deforestation linked to excessive grazing and other land uses, and hence accelerated water and wind erosion, the region has over the last millennium gradually turned into bare karst landscape. In the 18th and 19th century, the Kras (Karst) Plateau was a »rocky desert«. In the 19th century, systematic reforestation began, first unsuccessfully with oak and afterwards successfully with black pine. This process took place also in the first half of the 20th century. In the second half of the 20th century, reforestation was replaced by the process of spontaneous afforestation as a result of natural overgrowing of abandoned agricultural land.

Stability of Soils to Water Erosion when Treated with Polyacetonitrilebased Polymer

The anti-erosion effect of an anionic polymer based on polyacetonitrile, "VPRG reagent (dry hepane)", has been studied when its solution was applied to the surface of agro-black earth, sand and clay in laboratory conditions. It has been found that the use of VPRG has a clearly positive effect only on the anti-erosion stability of agro-black earth; a weak positive effect was observed on clay, and an increase in the amount of washed-off material was noted on sand relative to the standard. It has been confirmed that an increase in the concentration of VPRG leads to an increase in the anti-erosion stability of agro-black earth, but reduces it for clay and sand relative to the standard. It has been concluded that the optimal dose of VPRG application corresponds to 106 kg/ha when dissolved in 10 m3 of water for agro-black earth and clay.

Water erosion at different slope lengths

Water erosion is strongly influenced by slope length (Sl), among other factors. The objective of this work was to quantify the water losses (WL) and soil losses (SL) in different Sl, in a Haplic Distrudept. These losses were determined during one year in uncultivated and uncovered soil (BS) and then in soil cultivated in the form of no-tillage (NT) during three cropping cycles, under natural rainfall conditions. The treatments, with one repetition, consisted of the Sl of 11 m, 22 m, 33 m, and 44 m with 8% slope. In the 1st cycle, black oat (Avena strigosa) + forage radish (Raphanus sativus) + common vetch (Vicia sativa) was cultivated, in the 2nd cycle, single black bean (Phaseolus vulgaris) and in the 3rd cycle, single black oat. With the increase of Sl in the interval from 11 to 44 m, the WL and SL increased, and the SL increased with the increase of the WL. WL and SL were explained by Sl in 79% and 99%, respectively, and SL were explained in 76% by WL. The y = a + bx model was fitted to the data (p<0.01). Soil crop for one year in the form of NT reduced WL by 30% and SL by 99% compared to the losses that occurred in the condition in which the soil was under BS. The WL varied less than the SL, in the range from 11 to 44 m of slope.