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Soil Erodibility Factor (K-factor) is a crucial component of a widely used equation for soil erosion assessment known as the USLE (Universal Soil Loss Equation) or its revised version – RUSLE. It reflects the potential of the soil of being detached due to rainfalls or runoffs. So far, an extensive number of researches provide different approaches and techniques in the evaluation of K-factor. This study applies soil erodibility estimation in the soils of the South Caucasian region using soil data prepared by the International Soil Reference and Information Centre (ISRIC) with 250 m resolution, whereas the recent K-factor estimation implemented in the EU scale was with 500 m resolution. Soil erodibility was assessed using an equation involving soil pH levels. The study utilises Trapesoidal equation of soil data processing and preparation, as suggested by ISRIC, for various layers of surface soil data with up to 0-30 cm depth. Both usage of SoilGrids data and its processing as well as estimation of K-factor applying soil pH levels have demonstrated sufficient capacity and accuracy in soil erodibility assessment. The final output result has revealed the K-factor values varying from 0.037 and more than 0.060 t ha h/MJ mm within the study area.

Background Soil erosion can affect the distribution of soil nutrients, which restricts soil productivity. However, it is still a challenge to understand the response of soil nutrients to erosion under different soil types. Methods The distribution of soil nutrients, including soil organic carbon (SOC), soil organic nitrogen (SON), and soil major elements (expressed as Al2O3, CaO, Fe2O3, K2O, Na2O, MgO, TiO2, and SiO2), were analyzed in the profiles from yellow soils, red soils, and lateritic red soils in an erosion region of Southeast China. Soil erodibility K factor calculated on the Erosion Productivity Impact Calculator (EPIC) model was used to indicate erosion risk of surface soils (0∼30 cm depth). The relationships between these soil properties were explored by Spearman’s rank correlation analysis, further to determine the factors that affected the distribution of SOC, SON, and soil major elements under different soil types. Results The K factors in the red soils were significantly lower than those in the yellow soils and significantly higher than those in the lateritic red soils. The SON concentrations in the deep layer of the yellow soils were twice larger than those in the red soils and lateritic red soils, while the SOC concentrations between them were not significantly different. The concentrations of most major elements, except Al2O3 and SiO2, in the yellow soils, were significantly larger than those in the red soils and lateritic red soils. Moreover, the concentrations of major metal elements positively correlated with silt proportions and SiO2 concentrations positively correlated with sand proportions at the 0∼80 cm depth in the yellow soils. Soil major elements depended on both soil evolution and soil erosion in the surface layer of yellow soils. In the yellow soils below the 80 cm depth, soil pH positively correlated with K2O, Na2O, and CaO concentrations, while negatively correlated with Fe2O3 concentrations, which was controlled by the processes of soil evolution. The concentrations of soil major elements did not significantly correlate with soil pH or particle distribution in the red soils and lateritic red soils, likely associated with intricate factors. Conclusions These results suggest that soil nutrients and soil erodibility K factor in the yellow soils were higher than those in the lateritic red soils and red soils. The distribution of soil nutrients is controlled by soil erosion and soil evolution in the erosion region of Southeast China.

Natural succession and afforestation are the two main restoration methods of degraded soil in semiarid and arid regions. Up to now, the soil microbial communities and their roles in soil erodibility have been unclear. Our work aimed to evaluate the effects of ecological restoration on the diversity and composition of soil microbial communities at depths of 0–20 cm and their interaction with soil erodibility. Four main restoration types, natural succession land and Pinus tabuliformis, Armeniaca sibirica, and Robinia pseudoacacia plantations were chosen. Restoration with different vegetation communities decreased the soil erodibility K‐factor (K) by 13.37–20.64%. Proteobacteria, Acidobacteria, and Actinobacteria were dominant bacterial phyla at all sites. The dominant fungal phyla were Basidiomycota, Ascomycota, and Zygomycota. However, there were obvious differences in bacterial and fungal communities among restoration types due to variations in plant and soil properties. Redundancy analysis showed that the soil microbial communities explained 67.30% of the total variance in soil erodibility. Bacterial communities mainly affect the microaggregate formation, whereas fungal communities have a greater effect on macroaggregate formation. Additionally, the structural equation modeling also suggests that vegetation characteristics, soil organic carbon, and fungal communities, and macroaggregates (> 5 mm) have positive effects on mean weight diameter. Therefore, the combination of vegetation community, soil properties, and microbial communities improves the soil structure against erosion in this area. [ABSTRACT FROM AUTHOR]

Soil Erodibility Factor (K-factor) is a crucial component of a widely used equation for soil erosion assessment known as the USLE (Universal Soil Loss Equation) or its revised version -- RUSLE. It reflects the potential of the soil of being detached due to rainfalls or runoffs. So far, an extensive number of researches provide different approaches and techniques in the evaluation of K-factor. This study applies soil erodibility estimation in the soils of the South Caucasian region using soil data prepared by the International Soil Reference and Information Centre (ISRIC) with 250 m resolution, whereas the recent K-factor estimation implemented in the EU scale was with 500 m resolution. Soil erodibility was assessed using an equation involving soil pH levels. The study utilises Trapesoidal equation of soil data processing and preparation, as suggested by ISRIC, for various layers of surface soil data with up to 0-30 cm depth. Both usage of SoilGrids data and its processing as well as estimation of K-factor applying soil pH levels have demonstrated sufficient capacity and accuracy in soil erodibility assessment. The final output result has revealed the K-factor values varying from 0.037 and more than 0.060 t ha h/MJ mm within the study area. [ABSTRACT FROM AUTHOR]

Soil erodibility is a key parameter to measure soil susceptibility to water erosion and thus to soil erosion modelling, introduced as K factor in the Universal Soil Loss Equation (USLE) and the Revised Universal Soil Loss Equation (RUSLE). However, subject to soil spatial heterogeneity and data availability, large-scale K value acquisition has not been properly addressed. In this study, authors aimed to construct a new large-scale soil erodibility mapping technique to provide methodological support for regional soil erosion surveys. Taking the mountainous Yunnan province as a case, 743 soil samples from 252 typical soil series were collected. A 'GIS-based pedological method' was developed to construct a large-scale soil erodibility database by linking a soil map with soil properties. K value in Yunnan varied between 0.0004 and 0.0169 t ha h ha−1 MJ−1 mm−1, with an average of 0.0065 t ha h ha−1 MJ−1 mm−1. Significantly different K values were found among different types of soils and land use (p < 0.05). Redundancy analysis indicated that annual average temperature and latitude were the dominant control factors. The study showed that regional K value estimated by 'GIS-based pedological method' manifested an improvement compared to the traditional spatial interpolation method. [ABSTRACT FROM AUTHOR]

• Scarce literature exists about the application time of mulching in burned forests. • Erosion decreased by 67% for timely mulching and by 33% for delayed application. • After an extremely intense rainstorm, this effectiveness was equal to 85% • Overall, straw mulching should be immediately applied after a forest wildfire. Several studies have explored the effectiveness of straw mulching against soil erosion in wildfire-affected forests as post-fire management technique. In contrast, scarce literature exists about the application time of the mulch cover, although this factor - beside climate patterns of the application site - is essential to increase mulching effectiveness. To fill this gap, this study has evaluated the soil loss in two forest sites of Castilla La Mancha (Spain), in which straw mulching was applied in two burned forests immediately after the wildfire or four months after the fire event. These sites show similar characteristics (soil burn severity, soil type, and vegetation), and thus the difference in soil erosion can be attributed to the treatments. The mulching effectiveness has been measured as the difference between the soil loss per unit of erodibility comparing unburned and untreated, and burned and mulched plots. At a comparable rainfall erosivity (difference in EI 30 between the two sites lower than 40 %), soil loss decreased by 67 % (in the case of timely distribution) and 33 % (when the action is delayed) in mulched sites compared to the untreated areas. After a rainstorm with very high erosivity (+600 % of EI 30), soil loss reduction was equal to 85 % in the case of early mulching application. This higher effectiveness of early mulching compared to the delayed application was due to the quicker post-fire regrowth of vegetation, and the increased level of incorporation of vegetal residues into the soil. This result suggests to land managers that straw mulching should be applied immediately after a wildfire in burned forests, in order to achieve the highest anti-erosive effects. Further research is suggested to validate these results in other environments and after application of other mulches. [ABSTRACT FROM AUTHOR]

• Spatial position affects aggregate stability and soil erodibility by altering soil properties. • Regional positions affected aggregate stability and soil erodibility greatly with a contribution of 57.97. • Spatial variation in MWD and K was closely related to AK, Ks, SOC, TN and soil texture. The spatial heterogeneity of erosion can affect soil properties in agricultural areas, which can in turn alter the soil aggregate stability and erodibility. However, it remains elusive how aggregate stability and soil erodibility vary at different positions in the Mollisol region of northeast China, and how soil properties drive these variations. This study selected different slope positions across a latitudinal gradient in four hilly regions from cold temperate (Jiusan, JS; Keshan, KS) to middle temperate (Hailun, HL; Binxian, BX) areas in northeast China. The spatial variations of soil properties, geometric mean diameter (GMD), mean weight diameter (MWD), soil erodibility (K), and soil structural stability index (SSI) were calculated at topsoils (0–20 cm) and subsoils (20–40 cm). Total nitrogen (TN) and soil organic carbon (SOC) decreased with increasing latitudes, and gradually declined and finally rose with decreasing slope positions. MWD, GMD, and SSI were the highest in JS, and first obviously decreased from the top position to lower position, and then increased at the bottom position. The K followed an order of BX > HL > KS > JS, and decreased in the bottom position compared with that in the middle and lower positions across the four regions, which could be ascribed to the new aggregate formation promoted by fine soil particle deposition at the slope bottom. Redundancy analysis and variance decomposition analysis indicated that SOC, TN, and bulk density had higher vector values, and region (interpretation rate = 57.97 %) had the greatest influence on aggregate stability and soil erodibility. Available potassium (AK), saturated conductivity (K S), SOC, TN and soil texture were the main factors driving the variation of MWD and K. These findings highlight the spatial variations in soil aggregate stability and erodibility in Mollisol regions, providing a scientific basis for soil restoration in eroded farmland. [ABSTRACT FROM AUTHOR]

Aggregate breakdown strongly influences soil erosion process, during which slaking and mechanical breakdown are two dominant breakdown mechanisms. Despite of many methods on aggregate stability, there is a paucity of satisfactory one to disentangle how these two mechanisms interact in aggregate breakdown. Herein, on the basis of Le Bissonnais method (1996) including three treatments (i.e., fast wetting (FW), stirring after pre-wetting (WS), and slow wetting (SW)), a new treatment of water-stirring after fast wetting (SF) was proposed in order to evaluate the coupling effect of slaking and mechanical breakdown on aggregate stability. The coupling effect of slaking and mechanical breakdown was larger to a varying extent than their individual effects, and its difference with slaking showed a unimodal variation with increased aggregate stability. This new method can partition the unique and shared effects of these two breakdown mechanisms; the shared effect (0–77%) decreased logarithmically with increased aggregate stability; the unique effect of slaking (16–52%) showed a unimodal variation and much larger than that of mechanical breakdown (0–17%). As validated by previously published splash erosion data over a wide range of soils (including various soil types, land uses, textures and parent materials), the proposed aggregate stability indices in this new method showed better performance in predicting splash erosion compared to existing ones (e.g., RSI×RMI and RSI/RMI). Collectively, this new method facilitates a systematic understanding on aggregate breakdown mechanisms and exhibits great superiority in aggregate stability measurement and erosion prediction. • A new method is proposed to unravel how slaking and mechanical breakdown interact. • The unique and shared effects of slaking and mechanical breakdown are partitioned. • The coupling effects of slaking and mechanical breakdown differ from soils. • The new method performs better in splash erosion prediction than traditional ones. [ABSTRACT FROM AUTHOR]

The concept of erodibility has gained a great importance in the field of soil erosion modelling and applications of soil conservation. Soil erodibility factor has become one of the key factors which determine soil particles resistance to be detached by water erosion. This study was performed to determine soil erodibility factor and assess spatial variability of soil erodibility using geostatistics at El Hammam catchment. In this study 51 samples of surface soil (0-20cm) were collected across the study area of 1000 Ha by preparing point map at GIS. Sampling points were identified in field by a Global Positioning system. Some soil properties and organic matter were measured at laboratory, and permeability and structure were determined using soil texture analysis. Amount of soil erodibility changed from 0.16 to 0.66. The variability analysis has shown that soil properties and erodibility factor have varied significantly in cropland and have ranged from 63% in organic matter and 39% in K factor. The statistical analysis indicated negative correlations of erodibility with clay, organic matter and permeability and negative correlations of this factor with silt, sand and soil structure. Based on kriging interpolation method, soil erodibility factor map was generated using Ordinary Kriging. The spherical model has given the best model to predict spatial variability of soil erodibility which root-mean-square error and mean error values of interpolated map were very low. The range of the spatial dependency was equal to 460 m. The study basin has been classified as highly erodible and ecologically vulnerable.

Purpose: Land-use/cover management is one of the driven forces to induce soil erosion. Meanwhile, the loss of soil nutrients caused by soil erosion severely restricts soil fertility. However, the differences in soil nutrients under different land-use types in an erodible environment are complex and the factors are still unclear in tropical river basin. Methods: In the Mun River basin of Northeast Thailand, a total of six soil profiles were selected from the native forest, artificial forest, paddy land, and abandoned paddy lands with 1, 3, and 5-year abandoned history, respectively. The contents of soil nutrients, including soil organic carbon (SOC), soil organic nitrogen (SON), and inorganic minerals (Al2O3, CaO, Fe2O3, K2O, MgO, and MnO), in the soil profiles were analyzed to determine their distribution under different land-use types. Soil erodibility K factor was calculated by the erosion productivity impact calculator (EPIC) model to estimate the potential of soil erosion under different land-use types. Moreover, the relationships between soil nutrients and the K factor were determined by linear regression analysis and Spearman's rank correlation analysis. Results: The silty soils under artificial forest were significantly larger for the contents of SOC, SON, Al2O3, Fe2O3, and MnO than the sandy soils under native forest, which was mainly attributed to the abundant fine particles in the silty soils. Fine particles played a key role in being the main carriers of inorganic minerals and combining with organic matter. The contents of SOC, SON, and all inorganic minerals in the soils of the abandoned paddy lands were significantly lower than those in the paddy field, resulting from the severe loss of fine particles under intense soil erosion. The soils with abundant fine particles under the native forest land and paddy land had significantly higher K factors compared to the coarse-textured soils under other land-use types. The K factor was mainly controlled by the proportion of fine particles in the Mun River basin. The paddy field easily occurred severe soil erosion at the early stage (1 year) of paddy land abandonment due to the lack of protective management, which caused decreasing SOC, SON, and inorganic minerals with the loss of fine particles. However, the K2O, MgO, and CaO contents significantly increased after 3 ~ 5 years of paddy land abandonment through the supplement from high salinity groundwater. Conclusions: These results suggest that continual paddy cultivation can effectively maintain soil nutrients in the sandy soils of the tropical river basin. [ABSTRACT FROM AUTHOR]

Soil erosion by water often described as the most worst form of land degradation with serious environmental and socioeconomic ramification, which accelerated by human-induced activities and impacts agricultural productivity, water resources sustainability, and ecological conservations. Despite, the significant amount of research on the topic, location-specific soil erosion studies are still limited in Ethiopia, particularly in the study region. Therefore, this study investigates the spatial pattern of soil erosion risk and map the annual soil loss rate in the Upper Beles watershed of the Blue Nile Basin, Ethiopia. The Revised Universal Soil Loss Equation (RUSLE) model, coupled with geographical information system (GIS), has been adopted for soil loss estimation. The respective model factors were derived from rainfall, soil, land use/cover, and digital elevation model data. The raster layers of rainfall erosivity, soil erodibility, topographic, cover management, and conservation practices were processed and multiplied together in the GIS platform. The order of magnitude of the estimated soil loss was within the range of zero in bare areas and watercourses to well over 50 t ha−1 yr−1 in degraded slope and steep mountain areas. The resulting average annual soil loss was founded to be 13.2 t ha-1 yr-1, which exceeded the soil loss tolerances of Ethiopia's northern highlands. Based on soil erosion risk's spatial distribution, 58.2% of the watershed has suffered soil loss less than 5 t ha−1 yr−1. Result shows that high soil erosion prevails at steep slopes and mountainous areas with no vegetation covers and extensively cultivated areas. The RUSLE and GIS-based approach provides a reliable estimation of soil loss that helps identify the priority area for effective planning and implementation of sustainable soil management practices to reduce soil erosion, particularly for the sustainability of the Grand Ethiopian Renesance Dam (GERD) located at the downstream.

Terracing is the oldest technique for water and soil conservation on natural hilly slopes. In Northern Thailand, terraced paddy fields were constructed long ago, but scientific questions remain on how terraced paddy fields and upland rice (non-terraced) differ for soil organic carbon (SOC) stocks, soil nutrients and soil erodibility. Therefore, this study aims to evaluate and compare SOC stocks, soil nutrients and soil erodibility between terraced paddy fields and upland rice at Ban Pa Bong Piang, Chiang Mai Province, Thailand. Topsoil (0–10 cm) was collected from terraced paddies and upland rice fields after harvest. Results showed that SOC stocks were 21.84 and 21.61 Mg·C·ha−1 in terraced paddy and upland rice fields, respectively. There was no significant difference in soil erodibility between terraced paddies (range 0.2261–0.2893 t·h·MJ−1·mm−1) and upland rice (range 0.2238–0.2681 t·h·MJ−1·mm−1). Most soil nutrients (NH4-N, NO3-N, available K, available Ca and available Mg) in the terraced paddy field were lower than those in the upland rice field. It was hypothesized that the continuous water flows from plot-to-plot until lowermost plot caused dissolved nutrients to be washed and removed from the flat surface, leading to a short period for accumulating nutrients into the soil. An increase in soil erodibility was associated with decreasing SOC stock at lower toposequence points. This study suggested that increasing SOC stock is the best strategy to minimize soil erodibility of both cropping systems, while proper water management is crucial for maintaining soil nutrients in the terraced paddy field.

Runoff and erosion processes can increase after wildfire and post‐fire salvage logging, but little is known about the specific effects of soil compaction and surface cover after post‐fire salvage logging activities on these processes. We carried out rainfall simulations after a high‐severity wildfire and post‐fire salvage logging to assess the effect of compaction (uncompacted or compacted by skid traffic during post‐fire salvage logging) and surface cover (bare or covered with logging slash). Runoff after 71 mm of rainfall across two 30‐min simulations was similar for the bare plots regardless of the compaction status (mean 33 mm). In comparison, runoff in the slash‐covered plots averaged only 22 mm. Rainsplash in the downslope direction averaged 30 g for the bare plots across compaction levels and decreased significantly by 70% on the slash‐covered plots. Sediment yield totalled 460 and 818 g m−2 for the uncompacted and compacted bare plots, respectively, and slash significantly reduced these amounts by an average rate of 71%. Our results showed that soil erosion was still high two years after the high severity burning and the effect of soil compaction nearly doubled soil erosion via nonsignificant increases in runoff and sediment concentration. Antecedent soil moisture (dry or wet) was the dominant factor controlling runoff, while surface cover was the dominant factor for rainsplash and sediment yield. Saturated hydraulic conductivity and interrill erodibility calculated from these rainfall simulations confirmed previous laboratory research and will support hydrologic and erosion modelling efforts related to wildfire and post‐fire salvage logging. Covering the soil with slash mitigated runoff and significantly reduced soil erosion, demonstrating the potential of this practise to reduce sediment yield and soil degradation from burned and logged areas. [ABSTRACT FROM AUTHOR]

This paper aims to study structural differences and anti-erodibility properties of purple and loess soils in hilly terrains of southern and northern China. Yoder's method and Le Bissonnais method were used to determine the distribution of soil particle sizes, mean weight diameter (MWD), and geometric mean diameter (GMD). The sequences of water-stable aggregates in different sizes were as follows: On one hand, the sequence of purple soil aggregates was W2-5mm>W0.25-0.5mm>W0.5-1mm>W0-0.053mm>W0.053-0.25mm>W1-2mm>W>5mm. On the other hand, the sequence of the loess soil was W0-0.053mm>W0.053-0.5mm>W0.25-0.5mm>W0.5-1mm>W2-5mm>W1-2mm>W>5mm. Three LB treatments were carried out and the results were as follows: MWD and GMD of soil aggregates in the loess soil presented the trend of slow wetting (SW)>wetting stirring (WS)>fast wetting (FW), while those in the purple soil were WS>SW>FW. Under SW treatment, purple soil had higher erodibility factor (K) than loess soil, close to the result of Yoder's method. Yet under WS and FW treatments, K values of purple soil were much lower than that of loess soil (P<0.05). A significant difference in K, MWD, GMD, and soil organic matter (SOM) values was found between purple soil and loess soil (P<0.05). Slope positions greatly influence MWD, GMD, SOM content for the two soils (P<0.01), and the interaction between soil type and slope position showed an extremely significant positive correlation to MWD and GMD (P<0.01). Our study indicates that, under different breakdown mechanisms, purple soil has a more stable structure and higher anti-erodibility than loess soil. The results of this study will provide a theoretical basis for further understanding of the erosion mechanism of the main soils in China. [ABSTRACT FROM AUTHOR]

Soil erodibility is one of the major parameters for soil erosion prediction and conservation planning. Soil shear strength is an effective indicator of soil erodibility. Although shear strength has been extensively measured on agricultural lands, very limited measurements have been made within gullies. In this study, shear strength was measured at various geomorphic positions of gullies, in different types of deposits and gullies, as well as in inter‐gully areas in the Wangjiagou watershed on the Loess Plateau. In total, over 5,000 measurements were taken in the field prior to the rainy seasons in 2006 and 2008. The results demonstrated: (a) there is a drastic difference in soil shear strength among different types of geomorphic features and deposits in the gullies, with the highest on gully sidewalls and the lowest in new dry flow materials (a mean value of 110.7 vs. 1.3 kPa); (b) Among different types of gullies, the mean shear strength of headwater gully and hillside gully shows no statistically significant difference (14.8 vs. 14.3 kPa), but is much smaller than that of valleyside gully (26.4 kPa); (c) Soil shear strength has much greater variation in the gully area than in the inter‐gully area, with a standard deviation of 28.3 versus 12.3 kPa. Different erosion/deposition processes play a major role in the spatial heterogeneity of soil shear strength in the gully area, whereas land use and tillage practices are the controlling factors in the inter‐gully area; (d) All types of mass failures reduce soil shear strength dramatically, and therefore increase subsequent water erosion. [ABSTRACT FROM AUTHOR]

Background Soil erodibility (K factor) and soil aggregate stability are often used to assess soil degradation in an erodible environment. However, their applicability under land-use change is uncertain, especially agricultural abandonment. Methods Different land-use types, including cropland, abandoned cropland, and native vegetation land, were converted into the successive stages following agricultural abandonment by space-for-time substitution approach in a small karst catchment, Southwest China. The indexes of soil aggregate stability and K factor of the Erosion Productivity Impact Calculator (EPIC) model in soil profiles were calculated to identify which method is suitable to indicate soil degradation under land-use change. Results The indexes of soil aggregate stability in the soils at 0∼30 cm depth under native vegetation land were significantly larger than those under cropland and slightly larger than those under abandoned cropland. The K factor was not significantly different among the three land use examples because the EPIC model does not consider soil permeability. In the soil organic carbon (SOC)-rich soils (>2%), the K factor was significantly correlated with silt and clay content ranging within a narrow scope of near 0.010 t hm2 h/hm2/MJ/mm. While in the SOC-poor soils, the K factor was significantly increased with decreasing SOC content and was significantly correlated with soil aggregate stability. Conclusions Soil aggregate stability is more suitable to indicate soil degradation under land-use change. Sufficient SOC in erodible soils would restrain soil degradation, while SOC loss can significantly increase soil erosion risk.

Soil erodibility K factor is an important parameter for evaluating soil erosion vulnerability and is required for soil erosion prediction models. It is also necessary for soil and water conservation management. In this study, we investigated the spatial variability characteristics of soil erodibility K factor in a watershed (Changyan watershed with an area of 8.59 km2) of Enshi, southwest of Hubei, China, and evaluated its influencing factors. The soil K values were determined by the EPIC model using the soil survey data across the watershed. Spatial K value prediction was conducted by regression-kriging using geographic data. We also assessed the effects of soil type, land use, and topography on the K value variations. The results showed that soil erodibility K values varied between 0.039–0.052 t·hm2·h/(hm2·MJ·mm) in the watershed with a block-like structure of spatial distribution. The soil erodibility, soil texture, and organic matter content all showed positive spatial autocorrelation. The spatial variability of the K value was related to soil type, land use, and topography. The calcareous soil had the greatest K value on average, followed by the paddy soil, the yellow-brown soil (an alfisol), the purple soil (an inceptisol), and the fluvo-aquic soil (an entisol). The soil K factor showed a negative correlation with the sand content but was positively related to soil silt and clay contents. Forest soils had a greater ability to resist to erosion compared to the cultivated soils. The soil K values increased with increasing slope and showed a decreasing trend with increasing altitude.

The stability of soil aggregates against the impact of rainfall has become vital especially in South-eastern Nigeria whose soils are too fragile due to high rainfall distribution in the zone that facilities soil erosion. In trying to finding out ways of improving the aggregate stability of soils, two agricultural wastes (poultry droppings (PD) and saw dust ash (SDA) were applied individually and in combination of both at varying rates to evaluate its effects on soil aggregate stability, soil physicochemical properties and yield of maize. A randomized complete block design was used and the treatments were replicated three times. Pre and post planting soil samples were collected and analysed for physical and chemical soil properties using standard methods. Data collected from soil analyses and growth performances of maize were subjected to analysis of variance and significant treatment means were separated using least significant difference at 0.05 probability level. Results showed that plots amended with 10 t/ha PD + 10 t/ha SDA increased soil organic carbon by 25.4 %, soil total nitrogen by 25.7 %, effective cation exchange capacity by 34.3 % and base saturation by 19.2 %. Plots amended with 10 t/ha PD + 10 t/ha SDA reduced clay ratio (CR), clay dispersion index (CDI) and dispersion ratio (DR) by 75.2 %, 84.9 % and 93.7 % respectively while clay flocculation index (CFI) was increased by 82.3 %. The highest maize yield (74 kg/ha) was recorded from plots amended with 10 t/ha PD + 10 t/ha SDA. Therefore 10 t/ha PD + 10 t/ha SDA was recommended for improvement of soil properties, soil aggregate stability and yield of maize in acid soil.

Restoration resources are usually limited and strategic information on and erosion susceptible areas are required to avoid further degradation. This study has potential in the Mzimvubu River Catchment, South Africa, where two large reservoirs are planned on the Tsitsa tributary. The Tsitsa River Catchment, however, consists of highly erodible soils with widespread gully erosion evident. It is important to prevent further gully erosion in the catchment due to the presence of duplex and dispersive soils. Therefore, this study modelled areas that are susceptible to gully development in the Tsitsa River Catchment, as well as estimated the sediment yield potential from the susceptible areas if gully development occurs. This was achieved by mapping gully-free areas in a GIS that have the same DEM-derived topographical variables, soil associations and land cover as gullied areas, followed by scenario analysis of the potential sediment yield. More than 30 000 ha (7%) of the catchment is intrinsically susceptible to further gully development, consisting of drainage paths with a large contributing area and erodible duplex soils. If not protected, these susceptible areas could contribute an additional 300 million m3 of sediment to the river network, reducing the volumes of both reservoirs by more than 50%. [ABSTRACT FROM AUTHOR]

Plant community characteristics and functional traits may respond to soil erosion due to their high plasticity in varied environments. However, the linkages between plant functional traits and soil properties under erosion stress remain poorly understood, despite the fundamental role they play in controlling soil erosion. Here, we selected 50 plots on degraded land caused by long‐term water erosion representing three degrees of erosion that differed in terms of soil profile and erosion landform. We measured aboveground plant characteristics, root functional traits, and soil properties to explore their responses to the degree of erosion and to identify the main factors mitigating soil erodibility (Kr). The results showed that vegetation cover and root length density (RLD) were the plant variables that were most sensitive to the erosion stress. Topographic parameters strongly affected plant community characteristics (vegetation cover and litter mass) by favouring thicker soil layers and lower bulk densities, and soil texture strongly affected root functional traits (root mass density [RD] and RLD) by favoring lighter soils. Importantly, plant community characteristics and root functional traits were the main drivers of Kr mitigation through their mediation effects on a range of soil properties (e.g., soil organic matter, aggregate stability, and shear strength) during the restoration, and vegetation can still be efficient in maintaining and restoring soil functions, even on severely degraded land. Overall, these findings could guide restoration practices to meet soil conservation and ecosystem function goals in degraded ecosystems. [ABSTRACT FROM AUTHOR]

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Vegetation restoration is identified as an effective approach to control soil erosion and affects soil detachment and resistance to concentrated flow on the Loess Plateau. However, the effects of vegetation restoration at gully heads in loess‐tableland remains unclear. This study was performed to investigate the effects of nine vegetation restoration types at gully heads on soil detachment rate (Dr) and soil resistance to concentrated flow (i.e. soil erodibility, Kr and critical shear stress, τc). Undisturbed soil samples were collected from nine vegetation‐restored lands and one slope cropland (as the control) and were subjected to a hydraulic flume to obtain Dr values of gully heads under six inflow discharges (0.5–3.5 L s‐1). The results showed that the Dr values of nine revegetated gully heads were 77.11% to 95.81% less than that of slope cropland, and the grassland dominated by Cleistogenes caespitosa and the shrubland dominated by Hippophae rhamnoides had a relatively greater decrease in Dr than those of other seven restoration types. The Dr value of nine revegetated gully heads could be better simulated by stream power than by flow velocity and shear stress and was also significantly affected by soil disintegration rate (positively), soil bulk density, saturated hydraulic conductivity, organic matter content, and water‐stable aggregate stability (negatively). Additionally, roots with diameters of 0 to 0.5 mm showed a greater effect on Dr than those with larger diameters. Compared to cropland, the nine restored types reduced Kr by 76.26% to 94.26% and improved τc by 1.51 to 4.68 times. The decrease in Kr and the increase in τc were significantly affected by organic matter content, water‐stable aggregate, mean weight diameter of aggregate and root mass density. The combination of grass species (Cleistogenes caespitosa) and shrub (Hippophae rhamnoides) could be considered the best vegetation restoration types for improving soil resistance of gully heads to concentrated flow. © 2019 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Vegetation restoration has returned a large number of steep slope farmlands to forests and grasslands, and effectively controlled soil erosion in the Loess Plateau. In the loesstableland and gully region of the Loess Plateau, loess-tableland, hill-slope and gully-slope are widely distributed. Geomorphological location and land use may lead to differences in soil properties and vegetation root systems, and thus affect soil erodibility. However, few studies have been conducted to explore the impact of vegetation restoration at different geomorphological locations on soil erodibility, and the relationships between soil erodibility and influencing factors. This study was carried out in the Nanxiaogou watershed in the loesstableland and gully region of the Loess Plateau. The undisturbed topsoil (0-20 cm) of farmland, grassland, shrub land and woodland was sampled on loess-tableland, hill-slope and gully-slope (no farmland on gully-slope). The comprehensive soil erodibility index (CSEI) was obtained by weighted sum method. The results indicated that: (1) The significant difference in CSEI was found among different geomorphological locations. The CSEI of gully- slope was 8.1% and 77.7% higher than those of hill- slope and loess- tableland, respectively. (2) As for the loesstableland, the CSEI of grassland, shrub land and woodland decreased by 21.1%, 29.2% and 28.8%, respectively compared with that of farmland. For the hill- slope and gully- slopes, the CSEI of woodland was lower than that of other land use types. (3) The CSEI had significantly negative correlations with clay content, sand content, soil capillary porosity, root weight density, root mean diameter, root length density and root surface area density, but significantly positive correlations with silt content and soil bulk density. Multivariate linear stepwise regression indicates that silt content, root mean diameter and soil bulk density are the most important factors influencing CSEI, among which silt content has the greatest direct influence on CSEI, while root mean diameter exerts negative influence on CSEI through direct or indirect effects. This study suggests that shrubs should be the preferred vegetation for vegetation restoration on the loess- tableland. Revegetation with arbor as dominant community may be more effective in controlling soil and water loss on hill-slope and gully-slope. [ABSTRACT FROM AUTHOR]

Revegetation represents an effective measure for preventing soil erosion on the Loess Plateau. However, the effects of revegetation‐induced changes in soil and root properties on soil resistance to concentrated flow erosion (SRC) remain unclear. This study sampled soils and roots across a 25‐year chronosequence from farmland to grasslands of different ages (3, 7, 10, 18, and 25 years) to quantify variations in soil and root properties (soil bulk density, SBD; soil disintegration rate, SDR; saturated hydraulic conductivity, SHC; organic matter content, OMC; water‐stable aggregate, WSA; mean weight diameter, MWD; root mass density, RMD; root length density, RLD; and root surface area density, RSAD) and their effects on SRC. Farmland and grassland SRCs were obtained using a hydraulic flume. Soil properties and root density gradually improved with restoration time. In terms of the comprehensive soil property index calculated via principal component analysis, grassland values were 0.66 to 1.94 times greater than farmland values. Grassland SRCs increased and gradually stabilized (>18 years) over time and were 1.60 to 8.26 times greater than farmland SRC. SRC improvement was significantly related to increases in OMC, SHC, WSA, and MWD and decreases in SBD and SDR over time. SRC was effectively simulated by the Hill curve of RMD, RLD, and RSAD. SDR, SHC, and RMD (0.5–1.0 mm) affected SRC the most. This study scientifically describes how revegetation improves soil quality and soil resistance to flow erosion, and suggests that vegetations rich in 0.5–1.0 mm roots should be preferred during revegetation. [ABSTRACT FROM AUTHOR]

The effect of substitution of submontane beech forest (Helleboro odori - Fagetum moesiacae Soo&Borhidi 1960.) by Lawson's cypress (Chamaecyparis lawsoniana (A. Murr.) Parl.) on the soil properties affecting the erodibility factor was researched on one sample plot on the mountain Veliki Jastrebac in south-eastern Serbia. The research was performed in the Lawson's cypress artificially established stand aged 40 years and in the natural beech forests on dystric cambisol. Under the effect of Lawson's cypress and its dead organic residues, the content of total organic matter in the topsoil decreased by 10 cm compared to that in the natural beech forest. This resulted in the decrease in stability of the soil micro-structural aggregates and the increase in the soil erodibility factors. [ABSTRACT FROM AUTHOR]

Detailed information pertaining to soil erosion is required to ensure eco-environment protection and economic development for Xinjiang Uygur Autonomous Region, and remote sensing and geographical information system technologies are adopted to obtain an accurate distribution of soil erosion. An improved estimation method for wind erosion is developed, which proves to be effective with an overall precision of 87.24%. The proposed model uses six critical factors: number of snow cover days, soil erodibility, aridity index, vegetation fraction, soil crust index, and wind field intensity. Results show that soil wind erosion is widely distributed throughout the Xinjiang Uygur Autonomous Region. The average erosion intensity is 0.50, which is determined to be a moderate erosion level. The wind erosion intensity increases from a slight level in the western part to a severe level in the mid-eastern part. The mean intensity of soil wind erosion for varying land use types is ranked in descending magnitude of barren or sparse vegetation, open shrubland, grassland, cropland, evergreen coniferous forest, and mixed forest. There are large differences in soil wind erosion intensities among soil types; grassland has severe wind erosion and Luvic Arenosols has the lowest erosion intensity.

• Original RWEQ overestimated the wind erosion rate for compacted grassland soils. • 137Cs tracing results were used to examine the applicability of RWEQ for grassland. • An extended erodibility equation was developed accounting for soil compaction. • Wind erosion rates in Inner Mongolia were calculated using the extended RWEQ. The commonly used wind erosion models, including the Revised Wind Erosion Equation (RWEQ), are mainly based on data from loose soils, for which the erodibility factor (EF) reflects the abundance of erodible aggregates, and cannot be applied to simulate erosion of compacted soils such as some grassland soils. Taking the Inner Mongolia Autonomous Region in northern China as the study area, we used the 137Cs tracing technique to estimate the soil loss of grassland by wind erosion from 1963 to 2021, and used the results as criteria to verify the wind erosion rate (WER) predicted by RWEQ for the same period. We found that RWEQ accurately calculated the WER of cultivated farmland, but overestimated grassland WER. We believe that the main reason is that the equation did not consider the impact of soil compaction (SC) on EF , since the calculation methods for the weather factor, vegetation factor, surface roughness factor, and soil crust factor in RWEQ are applicable for grasslands. Therefore, we used the 137Cs tracing results to extrapolate the grassland EF while keeping the climate, soil crust, vegetation cover, and roughness factors constant, and combined SC and the proportion of aggregates smaller than 0.84 mm in diameter to develop an empirical equation for grassland EF. Compared with the original model, the extended model (RWEQ ext) that included the factor of SC more accurately estimated the WER of compacted grassland soil and could be applied to the whole study area. The RWEQ ext results showed that tolerable and slight levels of wind erosion dominated the grassland and gobi surfaces in the study area, whereas moderate wind erosion occurred in grasslands with sparse vegetation cover, and severe, very severe, and destructive wind erosion mainly occurred on loose surfaces such as sandy land with low vegetation cover. [ABSTRACT FROM AUTHOR]

• Organic soil height variation is mainly impacted by the bulk density, the erodible matter, the GMD and the MWD, water content and the elevation. • The wind erodibility index is affected by the organic matter content, the bulk density, the MWD and GMD, and the water content. • The high organic matter content (>80%), and low bulk density (<0.47 g/cm3) in the organic soil makes them more vulnerable to wind erosion. • BD, VW, OM, MWD, EM, GMD, elevation Z are key soil properties in sustainable management of organic soil with >80% OM and could be used in a wind erosion risk model adapted to organic soils. Cultivated organic soils are known to be highly susceptible to wind erosion. The aim of this research was to explore the relationships between organic soil properties and measured soil height variation (SHV) in a cultivated organic soil and to analyze field soil erodibility (wind erodibility index: WEI) from known models. In the fall, 81 georeferenced soil samples were collected at a depth of 0–10 cm and analyzed in the laboratory to determine different soil properties. At the same time, soil height variations were measured over a 35-day period. Simple and multiple linear regressions were used to explore relationships between soil properties and analyze SHV and WEI. The average SHV across the farm was −0.19 mm per day, equivalent to a loss of 0.665 cm during the measurement period. Simple linear regression showed weak relationships with SHV. Nevertheless, the analysis showed that soil loss areas had a larger fraction of macro-aggregates. Conversely, deposition areas with low bulk density (BD) contained more fine material (organic matter [OM] and erodible material [EM]), suggesting wind erosion effects, i.e., deposition of fine matter. Many soil properties were found to correlate significantly with one another. Applying multiple linear regression with SHV and WEI as dependent variables and soil properties as independent variables produced the following results: a) 24% of the SHV was significantly explained by 6 soil properties (α = 5 % , p = 0.001), BD, EM, mean weight diameter (MWD), elevation (Z), geometric mean diameter (GMD), and volumetric water (VW); and b) 75% of the variation in WEI was explained by 5 variables (α = 5 % , p = 0.001), BD, VW, OM, MWD and GMD. This result shows that BD, VW, OM, MWD, EM, GMD, elevation Z are key soil properties in sustainable management of organic soil with >80% OM and will be used in a wind erosion risk model adapted to organic soils. [ABSTRACT FROM AUTHOR]

• Spatial variations in soil erodibility was quantified by indicators in karst hillslope. • Identify the predominant factors affecting spatial variations in soil erodibility. • Land use and slope position had great effects on near-surface soil characteristics. • CSEI varied with land use and slope position, and affected by soil characteristics. Land use type and slope position have a considerable impact on soil properties and thus likely influence soil erodibility. Soil erosion on karst hillslopes in South China is still serious due to the high intensity of human activities and fragile ecological environment. Nevertheless, the potential effects of land use type and slope position on soil erodibility indicators in karst areas are still unclear. This study was conducted to investigate the spatial variations in soil erodibility indicators, namely, the saturated hydraulic conductivity (K S), mean weight diameter (MWD), soil structural stability (SSI), soil erodibility K factor, soil organic carbon content (SOC), and a comprehensive soil erodibility index (CSEI) for three typical land uses and three slope positions on a karst hillslope. The results showed that K S , MWD , SSI , K factor, SOC and CSEI varied significantly with land use type and slope position. The measured K S , MWD , SSI , K factor and SOC at the nine tested sites displayed a similar trend with soil depth. SOC , MWD and SSI contributed more to the CSEI , with contributions of 27.9%, 25.9% and 25.9%, respectively. K S and K factor contributed less to the CSEI , with contributions of 17.7% and 2.5%, respectively. Woodland is most susceptible to erosion on upper, cropland on middle and grassland on lower slope positions according to the values of CSEI. There were significant positive correlations among sand content, bulk density and CSEI , and there were significant negative correlations among clay content, silt content, root mass density, SOC and CSEI. The changes in soil properties and soil erodibility indicators with land use type and slope position led to the differences in the CSEI. The results provide valuable information for policymakers to select appropriate land use types to mitigate soil erosion and thus improve the healthy development of the ecological environment on karst slopes. Moreover, the results have crucial implications for understanding the mechanism of the spatial variation in soil erosion of karst hillslopes in Southwest China. [ABSTRACT FROM AUTHOR]

• MEMD was used to decompose K and related 13 environmental variables. • The decomposed scales of the variables were 114, 193, 320 and 670 km. • Effects of the influencing factors on K were different at different spatial scales. • Prediction model of K considering the scale effect had higher accuracy. Soil erodibility (K) is a key factor in the prediction of soil erosion. K on the Tibetan Plateau is affected by both soil properties and the alpine environment, but the intensity and scale of the influences of soil and environment variables on K have rarely been studied. This study aimed to identify the scale-specific factors controlling K and their relationships along a 1970-km transect on the plateau using multivariate empirical-mode decomposition. The transect was established in the central part of Tibet Autonomous Region, and 60 sampling points were set at an approximate fixed interval to investigate the properties of surface soil and associated environmental factors. Mean K of the transect was 0.0340 t hm2 h MJ−1 mm−1 hm−2, with a range of 0.0138–0.0464. K and 13 other soil and environmental variables were synchronously decomposed into four intrinsic mode functions (IMFs) and one residue. The spatial scales of IMF1-4 were 114, 193, 320 and 670 km, respectively. The proportion of variation of IMF1 in the total variation for all factors except mean annual precipitation (MAP) ranked first or second, indicating that most of the spatial variation of the variables mainly occurred at small scales. Sand, silt and clay contents had the same correlations with K at the sampling scale and each decomposed scale, and correlations of K with other environmental variables varied with scale due to the different main process scales of the variables and K. The accuracy of the prediction model established considering the scale effect was higher than the accuracy of the model without considering this effect. This study identified the main factors influencing K at different spatial scales along a long transect on the Tibetan Plateau and established K-prediction models considering the effect of scale, which provides a basis for accurately predicting soil erodibility in alpine regions. [ABSTRACT FROM AUTHOR]

The Revised Universal Soil Loss Equation (RUSLE) was used to predict the potential soil erosion; it simply multiplies rainfall erosivity and land cover management factors; it does not consider the dynamics of these two factors during a given year or the effect of vegetation growth cycle on soil erosion estimates. This study developed a new method that considers the vegetation growth cycle in different periods of the year by matching monthly rainfall erosivity and a management factor using the entire surface of China as the study area. The data were input into the original equation, and the two methods to estimate soil erosion were compared. Finally, patterns and mechanisms of the influence of vegetation growth cycle on RUSLE estimations under different climatic conditions were obtained. The results show that vegetation coverage inhibits the effect of rainfall on soil erosion potential, which is related to the average and coefficient of variation of cover-management factor and the average of rainfall erosivity due to the significant variations in weather patterns in winter and summer in China. This article discusses the influence of the vegetation growth cycle on the estimation of large-scale soil erosion, which is a key to having a better estimation.

ctivity index (AI) value characterizes the relationship between the plasticity index and clay content. In this study, AI value was investigated to determine whether it might be used as an indicator of soil structural stability or not. The AI values of 75 soil samples gave the significant negative correlations with their dispersion ratio (DR), soil erodibility factors (K) and erosion ratios (ER). Also, the AI values of the soils including clay and sandy clay loam textural class showed significant positive correlation with soil structural stability index (SSI). It seems that the AI value may be used as an indicator of soil structural stability.

As an important type of soil erosion, freeze-thaw erosion occurs primarily at high latitude and altitude. The overview on the effect of freeze-thaw on soil erosion was provided. Soil erosion was affected by freeze-thaw processes, as thawing and water erosion reinforce each other. Remote sensing provided an unprecedented approach for characterizing the timing, magnitude, and patterns of large-scale freeze-thaw and soil erosion changes. Furthermore, the essence of soil freeze-thaw was the freeze and thaw of soil moisture in the pores of soil. Freeze-thaw action mainly increased soil erodibility and made it more vulnerable to erosion by destroying soil structure, changing soil water content, bulk density, shear strength and aggregate stability, etc. However, the type and magnitude of changes of soil properties have been related to soil texture, water content, experimental conditions and the degree of exposure to freeze-thaw. The use of indoor and field experiments to further reveal the effect of freeze-thaw on soil erosion would facilitate improved forecasting, as well as prevention of soil erosion during thawing in regions with freeze-thaw cycles.

• Quantified land use type/structure was for the first time included into models. • The predictions highly depend on the quantification of land use type/structure. • It is effective to predict the soil stability distribution without soil variables. As indicators of soil degradation vulnerability, soil aggregate stability indices play important roles in representing soil resistance to water erosion, and their spatial variability provides both agriculturally and environmentally important information. The spatial variability of aggregate stability indices is synergistically affected by the soil, topography, vegetation, and human factors. To understand the formation processes of aggregates by a spatial analysis, a prediction model combining soil properties with natural and human factors should be developed to improve the accuracy of the spatial interpolation of soil aggregate stability indices. In this study, the mean weight-diameter (MWD, mm), water-stable aggregates greater than 0.25 mm (WSA >0.25 , %) and soil erodibility factor (K factor) were satisfactorily predicted by multiple stepwise regression (MSR) and regression kriging (RK) based on soil properties and natural and human factors (0.436≤ R2 ≤0.578). In addition, spatial variability and prediction modeling of aggregate stability indices were highly dependent on the quantification of land use type and landscape structure (the spatial structure of landscape elements and the connections between the different ecosystem types or landscape elements). It has received little attention in previous studies. The exclusion of all soil variables did not affect the predictions of K factor, and for MWD and WSA >0.25, even though the performance of the models may appear relatively low, but also significant (0.183≤ R2 ≤0.312), indicating that the prediction of the spatial distributions of aggregate stability indices with easily available auxiliary data is practicable and effective. Residual maps showed that high residuals are distributed around built-up land (transportation land and residential land) or farmland, indicating that anthropogenic factors increase the uncertainty of the models. The spatial distribution maps of MWD, WSA >0.25 and K factor can be useful in landscape planning and decision making to minimize water erosion risks. [ABSTRACT FROM AUTHOR]

Copyright of Anadolu Tarım Bilimleri Dergisi is the property of Ondokuz Mayis Universitesi, Ziraat Fakultesi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Planning soil conservation strategies requires predictive techniques at event scale because a large percentage of soil loss over a long‐time period is due to relatively few large storms. Considering runoff is expected to improve soil loss predictions and allows relation of the process‐oriented approach with the empirical one, furthermore, the effects of detachment and transport on soil erosion processes can be distinguished by a runoff component. In this paper, the empirical model USLE‐MB (USLE‐M based), including a rainfall‐runoff erosivity factor in which the event rainfall erosivity index EI30 of the Universal Soil Loss Equation (USLE) multiplies the runoff coefficient QR raised to an exponent b1 > 1 is tested by the measurements carried out for the Masse (10 plots) and Sparacia (22 plots) experimental stations in Italy. For the Masse experimental station, an exponent b1 > 1 was also estimated by tests carried out by a nozzle‐type rainfall simulator. For each experimental site in fallow conditions, the effect of the sample size of the plot soil loss measurements on the estimate of the b1 coefficient was also studied by the extraction of a fixed number N of randomly obtained pairs of the normalized soil loss and runoff coefficient. The analysis showed that the variability of b1 with N is low and that 350 pairs are sufficient to obtain a stable estimate of b1. A total of 1,262 soil loss data were used to parameterize the model both locally and considering the two sites simultaneously. The b1 exponent varied between the two sites (1.298–1.520), but using a common exponent (1.386) was possible. Using a common b1 exponent for the two experimental areas increases the practical interest for the model and allows the estimation of a baseline component of the soil erodibility factor, which is representative of the at‐site soil intrinsic and quasi‐static properties. Development of a single USLE‐MB model appears possible, and sampling other sites is advisable to develop a single USLE‐MB model for general use. [ABSTRACT FROM AUTHOR]

In order to provide reference for soil erosion research, potential risk assessment of soil environment, soil and water conservation and ecological environment construction in Yunnan Province, 274 soil profiles were collected and of which 222 typical profiles were investigated in the field. The K values of soil erodibility of all soil species were calculated by Wischmeier model and Williams model, and linked with 1∶750 000 soil map of Yunnan Province. The distribution map of soil erodibility K value in Yunnan Province was obtain, and then the spatial distribution characteristics of soil erodibility in different states (cities), watersheds and altitudes were analyzed. The results show that the average K value of soil erodibility in Yunnan Province is 0.006 2, belonging to the middle erodibility grade; the state (city) with the largest K value of soil erodibility is in Chuxiong and the largest watershed is Honghe River basin. The K value of soil erodibility with an altitude of 1 000-2 000 m is the maximum. [ABSTRACT FROM AUTHOR]

Soil erosion can pose a serious problem to environmental quality and sustainable development. On the Tibetan Plateau, soil erosion is one of the main challenges to regional ecological security. Our analysis investigates soil erosion and evaluates its economic value in alpine steppe, alpine meadow, alpine desert steppe and forest ecosystems on the Tibetan Plateau. Analysis was carried out from 1984 to 2013. The results show that the annual average potential soil erosion, practical soil erosion and soil conservation calculated by the Revised University Soil Loss Equation model were 2.19×109ta–1, 2.16×109ta–1 and 2.72×107ta–1, respectively. The economic value of retaining soil nutrients, reducing the formation of wasteland and the economic benefit of reducing sediment deposition were 1.98×108RMBa–1, 2.55×1012RMBa–1 and 7.44×104RMBa–1, respectively. From comparing different ecosystems, we found that the forest ecosystem had the greatest soil retention and economic values. We also found that the potential and actual soil erosion values were extremely high on the Tibetan Plateau. The study highlights that state and local policymakers must give greater emphasis to ecological protection in the future. [ABSTRACT FROM AUTHOR]