Soil Erosion Measurements Research Articles

Evaluation of structure from motion (SfM) photogrammetry on the measurement of rill and interrill erosion in a typical loess

Structure from motion (SfM) photogrammetry is a cost-effective topographic survey tool capable of producing high-quality 3-dimensional structure of a landform. Yet its application has rarely been reported in rill and interrill erosion at the relatively small spatial scales, especially when taking place in the loess that is vulnerable to erosion. The objective was to examine the accuracy and limits of SfM in quantifying rill and interrill erosion occurring in a typical loess during consecutive rainfall simulations. The loess collected from the plough layer of a cropland in the Loess Plateau of China was packed into a 200 × 100 × 35 cm runoff plot and received simulated rainfall at the intensity of 90 mm h−1 on three slopes of 10°, 15° and 20°. A portable laser scanner (LS) and SfM were used to measure soil surface at every 30 min until rill emergence and after another 30-min rainfall aiming to study rill development. Meanwhile, runoff and sediment samples were collected at the plot outlet and oven-dried to calculate the soil loss. The results showed that the elevation differences calculated by subtracting digital elevation models (DEMs) derived by SfM and LS mainly fell between −2 and 2 mm. Moreover, the root mean square error (RMSE) and mean absolute error (MAE) were mostly smaller than 3 mm, suggesting accurate soil erosion measurement made by SfM at the plot scale. Considering the surface variations, the relative RMSE and MAE, i.e., dividing over the mean elevations measured by LS, were found to decrease as soil erosion proceeded and rills emerged. The rill morphology comparison, however, suggested a better fit of SfM for rills larger than 9 cm in maximum surface width, 6.0 × 10−2 m2 in area and 0.9 × 10−3 m3 in volume. In accordance with DEM comparisons, the soil losses estimated by SfM and LS were statistically similar. Nevertheless, these values were much greater than the amount of sediments collected for the early simulation runs, which might be explained primarily by the settling of loess when subject to heavy rainfall. But as rainfall continued and rills further developed, the misestimations made by LS and SfM remarkably dropped, i.e., from −17.8% to 4.9% and from −18.1% to 4.3%, respectively. These findings suggest a generally higher accuracy of SfM in quantifying rill erosion with more fluctuating soil surface than in interrill erosion measurement.

Anecic earthworms generate more topsoil than they contribute to erosion – Evidence at catchment scale in northern Vietnam

Soil is considered as a non-renewable resource, which may be lost in sloping land more rapidly than it is formed thus leading to loss of fertility and ecosystem deterioration. We hypothesized that earthworms could counteract this process due to their cast forming activity. To test this hypothesis, we quantified the production of casts in small plots of 0.25 m2 established in three vegetation units (woodland, shrubland and meadow) in a catchment of 46 ha for 2.5 years in relation to their (micro-) pedoclimatic conditions. We also assessed the impact of cast formation on water runoff and soil detachment. Moreover, we quantified the mass of casts deposited in the entire catchment on a regular grid of 50 m and we measured soil erosion at the outlet of the catchment.Our results showed a high and variable production of casts (from 16 to 219 t ha−1 year−1) depending on vegetation, season and year. The mass of casts found in the entire catchment represented on average 7.4 t ha−1 with an annual production rate of 35 t ha−1. Since the annual erosion rate measured for the entire catchment (3 t ha−1 year−1) was much lower than the cast production rate, our results indicated that most of the soil bioturbated by earthworms remained in the catchment. Indeed, water runoff and soil detachment measured in small plots showed that casts were not transported in the water runoff but degraded by raindrop impacts with the material remaining at the place of deposition. This process led to the generating of a new soil horizon at the culmination point of the catchment of up to 6.5 cm after 2.5 years. We conclude that the surface activity of anecic earthworms could influence soil generation at scale and conteract the effects of soil erosion.

Hillslope erosion in a grassland environment: Calibration and evaluation of the SIBERIA landscape evolution model

AbstractField measurement and modelling of soil erosion provides insights into landscape systems as well as the potential for enhanced landscape management. There are a number of field and numerical methods by which soil erosion and deposition can be quantified. Here we examine the capability of the SIBERIA landscape evolution model to quantify short‐term erosion and deposition on a well‐managed cattle grazing landscape on the east coast of Australia. The model is calibrated by two methods (1) a geomorphological approach using a site digital elevation model (DEM) and soil data and (2) a laboratory‐scale flume. The two calibration processes resulted in similar model input parameters and estimated erosion rates of 3.1 t ha−1year−1and 4.4 t ha−1year−1, respectively. These were found to closely match erosion rates estimated using the environmental tracer137Cs (2.7–4.8 t ha−1year−1). However, erosion and deposition estimated at individual points along the hillslope was not well correlated with137Cs at the same position due to the temporal averaging of the model and microtopography. Sensitivity analysis showed the model was more sensitive to parameterisation than sub‐DEM‐scale topography. This places confidence in the model's ability to estimate erosion and deposition across an entire hillslope and catchment on decadal time scales. We also highlight the robustness and flexibility of the calibration methods.

Long-term monitoring of soil bulk density and erosion rates in two Prunus Persica (L) plantations under flood irrigation and glyphosate herbicide treatment in La Ribera district, Spain

Early season fruit production for the northern European market is highly intensive in fertilization, machinery, irrigation and the use of herbicides. Those conditions increase the soil losses and soil compaction and threaten the Sustainable Goals for Development of the United Nations by 2030. Long-term soil erosion measurements are necessary to determine the sustainability of agriculture managements. Moreover, soil erosion on flood irrigation land is a topic that request more surveys and research as rainfed sloping terrains attracted all the attention of scientists and research investment. Improved Stock Unearthing Method (ISUM) was applied to two 15 years-old herbicide treated fields of Saturn peaches (Prunus persica var. platycarpa) to determine long-term soil erosion rates (2004–2019). Using ISUM, a 1 mm thick nylon rope (700 mm length) was used to connect trees perpendicular to the direction of rows at the height of the graft. To detection soil lowering, the vertical distance of the rope to the soil surface was measured at 10 cm intervals along the rope. The ring method (264 samples at 0–6 cm) was used to determine the soil bulk density, which was in average 1.15 gr cm−3 for both plots. There was found a compaction in the centre of both plots due to the pass of machinery with mean bulk density values of 1.23 gr cm−3, meanwhile underneath of the trees, the soil bulk density was 1.05 gr cm−3. The topography survey carried out with ISUM (2508 sampling points) informed that flood irrigation redistributed the soil from the upper to the lower field position, where a sedimentation layer was measured. We found that the two studied fields showed a contrasted response, with low soil erosion values in Benimodo and high in L'Alcúdia study sites. Soil erosion rates were in average 1.46 Mg ha−1 yr−1 and 8.02 Mg ha−1 yr−1 for Benimodo and L'Alcúdia, respectively. However, the maps development using ISUM allow to inform that the pattern of soil redistribution is similar for both fields as the highest soil lowering was found in the upper field part, where the flood discharge detach soil particles. In the lower field position sedimentation takes place. The dataset allows us to conclude that soil erosion in Saturn peaches fields is non-sustainable and more soil conservation management should be applied to reduce the soil erosion rates due to the bare soils as a consequence of the use of herbicides. This research informs that soil erosion in flood irrigated fields is a relevant process that needs more investigations around the world, where 94% of the irrigated land is under flood or furrow irrigation, and where irrigation is growing year after year.

《生产建设项目土壤流失量测算导则》在仁沐新高速公路中应用的合理性探讨

《生产建设项目土壤流失量测算导则》在仁沐新高速公路中应用的合理性探讨

Investigation of on-site implications of tea plantations on soil erosion in Iran using 137Cs method and RUSLE

Tea plantations cover an area of ca. 31,000 ha in the Central North of Iran. This area, after clearing the original forests more than 50 years ago, became exposed to severe soil erosion. The objective of this study was to assess long-term soil erosion rates in tea farms and to evaluate their soil conservation effect at a whole-of-catchment scale. No previous information on direct measurements of soil erosion in this mountainous tea agro-ecosystem of Northern Iran is available. Point-based estimates of net erosion have been obtained using the 137Cs technique and these results were compared with estimates using the RUSLE model. Calculations of soil erosion rates from 137Cs inventories, based on the Mass Balance Model II, revealed that 1.3 mm year−1 and 1.45 mm year−1 of soils were lost from the two sub-catchments A1 and A2, into which the catchment can be divided. The annual net erosion rate of the entire catchment was 17.06 t ha−1 year−1 which is consistent with the rate of 20.4 t ha−1 year−1 obtained by the RUSLE model of at the same scale. This study suggests adopting soil conservation practices to control soil erosion, especially after deforestation and periodic pruning of tea bushes. Sustainable land-use plans are then necessary for tea farms of Iran to protect soil resources and to reduce the off-site impacts of land degradation (mainly siltation) on the reservoirs and coastal area.

Wet and dry spell analysis for crop planning using Markov's chain model

The Indian monsoon is characterised by a series of wet and dry spells. In semi-arid regions the number and length of dry spells decide the success or failure of the kharif crops. Hence, study of onset of monsoon and wet- and dry- spells assumes much importance in rainfed cropping systems in the country. In the present study, the Markov chain probability model was used to calculate the chances of occurrences of dry- and wet- spells for Rahuri using 44-year (1975 to 2018) weekly rainfall data. The average annual rainfall is found to be 564.55 mm and the coefficient of variation (CV) as 32.88% which is higher than the threshold limit (25) indicating the uneven distribution of rainfall. Monsoon starts on the 25th SMW (18th – 24th June) and remains active up to 43rd SMW (22–28th October) with a total length of 18 weeks (126 days). Initial, conditional and consecutive dry- and wet-week probabilities showed that chances of occurrence of a week getting wet is high at the beginning and ending of kharif season excluding 25th to 33rd weeks. Chances of occurrence of the wet week of more than 35% at the beginning of kharif season in the 23rd and 24th SMW indicates that summer ploughing and initial seed bed preparations and sowing operations could be taken up since 25th SMW with supplemental irrigations. Lower values of CV in kharif season showed that variability of rainfall during this period is less which supports the growing of rainfed crops. The significant contribution of weekly rainfall (>20 mm) during 34th – 40th SMW with high consecutive wet week probability indicates the potential of harvesting excess runoff water for future supplemental irrigations and also soil erosion measures to be taken up for soil erosion control.

Predicción de la erosión hídrica en la cuenca del Cañón del Sumidero, Chiapas

En la cuenca del Cañón del Sumidero, estado de Chiapas, México, el suelo es un componente del medio natural fuertemente afectado por la erosión debido al manejo inadecuado del recurso suelo. La medición de la erosión del suelo lleva mucho tiempo y los datos de las tasas de erosión del suelo en México son limitados y puntuales, además, aportan poca información sobre las tasas de pérdida de suelo a nivel de cuenca. En el presente estudio se usaron metodologías para la aplicación de la USLE/RUSLE, desarrolladas en diversos estudios y países, con el propósito de realizar la cartografía de erosión hídrica de la cuenca del Cañón del Sumidero, la cual constituye una herramienta significativa para tomar decisiones en el manejo y conservación de suelos. Se propone una serie de herramientas metodológicas para la generación de la cartografía de erosión hídrica usando información en México a diversas escalas. Los resultados se presentan como una referencia geográfica anual promedio de perdida de suelo y su distribución mensual. El análisis de resultados indica que 73% de la cuenca presenta algún grado de erosión, que junio es el mes que la erosión es mayor (7 021 906.9 t) y que la erosión promedio anual en el área de estudio es 41.5 t ha-1 año-1.

Soil Organic Carbon Sequestration and Active Carbon Component Changes Following Different Vegetation Restoration Ages on Severely Eroded Red Soils in Subtropical China

Degraded soil has a high carbon sink potential. However, the carbon sequestration capacity and efficiency of comprehensive control measures in soil erosion areas are still not fully understood, and this information is essential for evaluating the effects of adopted restoration measures. The objective of this study was to determine the restoration of soil organic carbon and active carbon components under the impact of soil erosion measures and reforestation following different restoration ages. A small watershed with four typical restored plots following the same control measures (combination measures with horizontal bamboo burl-groove + replanting trees, shrubs and grasses) but different restoration ages (4 years, 14 years, 24 years and 34 years) and two reference plots (bare land (carbon-depleted) and nearby undisturbed forest (carbon-enriched)) in subtropical China was studied. The results showed that the soil organic carbon contents at a 1 m soil depth and the dissolved organic carbon and microbial biomass carbon concentrations in the upper 60 cm of soils of the four restored lands were higher than those in the bare land. Furthermore, the restored lands of 4 years, 14 years, 24 years and 34 years had soil organic carbon stocks in the 1 m soil depth of 22.83 t hm−2, 21.87 t hm−2, 32.77 t hm−2 and 39.65 t hm−2, respectively, which were higher than the bare land value of 19.86 t hm−2 but lower than the undisturbed forestland value of 75.90 t hm−2. The restored forestlands of 34 years of ecological restoration also had a high potential of being a soil organic carbon sink. Compared to the bare land, the restored lands of 4 years, 14 years, 24 years and 34 years had soil organic carbon sequestration capacities of 2.97 t hm−2, 2.01 t hm−2, 12.91 t hm−2 and 19.79 t hm−2, respectively, and had soil organic carbon sequestration rates of 0.74 t hm−2 a−1, 0.14 t hm−2 a−1, 0.54 t hm−2 a−1 and 0.58 t hm−2 a−1, respectively. Our results indicated that the combined measures of horizontal bamboo burl-groove and revegetation could greatly increase carbon sequestration and accumulation. Suitable microtopography modification and continuous organic carbon sources from vegetation are two main factors influencing soil organic carbon recovery. Combination measures, which can provide suitable topography and a continuous soil organic carbon supply, could be considered in treating degraded soils caused by water erosion in red soil areas.

Runoff and soil loss responses of cultivated land managed with graded soil bunds of different ages in the Upper Blue Nile basin, Ethiopia

BackgroundIn view of a wide range of on-site and off-site impacts of soil erosion, different soil and water conservation measures have been implemented mainly over the last two decades in the Gumara watershed and Ethiopia at large. But their effects have not been sufficiently documented, and maintenance of structures received very little attention. This study investigated the effectiveness of graded soil bunds of zero and 11 years of age in reducing runoff and soil loss. Six hydrologically isolated experimental runoff plots (three treatments × two replicates) were prepared to observe rainfall, runoff, and sediment concentrations in the 2019 summer rainfall season (covering approximately 70% of the annual rainfall).ResultsNewly constructed soil bunds reduced runoff by 34.94 and 25.56% compared to the old and non-treated counterparts, respectively. Similarly, 59.6 and 48.3% soil loss reductions were observed. The amount of soil loss in non-treated plots was twice that from the new plots and even 1.6 times higher than that from the old-graded soil bund treatments. The rate of soil loss in the new- and old-graded soil bund-treated and non-treated plots was 23.5, 45.6, and 58.1 t ha−1 year−1, respectively. However, the effectiveness of the old soil bunds was much lower (only − 12.6 and − 21.7% in runoff and soil loss, respectively) than its new equivalent. Graded soil bunds, in its new form, reduced runoff, runoff coefficient, and soil loss significantly (P < 0.05). Regardless of the treatments, from the start of the rainy season to the end, runoff and runoff coefficient showed an increase, but sediment concentration decreased. Newly constructed soil bund is the most effective in reducing runoff and soil loss.ConclusionGraded soil bunds reduced runoff and soil loss significantly, but the rate even in the treated plots was very high when compared to both the soil loss tolerance (1–6 t ha−1 year−1) and formation rate (10–14 t ha−1 year−1) estimated for the area. Hence, these structures need to be supported by other measures such as grass strips, agro-forestry, and percolation ditches, for better results. Besides, regular maintenance by either removing sediments from bund furrows or increasing the bund height is recommended for sustained reduction of runoff and soil loss.

Using Nuclear Fallout to Measure Soil Erosion in Tunisia

Cesium-137 acts as a tracer to evaluate the efficiency of conservation methods.

Combination of 137Cs and 210Pb Radioactive Atmospheric Fallouts to Estimate Soil Erosion for the Same Time Scale.

Naturally occurring 210Pb and artificial 137Cs fallouts are widely used as radioactive tracers for the determination of water-induced soil erosion for different time scales equal to 50 and 100 years, respectively. There exist several calibration models useful to convert the variation of the inventory of these radiotracers in cultivated soil compared to its value on non-disturbed soil to a soil erosion rate. The most comprehensive calibration models are based on a mass balance approach. In the present work, a new calibration model is proposed. It consists on the generalization of the mass balance approach to a cultivated soil subject to two successive and continuous periods of cultivation. The proposed model combines 210Pb and 137Cs fallouts for the same time scale by relaxing the constraint on 210Pb fallout from being used for 100 years’ time scale. The model was applied successfully to hypothetical cases and can be used to measure soil erosion rates for practical cases. It is important to note that the proposed model has two main advantages. First, the complementarity between 210Pb and 137Cs fallouts is for the same time scale and not for different time scales, as usually considered and believed in this field. Second, 210Pb fallout is used for time scales less than 100 years. This makes the model useful to estimate soil erosion rates for two successive periods of cultivation. To the best knowledge of the authors, the combination of 210Pb and 137Cs fallouts for the determination of soil erosion rate variation due to change in cultivation practices for the same time scale has never been developed or applied in the past.

Kajian Erosi Tanah menggunakan Isotop 137Cs dan 210Pb Excess di Sub DAS Ciesek, DAS Ciliwung Hulu, Bogor

Metode jatuhan radioisotop (Fallout Radio Nuclides) telah lama dimanfaatkan dan dikembangkan untuk mempelajari dan mengukur erosi tanah. Penelitian ini bertujuan menduga erosi/deposisi tanah di Sub DAS Ciesek, DAS Ciliwung Hulu menggunakan jatuhan radioisotop 137Cs dan 210Pb excess di alam. Pengambilan sampel tanah dilakukan menggunakan soil core pada empat transek penggunaan lahan yang berbeda. Sampel tanah dianalisis menggunakan Multi Channel Analyzer (MCA) untuk mendapatkan nilai inventori kedua radioisotop tersebut. Hasil penelitian menunjukkan perbedaan pola distribusi erosi/deposisi antara isotop 137Cs dan 210Pb excess. Penggunaan isotop 137Cs menunjukkan proses erosi tanah terjadi pada lahan kebun campuran dan tegalan, tapi proses deposisi terjadi di lahan terbuka. Penggunaan 210Pb excess menunjukkan erosi tanah terjadi di lahan terbuka, namun deposisi terjadi di lahan kebun campuran dan tegalan. Penggunaan 210Pb excess pada penelitian ini lebih dapat diandalkan dibandingkan dengan 137Cs, dalam hal pendugaan erosi tanah

Soil Erosion and Typical Soil and Water Conservation Measures on Hillslopes in the Chinese Mollisol Region

The Chinese Mollisol region is affected by soil erosion. Soil and water conservation (SWC) measures are effective in preventing these phenomena. However, few studies have systematically reviewed soil erosion and SWC measures in this region. The objectives of this paper were to analyze soil erosion and identify typical SWC measures on hillslopes in this Mollisol region. A literature review and analysis were conducted. Soil erosion is widespread in this region and is dominated by snowmelt and wind erosion in winter and spring, rainfall in summer and wind erosion in autumn. The A-horizon thicknesses and organic matter content of the Mollisol decreased with an increase in the number of years of cultivation. Therefore, controlling soil erosion is a means to protect this precious Mollisol resource. The characteristics of 39 SWC measures used on hillslopes were summarized. Among these measures, the contour ridge, large ridge, minimal tillage with residue mulching, no-tillage, straw returning, slope terrace, ridge belt, and agricultural protection forest approaches were the most typical SWC measures. Furthermore, the new tillage measure of half-ridge planting needs to be examined in future studies. In conclusion, it is of practical significance to select suitable SWC measures for different hillslopes in the Mollisol region.

Erosion and soil and water conservation in South‐Kivu (eastern DR Congo): The farmers' view

AbstractDespite being one of the hotspots for soil erosion in the world, little is known regarding farmer's knowledge of soil erosion in the highlands of South‐Kivu in the Democratic Republic of Congo. A proper understanding of farmers' knowledge regarding soil erosion and conservation measures is a prerequisite for implementing resilient erosion control measures. The objective of this study was therefore to assess farmers' knowledge of soil erosion, to document existing soil and water conservation (SWC) measures and to identify their adoption constraints in the highlands of South‐Kivu. Data were collected using interviews with a semi‐structured questionnaire involving 720 respondents from eight watersheds in four territories. Farmers reported eight main erosion indicators. As opposed to gullies (80% of farmers), rills were perceived as important erosion indicators by only 50% of farmers, despite their common occurrence. Farmers were largely unaware of the potential impact of their crops and cropping practices on erosion. Farmers knew about only a limited range of SWC measures, which were perceived to be little to moderately efficient. Furthermore, the average level of adoption was very low (21%). Adoption constraints varied widely depending on the SWC measure. Thus, future interventions need to place much greater emphasis on awareness regarding soil erosion and SWC measures, to strengthen farmers' capacity for experimentation and adaptation to new technologies and finally to create a policy and institutional environment that stimulates widespread adoption of SWC techniques.

Soil erosion and overland flow in Japanese cypress plantations: spatio-temporal variations and a sampling strategy

ABSTRACT Many studies have focused on soil erosion in unmanaged Japanese cypress plantations because the sparse understory vegetation and litter covering the forest ground enhance soil erosion. In this study, soil erosion, litter, and overland flow measurements were conducted over 14 months to identify the spatio-temporal variation and examine the optimal sample size. Fifteen traps (each 0.25 m wide) were installed in line along the bottom of a 15-m-wide slope. Soil erosion and overland flow had large spatial variations as compared to litter. The temporal coefficient of variation of soil erosion and overland flow was highest during dry seasons, while smaller during wet seasons. The random sampling analysis showed that the rate of decrease in spatio-temporal variation became moderate as the sample size increased beyond six. This result indicated that the optimal sample size was five, the total width of which was equivalent to about 8% of the monitored slope width.

Long-term experience with conservation tillage practices in Austria: Impacts on soil erosion processes

In 1994 a field study started at three sites in eastern Austria to investigate the impacts of mulch till and no-till on soil erosion, surface runoff, nutrient and pesticide losses. The aim of this paper is to show long-term impacts of reduced tillage on runoff, erosion and related processes.The experiments were carried out on fields of agricultural schools in Lower Austria about 100 km north and west of Vienna. Soil textures range from silt loam to silty clay loam. Average annual rainfall at the sites ranges from 621 to 916 mm with average annual air temperatures between 9.4 and 10.4 °C. The following soil tillage treatments were investigated: (1) conventional tillage system with ploughing in fall (CT), (2) mulch tillage with cover crops during winter (MT) and (3) no-till with cover crops during winter (NT).Throughout growing season event based measurements of soil erosion, surface runoff, and nutrient and carbon losses were conducted for all sites and tillage systems. Data on losses of pesticide residues are only available for a few years. The crop rotation at the sites was mainly small grains-root crop but included also other field crops.On a long-term basis reduced tillage practices decreased surface runoff from silt loam by 25–55 % (MT) and 49–60 % (NT). For the not well drained silty clay loam soil an increase by 12–21 % was observed which is related to significantly higher soil bulk densities of MT and NT in the 0−20 cm depth. Mean long-term annual erosion rates for CT ranged between 8.6 and 33.2 t ha−1, for MT between 3.6 and 5.3 t ha−1and for NT between 1.9 and 3.0 t ha−1. Compared to conventional tillage MT and NT reduced soil loss from a silty clay loam by 38 and 65 %, and from silt loam by 70–88 % and 84–93 %, respectively. 10−30% fewer erosion events occurred from MT plots and about 20 % fewer events from NT plots. Higher aggregate stabilities of MT and NT due to higher soil organic carbon contents in the 0−10 cm soil depth, higher soil cover as well as lower flow velocities are responsible for this reduction in soil loss from reduced tillage treatments.Low erosion rates from the reduced tilled plots correlated with low runoff losses of nitrogen and phosphorus. Total nitrogen losses ranged from 13.3–48.1 kg ha−1 for CT, from 4.5–18.7 kg ha−1 for MT and from 1.6–9.4 for NT. Total nitrogen losses ranged from 13.3–48.1 kg ha−1 for CT, from 4.5–18.7 kg ha−1 for MT and from 1.6–9.4 for NT. Corresponding total P losses ranged from 6.7–29.4 kg ha−1 for CT, 2.1 to 3.7 kg ha−1 for MT and from 0.7 to 2.4 kg ha−1 for NT. Low erosion rates from the reduced tilled plots correlated with low runoff losses of nitrogen and phosphorus even though N and P concentrations in runoff were greater than from CT and sediments were enriched severalfold in N and P. Conservation tillage methods reduced the SOC losses by 34–86 % for MT and by 58–89 % for NT. Other studies show that these results are not only obtained in central Europe but also in other regions worldwide.The long-term results of this study show that the use of mulch and no tillage in well-drained soils is beneficial for the farmers under central European conditions by improving soil´s aggregate stability and soil water contents and for the environment by reducing soil and nutrient losses.

Spatial Variation Characteristics of Soil Erodibility in the Yingwugou Watershed of the Middle Dan River, China.

Knowledge of soil erodibility (k-value) is vital for measuring soil erosion and conservation planning. Through field sampling, laboratory analysis, and geostatistical analysis, the effects of land use type and soil depth on soil erodibility were studied in a typical watershed of China. The spatial distribution of k-value was determined by Kriging interpolation. Results showed that: (1) soil organic carbon (SOC) content in the study aera is 0.09–150.00 g/kg, and the soil is dominated by silt. The soil erodibility k-values obeyed normal distribution, with an average value of 0.032 t·hm2·h/(MJ·mm·hm2) and a medium degree variation. (2) k-values increased with soil depth. The k-values of surface soil (0–10 cm) for the six different vegetation types ranked in the following order: oak forest > peanut field > grassland > pine forest > tea field > corn field. (3) The theoretical semivariogram model of k-values was a spherical model; k-values in the study area gradually decreased from south to north and east to west, with an obvious banding distribution. Human activities have the greatest effect on k-value such that specific corresponding managements are needed. This could provide scientific and technological support for soil and water conservation measures and comprehensive utilization of the resources.

Control of soil erosion measures on mountain slopes

Control of soil erosion measures on mountain slopes

Self-Organizing Map Network-Based Soil and Water Conservation Partitioning for Small Watersheds: Case Study Conducted in Xiaoyang Watershed, China

Soil and water conservation partitioning (SWCP) considers complex environmental statutes and development demands and serves as a scientific basis for conducting soil erosion management and practice. However, few studies have researched partitioning in small watersheds (&lt; 50 km2), and guidelines for enabling region-specific measures are lacking. In this study, the Xiaoyang watershed located in the red soil region of southern China was selected as a representative small watershed in which to conduct partitioning. The pressure–state–response (PSR) model was used as a framework for establishing an indicator system that included soil erosion sensitivity, the soil erosion condition, and ecosystem services. With three soil and water conservation variables as the input layer, a one-dimensional self-organizing map was applied to identify clusters in the small watershed. The silhouette width was evaluated to determine the optimal number of regions. Based on the associated results, the Xiaoyang watershed was divided into five regions accounting for 82%, 9%, 8%, 2%, and 1% of the total area, respectively. This study provides a framework on which region-specific soil erosion measures can be planned, and it also provides a partitioning method that can be employed in other areas.