Detachment Of Soil Particles Research Articles

Soil Erosion Analysis with GIS: A Case Study of Oued Sly Catchment, Northern Algeria

Soil erosion is a process that involves the detachment and transportation of soil particles by water, presenting notable challenges of the depletion of soil fertility, diminished agricultural productivity, and consequences for water reservoirs. The integration of Geographic Information System (GIS) and modeling techniques provides a valuable platform for assessing and addressing soil water erosion. This study specifically examines the risk of soil water erosion in the Oued Sly catchment within the Middle Cheliff watershed in northern Algeria. Employing the Universal Soil Loss Equation (USLE) and thematic maps, the research evaluates the key factors influencing erosion. Results reveal that the catchment generally experiences low to moderate erosion levels, averaging 23.4 to 40 t ha-1 yr-1 across 90.7% of the total area. However, around 9.3% of the catchment exhibits higher erosion rates exceeding 40 t ha-1 yr-1. These findings offer valuable insights for informed watershed management and strategies to mitigate soil water erosion in comparable regions

Assessment of nutrient differences in detached soil particles between cropland and revegetated abandoned land

AbstractCropland (CRL) abandonment is a worldwide phenomenon of land use change with significant impacts on agro‐ecosystems. This research attempts to deepen the analysis of the positive and negative effects arising by focusing on the changes in soil properties and the amount and composition of soil particles detached after several periods of rainfall and the resulting exported sediment that occurs in abandoned areas with natural revegetation compared to CRL. The study was carried out in an agroforestry catchment with a temperate climate, on which CRL and abandoned land with natural vegetation were compared. The soil was sampled along two representative hillslopes integrating elements of the landscape and land use/land covers. Sediments were collected after seven periods in which flood events were recorded during the period July 2016 to December 2017, using artificial‐lawn mats. Soil and sediment composition (texture, soil organic carbon [SOC] and nutrients [total nitrogen and total phosphorous]) under both land uses were assessed and compared and related to rainfall characteristics using principal component analysis. Nutrient enrichment factors in the sediments compared to soils were also evaluated. The results highlight that after abandonment, SOC increased significantly, reaching contents almost three times higher than in CRL. Consequently, soil erodibility decreased, resulting in substantially lower sediment generation after erosive rainfall events. On average, sediment generation was three times lower in abandoned areas than in CRL, despite their steeper slopes. Soil total nitrogen also increased on abandoned lands, reaching values about twice as high as those in CRL. However, total phosphorous content was almost twice as high in CRL than in abandoned land posing a potential risk for water due to higher erosion rates recorded in CRL. The results confirmed the association of phosphorous with smaller particles and also demonstrated the total phosphorous‐SOC link in abandoned land. Furthermore, the effect of rainfall intensity on phosphorous mobilisation was confirmed, whilst nitrogen losses were mainly related to the total amount of rainfall recorded. In a scenario of increasing extreme precipitation, both total amount and increased precipitation intensity may exacerbate water pollution problems following nutrient loss in cultivated areas. This research contributes to identifying the impacts on agroforestry systems within the current context of converting natural areas into cultivated land, whilst in other regions revegetated natural areas are developed from abandoned agricultural land.

Effects of tree and shrub species on soil quality, sediment detachment capacity caused by rills and surface slope stability in forest lands of Northern Iran

A root system is an important factor to increase soil resistance to detachment of soil particles. However, due to the large number of species, there is a need for studying the impacts of native plant species on soil quality and soil erodibility. This investigation did flume experiments at various soil slopes (9.2%, 18.1%, 25.1%, and 32.5%) and different water flow rates (0.56, 0.67, 0.74, 0.81, and 0.94 L/(m·s)), to evaluate sediment detachment capacity caused by rills (Dc) and rill erodibility (Kr) as well as the soil quality of hillslopes with three common species including Carpinus betulus (as a natural tree species), Alnus glutinosa (as a planted tree species) and Mespilus germanica (as a shrub species) in forestland of northern Iran. The variability of Dc has been associated with soil properties and root characteristics of Carpinus betulus. Dc was significantly lower (average, −45%) for soils under Carpinus betulus compared to soils with the two other plant species (p < 0.01). This was due to the higher values of soil properties including medium weight diameter of soil aggregates (MWD), organic carbon (OC), total nitrogen (TN), total phosphorous (TP), potassium (K), calcium (Ca), magnesium (Mg) as well as to the more extended root system, as confirmed by the negative correlations between Dc and the studied variables. Kr also was different among the studied soils and plant species. The root system of Carpinus betulus also played a useful role for increasing soil resistance to rill erosion yielding a safety factor (1.61) in the studied forest ecosystem. Overall, the current study supports a broader use of native species (such as Carpinus betulus) in areas exposed to surface erosion and instability, as an effective eco-engineering conservation technique and an alternative technology instead of utilizing artificial and expensive management practices.

Predicted Contribution of Snowmelt to Subsurface Drainage Discharge in Two Subsurface-Drained Fields in Southern Quebec and Ontario

Highlights RZ-SHAW model delivered a satisfactory simulation for winter subsurface drainage discharge. Snowmelt dominated the drainage discharge during the winter and spring snowmelt seasons in southern Quebec. Snowmelt contributed to 29% and 18% of winter and annual drainage discharge, respectively, in southern Ontario. Abstract. Late winter/early spring has been recognized as a critical period for subsurface drainage discharge and associated nutrient losses due to snowmelt and rainfall in croplands under cold, humid climates in North America and Europe. Although the detachment and transport processes of soil particles under snowmelt and rainfall are known to be different, studies quantifying the contribution of snowmelt to winter drainage discharge are limited. This study aims to investigate the contribution of snowmelt to subsurface drainage discharge at two winterized experimental sites in southern Quebec and Ontario, Canada, using observed data and the Root Zone Water Quality Model-Simultaneous Heat and Water model (RZ-SHAW model). The RZ-SHAW model was calibrated and validated against the measured snow depth and year-round subsurface drainage discharge data from 2021 to 2023 at St. Emmanuel, Quebec, and from 2000 to 2003 at Harrow, Ontario. RZ-SHAW demonstrated satisfactory Nash-Sutcliffe model efficiency values (NSE = 0.50) for simulating snow depth, soil temperature, and winter subsurface drainage discharge. The calibrated RZ-SHAW model was used to simulate the contribution of snowmelt to subsurface drainage for the two sites from 1990 to 2022. The snowmelt was predicted to contribute 55% and 44% of the winter and annual subsurface drainage discharge for the cropland in Southern Quebec. In contrast, for the southern Ontario site, the contribution of snowmelt to winter and annual subsurface drainage discharge was 29% and 18%, respectively. Considering that snowmelt in Southern Quebec contributed a significant fraction of winter and annual subsurface drainage discharge, more attention should be devoted to adapting and developing new winter management for nutrient loss in future research in the region. Keywords: Cold region, Cropland drainage, Drainage partition, RZ-SHAW, RZWQM2, Snowmelt, Soil freeze and thaw, Winter subsurface drainage.

SOIL EROSION RISK IN RELATION TO RAINFALL EROSIVITY IN GUNUNG ALAB AND INOBONG OF CROCKER RANGE PARK IN SABAH, MALAYSIA

The rainfall ability to erode and detach soil particles, resulting in soil erosion, is referred to as rainfall erosivity (R). This research aims to estimate the risk of soil erosion from rainfall intensity in Gunung Alab and Inobong of Crocker Range Park, Sabah. Daily rainfall data from 2017 and 2020 where an observed mild La Nina were extracted. The 30-minute Maximum Rainfall Intensity (I30) and Rainfall Kinetic Energy (E) were determined for estimating the R Factor. ROSE Index was then referred to in classifying the soil erosion risk. The estimated monthly R Factor in Gunung Alab ranged from 15282.2 to 32029.2 MJ.mm (ha.h)-1 in 2017 and from 16069.5 to 35401.6 MJ.mm (ha.h)-1 in 2020. Gunung Alab was rated as having an “extremely high” and “critical” risk of soil erosion 80% of the time in 2017 and 50% in 2020. At the Inobong substation, the monthly R Factor in 2017 (16069.5 to 58348.0 MJ.mm (ha.h)-1) and 2020 (16863.6 to 36246.4 MJ.mm (ha.h)-1) translates to an erosion risk (extremely high-critical) throughout 67% and 92% of the time, respectively. Given the possibility of landslides, rainfall erosivity is useful information in assessing soil erosion risk and could be used in soil and land management

Rainfall erosivity in the Republic of North Macedonia: Fournier index approach

Rainfall erosivity is a crucial factor influencing soil erosion, which results from the detachment, transportation, and deposition of soil particles caused by rainfall and runoff. Rainfall erosivity assessment is a fundamental process aimed at quantifying the erosive power of rainfall events in a given region. The paper provides an overview of rainfall erosivity assessment in several heterogeneous regions of the Republic of North Macedonia based on rainfall data from meteorological stations characterized by different climatic and geographical conditions. Having into consideration that rainfall erosivity can be quantified by using various indices, this study uses two common ones: Fournier Index (FI) and the Modified Fournier Index (MFI) based on monthly and annual precipitation totals for the period 1951-2020. The results imply that in general, the studied stations belong to a low class of erosivity. It is found that FI has greater sensitivity and provides more details, also showing years with high and even very high rainfall erosivity while MFI gives more information for moderate rainfall erosivity.

Influence of Non-Woven Geotextile Over Chemically Stabilized Soil in Controlling Erosion

Abstract: Soil erosion is the most significant hazard in sloping terrain. It affects the hilly regions by the loss of top layer of the soil. Soil erosion is mainly induced by rainfall. As the surface runoff flows with high velocity, the detachment of soil particles takes place and it moves down slope. It causes instability and leads to slope failure. The soil erosion depends on erodibility, rainfall erosivity and spatial variability. Non-woven geotextile has the interlocking fibers which retain the fine soil particles and allow water to pass through the fabric. In this study, non-woven geotextile is used over chemically stabilized soil to control the erosion. The stabilizers used are Guar gum powder and Magnesium Stearate powder. Erosion tests are conducted in the slope model for maximum hourly rainfall intensities of 60mm/hr and 70mm/hr on an inclined slope having inclination of 20°. The erosion rates for the slope wherein geotextile is used as reinforcement on soil treated with Guar gum powder in the slope model for rainfall intensities 60mm/hr and 70mm/hr are 2112g/m²/hr and 2798g/m²/hr respectively. Similarly, the same soil slope model in which the stabilizer used as Magnesium Stearate and reinforced with geotextile sheet and for the same rainfall of 60mm/hr and 70mm/hr intensities produced reduction in erosion rate of 1950g/m²/hr and 2312g/m²/hr respectively. The results show, that the erosion rate decreased with the use of geotextile on chemically stabilized soil with Magnesium Stearate when compared to the other method

On the variation of the correction factor of surface velocity with the measurement vertical for shallow flows over rough beds

AbstractConsidering that water flow energy affects the detachment of soil particles, the transport and deposit of the detached particles, the flow velocity is a key variable governing the soil erosion processes at the hillslope scale. The simple dye‐tracer technique for measuring mean flow velocity can be applied in non‐controlled field applications for which some measurement difficulties (e.g. due to sediment transport, and shallow flows) can occur. The correction factor is usually obtained as the ratio between the mean velocity, deriving from measurements of flow discharge and water depth, and surface velocity. Alternatively, the possibility of using the velocity profile in a given vertical to determine a suitable correction factor has not yet been explored. In this article, the flow velocity measurements were carried out in five verticals having a different distance from the wall of a flume whose bed was covered by hemispheres with different concentrations (9%–64%) and organized in two arrangements (square, staggered). Fifteen runs, characterized by different Reynolds and Froude numbers, were performed and the correction factor αvv was calculated for each vertical. For the axial vertical αvv was independent of the arrangement, decreased with the hemisphere concentration, and increased with both the Froude and Reynolds numbers. Furthermore, αvv decreased from the bank to the flume axis as a result of the varying shape of the velocity profile. The analysis showed that the frequency distributions of the ratio between αvv and its mean value αm were overlaid and αm was used to represent the correction factor, accordingly. A relation of αm with the distance from the flume wall was detected. For the measured velocity profiles having a power shape, the analysis also demonstrated that the αvv values, obtained by fitting the power law to the measurements, were close to both those calculated as the ratio between the mean velocity along the vertical and the surface velocity and their averaged values across the hydraulic section. These three methods give comparable average values of the correction factor, in the range of 0.72–0.75, which are close to the commonly applied value of 0.8. Finally, this investigation demonstrated that a single survey of a power velocity profile allows for obtaining the correction factor accounting for different verticals across the entire hydraulic section.

Simulation of Rainfall Erosivity Dynamics in Romania under Climate Change Scenarios

Soil erosion is triggered by rainfall through the detachment of soil particles and their transport downslope, playing a key role in soil erosion models. Together with the vegetation cover, rainfall is a temporal dynamic factor, inducing corresponding time variations of erosion rates. Under current climate change, rainfall is also changing its characteristics and our study aimed to reveal whether these changes will significantly affect rainfall erosivity in Romania, and implicitly the soil erosion. To achieve this purpose, we developed a statistical non-parametric model for predicting rainfall erosivity on the basis on the modified Fournier index and applied it to future precipitation evolution scenarios. The precipitation data were extracted from the CHESLA database for the Romanian territory for two climate change contrasting scenarios (RCP 4.5 and 8.5). Average predictions from five selected climate models were used in order to minimize prediction uncertainty. The results show that rainfall erosivity is likely to increase, at least during the 2041–2060 period, especially in the south-western, western and eastern part of the country, which may cause a corresponding increase in soil erosion rates, with an average of 1–2 t ha−1 yr−1. During the 2061–2080 period, rainfall erosivity is likely to decrease in central and eastern Romania.

Analysis of sediment load on meandering channel due to combined effect of rainfall and flow

Topography, geology, climate change and anthropogenic activity are key factors for erosion that affects channel morphology. Water erosion leads to sedimentation. The study of sediment is important for the management of water quality, river structures as well as flood control. Erosion of soil by water poses a serious problem in terms of degradation of land and eutrophication of water. River or stream erosion is mainly caused by rainfall and streamflow as they detach soil particles and transport them as sediment. The meandering channel is common in most rivers or streams where it is formed by the deposition of sediments due to the depletion of water energy. Therefore, this study aims to analyse the sediment load under the combined effect of rainfall and flow for a meandering channel. This study was conducted based on the Advanced Environmental Hydrology System to determine the relationship among sediment load, rainfall and flow rate. Twenty-five sets of experiments were conducted on a 2 m long, 20 cm wide and 4 cm deep model meandering channel, moulded in the Armfield S12 MKII on a 1% constant slope. Five different rainfalls intensities (0.46 mm/hr, 1.39 mm/hr, 2.78 mm/hr, 3.70 mm/hr and 4.63 mm/hr) and five different flow rates (0.5 L/min, 1.0 L/min, 1.5 L/min, 1.75 L/min and 2.0 L/min) were used to analyse the different trends of sediment load with respect to rainfall and flow rate. This study shows that there is a correlation among rainfall, flow and sediment load. The erosion rate during lowest flow and rainfall is 4.75 g/min and for highest rainfall and flow is 70.2 g/min.

Effects of Selected Manure Sources on Runoff, Soil Loss, and Nutrient Transport

Highlights Surface water runoff was reduced following manure additions. Sediment yield was reduced following manure additions. Nutrient loss was increased following manure additions. Abstract. Soil erosion models are becoming increasingly accurate and now can simulate a variety of surface covers which can lessen erosion by reducing detachment and movement of soil particles. Currently, there is limited data on the effects of animal manure on soil erosion. Most process-based models credit animal manure as crop residue cover. Thus, there is a need for bench studies under laboratory conditions, as well as field studies to determine the effects manure applications have on runoff and sediment loss. Rainfall simulation studies were conducted to evaluate the influence of different animal manures on runoff, sediment yield, and nutrient loss using undisturbed soil monoliths placed in perforated trays. The soil was collected from fields managed under long-term no-till and a conventional till for over 15 years. Poultry litter, solid dairy manure, liquid swine manure, liquid dairy manure applied to the experimental units were compared to a no manure treatment. Generally, sediment yield and runoff amounts were reduced following manure application regardless of source (averaged across all rainfall events and manure rates), with reductions generally occurring with increasing rates of manure. When evaluating each rainfall event separately, runoff increased with increasing rates of manure for the liquid dairy manure only in the initial rainfall simulation events due to surface sealing. However, the effects of surface sealing decreased from the first rainfall simulation event to the third event. Sediment yield tended to be higher in conventional till versus no-till (only evaluated with liquid dairy manure); however, the addition of manure tended to be more effective at reducing sediment loss with conventional till. Dissolved reactive P, NH4-N, and NO3-N levels in the runoff effluent increased for all of the manure sources with increasing rates of manure. These results suggest that manure applications can reduce soil loss, especially from the conventionally-tilled treatment. Keywords: Manure, Rainfall simulation, Runoff, Soil erosion.

Soil splash erosion: An overlooked issue for sustainable rubber plantation in the tropical region of China

Soil erosion by water is known to be a major driver of land degradation. Splash erosion is the initial stage of water erosion and directly contributes to the detachment of soil particles on sloping land. Splash erosion may be exacerbated or mitigated by ongoing land use/cover change. To estimate the effects of various land use and management systems on splash erosion in the humid tropics, we measured the actual splash erosion under natural rainfall conditions in a tropical rainforest (TR), rubber monoculture (RM), and four rubber agroforestry ecosystems in Xishuangbanna, Southwestern China. The average cumulative splash mass in the RM was 48.7 times higher compared to that in the TR, indicating that the replacement of TR by RM results in severe splash erosion. In the rubber agroforestry systems, the throughfall kinetic energy and splash mass were 34–76% and 86–97% lower, respectively, than that in the RM, indicating that intercropping crops with rubber trees can effectively alleviate erosive power of throughfall and thus splash erosion. Under all land use regimes, in the plots where the litter layer was removed, splash erosion was significantly (2.0–12.1 times) higher and more spatially heterogeneous than in those with litter cover. This highlighted the key role of the forest litter layer in protecting the soil from raindrop detachment. In the study area, the actual splash erosion was strongly correlated with the conditions of precipitation (amount and intensity (I10) of rainfall) and the vegetation structure (especially the crown base height, leaf area index, and canopy cover), but weakly correlated with the soil properties. Given the importance of near-ground intercrops (height <5 m) for improving the vegetation structure, surface cover, and soil conditions, the intercropping of Camellia sinensis and Theobroma cacao with rubber trees is a promising approach for controlling splash erosion and also has benefits on the sustainable development of rubber plantation.

Comparison of Critical Shear Stress of Rill Erosion Estimated from Two Methods

Various disputes exist regarding the critical shear stress (τc) of rill erosion determined by linear regression. Alternatively, some researchers have attempted to measure critical shear stress (τo) of rill erosion by observing the start of soil particle detachment and showed promising results. However, few studies have been conducted to evaluate the reliability of the method determining τo. Thus, this study was conducted to identify the reliability of the method determining τo by comparing the values of τc and τo and their relationships with rill erodibility (Kr) and influencing factors, using 360 disturbed soil samples (standing for the freshly tilled condition) from six sampling sites along a 330 km transect in the Loess Plateau. Results indicated that the mean τc was 1.90 times greater than that of τo. No significant relationship was found between τc and Kr. An inverse changing trend between Kr and τo was observed from Yijun to Zizhou, while both Kr and τo exhibited increasing trends from Zizhou to Yulin. The τo of six sampling sites all demonstrated increasing trends with slope gradient (S), which contradicted the statement of the WEPP model that τc was independent of S. The relationships between τc and the measured soil properties were poor, whereas the τo increased exponentially with soil organic matter. Generally, τo did not present significantly better results than τc; the reliability of τo also showed some uncertainties, such as the subjective judgment of the beginning detachment of soil particles. This result has great importance for deepening our understanding of the rill erosion mechanism.

Evaluation of microstructural strength of bio-cemented sand crust using rheometry

Testing using a dynamic shear rheometer (DSR) and rheological analysis were conducted to analyse the detachment behaviour of bio-cemented soil at a microstructural level. Preventing detachment of soil particles from the ground surface is the key to mitigating the generation of fugitive dust due to wind-blown soil, a significant environmental problem in arid and semi-arid regions. Bio-cementation by way of enzyme-induced carbonate precipitation (EICP) has shown potential for mitigating soil particle detachment and the associated fugitive dust emissions. A strong correlation between particle detachment rate measured in wind tunnel tests and amplitude sweep test results using the DSR demonstrates the ability of the device to capture the detachment potential of soil bio-cemented using EICP. In addition to facilitating optimisation of bio-cementation for dust control, the rheometer tests also give an insight into the efficacy of rheometry for assessing soil microstructure strength for other geotechnical applications.

The effect of altitude on the prediction of momentum for rainfall erosivity studies in Mexico

Soil erosion is a mechanical process described by indices, such as kinetic energy or momentum of rainfall (M), which alters the protective cover of the ground surface. Optical disdrometer (PWS100) data, obtained between 2014 and 2018 at four sites across Mexico, were used to study the features of power and linear relationships between M and rainfall amounts (Acc). A comparison of the measurements showed that PWS100 usually estimated larger amounts of rainwater (PBIAS from 2 to 25%) with respect to gauges. The M-Acc relationships exhibited low dispersion, and the coefficients of the fitted expressions suggest an increase in M based on site altitude. Normalization of M based on the rainwater amount (M/Acc in N m−2 mm−1, hereafter Mmm) depended on the median volumetric diameter, D0, and speed of raindrop fall. The D0 was used as a proxy of raindrop spectrum broadness. Effect size results exhibited large values (d > 1.1) when Mmm means were compared between coastal and continental platforms. Furthermore, y-coefficients of the Mmm–D0 relationships suggested an effect of the altitude (related to the air density in the sampling site) over Mmm estimates. Based on the v(D) empirical formulas, a set of expressions were proposed to fit the Mmm observations of the four sampling sites using D0 and the corresponding atmospheric pressure or air density estimates. The results of performance measures showed that all equations predicted Mmm adequately thus suggesting that this erosivity parameter depended on both the amount of precipitation and the altitude (expressed as air density or atmospheric pressure) of the site at which the measurements were performed. These findings reinforce ideas regarding magnification of soil particle detachment via individual drops at higher altitude locations, as the force exerted is more significant with a decrease of air pressure and density.

Predicting land susceptibility to atmospheric dust emissions in central Iran by combining integrated data mining and a regional climate model

This study aims to predict land susceptibility (a term that indicates the degree of sensitivity of land to detachment of soil particles by wind) to dust emissions in Yazd province, central Iran, by combining a new integrated data mining (DM) model and the RegCM4 climatic model. The study further determines the relative importance of key factors controlling dust emissions by applying 12 individual DM models. The integrated model is based on the individual models returning Nash Sutcliffe coefficient (NSC) values > 90% for the spatial modelling of land susceptibility to dust emissions and using the area under the curve (AUC) for validation. 13 key factors controlling dust emissions are mapped including soil characteristics, climatic variables, vegetation cover, a Digital Elevation Model (DEM), geology and land use. Based on Spearman clustering analysis and multi-collinearity tests (tolerance coefficient -TC and variance inflation factor -VIF), the effective factors for dust emissions are classified into nine clusters and no multi-collinearity is found among the effective factors. DEM, NDVI (normalized difference vegetation index), geology and calcium carbonate are identified as the most important factors controlling dust emissions. Seven individual models return NSC in the range of 90–98% and are used to generate the integrated model for the final mapping of land susceptibility to dust emissions. Among 851 pixels located in the dust sources, 30% (255 pixels) and 70% (596 pixels) are randomly selected as validation and training datasets, respectively for the new integrated model. Using this model, 9%, 17%, 7% and 67% of the study area correspond to low, moderate, high and very high susceptibility classes, while the validation results in AUC = 99.3%. Simulations with the RegCM4 model reveal high consistency regarding the spatial distribution of the most susceptible areas and dust emissions. Overall, combining DM approaches and physical models is useful in aeolian geomorphology studies.

Effect of storm pattern on soil erosion in damaged rangeland; field rainfall simulation approach

Raindrop size, rainfall intensity and runoff discharge affect the detachment and transportation of soil particles. Among these three factors, the rainfall intensity seems to be more important because it can change other two factors. Storm patterns can be determined by changing the rainfall intensity during the storm. Therefore, the objective of this research is to test the influence of storm pattern on runoff, soil erosion and sediment concentration on a rangeland soil slope under field rainfall simulation. Four storm rainfall intensity patterns were selected for examining the effects of variations in storm event characteristics on soil erosion processes. The selected storm patterns were: I (45, 55 and 70 mm h−1); II (45, 70 and 55 mm h−1); III: (70, 55 and 45 mm h−1); and IV (55, 45 and 70 mm h−1). The last pattern is a new one instead of the uniform pattern which has been sufficiently studied in previous researches. The experiments were conducted in field plots (in Kojour watershed, Mazandaran Province, Iran) with an area of one square meter and an constant slope gradient of 18%, surrounded by galvanised sheets. Following the non-uniform prioritization of the storm patterns for the studied variables, time to runoff (I>II>IV>III), runoff volume (III>IV>II>I), sediment concentration (IV>III>I>II) and soil erosion (III>IV>II>I)), it can be generally inferred that each pattern has specific effect on soil erosion processes during a storm. The results of the general linear model (GLM) test indicated that the effects of storm pattern on time to runoff, total runoff volume, runoff coefficient and soil erosion were significant at a level of 99%. The Duncan test showed that the storm patterns can be divided into three groups of III, IV; II; I (for time to runoff), I, II; IV, III (for runoff coefficient), and I; II; IV, III (for runoff volume and soil erosion).

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

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

Capability of high-resolution RGB imagery to accurately document residue in row-crop fields

Sustaining agriculture and civilizations requires protecting topsoil from erosion. Residue on the soil surface dissipates energy in raindrops, runoff, and wind, reducing detachment and transport of soil particles. Our objective was to contrast transect residue estimates based on (1) in-field evaluation of 100 evenly spaced points along a 15 m tape; (2) evaluation of imagery of the same tapes obtained at two ground sampling distances: 0.014 and 0.06 cm pixel^–1; and (3) a 100 point grid analysis of 50 contiguous 0.3 × 0.2 m images (0.014 cm pixel^–1) adjacent to the tape. Data were collected from May through early July of 2018 in row-crop fields in four Missouri counties: Audrain, Boone, Callaway, and Cooper. We used data from 60 15.2 m transects in 20 fields. Residue estimates based on field readings of the transect tape ranged from 6% to 99%. Reading images of tapes resulted in a mean decrease of 2.5 percentage points of residue. The bullseye grid point method documented tremendous variability along the transect (mean transect sd = 12.4) and a substantially lower estimate of residue cover compared to field tape readings (mean difference –10.3 percentage points). Consistent with a systematic bias to overestimate residue with the tape transect method, the difference increased with increasing residue for residue &lt;50%, was more pronounced with soybean (<i>Glycine max</i> [L.] Merr.) than corn (<i>Zea mays</i> L.), and the difference could be eliminated by rereading tapes with scrupulous attention to the details of transect methodology. Image-based methods have the potential to improve the accuracy of residue estimates by facilitating methods less prone to reader bias such as the bullseye grid approach. Additionally, to improve accuracy, image-based protocols should be integrated into training and quality control assurance protocols of USDA Natural Resources Conservation Service (NRCS) assessments of residue using transect methods.

Effects of Slope Gradient on Runoff and Sediment Yield on Machine-Induced Compacted Soil in Temperate Forests

There has been a severely negative impact on soil water resources in temperate forests caused by the introduction of the type of heavy machinery in the forestry sector used for forest harvesting operations. These soil disturbances increase the raindrop impact on bare mineral soil, decrease infiltration rate, detach soil particles, and enhance surface flow. According to several studies, the role of slope gradient influence on runoff and soil loss continues to be an issue, and therefore more study is needed in both laboratory simulations and field experiments. It is important to define and understand what the impacts of slope gradient in harvesting practices are, so as to develop guidelines for forest managers. More knowledge on the key factors that cause surface runoff and soil loss is important in order to limit any negative results from timber harvesting operations performed on hilly terrains in mountainous forests. A field setting using a runoff plot 2 m2 in size was installed to individualize the effects of different levels of slope gradient (i.e., 5, 10, 15, 20, 25, 30, 35, and 40%) on the surface runoff, runoff coefficient, and sediment yield on the skid trails under natural rainfall conditions. Runoff and sediment yield were measured with 46 rainfall events which occurred during the first year after machine traffic from 17 July 2015 to 11 July 2016 under natural conditions. According to Pearson correlation, runoff (r = 0.51), runoff coefficient (r = 0.55), and sediment yield (r = 0.51) were significantly correlated with slope gradient. Results show that runoff increased from 2.45 to 6.43 mm as slope gradient increased from 5 to 25%, reaching to the critical point of 25% for slope. Also, further increasing the slope gradient from 25 to 40% led to a gradual decrease of the runoff from 6.43 to 4.62 mm. Runoff coefficient was significantly higher under the plot with a slope gradient of 25% by 0.265, whereas runoff coefficient was lowest under the plot with a slope gradient of 5%. Results show that sediment yield increased by increasing the slope gradient of plot ranging 5% to 30%, reaching to the critical point of 30%, and then decreased as the slope gradient increased from 35% to 40%. Runoff plot with a slope gradient of 30% (4.08 g m−2) ≈ plot length of 25% (3.91 g m−2) had a significantly higher sediment yield, whereas sediment yield was lowest under the plot with a slope gradient of 5% and 10%. A regression analysis of rainfall and runoff showed that runoff responses to rainfall for plots with different slope gradients were linearly and significantly increased. According to the current results, log skidding operations should be planned in the skid trails with a slope gradient lower than the 25 to 30% to suppress the negative effect of skidding operations on runoff and sediment yield.