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Contribution of raindrop impact to the change of soil physical properties and water erosion under semi-arid rainfalls

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Abstract

Soil erosion by water is a three-phase process that consists of detachment of soil particles from the soil mass, transportation of detached particles either by raindrop impact or surface water flow, and sedimentation. Detachment by raindrops is a key component of the soil erosion process. However, little information is available on the role of raindrop impact on soil losses in the semi-arid regions where vegetation cover is often poor and does not protect the soil from rainfall. The objective of this study is to determine the contribution of raindrop impact to changes in soil physical properties and soil losses in a semiarid weakly-aggregated agricultural soil. Soil losses were measured under simulated rainfalls of 10, 20, 30, 40, 50, 60 and 70 mm h− 1, and under two conditions: i) with raindrop impact; and, ii) without raindrop impact. Three replications at each rainfall intensity and condition resulted in a total of 42 microplots of 1 m × 1.4 m installed on a 10% slope according to a randomized complete block design. The contribution of raindrop impact to soil loss was computed using the difference between soil loss with raindrop impact and without raindrop impact at each rainfall intensity. Soil physical properties (aggregate size, bulk density and infiltration rate) were strongly damaged by raindrop impact as rainfall intensity increased. Soil loss was significantly affected by rainfall intensity under both soil surface conditions. The contribution of raindrop impact to soil loss decreased steadily with increasing rainfall intensity. At the lower rainfall intensities (20–30 mm h− 1), raindrop impact was the dominant factor controlling soil loss from the plots (68%) while at the higher rainfall intensities (40–70 mm h− 1) soil loss was mostly affected by increasing runoff discharge. At higher rainfall intensities the sheet flow protected the soil from raindrop impact.

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... Vaezi et al. (2017) reported that on surfaces without vegetation cover and on slopes with a slope of 10%, surface runoff was generated to 68% by splash caused by falling raindrops [37]. During the study period, runoff occurred in 3 snowmelt periods and after 48 rainfall events (Table 1). ...
... Precipitation below 20 mm rarely caused erosion, because almost all of the water supplied by the rainfall soaked deep into the soil profile. Vaezi et al. (2017) reported that on surfaces without vegetation cover and on slopes with a slope of 10%, surface runoff was generated to 68% by splash caused by falling raindrops [37]. During the study period, runoff occurred in 3 snowmelt periods and after 48 rainfall events (Table 1). ...
... Precipitation below 20 mm rarely caused erosion, because almost all of the water supplied by the rainfall soaked deep into the soil profile. Vaezi et al. (2017) reported that on surfaces without vegetation cover and on slopes with a slope of 10%, surface runoff was generated to 68% by splash caused by falling raindrops [37]. During the study period, runoff occurred in 3 snowmelt periods and after 48 rainfall events (Table 1). ...
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Mountain ecosystems are among the most difficult areas for plant cultivation due to water erosion occurring on the slopes. Growing plants in these areas may lead to a weakening of ecosystem functions and in degradation of these areas and threatens sustainability. In this experiment, the anti-erosion effectiveness of maize, oat and spring vetch were assessed through the measuring of LAI and sheet wash from a slope where cultivation had occurred. Averaged values from the six years field experiment (2017–2022) reveal that maize achieved maximum soil protection between the 115th and 128th day of vegetation (14 days), when the LAI value equals to 3.8–4.0. The corresponding values for oats were 63–81 days of vegetation (19 days; LAI 2.4–2.7). The longest period of maximum soil protection was achieved from the cultivation of spring vetch compared to maize and oats (between the 49th and 82nd day of its vegetation, i.e., 34 days), when the LAI value was in the range of 2.2–3.0. Soil cover at their maximum development is conservative compared to mountain ecosystems, and in the case of the studied plants, the protection time varied. These relationships were quantified by simple regression equations. Additionally, taking into account the compiled climate data, the average air temperature in the years of research (2017–2022) was higher than the multi-year average (1961–2000) by 2.15 °C, which may confirm the fact that the climate is warming in the region of Southern Poland.
... Forests enhance soil permeability and emit water into the atmosphere through evapotranspiration, which helps minimize rainwater runoff. These processes also protect the soil against water erosion, that is, the detachment or displacement of soil particles by raindrop impact or surface water flow (Ganasri & Ramesh, 2016;Vaezi et al., 2017). Soil water erosion is a major threat to the sustainability of terrestrial ecosystems and one of the most important environmental problems worldwide (Vaezi et al., 2017). ...
... These processes also protect the soil against water erosion, that is, the detachment or displacement of soil particles by raindrop impact or surface water flow (Ganasri & Ramesh, 2016;Vaezi et al., 2017). Soil water erosion is a major threat to the sustainability of terrestrial ecosystems and one of the most important environmental problems worldwide (Vaezi et al., 2017). For example, it has negative consequences for land resource degradation (e.g., the loss of fertile topsoil), depletion of soil organic matter, and water pollution (Lal, 2004;Pimentel, 2006;Rothwell et al., 2005). ...
... Apart from the forest canopy, soil physical properties also play a crucial role in influencing the rate of soil degradation by natural phenomena such as water erosion. The stability of soil is an important factor concerning the risk of water erosion (Blanco-Canqui, 2017;Vaezi et al., 2017). Soil stability can be quantified through shear strength measurements. ...
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Thinned steep forests are particularly vulnerable to soil physical degradation. Retaining deadwood logs from thinning operations on the forest floor can potentially mitigate soil physical degradation by modifying its physical properties through increased carbon content in steep regions. We aimed to investigate the effect of spruce deadwood logs from thinning operations on the physical properties of a loamy sand Podzol soil in a steep (30°) temperate spruce forest in Bavaria, Germany. The soil organic carbon (SOC) content was 56% higher under deadwood logs compared to the control areas (p-value = 0.097). Deadwood logs also increased the soil water repellency by 13% (p-value = 0.269), while decreasing the soil shear strength by 35% (p-value = 0.001). Shear strength and water repellency strongly correlated with SOC content, with r = - 0.87 and r = 0.86, respectively. Although retaining deadwood logs seems a promising carbon sequestration strategy, it can adversely affect soil shear strength and water repellency and potentially lead to soil degradation. Therefore, the choice to keep deadwood logs on the forest floor may align with specific management goals.
... Runoff and soil erosion are largely determined by rainfall characteristics (Asadi et al., 2007;Mohamadi & Kavian, 2015). Soil can be directly removed by raindrops and surface wash (Vaezi et al., 2017). Furthermore, rainfall indirectly causes soil erosion by altering the soil physical properties, such as soil aggregates, compaction, infiltration rate and crusting (Chahinian et al., 2006;Angulo-Martínez et al., 2016). ...
... Furthermore, rainfall indirectly causes soil erosion by altering the soil physical properties, such as soil aggregates, compaction, infiltration rate and crusting (Chahinian et al., 2006;Angulo-Martínez et al., 2016). The direct and indirect effects of rainfall on soil erosion depend on the amount, intensity, kinetic energy, duration and erosivity of rainfall (Vaezi et al., 2017;Zhu et al., 2022). It is well known that soil erodibility is usually indicated by soil erodibility K factor, soil saturated conductivity (Zhu et al., 2022), soil cohesion (Liu, Fang, Huang, et al., 2023;Liu, Fang, Shi, et al., 2023) and soil aggregate stability (Vaezi et al., 2017;Barth es & Roose, 2002). ...
... The direct and indirect effects of rainfall on soil erosion depend on the amount, intensity, kinetic energy, duration and erosivity of rainfall (Vaezi et al., 2017;Zhu et al., 2022). It is well known that soil erodibility is usually indicated by soil erodibility K factor, soil saturated conductivity (Zhu et al., 2022), soil cohesion (Liu, Fang, Huang, et al., 2023;Liu, Fang, Shi, et al., 2023) and soil aggregate stability (Vaezi et al., 2017;Barth es & Roose, 2002). ...
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Global climate change and overgrazing are driving shifts in the plant composition of grassland communities, which may profoundly affect the function of grassland ecosystems in regulating runoff and soil erosion. Here, we examined the shift effects of normal hillslope alpine meadow to shrub and severely degraded meadow states on runoff and sediment generation under natural rainfall conditions, and determined the contributions of plant and soil properties changes to soil erodibility, runoff and sediment generation by in situ rainfall experiment and monitoring on the hillslope of Qinghai-Tibetan Plateau. The results showed that normal meadow shift into severely degraded meadow state, mean weight diameter, soil saturated hydraulic conductivity, soil cohesion and soil erodibility K-factor at the topsoil decreased by 70.3%, 73.1%, 80.3% and −13.1%, respectively, and when normal meadows shift into shrub meadow state, they reduced by 49.1%, −1.3%, 49.4%, and −8.3%, respectively. Runoff and soil loss significantly changed by - 40.0% and 177.8% when normal meadow shifted into a severely degraded meadow state, while runoff and soil loss significantly changed by + 65.0% and +77.8% when normal meadow shifted into a shrub meadow state. Our findings highlight that the two divergent shifts both increased soil loss compared to the normal hillslope alpine meadows. Overall, our results indicate that the divergent shifts of normal alpine meadows exacerbated soil erodibility and soil loss of hillslope alpine meadows. These results obtained here offer a novel perspective on the regulation of runoff and soil erosion in the alpine meadow ecosystem.
... The determination of critical land is based on land use, land cover, slope, erosion, and rainfall. Soil erosion is strongly influenced by the physical, chemical, and biological characteristics of the soil (Vaezi, et al., 2017;Teka et al., 2020). Critical land results from the analysis of four parameters of land use, relief, plant canopy density, and rainfall, as shown in Table 6 and Figure 7. (Zsigmond et al., 2022). ...
... Factors that influence the potential for critical land are then slopes, which have a role in managing water that falls to the ground (Supandi et al., 2023). Soils with different slope conditions will have different effects on the amount of infiltrated water and runoff (Moradi et al., 2015;Vaezi et al., 2017). Slopes also affect the processes of soil formation and soil development because slopes affect translocation and transformation through the management of water that falls to the ground (Baskan et al., 2016). ...
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Indonesia is in the ring of fire, which has an impact on the characteristics of volcanoes, one of which is Mount Raung. Mount Raung, part of the Iyang-Argopura mountains, has a role in influencing the development of soil types and the environment; it was recorded in 1586, 1987, 1597, and 1638. Soil types and environmental parameters have an influence on critical land conditions. Remote sensing technology has been used in various fields, one of which is land evaluation. This study examined the distribution of soil characteristics and the mapping of critical lands through remote sensing approaches. The method used to identify the morphological characteristics of soil classification and the potential for critical land was a descriptive-exploratory method. The results of the research on soil types are divided into three orders, namely Andisols, Inceptisols, and Alfisols. The three land orders are divided into nine great groups, with Lithic Eutrudepts having the highest area of 38.02%, followed by Typic Hapludalfs (21.70%), Typic Eutrudepts (9.79%), Typic Epiaquepts (7.84%), Aquic Eutrudepts (7.71%), Aquic Eutrudepts (5.64%), Fluventic Epiaquepts (5.30%), Typic Udivitrands (2.16%), and Vitric Hapludands (1.83%). Critical land based on the analysis of five factors of erosion, land use, slope, rainfall, and soil canopy density, is divided into four criteria i.e., critical area of 895.88 ha, medium critical 9,027.69 ha, and lightly critical of 14,096.89 ha. Land use, slope, and plant canopy density play a major role in the potential for critical land with a strong-very-strong level of closeness (0.350-0.610).
... Although the rapid development of the mining industry has promoted global economic development, it has also caused considerable damage to the ecological environment (Dutta et al. 2016;Prosdocimi et al. 2016;Vaezi et al. 2017), particularly to soil environment (Lee et al. 2001;Pourret et al. 2016). Despite increasing efforts toward the environmental management of mines and ecological restoration have increased (Neldner and Ngugi 2017;Ahirwal and Maiti 2018), tailings ponds continue to present environmental and Responsible Editor: Kitae Baek ecological safety issues, such as desertification, soil erosion, biomass and diversity loss, and surface soil and groundwater contamination with heavy metals (Chen 2010;Dutta et al. 2016;Prosdocimi et al. 2016;Tang et al. 2000;Vaezi et al. 2017). ...
... Although the rapid development of the mining industry has promoted global economic development, it has also caused considerable damage to the ecological environment (Dutta et al. 2016;Prosdocimi et al. 2016;Vaezi et al. 2017), particularly to soil environment (Lee et al. 2001;Pourret et al. 2016). Despite increasing efforts toward the environmental management of mines and ecological restoration have increased (Neldner and Ngugi 2017;Ahirwal and Maiti 2018), tailings ponds continue to present environmental and Responsible Editor: Kitae Baek ecological safety issues, such as desertification, soil erosion, biomass and diversity loss, and surface soil and groundwater contamination with heavy metals (Chen 2010;Dutta et al. 2016;Prosdocimi et al. 2016;Tang et al. 2000;Vaezi et al. 2017). As a large mining nation with an annual tailings production of more than 600 million tons, China has more than 15,000 tailings ponds comprising more than 20 billion tons (Wang 2019). ...
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This study investigated the soil physicochemical properties and vegetation community characteristics of the Baotou light rare earth tailings pond after 10 years of aggregate spray seeding ecological restoration (S1) and ordinary soil spray seeding ecological restoration (S2), and the naturally restored dam slope area without human intervention (S3). The results showed that the vegetation community of S1 was dominated by Caragana korshinskii Kom, and its importance and abundance values were 0.40 and 38.4, respectively, while the vegetation communities of S2 and S3 mainly comprised herbaceous plants. Additionally, the vegetation biomass of S1 was significantly higher than that of S2 and S3 by 215.20% and 1345.76%, respectively, and the vegetation diversity index of S1 was the highest among the three treatment groups. The soil porosity (SP), water content (W), electrical conductivity (EC), and available K were significantly improved in S1, while soil bulk density (BD) was significantly reduced compared with that of S2 and S3. In addition, redundancy analysis revealed that SP, EC, W, and K positively correlate with the biomass, Shannon, Pielou, Simpson, and Marglef indices. Principal component analysis further showed that the comprehensive score of S1 (0.983) was higher than that of S2 (− 0.261) and S3 (− 0.648). Collectively, these findings indicate that appropriate ecological restoration can improve soil structure and vegetation community characteristics, thereby accelerating vegetation restoration, ultimately increasing the stability of the ecosystem.
... Natural soils often undergo significant changes in their engineering properties due to rainfall, irrigation, or rising groundwater levels [1][2][3]. Typically, soils exhibit high strength at low water contents, but water infiltration rapidly reduces their strength, causing deformation and potential disasters [4,5]. Wetting-induced soil deformation has led to numerous geotechnical issues, such as ground subsidence, slope instability, and road collapses [6,7]. ...
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Wetting-induced soil deformation significantly impacts land stability and management on the Chinese Loess Plateau. This study analyzed silt soils from the Late Pleistocene (1 m depth) and Middle Pleistocene (25 m depth) to investigate compression and collapsible deformation during wetting. The compression in both soils progressed through three stages: slow deformation under low pressure, accelerated deformation under moderate pressure, and decelerated deformation under high pressure. Wetting intensified the compression in the 1 m sample but reduced it in the 25 m sample, with the deformation becoming more sensitive to the initial water content under higher pressures. Collapse tests showed contrasting behaviors: the 1 m sample exhibited collapsibility, while the 25 m sample displayed expansiveness (a negative collapsibility coefficient). Microstructural analysis revealed that the 1 m sample with abundant macropores and overhead structures had a lower structural stability than the 25 sample with more stable, rounded micropores. The wetting-induced deformation was governed by the balance between clay mineral expansion and structural collapse, with collapsibility prevailing when collapse dominated and expansiveness prevailing when expansion was predominant. These findings provide valuable insights into soil–water interactions and support improved land use and management strategies in the loess region.
... Soil erosion is basically the process through which soil components are detached and transported by wind or water (Morgan 2005). Raindrops falling on bare soil cause soil erosion as they detach soil particles and disrupt the surface soil's structure (Vaezi et al. 2017). Soil erodibility (K) in the Universal Soil Loss Equation (USLE) is the intrinsic resistance of a soil to erosion when it is continuously maintained in a clean fallow condition with tillage performed up and down slope without land management practices (Derahman et al. 2022;Wischmeier and Smith 1978). ...
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Soil erodibility (K) is the intrinsic resistance of a soil to erosion which is a key factor required in soil erosion modeling and other process based models across the world. Soil erosion is a major problem in Ethiopia and estimation using models can help decision makers for interventions. But our K factor determinations in models have limitations and yet rare study has been done to determine K on process based approach. Disturbed soil samples of the five major soil types of Upper Blue Nile Basin, Ethiopia (Guder and Aba Gerima watershed) were collected from the field. Runoff plots’ using simulated rainfall was used to determine K values of soil. Rainfall simulator was used to generate runoff and sediment concentration data from the soils in one- hour simulated rainfall events, and an optical disdrometer was used to characterize the erosivity of the events. The results indicated that the K values of major soil types of the study area ranged between 0.046 to 0.140 t ha hMJ⁻¹mm⁻¹ha⁻¹. The lower K values was obtained in both Chromic Vertisols and Lithic Leptosols and were significantly (P < 0.05) different from the other soil types. However, statistically insignificant differences were observed in K values among the Cambisols, Haplic Acrisols and Chromic Luvisols. The mean K value of the Haplic Acrisols was 0.14 t ha hMJ⁻¹mm⁻¹ha⁻¹ and ranged from 0.04 to 0.32, whereas the K value of the Chromic Vertisols ranged from 0.03 to 0.08 t ha hMJ⁻¹mm⁻¹ha⁻¹ with a mean value of 0.05. These results have important implications as potential replacements to the use of K values obtained from soil color and nomograph method.
... The amount of soil loss under surface mat was lower compared to other engineering approach, regardless of the manure application treatment. Geotextile soil cover protects soil surface from direct impact of raindrops, mitigating the erosion processes of detachment, transportation, and deposition of soil particles (Vaezi et al., 2017). The values obtained under surface mat (0.91-1.64 Mg ha −1 year −1 ) were lower than the soil loss tolerance limit. ...
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Monitoring soil erosion is crucial for soil conservation policies, especially in tropical regions that are prone to water erosion. A 2-year field study was conducted to assess the impact of simple engineering approaches and poultry manure application on soil loss, soil physical properties, maize yield, and economic benefit in Southwest Nigeria. The experiment was a 4 × 2 factorial arrangement with three replications. The treatments included four engineering approaches (surface mat, silt fencing, furrow dike, and no approach [control]) and two poultry manure application rates at 0 and 20 t ha⁻¹. Annual soil loss was higher under the control (6.22–8.01 Mg ha⁻¹ year⁻¹). The combination of engineering approaches with poultry manure at 20 t ha⁻¹ significantly (p ⩽ .05) reduced soil loss by 9.7% to 85.4% compared to control. Engineering approaches and poultry manure application did not significantly improve soil physical properties; however, saturated hydraulic conductivity was highest under surface mat combined with poultry manure at 20 t ha⁻¹ in both years. Maize yield increased by 27.7% under surface mat compared to control, while an additional grain yield of 0.14 Mg ha⁻¹ was obtained for 20 t ha⁻¹ poultry manure over 0 t ha⁻¹. Soil loss was negatively and significantly correlated with grain yield. The results suggest that integrating surface mats with poultry manure can be effective in controlling soil loss, enhancing soil properties, and improving maize yield.
... Структура почвы защищает органическое вещество (ОВ) и влияет на скорость его оборачиваемости [25]. Положительное влияние агрегирования на стабилизацию углерода в почве отмечается во многих работах [2,28,33,39,[44][45][46][47]52]. Структурные отдельности непосредственно влияют на скорость минерализации ОВ, за счет механизмов его физической стабилизации, обеспечивая пространственную недосягаемость микроорганизмам и ферментам. ...
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Методом твердотельной 13 C-ЯМР-спектроскопии изучена химическая структура пулов органического вещества (ОВ) водоустойчивых макроагрегатов размером 2-1 мм, выделенных их воздушно-сухих агрегатов того же размера пахотных горизонтов полнопрофильного, эродированного и намытого агрочерноземов. Дана оценка изменения их химической структуры в денудационно-аккумулятивном ландшафте. Выявлено, что подавляющая часть водоустойчивых макроагрегатов в эрозионной зоне-новообразованные за счет динамического замещения ОВ in situ, что демонстрируют интегральные показатели х ими ческой структуры всех пулов ОВ макроагрегатов. Аналитические данные свидетельствуют в пользу преобладающей транспортировки именно новообразованных макроагрегатов. Разрушение макроагрегатов во время транспортной фазы сопровождается высвобождением ранее физически защищенного агрегированного ОВ, которое подвергается частичной минерализации. Причем минерализуется преимущественно наиболее лабильная его часть (гидролизуемая), а его стабильная часть остается мало/ неизмененной. Минерально-ассоциированное ОВ (ил и остаток) не/мало меняется, сохраняя относительную свежесть, что может быть косвенным признаком транспортировки из эрозионной зоны преимущественно новообразованных макроагрегатов. Бóльшая степень свежести свободного ОВ макроагрегатов в намытом агрочерноземе - результат преобладания в нем свежих остатков культурной растительности аккумулятивной зоны, в совокупности с перемещенным из зоны эрозии.
... Plant canopy intercepts the amount of precipitation reaching the ground, decreasing the volume of water permeating the soil. However, part of rainwater will pass through the leaves and reach the ground (i.e., throughfall) with a reduced energy of rain drops and hence reduced soil detachment by droplet erosion (Fu et al., 2017;Vaezi, Ahmadi and Cerdà, 2017). ...
... These fertile patches may result from downstream clay sedimentation caused by soil erosion. Clay is the most significant soil particle contributing to downstream sedimentation (Vaezi et al. 2017). Several studies have demonstrated that a high clay content in soil improves nutrient composition and availability for plants, boosts water retention, and encourages microbial activity (Seymour 2023;Erpenbach et al. 2017;Padonou et al. 2023), all of which can promote the clustering of tree establishment. ...
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Termite restore plant diversity and soil on altered lands in West Africa with particular abundance of small mound made by Trinervitermes trinervitus, Trinervitermes geminatus, Cubitermes spp. or Microcerotermes spp. The particular abundance of small mounds on altered lands suggests the existence of underlying abiotic and biotic factors. This study investigated the spatial patterns of termite mounds on the altered lands and its relationship with tree distribution in order to sustain the ecological restoration of the altered lands. Thus, unmanned aerial vehicle (UAV) was used to collect images on three different altered land sites of 18 ha characterised with termite mounds. The images were ortho-mosaicked with Pix4D Mapper software. Termite mounds and trees were digitalised on these images in ArcGIS software. The Ripley's pair correlation function using spatstat package was applied to assess the spatial pattern and association of mounds and trees. An aggregative pattern (g(r) > 1) was revealed in the spatial distribution of both termite mounds and trees across all sites. Furthermore, a positive clustered association between termitemounds and trees was noted at two study sites, likely due to the absence of human disturbance. Therefore, this interaction should be vital for assisted ecological restoration and can be factored into efforts to accelerate the restoration of soils and plants on degraded lands. The authors then recommend future research to explore the specific role this attractive relationship plays in ecosystem restoration.
... Furthermore, irrigation with treated wastewater (TWW) contributes to salinization of soils and groundwater resources, especially in semi-arid regions characterized by limited rainfall (Foster et al. 2018), with limited draining of soils, and heavy rain events that can lead to soil erosion and transport of nutrients to water bodies (Muyen, Moore, and Wrigley 2011;Shtull-Trauring et al. 2020;Vaezi, Ahmadi, and Cerdà 2017). The extent of soil and groundwater salinization is affected by the quality of the irrigated water, the irrigation regime, soil properties, and a range of agricultural practices (Foster et al. 2018;Pulido-Bosch et al. 2018;Suarez 1989). ...
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Degraded water quality is one of the well‐documented adverse effect of intensive agriculture on the riverine environment. It can result from nutrient leaching from agricultural fields, stream flow harvesting, irrigation with treated wastewater, full or partial damming, and cultivating the riparian zone. The weight of each cause on the regime water quality is only sometimes apparent. Thus, stream restoration planning requires understanding of the dynamics of water quality, and stakeholders' efforts do not address the right stressors on time. This is further exacerbated in Mediterranean agriculture catchments, which are prone to water scarcity, seasonal rainfall and streamflow variations. We therefore aim to evaluate how monitoring water quality parameters can help direct river restoration projects in Eastern Mediterranean watersheds. The present project focused on water quality dynamics along the main channel of the Nahalal stream and employed high spatiotemporal monitoring of basic water quality parameters: pH, electrical conductivity (EC), and macro‐nutrients in the context of (1) spatial gradients: Channel upstream vs. downstream; (2) seasonality: Base flow vs. flood water flows; and (3) hydraulic constraint: open vs. closed channel sluice gate. The results from the systematic stream grab water sampling, 34 times over two years at 13 locations, revealed increased concentrations at the downstream direction by dry‐wet conditions prior to the date of sampling. Contrary to expectations, higher concentrations of nitrates were found upstream near a spring—a source for base flow, than at the downstream reach, and the opposite trend was found for P concentrations. The results suggest that combined effects of several stressors control stream water quality dynamics: Riparian vegetation dominated by Phragmites australis , soil‐erosion processes, and water resources management. Lack of high spatiotemporal monitoring could result in misinterpretation of the intervention actions needed at the channel and watershed scales and may lead to poor initiation of self‐stream restoration ecology.
... Furthermore, in semi-arid regions of Southern Africa, substantial soil degradation has resulted from the decline in soil organic matter content caused by drought and traditional agronomic practices utilized by smallholder farmers [57]. For example, in South Africa, there have been concerning changes in soil fertility and quality over the past thirty years. ...
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Sustainable agricultural practices (SAPs) remain the panacea to addressing challenges relating to climate change, low rainfall, and low agricultural productivity in many rural parts of sub-Saharan Africa (SSA). These practices include but are not limited to crop rotation, intercropping, cover cropping, and conservation tillage. The aforementioned practices have been scientifically proven to enhance crop productivity while safeguarding environmental resources. This review assesses the trends, effectiveness, and challenges associated with the adoption and utilization of SAPs among smallholder farmers in the SSA region, analyzing the literature and reports from 2000 to 2024 sourced from databases such as Google Scholar and Scopus. The inclusion criteria focused on key concepts such as SAPs, adoption, and challenges. Findings indicate that crop rotation, intercropping, improved seed varieties, manure, and mulching are among the most adopted practices. In reality, practices such as conservation tillage, agroforestry, and water harvesting systems remain the least adopted practices in many rural parts of SSA. The review further reveals that challenges relating to land tenure insecurity, lack of knowledge, training, and limited access to financial institutions all have a direct or indirect influence on farmers’ choice of adoption. Overcoming the aforementioned challenges through policy interventions and capacity building is vital for improved crop productivity and rural livelihoods.
... Dispersed clay particles tend to migrate with water, facilitating the formation of micropores [18,40]. Prolonged immersion can lead to the swelling, loosening, and loss of soil particles in the upper soil layers [41]. Furthermore, the combined effects of water pressure and soil gravity potential can cause an increase in bulk density in the deeper soil column [42]. ...
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As a promising alternative water source to alleviate irrigation water scarcity in red soil regions in southern China, low-quality water could enhance regional water resource utilization and promote sustainable agriculture. However, its soluble salt and ions could affect soil solute distribution and transport, potentially hindering crop growth. Undoubtedly, it is necessary to understand the mechanism of solute transport in red soil under low-quality water irrigation with different water salinity levels. Therefore, a one-dimensional vertical water infiltration experiment and a solute breakthrough experiment were conducted to evaluate the solute transport (soluble salt, Na+, and Cl−) in unsaturated and saturated homogenous red soil at different salinity levels [1 (S1), 2 (S2), 3 (S3), 5 (S5), and 10 (S10) g/L] when irrigated with simulated low-quality water using analytical-grade NaCl. Moreover, the potential factors affecting salt distribution in unsaturated red soil were determined. The findings indicate positive linear relationships between accumulations of three solutes and irrigation water salinity. Generally, the depth of maximum solute concentration increased with the increase in irrigation water salinity. Soluble salt, Na+, and Cl− exhibited early breakthrough and trailing in red soil, but higher irrigation water salinity could reduce PV and retardation. A mobile and immobile water model (MIM) showed that convection was dominant in solute transport in red soil under low-quality water irrigation. D decreased as a power function with increasing irrigation water salinity, while v and R decreased linearly. Furthermore, the red soil can adsorb Cl− resulting from its special charge characteristics under low-quality water irrigation, which may be the main source of salt adsorption. Additionally, v > soil pH > βsalt primarily influenced salt distribution in the 0–40 cm soil profile. This study can provide insights into solute transport in red soil under low-quality water irrigation, facilitating soil fertility and structure, as well as low-quality water irrigation strategy optimization.
... The ejected particles tend to accumulate at the bottom of low topography slopes and mix with 42 stagnant water to form a layer of slurry that can clog soil pores and prevent rainwater infiltration, 43 further increasing soil erosion from surface runoff (Vaezi et al., 2017). Meanwhile, soil contains a 44 variety of microbials, including pathogens such as enteroviruses, hepatitis A viruses and 45 coronaviruses that are harmful to human digestive or respiratory tract. ...
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The impact of a liquid drop on a granular medium is a common phenomenon in nature and engineering. The possible splashing droplets and ejected particles could pose a risk of pathogen transmission if the water source or granular medium is contaminated. This work studies the liquid drop impact on the granular medium using high-speed photography and considers the effects of liquid properties, drop impact characteristics, and granular medium properties. Four flow regimes, including direct penetration, prompt splashing, spreading, and corona splashing, are observed and a regime map is created to identify their thresholds. The spreading regime can eject a large number of particles, and the corona splashing regime can produce splashing droplets in addition to the ejected particles. For the splashing droplets, their median diameters and velocities are in the ranges 0.11 to 0.21 and 0.15 to 0.37 of the diameter and velocity of the impact drop, and their median splashing angles range from 14° to 27°. Two particle ejection mechanisms are observed, falling squeeze and forward collision, driven by the collapsing and forward spreading of the liquid lamella, respectively. The particles ejected by the latter mechanism have larger ejection velocities, angles and distances from the impact center, which can facilitate their long-range transmission. In addition, the process of spreading and retracting of the lamella formed by the drop impact is also studied, and it is found that the maximum spreading diameter of the lamella is proportional to the crater diameter. These results improve the understanding of the phenomenon after the drop impact on granular medium and the characteristics of the splashing droplets and ejected particles, contributing to the prediction and risk assessment of contaminated particle transmission.
... Similarly, soil organic matter lowers K values by forming a substance that links soil particles together and increases aggregation. This reduces the effect of a raindrop detaching soil particles, increases infiltration, and lowers surface runoff (Renard et al. 2011, Vaezi et al. 2017. Although soils of the same color can have quite different K values, Hurni (1985) found that the K-factor derived by soil color is frequently not very accurate (Kaltenrieder et al. 2007). ...
Article
Land degradation is a serious problem for Ethiopia's productive capacity for land resources. To reverse these environmental dynamics, slow down soil degradation, and raise smallholder farmers' agricultural yields, watershed management interventions have been implemented in Ethiopia since the 1980s. Thus, this study was aimed at assessing the effects of watershed management interventions on soil erosion reduction by using the InVEST model in the Yezat watershed, northwest Ethiopia. The modified ecosystem services valuation model (InVEST) was employed to evaluate soil loss reduction in response to watershed management interventions. Different watershed management intervention scenarios (baseline scenarios, afforestation scenarios, soil/ stone bund scenarios, and integrated scenarios) were also applied to evaluate the effectiveness of watershed management interventions on soil loss reduction. The result of the study indicated that a high amount of mean annual soil loss (111 tons ha −1 year −1) was observed in 2000 in the study area due to the expansion of cultivated land and built-up area at the expense of forest, shrubland, and grassland. However, the mean annual soil loss decreased from 111 tons per year in 2000 to 79 tons per year in 2021 in the study area due to different watershed management interventions. Additionally, at the baseline scenario, the estimated mean annual soil loss of the watershed was 111 tons ha-1 yr-1. Conversely, it was reduced to 49.3 ton ha-1 yr-1 in the reforestation scenario, 16.49 ton ha-1 yr-1 in the soil bund scenario, and 8.26 ton ha-1 yr-1 in the integrated scenario. The watershed covered by the very severe soil erosion severity class was reduced in all watershed management intervention scenarios. Among others, the highest soil erosion reduction was observed in the integrated (bio-physical) scenarios of watershed management interventions. Therefore, watershed management interventions and scenarios were the best mechanisms for soil loss reduction. ARTICLE HISTORY
... Soil structure protects the organic matter (OM) and influences its turnover rate of [25]. A positive effect of aggregation on the carbon stabilization in soil is reported in many papers [2,28,33,39,[44][45][46][47]52]. Structural units directly influence the rate of OM mineralization via the mechanisms underlying its physical stabilization providing the spatial unavailability for microorganisms and enzymes. ...
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The chemical structure of organic matter (OM) pools in the 2–1-mm water-stable macroaggregates isolated from air-dry aggregates of the same size in arable horizons of noneroded, eroded, and depositional agrochernozems was studied with solid-state 13C-NMR spectroscopy. The changes in their chemical structure in the denudation–accumulative landscape are assessed. The overwhelming majority of water-stable macroaggregates in the erosional zone are newly formed due to dynamic replacement of OMin situ, which is clearly demonstrated by the integral chemical structure indicators in all OM pools in macroaggregates. Analytical data suggest the prevalent transport of newly formed macroaggregates. The destruction of macroaggregates during the transport phase is accompanied by the release of previously physically protected aggregated OM, which undergoes partial mineralization. Note that its most labile(hydrolyzable) part is predominately mineralized, whereas its stable part remains weakly changed or intact. Mineral-associated OM (clay and residue) weakly changes or does not change at all, retaining relative freshness, which indirectly suggests the prevalent migration of newly formed macroaggregates from the erosional zone. A greater degree of freshness of LFfr (free OM) in macroaggregates of depositional agrochernozem results from the abundance of fresh crop residues of the depositional zone together with the residues transported from the erosional zone.
... During rainfall, the energy of falling raindrops is transferred to the soil surface. The effect of rainfall intensity and the impact on soil stability, bulk density, and infiltration rate directly depends upon soil cover (Vaezi et al. 2017). For example, high amounts of cover protect the soil surface from raindrop impact, while bare soil is directly exposed to the energy of falling raindrops, which can detach soil particles from the bulk soil matrix and leave them susceptible to erosion. ...
Article
This paper explores the growing interest in soil health, emphasizing its importance in optimizing crop production, ecosystem function, and biodiversity. Defined by the USDA-NRCS as the soil’s capacity to function as a vital ecosystem, soil health involves filtering contaminants, cycling nutrients, supporting infrastructure, and regulating water movement. Traditional approaches to quantifying soil health focus on chemical, physical, or biological properties, often calling for a more integrated measurement method. While practices enhancing soil health, such as no-tillage, cover crops, and biodiversity, have long been promoted, their broader impacts on the hydrologic cycle are less documented. This paper aims to fill this gap by reviewing the literature on soil health practices’ effects on the hydrologic cycle and providing evidence and guidelines for policy- and decision-makers. It highlights the benefits of improved soil health, including increased water infiltration, higher crop yields, and reduced greenhouse gas emissions.
... In stagnant air, the physical behaviors of raindrops are relatively stable, known as the equilibrium state, and the shape, orientation as well as fall speed can be well parameterized as a function of raindrop diameter (Beard & Chuang, 1987). This equilibrium state assumption has facilitated the parameterization of rainfall processes in multiple applications, such as remote sensing (Chandrasekar et al., 2023;Kumjian et al., 2022;Ryzhkov & Zrnic, 2019;Zheng et al., 2024), numerical models (Lin et al., 1983;Matsui et al., 2019;Morrison & Milbrandt, 2015), disaster prevention/evaluation Vaezi et al., 2017), etc. ...
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The physical behavior of a falling raindrop is governed by delicate fluid dynamics and thermodynamics, and oscillates with time. Despite this time‐variant nature, past observational and simulation studies have aimed to generalize parameterizations for describing rain microphysics bearing the assumption that raindrops fall at terminal speeds with an equilibrium shape. However, the applicability of this hypothesis in a realistic atmosphere that is inherently turbulent remains an open question. Here, we employ novel retrieval techniques to quantify the impact of turbulence on raindrop microphysics using long‐term in situ observations with careful assessment of the wind effect. We find that raindrop microphysics increasingly deviate from the equilibrium state as the turbulence dissipation rate increases, and this effect is more pronounced for large raindrops. We present turbulence‐invoked rain microphysical parameterizations which shed light on the complex interactions between turbulence dynamics and raindrop microphysics.
... Runoff discharge and total runoff increased with the increase in rainfall intensity. High rainfall intensity usually leads to the destruction of more aggregates in the topsoil, thus increasing soil crust and pore blockage with the accumulation of rainfall [77,78]. Under the condition of the same slope gradient and soil surface gravel content, the greater the rainfall intensity, the smaller the fluctuation in the runoff rate. ...
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The hydrological characteristics of gravel-containing soils are different from those of gravel-free soils, so it is worth further understanding and enriching the theory of soil and water conservation. In this study, adjustable slope (10°, 20°, 30°) test soil boxes with different surface gravel contents (0%, 25%, 50%, 75%, 100%) were prepared to study the runoff erosion characteristics of gravel-covered land slopes under different rainfall conditions (10 mm/h, 20 mm/h, 30 mm/h). Compared with the bare soil, the runoff start time of the three slopes covered with 100% soil surface gravel content is delayed by 38.90, 32.83 and 73.39%, the runoff producing rate of gravel condition under different slopes decreased by 7.20–71.52% and the total amount of sediment yield decreased by 7.94~84.57%. Surface gravel cover can effectively reduce runoff and sediment yield, which is beneficial for better soil and water conservation. The results of this study have a certain reference value for the theory of soil and water conservation and can be used as a basis for guiding efficient agricultural production in gravel-mulched land and construction (like road slope improvement).
... Smaller droplets are affected by wind and prone to greater evaporation and drift losses, thereby reducing irrigation efficiency (Sarwar et al. 2021). Hence, precise measurements of droplet micro-physical characteristics hold paramount importance in assessing soil erosion, crop leaf damage, farmland microclimate, and overall irrigation system efficiency (Vaezi et al. 2017;Wang et al. 2020;Zhu et al. 2022). ...
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The study of the micro-physical characteristics of spray droplets provides crucial insights into the impact of sprinkler water on soil erosion, leaf impact, and the microclimate of agricultural environments. However, the variability in measurement outcomes across different technologies due to their distinct measurement principles is a significant challenge. This research aims to evaluate and compare the droplet diameter, velocity, application rate, and kinetic energy rate using four distinct measurement technologies: the paper stain method (PS), flour pellet method (FP), laser precipitation monitor (LPM), and two-dimensional video disdrometer (2DVD), alongside a rain gauge (RG) in the context of sprinkler irrigation conditions. The results reveal that: (1) The FP method struggled to capture small droplets under the same spray conditions, while the PS method recorded a maximum droplet diameter exceeding 7 mm. The LPM registered the highest droplet count per unit area and time, notably capturing a significant number of small droplets (< 1 mm). Conversely, the 2DVD provided a more uniform distribution of droplet sizes, with the LPM’s mean equivalent droplet diameter (dv) being 0.86 times that of the 2DVD. (2) Although droplet diameters and velocities measured by the 2DVD, LPM, FP, and PS, decreased with increased working pressure, these technologies concurred when assessing low-velocity and small-diameter droplet. (3) The 2DVD’s larger sampling area compared to other methods enables the acquisition of more representative droplet characteristics, including their irregular shapes, suggesting its utility in measuring the micro-physical properties of sprayed droplets. (4) Based on the kinetic energy rate measured by the 2DVD under identical conditions, kinetic energy rate calibration factors of 0.88, 1.15, and 1.10 are suggested for the LPM, FP, and PS, respectively. This study provides essential data for calibrating and applying various droplet measurement technologies.
... After twelve months (M12), the BD values decreased slightly, although remaining greater than the initial values (M0), with a range of values between 1.06 to 1.21 g cm −3 with a mean value of 1.13 g cm −3 (CV = 4.53%). Differences in BD values observed across the three sampling dates were mainly due to compaction phenomena caused by the impacts of raindrops that break soil aggregates (Vaezi et al. 2017). Indeed, a seasonal trend could be observed in BD with compaction mainly occurring in the first six rainy months (M0-M6) followed by a partial recovery during the dry season (M6-M12) (Fig. 1). ...
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Compost can enhance the soil's ability to retain water, resulting in an overall improvement of soil physical quality (SPQ). The purpose of this study was to evaluate the temporal variability of physical and hydraulic properties of a sandy loam soil amended with a compost obtained from orange juice processing wastes and garden cleaning. The soil water retention curve of repacked soil samples at varying compost to soil ratios, r, was determined at the time of compost embedding (M0) and after six months (M6), and twelve months (M12). Indicators of SPQ linked to soil water retention curve such as air capacity (AC), macroporosity (Pmac), plant available water capacity (PAWC), relative field capacity (RFC) and Dexter S-index (S), were estimated. The effect of compost addiction of the pore volume distribution function was also evaluated. The elapsed time from compost application influenced all SPQ indicators but the maximum beneficial effects of compost amendment were achieved within approximately the first six months. Indicators linked the macro- and mesoporosity (Pmac and AC) decreased with r whereas indicators linked to plant water availability (PAWC and RFC) increased with r. The combined effect of time and rate was statistically observed only for Pmac, PAWC and S. Compost addiction reduced the soil compaction and modified the pore system, as the fraction of structural porosity (i.e., macropores) decreased and the fraction of textural porosity (i.e., micropores) increased. It was concluded that even a single application of compost could have a significant impact on soil water retention and microstructure with positive implications for soil health, precision agriculture and crop productivity.
... Cameira et al. (2003) and Mubarak et al. (2009) also observed a significant sealing of pores post rainfall. Raindrop impact can cause pore sealing, compaction, aggregate breakdown in agricultural soils (Vaezi et al., 2017). Bodner et al. (2013) and de Oliveira et al. (2022) confirmed that within-season variability of soil pore properties can be significantly affected by wetting and drying cycles. ...
Article
Changes in soil pore size distribution and connectivity can affect contaminant transport. Climate, soil type, and agricultural management practices can influence these characteristics. Conservation tillage practices, such as strip tillage, have been promoted as agricultural management practices that can help reduce soil erosion and nutrient loss in runoff. However, limited information exists in the literature on the effect of strip tillage on soil pore characteristics. Thus, the objective of this research study was to assess the effects of different tillage practices i.e., conventional tillage (CT) vs. strip tillage (ST), on soil pore properties and quantify change in soil pore characteristics as a function of season. Undisturbed cylindrical soil columns (150 mm diameter and 640 mm length) were collected from a field in Alabama, USA planted with cotton (Gossypium hirsutum L.) under ST and CT treatments during two seasons i.e., fall 2021 and spring 2022. Soil cores were collected from CT and ST portions of the field, in the fall, following cotton harvest and before planting a cover crop (season 1), and in the spring, after the cover crop had matured (season 2). X-ray computed tomography was used to scan the soil cores and quantify soil pore characteristics. Results show that the ST treatment had significantly (p < 0.05) greater macroporosity values, network density, macropore length density, and interconnectivity compared to the CT in season 1. This was attributed to ST being a minimally disturbed treatment: thereby, it has a better chance of preserving cracks and biological activity as compared to CT, which is more prone to destruction of large macropores. The pore properties also showed a drastic decrease in values during season 2, especially for the top 200 mm of the soil profile in response to rainfall induced soil reconsolidation in both the tillage systems. Overall, this study showed that pore morphology can be affected by tillage and seasonal aspects associated with them.
... However, the sprinkler droplets that continue to hit the soil can easily cause soil surface sealing, resulting in surface runoff on sloping land and affecting the absorption of water by crops [9,10]. Results from previous studies have suggested that soil surface sealing is mainly due to the separation of soil particles from aggregates [11,12], and it is generally considered to be closely related to sprinkler droplet kinetic energy [13][14][15][16]. ...
Article
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Droplet impact angle and shear stress are important indicators of surface runoff under sprinkler irrigation, and determining the distribution characteristics of these two indicators on sloping land is of great significance for preventing soil surface erosion. Therefore, three slopes (0, 10%, and 20%) and two directions (uphill and downhill) under a Rainbird LF1200 rotary sprinkler were considered in this study. The distribution of droplet impact angles and shear stresses along the radial direction were investigated under various working conditions. The correlations among the droplet impact angle, shear stress, and distance from the sprinkler were also analyzed. These results indicated that the closer to the sprinkler, the larger the droplet impact angle and the smaller the shear stress, and the two indicators gradually decreased and increased with the increase of distance from the sprinkler, respectively. Accordingly, there was a very high potential for soil surface runoff at the spray jet end. It was also observed that the uphill direction generally had a greater impact angle and less shear stress than flat land, while the downhill direction had exactly the opposite result. However, regardless of the direction, an increase in the slope could intensify its effect on the droplet shear stress and impact angle. Therefore, there is an urgent need to focus on the occurrence of surface runoff in soils with larger slopes. In addition, two radial droplet shear stress distribution models were developed, and it was verified that Model 2 had higher accuracy (MAE = 176.6 N m−2, MBE = 32.8 N m−2, and NRMSE = 14.4%) and could be used to predict the average droplet shear stresses at different slopes, directions, and distances from the sprinkler. This study contributes to the soil erosion prevention and the sprinkler irrigation system optimization on sloping land.
... The reason for this result is that rainfall with an intensity of 2.0 mm min − 1 caused the runoff unable to infiltrate in a timely manner and formed excess runoff compared to rainfall at a 0.8 mm min − 1 intensity. High-intensity rainfall could break down soil aggregates more quickly and then increase crust formation reducing infiltration rates (Vaezi et al., 2017). ...
Article
Mass movement erosion on the gully sidewalls is recognized as an important erosion mode and sediment source in hilly and gully watersheds. However, the trigger of mass movement erosion and transport of gravity-detached material remain poorly understood. A series of rainfall simulation experiments were conducted on six loess gully sidewall models, with a height (1 m), three rainfall (60 mm, 48 mm and 24 mm) and two slope gradients (70 • and 80 •), to quantitatively explore the sensitivity factor and transport mechanisms of mass movement. Results revealed that the accumulation volume and initiation of the mass failure were significantly influenced by rainfall amount. The accumulative volume of failure events was observed to increase in a linear pattern with increasing rainfall amount. The minimum cumulative rainfalls for the initiation of mass failure on the loess gully sidewalls were approximately 43.6, 28.2 and 65.6 mm for short-duration and high-intensity, medium-duration and moderate-intensity and short-duration and moderate-intensity rainfalls, respectively. This implied that the initiation of mass failure was more prone to rainfall events with a medium-duration and moderate-intensity than those with a high intensity and short duration. Rainfall amount and initial slope gradient were the most sensitive elements driving the number and volume of the mass movement erosion. Mass movement erosion raised sediment concentration, but the eroded material was unable to be transported by runoff in a timely manner. Average sediment concentrations at the model outlet increased by 1.9-11.9 times following the occurrence of mass failures compared to those before. A low instantaneous sediment delivery ratio of 0.032 for the mass movement erosion. The experimental findings help comprehend the influence of mass movement erosion on sediment supply on the gully sidewall in the hilly and gully network, i.e. the Loess Plateau.
... Terry (1998) reported that the first stage of splash erosion is soil aggregate breakdown. Disintegrated fine particles provided material for runoff transport, and blocked soil pores to reduce infiltration and increase runoff (Bresson and Boiffin, 1990;Legout et al., 2005;Li et al., 2013;Vaezi et al., 2017). The mechanisms of slaking, differential swelling, raindrop impact and physico-chemical dispersion are defined as the main soil aggregate breakdown mechanisms by Le Bissonnais (2016) (Fig. 1). ...
Article
Soil aggregate breakdown is the initial stage of splash erosion. Preventing aggregate disintegration can effectively control the material source for sediment transport. The impact factors of aggregate disintegration have been partially studied, but the effect of soil moisture content on slaking and physico-chemical dispersion remains unclear. In this study, simulation tests of splash erosion were carried out on three sandy clay loam soils with different years of vegetation restoration (S1, S2 and S3 were 55, 80 and 100 years of reforestation and land restoration, respectively). Three rainfall heights (1.5 m, 2 m and 2.5 m) were used to simulate aggregate disintegration caused by different rainfall kinetic energies. Soil aggregates with five antecedent moisture contents (air drying, 5 %, 10 %, 15 %, and 20 %) were subjected to three different pretreatments: fast wetting (FW), slow wetting (SW) and shaking after prewetting (WS). It was found that the mean weight diameter in the fast wetting (MWD FW) treatment increased and then decreased with increasing moisture content. Aggregate sensitivity to slaking decreased with increasing moisture content. After rainfall, the macroaggregates content (>0.25 mm) increased and then decreased with increasing moisture content. In the S1 sample, the contribution of physico-chemical dispersion to splash erosion was dominant for increasing splash erosion rate at the moisture content of 15-20 %. The slaking contributed more to decreasing splash erosion rate with increasing moisture content in the S2 and S3 samples. This study clarifies the response of slaking and physico-chemical dispersion to moisture content, which is helpful for thoroughly understanding the disintegration mechanisms of soil aggregates.
... However, urban soils are mainly considered as a support surface for buildings and infrastructure and are usually characterized only by their geotechnical properties (Blanchart et al. 2018). The decreasing trend found on water regulation service levels with increasing precipitation value was also described by Maragno et al. (2018) and Vaezi, Ahmadi and Cerdà (2017). This would be associated with soil's water storage capacity, that depends mainly on the infiltration rate and depth of the soil (Poca et al. 2018) and which, once exceeded by precipitation, restricts vertical water movement and increases surface runoff (Eiza and Carfagno 2018). ...
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This work aims to evaluate the water regulation ecosystem service in a peri-urban sector of Bahía Blanca, an intermediate city of Argentina. Variations in the level of provision are analyzed within the framework of an urbanization scenario. For this purpose, we used the tool ‘Retention of excess precipitation by vegetation cover’, included in the ECOSER protocol, which is based on the Curve Number method.Future urbanization in Bahía Blanca peri-urban area would decrease the level of provision of the water regulation ecosystem service between 0.5 and 2.5%. The best response in rainfall retention was observed for the shrubland land cover. Likewise, the provision level of the ecosystem service decreases regarding the Antecedent Runoff Conditions and the amount of rainfall. This study contributes to generating knowledge to understand the dynamics of a particularly important ecosystem service in cities, given its direct relationship with stormwater management.
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Biological SWC practices of chomo grass, vetiver grass are the most productive, easy to accept and effective at reducing soil erosion and increasing soil organic matter. The objective of this research was to evaluate their effect on some selected soil physicochemical properties in Mana Sibu area. The land treated with chomo grass, vetiver grass, and adjacent untreated lands, as well as the three age groups of these grasses, young (0-10), middle (10-20), and old (20-30) years were considered. A total of 27 soil samples were collected from the subsurface of 0–20 cm soil depth in a 'zigzag' design because of vetiver strips impractical for means. The gathered soil samples were evaluated using laboratory procedures, and the general linear model included a total of 8 variables. The dry sieving analysis was carried out to separate the soil aggregate stability. Chomo and vetiver grasses effect on soil physicochemical properties, the clay soil texture was statistically highly significant at p < 0.001 following the treatments and at p < 0.01 along with age categories, while silt was not significant. The highest mean value of clay (72.67%) in the chomo grass treatment and age category (73%). The soil aggregate stability was shown to have statistical significance at p< 0.01 in the soil dry aggregate stable size fractions of > 2 mm, 0.075-0.425 mm, and 0.075 mm. Results for SOC were statistically significant at p< 0.05, while TN was at p < 0.05, soil PH at P < 0.01, and CEC at p <0.01.
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BACKGROUND: Potato is a crop that requires the creation of a fine-grained structure of the upper tuber-inhabited soil layer to form tubers of the correct shape, as well as to ensure conditions for good soil separation during harvesting. For this purpose, most technologies for cultivating this crop provide for the formation of a profiled field surface. One of the results of global climate change is an increase in the frequency of heavy rainfall during the growing season. At the same time, the presence of a profiled surface on fields with even a slight slope leads to significant risks of water erosion during heavy rains due to water flowing from the ridge walls into the row spacing. This leads to annual irreparable losses of the fertile soil layer. Therefore, in order to ensure the preservation of the level of natural soil fertility and eliminate the risks of water erosion when using intensive potato production technologies in the context of global climate change, it is necessary to improve the technological methods and technical means used to form a profiled field surface. AIM: The aim of the study is to protect soil from water erosion during potato cultivation on a profiled field surface by improving technological methods and technical means used to form a profiled field surface, as well as substantiating the parameters and modes of their operation. METHODS: The object of the research is a non-powered rotary dyker mounted on a row-crop cultivator-subsoiler. To select rational parameters of the dyker's blades theoretical studies were conducted on the basis of which the rotor diameter of its blades was selected. The following assumptions were adopted as initial data for determining the technological parameters of the dyker: intensity of rainfall; depth of the loosening tines of the row-crop cultivator-subsoiler; the rate of rain absorption by capillaries on medium-loamy soils at a certain degree of field slope. The theoretical calculation of the technological parameters of thedyker was performed on the basis of the constructed trajectories of the rotor center and its blades during the work process. The calculation of the parameters of the dyker was carried out taking into account that the front and rear walls of the mini pit are formed by its blade by pushing loose soil during rolling with a step t relative to a fixed point at a certain depth h, the step of the dyker's blades t is determined by the design parameters of the rotor: diameter D and the number of blades on it. RESULTS: To determine the number of mini pits per linear meter the volume of water that gets between the rows during a downpour was calculated depending on their interrow width. The calculation results showed that with a precipitation intensity of 15 mm/h the number of mini tip per linear meter of the profiled surface of the field varies from 2.4 to 3.1 pcs/m. These data made it possible to determine the rational parameters of the dyker for protection against water erosion of the fields located on slopes when cultivating potatoes on the profiled surface. CONCLUSION: An effective method for preventing water erosion on the profiled surface of a field when cultivating potatoes is deep loosening between rows with simultaneous formation of mini pits at the bottom of the furrow. For this purpose it is proposed to use a non-powered rotary pit cultivator. When using a dyker with a rotor diameter of 600 mm the number of mini pits per linear meter varies from 2.4 pcs/m with a inter row spacing of 70 cm to 3.1 pcs/m with a inter row spacing of 90 cm. For reliable protection of soils from water erosion with a inter row spacing of 70 cm it is enough to install 4 blades on the rotor, with inter row spacing of 75 and 80 cm best result available with 5 blades per rotor and with a width of 90 cm 6 blades per rotor will be required.
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The factors influencing soil erosion are diverse and complex. However, a comprehensive comparative analysis of the various factors remains insufficient. By collecting, selecting and summarizing related studies across China, this study established a comprehensive dataset that includes runoff depth (R) and soil loss (SL) under various soil erosion factors (soil order, land use, vegetation coverage, slope length, slope gradient, and precipitation), to identify erosion pattern in different runoff plots based on rainfall events. Results showed that the average runoff depth (WR) and weighted average soil loss (WSL) of observed water erosion events in China are 20.10 mm and 331.92 t/km2, respectively. Semi-alfisols, amorphic soils, and pedocals reveal significantly higher R and SL. Forests prove most effective in mitigating soil and water loss, whereas grasslands and bare land exhibit similar runoff levels. Vegetation coverage of 40–60 % notably reduces both R and SL. R and SL fluctuate with the increase in slope length and slope gradient, but increase with growing precipitation. When the slope length exceeds 15 m and the gradient surpasses 25°, R and SL decrease significantly. Precipitation is the most significant factor impacting both R (contributing 58.70 %) and SL (contributing 30.25 %). This study underscores interactions among erosion factors and proposes multivariate linear regression models to predict R and SL based on these variables. It also contributes to clarifying the effects of erosion factors on slopes, providing a scientific basis for soil erosion modeling and control.
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Cultivated land is the primary source of runoff and soil loss in a watershed. Quantifying the soil erosion response of dominant cereal crops at different slope gradients is vital to sustainable land use, crop management, and conservation options. This study evaluated the runoff loss (Ro), runoff coefficient (RoC), and soil loss (SL) responses of teff (Eragrostis tef), maize (Zea mays), and wheat (Triticum aestivum) cropland use under different slope conditions. During 2020 and 2021, 18 experimental erosion plots (3m x 10m) having 3 crops x 3 slope gradients (8%, 18%, and 32%) with two replicates were installed. Soil loss and runoff analysis were made and the significance variation among land uses and slopes was tested using ANOVA. On average, the highest Ro is recorded from teff land use (700mm) followed by wheat (651.2mm), and maize (570mm) land uses. The Ro generated from the teff crop land use exceeds 18.5% and 6.9% compared to maize and wheat crop land uses (P < 0.05). The lower proportion of the rainfall was converted to runoff (RoC=38%) under the maize crop land use, however, nearly half of the rainfall (RoC=46.6%) became runoff in the teff crop. The average (three slope gradients) rate of SL in teff, wheat, and maize crop land uses was found to be 54.86, 45.61, and 38.27 t ha-1 year-1, respectively. Although the result shows high soil erosion in all cereal crops, cultivation of the teff crop in general and on steep slopes in particular leads to a high Ro and SL. Therefore, sustainable land management practice and setting land use policy are recommended, particularly for teff cultivation. Keywords: Crops, Runoff, Runoff coefficient, Slope gradient, Soil erosion, Soil loss
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Detailed information on the spatial variability of soil aggregate-size fractions (SASF) is crucial for soil erosion modelling and agricultural production. The effects of intrinsic and extrinsic factors on SASF have been widely studied at the grain to small-watershed scales, but rarely studied at the regional scale. This study aimed to investigate the influence of 19 environmental factors on the spatial variability of SASF in southwestern China, where similar tillage practices were used in local tobacco fields. A total of 2238 soil samples were randomly collected from the topsoil (0–20 cm) for analysis. The random forest model was used to identify the relationship between SASF and environmental factors. Random Forest explained 43–54% of SASF variability. Total precipitation during the non-growing period (NGP) was the main factor influencing the variation of SASF, which was 2 to 3 times more important than total precipitation during the growing season (GP) and nitrogen fertilizer application, which ranked second or third, respectively. After NGP exceeded the threshold values, aggregate formation slowed down, while after GP exceeded the threshold values, aggregate fragmentation accelerated. Additionally, excessive nitrogen fertilization not only negatively affected soil aggregate formation, but also weakened the promotional effects of NGP. Overall, our regional-scale study identified the effects of precipitation and nitrogen fertilization on SASF, which might be useful for regional soil erosion modelling and climate-adapted agricultural policies.
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The degradation of soil quality and agricultural sustainability is threatened by soil erosion, which poses a serious threat to livelihoods and food security. Maintaining soil fertility and reducing the danger of erosion require efficient evaluation and management strategies. This research presents an innovative approach to assess soil erosion in Nowshera District, leveraging remote sensing technology coupled with Geographic Information System (GIS) tools. The study intends to offer a thorough and accurate understanding of erosion patterns and drivers in the area by incorporating these cutting-edge approaches. Cloud-free LANDSAT 8 multispectral images, characterized by minimal vegetation cover, serve as the primary dataset for this analysis. The integration of the RUSLE model with GIS and remote sensing techniques enables the calculation of soil erosion rates throughout the research region. The study demonstrates variation in soil erosion parameters across different locations, as indicated by R factor values, which range from 603.43 to 696.43 MJ mm/ha/h/year. The southeastern portion demonstrates significantly lower erosion rates than the northwestern part, which can be linked to variations in topography and land use patterns. This study highlights the significance of using remote sensing techniques to evaluate soil erosion changes over time and provide valuable information for land management plans in Nowshera District, Pakistan. The study results can prove valuable during decision-making regarding conservation planning and agricultural sustainability.
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The degradation of soil quality and agricultural sustainability is threatened by soil erosion, which poses a serious threat to livelihoods and food security. Maintaining soil fertility and reducing the danger of erosion require efficient evaluation and management strategies. This research presents an innovative approach to assess soil erosion in Nowshera District, leveraging remote sensing technology coupled with Geographic Information System (GIS) tools. The study intends to offer a thorough and accurate understanding of erosion patterns and drivers in the area by incorporating these cutting-edge approaches. Cloud-free LANDSAT 8 multispectral images, characterized by minimal vegetation cover, serve as the primary dataset for this analysis. The integration of the RUSLE model with GIS and remote sensing techniques enables the calculation of soil erosion rates throughout the research region. The study demonstrates variation in soil erosion parameters across different locations, as indicated by R factor values, which range from 603.43 to 696.43 MJ mm/ha/h/year. The southeastern portion demonstrates significantly lower erosion rates than the northwestern part, which can be linked to variations in topography and land use patterns. This study highlights the significance of using remote sensing techniques to evaluate soil erosion changes over time and provide valuable information for land management plans in Nowshera District, Pakistan. The study results can prove valuable during decision-making regarding conservation planning and agricultural sustainability.
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Effective use of rainfall water is a key issue in agricultural development in the arid and semi-arid regions since rainfall water is a precondition for crop production there. This study was conducted in a semi-arid agricultural region with 900 km2 in area in Hashtroud, northwest of Iran to determine the relationship between rainwater use efficiency (RWUE) and soil properties. Winter wheat yield and soil properties were determined at 108 plots (40.41 m2 in area) installed in thirty six dry-farming lands. RWUE of each plot obtained from the ratio of crop dry matter per unit of abstracted rainfall water volume (ARWV). ARWV was computed from deduction of the rainfall and runoff volume during a two-growth period. Runoff data for each land was obtained from field measurements at the plots under natural rainfalls. Analysis of rainfalls uniformity using four rain gauge stations data showed that spatial distributions of rainfalls were homogeneous in the area. The RWUE values in the lands were ranged from 0.35 kg m-3 to 1.49 kg m-3 with an average of 0.84 kg m-3. Soil properties which considerably affected either the infiltration capacity or the available water controlled the RWUE in the study area. Multi-regression analysis indicated that the RWUE significantly related to silt, organic matter and lime (R2=0.82, p < 0.001). Maintaining crop residues and incorporating with the soil can be proper techniques and sustainable strategies to improve the soil properties and enhance the RWUE in the dry-farming lands.
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A widespread pattern of the Tibetan plateau is mosaics of grasslands of Cyperaceae and grasses with forbs, interspersed with patches covered by lichen crusts induced by overgrazing. However, the fate of inorganic and organic N in non-crusted and crusted patches in Kobresia grasslands remains unknown. We reported on a field 15N-labeling experiment in two contrasting patches to compare retention of organic and inorganic N over a period of 29 days. 15N as KNO3, (NH4)2SO4 or glycine was sprayed onto soil surface. Crusted patches decreased plant and soil N stocks. More 15N from three N forms was recovered in soil than plants in both patches 29 days after the labeling. In non-crusted patches, 15N recovery by the living roots was about two times higher than in crusted ones, mainly because of higher root biomass. Microorganisms in non-crusted patches were N-limited because of more living roots and competed strongly for N with roots. Inorganic N input to non-crusted patches could alleviate N limitation to plants and microorganisms, and leads to higher total 15N recovery (plant + soil) for inorganic N forms. Compared to non-crusted patches, microorganisms in crusted patches were more C-limited because of depletion of available C caused by less root exudation. Added glycine could activate microorganisms, together with the hydrophobicity of glycine and crusts, leading to higher 15N-glycine than inorganic N. We conclude that overgrazing-induced crusts in Kobresia grasslands changed the fate of inorganic and organic N, and lead to lower total recovery from inorganic N but higher from organic N.
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. In this forum paper we discuss how soil scientists can help to reach the recently adopted UN Sustainable Development Goals (SDGs) in the most effective manner. Soil science, as a land-related discipline, has important links to several of the SDGs, which are demonstrated through the functions of soils and the ecosystem services that are linked to those functions (see graphical abstract in the Supplement). We explore and discuss how soil scientists can rise to the challenge both internally, in terms of our procedures and practices, and externally, in terms of our relations with colleague scientists in other disciplines, diverse groups of stakeholders and the policy arena. To meet these goals we recommend the following steps to be taken by the soil science community as a whole: (i) embrace the UN SDGs, as they provide a platform that allows soil science to demonstrate its relevance for realizing a sustainable society by 2030; (ii) show the specific value of soil science: research should explicitly show how using modern soil information can improve the results of inter- and transdisciplinary studies on SDGs related to food security, water scarcity, climate change, biodiversity loss and health threats; (iii) take leadership in overarching system analysis of ecosystems, as soils and soil scientists have an integrated nature and this places soil scientists in a unique position; (iii) raise awareness of soil organic matter as a key attribute of soils to illustrate its importance for soil functions and ecosystem services; (iv) improve the transfer of knowledge through knowledge brokers with a soil background; (v) start at the basis: educational programmes are needed at all levels, starting in primary schools, and emphasizing practical, down-to-earth examples; (vi) facilitate communication with the policy arena by framing research in terms that resonate with politicians in terms of the policy cycle or by considering drivers, pressures and responses affecting impacts of land use change; and finally (vii) all this is only possible if researchers, with soil scientists in the front lines, look over the hedge towards other disciplines, to the world at large and to the policy arena, reaching over to listen first, as a basis for genuine collaboration.
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Aggregate breakdown is an important process which controls infiltration rate (IR) and the availability of fine materials necessary for structural sealing under rainfall. The purpose of this study was to investigate the effects of different slope gradients, rain intensities and particle size distributions on aggregate breakdown and IR to describe the formation of surface seal. To address this issue, 60 experiments were carried out in a 35 × 30 × 10 cm detachment tray using a rainfall simulator. By sieving a sandy loam soil, two sub-samples with different maximum aggregate sizes of 2 mm (Dmax2 mm) and 4.75 mm (Dmax4.75 mm) were prepared. The soils were exposed to two different rain intensities (57 and 80 mm h−1) on several slopes (0.5, 2.5, 5, 10 and 20%) each at three replicates. The result showed that for all slope gradients and rain intensities, the most fraction percentages in soils Dmax2 and Dmax4.75 mm were in the finest size classes of 0.02 and 0.043 mm, respectively. The soil containing finer aggregates exhibited higher transportability of pre-detached material than the soil containing larger aggregates. Also, IR increased with increasing slope gradient, rain intensity and aggregate size under unsteady state conditions because of less development of surface seal. However, under steady state conditions, no significant relationship was found between slope and IR. The findings of this study revealed the importance of rain intensity, slope steepness and soil aggregate size on aggregate breakdown and seal formation, which can control infiltration rate and the consequent runoff and erosion rates.
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Soil erosion is a major threat to soil functioning. The use of vegetation to control erosion has long been a topic for research. Much of this research has focused on the above-ground properties of plants, demonstrating the important role that canopy structure and cover plays in the reduction of water erosion processes. Less attention has been paid to plant roots. Plant roots are a crucial yet under-researched factor for reducing water erosion through their ability to alter soil properties, such as aggregate stability, hydraulic function and shear strength. However, there have been few attempts to specifically manipulate plant root system properties to reduce soil erosion. Therefore, this review aims to explore the effects that plant roots have on soil erosion and hydrological processes, and how plant root architecture might be manipulated to enhance its erosion control properties. We demonstrate the importance of root system architecture for the control of soil erosion. We also show that some plant species respond to nutrient-enriched patches by increasing lateral root proliferation. The erosional response to root proliferation will depend upon its location: at the soil surface dense mats of roots may reduce soil erodibility but block soil pores thereby limiting infiltration, enhancing runoff. Additionally, in nutrient-deprived regions, root hair development may be stimulated and larger amounts of root exudates released, thereby improving aggregate stability and decreasing erodibility. Utilizing nutrient placement at specific depths may represent a potentially new, easily implemented, management strategy on nutrient-poor agricultural land or constructed slopes to control erosion, and further research in this area is needed.
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Land degradation processes start with accelerated runoff and sediment delivery. In this study, rainfall-runoff induced sediment transport is investigated using data from an indoor laboratory experimental setup consisting of a rainfall simulator and an erosion flume. The data are analysed to develop empirical models using sediment discharge, slope, flow discharge, rainfall intensity and sediment size. Fine and medium sands are considered as bare soil in experiments. Four rainfall intensities (45, 65, 85 and 105mmh-1) are applied with combinations of lateral and longitudinal slopes of 5%, 10%, 15% and 20%. Eighty experiments are conducted. Flow is measured, and sediment within flow is separated and weighted. Experimental data are used for developing empirical models through multiple regression with parameters optimized by genetic algorithm. Results show that slope is the main contributing variable to the sediment transport over hillslopes. Accommodating variables among slope, rainfall intensity, flow discharge and median diameter of sediment as independent variables, one-variable, two-variable and four-variable models are developed considering also that higher number of parameters increases the performance of the model with higher cost of parameterization.
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The characteristics of crusts are closely related to soil erosion in red loam under a rainfall condition. To better manage crust-prone soils and to accurately predict hydrological processes, it is necessary to understand the mechanism of crust formation. Wetting rate is an important factor influencing soil aggregate stability and crust formation. In this study, we considered two factors, wetting rate (slow 2 mm h−1, fast 50 mm h−1) and rainfall quantity (intensity of 60 mm h−1 with every 5 min as a treatment from 0 to 60 min). The results show that soil in the fast wetting treatment had higher bulk density, stronger crust strength and lower infiltration rate. Therefore, the fast wetting treatment had higher ability to resist the damage caused by raindrops and to resist soil erosion, and higher runoff rate than slow wetting treatment. Crust formation–destruction–formation process appeared sharp in fast wetting treatment but gentle in slow wetting treatment. Surface morphology and profile microstructure show that crusts were formed earlier in fast wetting treatment. The aggregates in slow wetting treatment had higher stability than those in fast wetting treatment. The crust strength of the soil pretreated by slow wetting was weaker than that in fast wetting case due to the persistent presence of stable aggregates, albeit microaggregates, and, consequently, reduced levels of compaction.
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The holistic study of soils requires an interdisciplinary approach involving biologists, chemists, geologists, and physicists amongst others, something that has been true from the earliest days of the field. In more recent years this list has grown to include anthropologists, economists, engineers, medical professionals, military professionals, sociologists, and even artists. This approach has been strengthened and reinforced as current research continues to use experts trained in both soil science and related fields and by the wide array of issues impacting the world that require an in-depth understanding of soils. Of fundamental importance amongst these issues are biodiversity, biofuels/energy security, climate change, ecosystem services, food security, human health, land degradation, and water security, each representing a critical challenge for research. In order to establish a benchmark for the type of research we seek to publish in each issue of SOIL we have outlined the interdisciplinary nature of soil science research we are looking for. This includes a focus on the myriad ways soil science can be used to expand investigation into a more holistic and therefore richer approach to soil research. In addition, a selection of invited review papers are published in this first issue of SOIL that address the study of soils and the ways in which soil investigations are essential to other related fields. We hope that both this editorial and the papers in the first issue will serve as examples of the kinds of topics we would like to see published in SOIL and will stimulate excitement among our readers and authors to participate in this new venture.
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The set-up and characterization of an indoor nozzle-type rainfall simulator (RS) at Wageningen University, The Netherlands is presented. It is equipped with 4 Lechler nozzles (two nr. 460.788 and two nr. 461.008). The tilting irrigation plot is 6 m long and 2.5 m wide. An electrical pump supplies the constant flow during the experiments. The spatial distribution of the rainfall was measured with 60 rain gauges equally distributed on the experimental plot. Thies® Laser Precipitation Monitor (LPM) was used to measure the size and falling velocity of the raindrops. Four different flow rates were applied (Q1-4). From the collected data spatial rainfall intensity and spatial kinetic energy distribution maps were created, Christiansen Uniformity coefficient (CU) was calculated for each flow rate. The results of the experiments revealed that the rainfall parameters (spatial rainfall intensity, kinetic energy, raindrop size distribution, fall velocity) in the RS are not homogeneous (CU ranges from 68.5% to 83.2%). Accordingly the whole plot can only be irrigated irregularly applying a wide range of intensities and rainfall energies. The RS offers good opportunity to study great variety of process intensities such as splash erosion, runoff generation, soil aggregate stability, organic matter migration and scaled landscape development. This article is protected by copyright. All rights reserved.
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Rainfall characteristics affect crust formation, infiltration rate and erosion depending on intrinsic soil properties such as texture and mineralogy. The current study investigated the effects of rainfall pattern on crust strength, steady state infiltration rate (SSIR) and erosion in soils with various texture and minerals. Soil samples from the top 0.2 m layer were exposed to 60 mm·h-1 simulated rainfall. The rainfall was applied either as an 8-min single rainstorm (SR) or 4 x 2-min intermittent rainstorms (IR) separated by a 48 h drying period. Rainfall pattern significantly (p < 0.05) affected crust strength, SSIR and erosion. The IR resulted in higher crust strength and SSIR than SR. The effect of rainfall pattern on SSIR was mostly influenced by the primary minerals, namely, quartz. Therefore, the predicted shift from long duration to short duration rainstorms due to climate change is likely to enhance crust formation and soil loss in semi-arid areas such as the Eastern Cape Province of South Africa. Keywords: hydrology, penetration resistance, quartz, soil organic matter
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Southern Portugal experiences the lowest amounts of annual precipitation and the highest level of susceptibility to soil erosion, drought events and desertification phenomena in mainland Portugal. The first goal of this paper was to analyze spatial variability and trends in annual precipitation and erosivity in southern mainland Portugal for the period 1950/51-2007/08. The second objective was to evaluate seasonality in relation to precipitation distribution, erosivity and concentration over the same period of time, and to evaluate and detect possible changes in the time trend for precipitation erosivity. In order to achieve these objectives, the annual and seasonal precipitation figures, corresponding to data from 90 rain gauges, were analysed and the Modified Fournier Index (MFI) and Precipitation Concentration Index (PCI) calculated for each station. The results obtained revealed distinct behaviour patterns for yearly precipitation, erosivity and concentration trends. Decreases in annual precipitation and erosivity figures accompanied by increases in precipitation concentration were found. Nevertheless, no generalised significant trends have been detected for these variables. In seasonal terms, there was a general trend towards an increase in amount, concentration and precipitation erosivity in autumn and summer, and a significantly reducing in winter. The increase in precipitation erosivity, particularly in the autumn, the most water-erosive season, suggests a rising in potential soil erosion risk in southern Portugal. This article is protected by copyright. All rights reserved.
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In actual project, the different locations of the column will form a non-uniform thermal boundary conditions, such as single-side, adjoining or back to back two sides and three sides. The temperature field distribution and the fire resistance limit of the concrete-filled square steel tubular(CFST) columns with encased profiled steel was calculated with software ABAQUS. It is found that the non-uniform distribution of temperature field should result in additional eccentricity and deflection which is different from uniform fire cases. The mid-span contact stress and parametric change of members were also calculated. Results show that the cross-section dimension and slenderness ratio of column have more significant effects on the non-uniform fire bearing capacity of the column.
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No-tillage (NT) is promoted for soil and water conservation, but research findings on overland flow and soil erosion are inconsistent across different ecosystems, with some studies showing no benefits of NT over conventional tillage (CT). A global literature review was conducted to quantify the impact of NT on water runoff, sediment concentration and soil losses. The objective was to identify the underlying causes of the variability in the performance of NT across different environments. Data from 282 paired NT and CT runoff plots from 41 research studies worldwide were analysed using meta-analysis and principal component analysis (PCA). Sediment concentration and soil losses were 56 and 60% lower under NT than CT, respectively. These tended to be greater under CT than NT on long plots (90% for sediment concentration and 94% for soil losses) and steepest slopes (79 and 77%, respectively). Greater differences in sediment concentration and soil losses between NT and CT were observed in low clay soils and under temperate climates. While on average there were no differences on runoff coefficient, NT decreased runoff coefficient by about 40% compared to CT in mulched soils, under cool climate (<10 °C), and for experiments done >5 years. Overall, the results indicated that NT has greater potential to reduce runoff and soil losses in temperate regions where soils of peri-glacial influence are relatively young, moderately weathered and fragile compared to the heavily weathered clayey tropical soils that are well aggregated and less erodible. The results of this study are expected to inform scientists, practitioners and policy makers on the links between land management and soil functioning processes. Policy makers and development implementers will be able to make informed choices of land management techniques for effective NT implementation, for instance by having more mulch input under warm climates.
Article
Soil management has important effects on soil properties, runoff, soil losses and soil quality. Traditional olive grove (OG) management is based on reduced tree density, canopy size shaped by pruning and weed control by ploughing. In addition, over the last several decades, herbicide use has been introduced into conventional OG management. These management strategies cause the soil surface to be almost bare and subsequently high erosion rates take place. To avoid these high erosion rates several soil management strategies can be applied. In this study, three strategies were assessed in OG with conventional tillage in three plots of one hectare each. Soil properties were measured and soil erosion rates were estimated by means of the RUSLE model. One plot was managed with no amendments (control), and the other two were treated with olive leaves mulch and oil mill pomace applied yearly from 2003 until 2013. The control plot experienced the greatest soil loss while the use of olive leaves as mulch and olive mill pomace as an amendment resulted in a soil loss reduction of 89.4% and 65.4% respectively (assuming a 5% slope). In addition, the chemical and physical soil properties were improved with the amendments. This combined effect will created a higher quality soil over the long term that it is more resilient to erosion and can provide better ecosystem services, as its functions are improved.
Article
Determination of rainfall kinetic energy (KE) is required to calculate erosivity, the ability of rainfall to detach soil particles and initiate erosion. Disdrometers can measure rainfall KE by measuring raindrop size and velocity. In the absence of such devices, KE is usually estimated with empirical equations that derive KE from measured rainfall intensity (I). We evaluated the performance of 14 different KE–I equations to estimate the 1 min KE and event total KE, and compared these results with 821 observed rainfall events recorded by an optical disdrometer in the inner Ebro Basin, NE Spain. We also evaluated two sources of bias when using such relationships: bias from use of theoretical raindrop terminal velocities instead of measured values; and bias from time aggregation (recording rainfall intensity every 5, 10, 15, 30, and 60 min). Empirical relationships performed well when complete events were considered (R2 > 0.90), but performed poorly for within-event variation (1 min resolution). Also, several of the KE-I equations had large systematic biases. When raindrop size is known, estimation of terminal velocities by empirical laws led to overestimates of raindrop velocity and KE. Time aggregation led to large under-estimates of KE, although linear scaling successfully corrected for this bias.
Article
Soil aggregates profoundly influence soil fertility and soil erosion. A large number of studies have showed that soil aggregate loss was mainly affected by raindrop impact and runoff detachment during hillslope erosion process; however, few attempts have been made to investigate which one plays the dominant role in soil aggregate loss. Therefore, a laboratory study was conducted to quantify the effects of raindrop impact and runoff detachment on soil erosion and soil aggregate loss during hillslope erosion processes. A soil pan (8 m long, 1.5 m wide, and 0.6 m deep and with an adjustable slope gradient of 0–35°) was subjected to rainfall simulation experiments under two soil surface conditions: with and without raindrop impact through placing nylon net over soil pan. Two rainfall intensities (50 and 100 mm h−1) of representative erosive rainfall and two slope gradients (5 and 10°) in the Mollisol region of Northeast China were subjected to two soil surface conditions. The results showed that raindrop impact played the dominant role in hillslope soil erosion and soil aggregate loss. Soil loss caused by raindrop impact was 3.6–19.8 times higher than that caused by runoff detachment. The contributions of raindrop impact to hillslope soil erosion were 78.3% to 95.2%. As rainfall intensity and slope gradient increased, soil loss caused by raindrop impact and runoff detachment both increased. The loss of each size aggregate was greatly reduced by 46.6–99.4% after eliminating raindrop impact. Meanwhile, the contributions of raindrop impact to the >2, 1–2, 0.5–1, 0.25–0.5 and <0.25 mm soil aggregate loss were 79.1% to 89.7%. Eliminating raindrop impact reduced rainfall intensity effect and increased slope gradient impact on aggregate loss.
Article
The aim of this study was to enable a quantitative comparison of initial soil erosion processes in European vineyards using the same methodology and equipment. The study was conducted in four viticultural areas with different characteristics (Valencia and Málaga in Spain, Ruwer-Mosel valley and Saar-Mosel valley in Germany). Old and young vineyards, with conventional and ecological planting and management systems were compared. The same portable rainfall simulator with identical rainfall intensity (40 mm h-1) and sampling intervals (30 minutes of test duration, collecting the samples at 5-minute-intervals) was used over a circular test plot with 0.28 m2. The results of 83 simulations have been analysed and correlation coefficients were calculated for each study area to identify the relationship between environmental plot characteristics, soil texture, soil erosion, runoff and infiltration. The results allow for identification of the main factors related to soil properties, topography and management, which control soil erosion processes in vineyards.. The most important factors influencing soil erosion and runoff were the vegetation cover for the ecological German vineyards (with 97.6±8% infiltration coefficients) and stone cover, soil moisture and slope steepness for the conventional land uses.
Article
Modeling sediment yield is a complex task because of the nonlinearity of natural processes intervening at slope and basin scale. In this study slope steepness, vegetation cover, and soil properties along with sediment yield were studied in 20 pasture micro-catchments in a semi-arid region, NW Iran in order to understand and predict sediment yield. The micro-catchments included only one first-order gully and drain toward a rock check dam in the outlet. The sediment yield of each micro-catchment was calculated using the measurement of sediment mass in the check dams for a 16-year period (1994-2010). Relationships between sediment yield and drainage characteristics were analyzed using correlation matrix and multiple linear regression method. Based on the results, sediment yield in the micro-catchments varied from 0.29Mgha-1y-1 to 14.81Mgha-1y-1, with an average of 5.04Mgha-1y-1. It was significantly related to slope steepness, vegetation cover, and soil organic matter using a linear regression equation (R2=0.87, p<0.001). The slope, vegetation, and soil organic matter explained about 44%, 23%, and 20% of total variance in sediment yield, respectively. The spatial validation of the model using data from eight different micro-catchments located nearby showed that the model efficiency is 0.94. Therefore, the model can be used for predicting sediment yield in this and similar study area, with a high degree of accuracy.
Article
There is a strong need to develop a simple method for rapid estimation of erodibility using readily available data. In this study, soil erodibility was measured using eleven soil textures at the plot scale (60 cm × 80 cm) on a slope of 9% in a semi-arid region. A total of 110 soil erosion experiments were conducted using ten simulated rainfalls (50 mm h− 1 for 30 min). A regression model was developed based on silt and clay content (R2 = 0.82, p < 0.001) and was applied to estimate erodibility for 231 soils in the textural triangle. Kriging was used to spatial interpolate erodibility using these data to unknown soils on the textural triangle. A soil erodibility triangle was developed using kriging technique and its accuracy was evaluated using seven other soils. The technique showed a 5.4% error and allowed the prediction of soil erodibility in semi-arid areas by using the soil erodibility triangle.
Article
Understanding soil erosion processes in the Ecuadorian Andes with a tropical wet-dry climate and a variable topography, is fundamental for research on agriculture sustainable, environmental management, as well as for a stable water supply for the local populations. This work proposes method to estimate soil erosion risk in the semiarid Catamayo basin with limited data. The results show that the rainfall distribution and the erosivity along with the rugged topography, followed by the land cover (C-factor), are the most important factors to estimate soil erosion risk. The soil erodibility is the most important factor in the dry season for agricultural areas and where the ground cover is sparse. Soil erosion risk is higher in the centre and southwest than in the northeast of Catamayo basin. In protected areas with evergreen vegetation, the soil erosion risk is very low, even with steep slopes and high annual rainfall amounts. The methodology developed allows understanding of the soil erosion processes and the factors that lead to the spatio-temporal variability of soil erosion risk, and as a consequence improves the potential to achieve sustainability of this ecosystem through proposed conservation measures.
Article
Soil erosion by water is the main factor of land degradation, particularly in semi-arid regions where soil productivity is usually low and lowering soil quality can severely decrease crops yields. This study was done in an area of 900 km2 in the semi-arid agricultural region of Hashtroud in northwestern Iran to determine the relationship between soil productivity and soil erodibility. Wheat grain yield (WGY) and soil erodibility factor (K) were measured separately at 108 plots in 36 dry-farming lands under natural rainfall conditions for a two-year period from March 2005 to March 2007. Based on the results, significant differences were observed among the lands in WGY (P< 0.001) and K (P< 0.001). These differences were attributed to variations of soil properties among the lands. There was a negative relationship between WGY and K (R2= 0.77). Multiple regression analysis indicated that both WGY and K were significantly related to aggregate stability and infiltration rate, with a determination coefficient (R2) of 0.74 and 0.90, respectively. Organic matter and calcium carbonate equivalent were the most effective soil properties that enhanced both aggregate stability and infiltration rate. The study revealed that soils with a lower percentage of water-stable aggregates and a lower infiltration rate also tended to have a higher susceptibility to erosion and a lower potential for crop production.
Article
No-tillage (NT) has been promoted as a strategy for sequestering soil organic carbon (SOC) in crop production systems. However, recent research suggests stratification rather than sequestration of SOC may occur following adoption of NT, with no net increase in SOC. Our objective was to determine if SOC was sequestered in long-term NT plots in a cool semiarid region. Soil was collected from 0- to 30-, 30- to 60-, and 60- to 90-cm depth intervals in plots arranged in a randomized complete block where clean-tillage (CT), reduced-tillage (RT), and NT treatments had been maintained in eight blocks for 20 yr at Dickinson, ND, USA. More SOC occurred at the 0- to 30-cm depth under NT (64 Mg C ha–1) than under both RT and CT (£55 Mg C ha–1) management (SE = 2; P < 0.001) and at the 30- to 60-cm depth under NT than RT (33 vs. 28 Mg C ha–1, P < 0.03). Similarly, more SOC occurred at the 60- to 90-cm depth under NT than RT (29 vs. 22 Mg C ha–1, P = 0.003). Overall, amounts of SOC in the upper 90 cm of soil were greatest under NT at 127 Mg C ha–1 compared with 104 Mg C ha–1 under RT and 112 Mg C ha–1 under CT (P = 0.005). Results of this research indicate that conversion of CT and RT to NT in cool semiarid regions can result in the sequestration of SOC when both surface and subsurface depths are considered.
Article
Rainfall kinetic energy is a widely recognized indicator of a raindrop's ability to detach soil particles in rainsplash erosion. However, it is challenging to estimate the kinetic energy (KE) of a given rain event, because it involves analysis of the terminal velocity and drop size distribution (DSD) of raindrops. A preferred alternative is to relate KE to rainfall intensity. Therefore we sought to characterize simulated rainfall, establish a relationship between kinetic energy and intensity as a function of both time (KEt, J m(-2) h(-1)) and volume (KEvol, J m(-2) mm(-1)), and examine the erosivity potential of each event. A rainfall simulator and Laser Precipitation Monitor (optical disdrometer) were used to characterize raindrop size, terminal velocity and ME at different rainfall intensities (1.5 to 202 mm h(-1)). Values of KEt ranged from 26.67 to 5955 J m(-2) h(-1) and KEvol ranged from 16.10 to 34.85 J m(-2) mm(-1), which is comparable to values determined from natural rain of similar intensity ranges. A power-law function and a polynomial function between KEt and rainfall intensity had coefficients of determination (R-2) of 0.99 and 0.98 (P < 0.0001), respectively. The best-fitting relationship between KEvol and intensity was a power-law function (R-2 = 0.95; P < 0.001). We found that erosivity had a very strong correlation with rainfall depth (R-2 = 0.99; P < 0.0001) in power-law function. Furthermore, regardless of rainfall intensity, ME is more strongly correlated with raindrop size than volume of raindrop.
Article
This paper presents measurements of the velocities of water‐drops of sizes ranging from one to six mm in diameter, falling in still air from heights of 0.5 meter to 20 meters. A few measurements of raindrop velocities are also reported. The measurements were undertaken to assist in an understanding of the action of rain, both real and artificial, in eroding soil. The drop‐sizes of rains have also been measured and will be reported separately. All of these studies were carried out at the Hydraulic Laboratory of the National Bureau of Standards as a part of the work of the Soil Conservation Service.
Article
Vegetation plays an important role in soil erosion control, but few studies have been performed to quantify the effects of vegetation stems on hydraulics of overland flow. Laboratory flume experiments were conducted to investigate the potential effects of vegetation stems on Reynolds number, Froude number, flow velocity and hydraulic resistance of silt-laden overland flow. Cylinders with diameter D of 2.0, 3.2 and 4.0 × 10−2 m were glued onto the flume bed to simulate the vegetation stems, and a bare slope was used as control. The flow discharge varied from 0.5 to 1.5 × 10−3 m3 s−1 and slope gradient was 9°. Results showed that Reynolds number on vegetated slope was significantly higher than that on bare slope due to the effect of vegetation stems on effective flow width. All the flows were supercritical flow, but Froude number decreased as D increased, implying a decrease in runoff ability to carry sediment. The Mean flow velocity also decreased with D, while the velocity profile became steeper, and no significant differences were found in surface flow velocities among longitudinal sections on all slopes. Darcy–Weisbach friction coefficient increased with D, implying that the energy consumption of overland flow on hydraulic resistance increased. Reynolds number was not a unique predictor of hydraulic roughness on vegetated slopes. The total resistance on vegetated slopes was partitioned into grain resistance and vegetation resistance, and vegetation resistance accounted for almost 80% of the total resistance and was the dominant roughness element. Further studies are needed to extend and apply the insights obtained under controlled conditions to actual overland flow conditions. This article is protected by copyright. All rights reserved.
Chapter
Total carbon (C) in soils is the sum of both organic and inorganic C. Organic C is present in the soil organic matter fraction, whereas inorganic C is largely found in carbonate minerals. The wet combustion analysis of soils by chromic acid digestion has long been a standard method for determining total C, giving results in good agreement with dry combustion. Methods for total C are basic for many of the procedures used to determine organic C in soils. In contrast to noncalcareous soils, inorganic C must be removed from calcareous or limed soils before the analysis if wet or dry combustion techniques are used to directly measure the organic C present. The organic matter content of soil may be indirectly estimated through multiplication of the organic C concentration by the ratio of organic matter to organic C commonly found in soils.
Article
Over the last 3yr, a cooperative effort between scientists and users to update the USLE is nearing completion and will produce a revised version of the USLE known as the RUSLE. Some of the improvements in the RUSLE will include: A greatly expanded erosivity map for the western United States. Minor changes in R factors in the eastern United States. Expanded information on soil erodibility. A slope length factor that varies with soil susceptibility to rill erosion. A nearly linear slope steepness relationship that reduces computed soil loss values for very steep slopes. A subfactor method for computing values for the cover-management factor. Improved factor values for the effects of contouring, terracing, stripcropping, and management practices for rangeland. -from Authors
Article
Experiments were performed in flows with and without rainfall to isolate the contributions to transport capacity from surface runoff and raindrop impact. Theory and measurement indicated that the runoff contribution was determined by discharge and bedslope. The transport capacity was greatly enhanced by raindrop impact, and the enhancement depended on rainfall intensity and bedslope. Rainfall momentum and kinetic energy fluxes were also significant in explaining the transport enhancement. Interrill transport capacity equations based on the separate runoff and raindrop impact contributions were developed. Observations of restricted flow competence suggested that the transport capacity of interrill flow is dependent on soil, as well as on hydraulic and rainfall properties. Additional study results are discussed.
Article
During runoff on soil surface, aggregates travel, abrade, and produce finer and more transportable particles, resulting in a significant effect on sediment transport, water infiltration and soil erosion. This study was to assess the effects of stability, transport distance and two hydraulic parameters on aggregate abrasion using Ultisols in subtropical China. Aggregate stability was investigated for soils from two parent materials (Shale and Quaternary red clay) with different land uses using LB methods. They were studied with a series of aggregate abrasion experiments in a 3.8 m long flume with a fixed bed. Results indicated that slaking and mechanical breakdown were probably the main mechanisms of aggregate breakdown in these study soils. Two stages of aggregate abrasion process could be distinguished via the coefficient α in different transport distances. Aggregates were first rapidly abraded, became round, and was predominantly broken apart into smaller fragments, followed by weakly abrasion of smaller fragments and round aggregates, making them even light and less angular. A good multiple regression equation was obtained for estimating aggregate abrasion in overland flow with consideration of mechanical breakdown index RMI and transport distance x. From two selected Ultisols (SX3 and QX1) and under the combination of five slopes and five discharges, exponential relationships were found between aggregate abrasion and flow depth or friction factor. This research makes a good attempt at analyzing the aggregate abrasion in overland flow from simple laboratory experiments settings, and the results of the analysis could be valuable for the development of adequate soil erosion models.