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Zusammenfassung Die Wirkung unterschiedlich intensiver Regenereignisse auf Splash-Erosion ist noch nicht genau bekannt. Um diese zu untersuchen, wurde sandiger Lehm in einem Laborversuch durch einen Starkregensimulator mit zunehmender, abnehmender oder konstanter Regenintensität beregnet. Alle Intensitätsabfolgen wiesen im Mittel eine Regenintensität von 24,7 mm h−1 auf und bestanden aus drei Intensitätsstufen mit einer Beregnungsdauer von je 20 min. Der ausschließlich durch Splash-Erosion abgetragene Boden wurde nach jeder Beregnungsphase gesammelt. Die Ergebnisse zeigen, dass Regenereignisse mit hoher Intensität am Anfang zu 32 % mehr Splash-Erosion führen als jene mit maximaler Intensität am Ende. Die kumulativ wirkende kinetische Energie der Regentropfen, verstärkt durch einen dünnen Wasserfilm auf den Proben, führt dazu, dass die Splash-Erosion am Ende einer Simulation stärker wirkt als zu Beginn. Aus den Untersuchungsergebnissen kann zudem durch Extrapolation der Regressionsgeraden eine minimale Regenintensität zwischen 10 mm h−1 und 15 mm h−1 zur Erzeugung von Splash-Erosion angenommen werden.

The effect of long-term (about 25 years) use of different farming practices on a set of soil properties and development of erosion in Lower Austria has been studied. Three tillage systems—zero, or no-till (NT); minimum, or conservation (CS); and conventional (CV)—are compared. The comparison demonstrates that the properties of Typic Argiudols (Luvic Phaeozems), formed on steep (13.2%) slopes, change depending on both the tillage type and the position on the slope. Unlike the CV tillage, the soil-saving technologies provide higher contents of nutrients, silt, and clay, as well as better water permeability and water stability of soil aggregates. Despite an almost doubled amount of lumpy fractions (>10 mm), the soil aggregate states after NT and CS tillage are estimated as “excellent”. Independently of the tillage system, all agrochemical, electrophysical, and hydrophysical parameters (except for pH and bulk density) increase downward the slope, which is associated with erosion, namely, the washout of suspended sediments by water flows. The Corg content in the soil tightly correlates with the water stability of soil aggregates (r = 0.91), the concentration of soluble humic substances and fine solids (SAK; r = 0.76), and electroconductivity (r = 0.75). An anti-erosion efficiency of tillage practice increases in the series CV–CS–NT. The NT or CS systems are recommended for the erosion-prone slopes of Alpine foothills.

This article outlines the major scientific objectives of the SHui project that seeks to optimize soil and water use in agricultural systems in the EU and China, by considering major current scientific challenges in this area. SHui (for Soil Hydrology research platform underpinning innovation to manage water scarcity in European and Chinese cropping systems) is large cooperative project that aims to provide significant advances through transdisciplinary research at multiple scales (plot, field, catchment and region). This paper explains our research platform of long-term experiments established at plot scale, approaches taken to integrate crop and hydrological models at field scale; coupled crop models and satellite-based observations at regional scales; decision support systems for specific farming situations; and the integration of these technologies to provide policy recommendations through socio-economic analysis of the impact of soil and water saving technologies. It also outlines the training of stakeholders to develop a basic common curriculum despite the subject being distributed across different disciplines and professions. As such, this article provides a review of major challenges for improving soil and water use in EU and China as well as information about the potential to access information made available by SHui, and to allow others to engage with the project., This work has been supported by Project SHui which is co-funded by the European Union Project GA 773903 and the Chinese MOST. This work has been supported by P12-AGR-0931 (Andalusian Government), RTA2014-00063- C04-03 (Spanish government), SHui (European Commission Grant Agreement number: 773903) and EU‒FEDER funds

In recent years, Compound Specific Stable Isotope (CSSI) techniques have enabled promising new tracers to track land-use-specific sediment sources. However, empirical data exploring the technique, particularly under controlled conditions, is still scarce. Hence, the main goal of this study is to explore the suitability of CSSI to identify sediment sources under different land use in the small agricultural site of Mistelbach (8.7 ha) located in Austria. In a previous study, the authors quantified, with a 137 Cs-based reconnaissance approach, a sedimentation magnitude of 4 mm year − 1 in the deposition zone at the outlet of that study site. To obtain detailed information on the sediment provenance, CSSI techniques based on the measurement of δ 13 C signatures of natural fatty acids (FAs), were used. A cost effective sampling approach involving composite sampling, identified potential sediment source materials from the four main agricultural fields. Two long-chain FAs (i.e. C22:0 = behenic acid; C24:0 = lignoceric acid) as well as bulk δ 13 C allowed the best statistical discrimination for apportioning the origin of the sediments. Four mixing models (i.e. IsoSource, SIAR, MixSIAR and SIMMR) applied to the data generated similar results. IsoSource performed as well as the other Bayesian models tested. The main grazed waterway of the basin, identified as one of the four sources of the sediment, was evaluated to have contributed 55.1 ± 5% (IsoSource), 53.9 ± 2.7% (SIAR), 53.9 ± 2.7% (MixSIAR) and 54.0 ± 2.7% (SIMMR) to the sediment. The estimated contributions of the sources to the sediment are consistent with the land use information and the distance of the sources to the outlet. More than 80% of the sediment deposited at the basin exit originates from the two sources which had maize cultivation, one of the more erosive crops, in particular at the beginning of the growing season. This study emphasizes that CSSI and 137 Cs techniques are complementary for establishing land sediment redistribution. Their combined use could provide key decision support knowledge for optimised decision-making of land managers to ensure the sustainability of agro-ecosystem management.

Under conditions of climate change, the severity and probability of storm events and droughts are expected to increase, this may affect the partitioning into surface and subsurface runoff. However, there is still a debate on how such extreme weather conditions affect the leaching of soil organic carbon. The aim of this study was to ascertain the impact of rainfall intensity (63 vs 79 mm h−1) and antecedent soil moisture (Matric potential: −10 hPa vs −450 hPa) on flow partitioning in the transportation (fluxes and timing) of dissolved (DOC) and particulate organic carbon (POC). Rainfall simulation experiments using undisturbed soil monoliths (1 m × 0.5 m × 0.3 m) allowed to monitor the transport of water, sediments, DOC, and POC via surface and shallow subsurface runoff. In addition, the composition of the leached organic matter was analysed using photometric and fluorometric methods. Most of the organic carbon was transported as POC via surface runoff. In the surface runoff, the influence of antecedent soil moisture on POC loss was larger than rainfall intensity, while rainfall intensity had a greater influence on DOC losses. Under initially unsaturated conditions, surface sealing reduced the infiltration rate, thus fuelling the total surface runoff, which, in turn, enhanced the transported total sediment and POC load of the surface runoff. While POC dominated surface runoff, DOC played a crucial role in the subsurface runoff with higher DOC concentrations under unsaturated conditions. In contrast to other treatments, DOC exported from unsaturated soils rained with high intensity had a unique composition with the highest proportion of humic-like peaks (A, M, C), protein-like peaks (T) and components (C4), suggesting a concentrating effect on DOC at those soils. Altogether, this research acquires new insights into how flow partitioning under extreme weather conditions affects organic carbon losses and which transport mechanism might pose a risk for aquatic systems.

SummaryCover cropping is a key agro-environmental measure in Europe. Cover crops may reduce N2O emissions by reducing soil nitrate content, while easily decomposable residues can enhance greenhouse gas losses. In a field study, emissions from the cover cropped fields compared to the fallow at two climatically different sites (semi-arid vs. humid) in Austria were measured with closed chambers and different driving factors were studied. The height of post-cover crop emissions was compared to gaseous losses during the management operations in the subsequent main crop maize. N2O and CO2emissions following the cover crops were low even at high emission moments compared to the losses induced by the main crop management operations. Highest risk of N2O losses was from mustards due to low C/N ratio and possibly as a consequence of glucosinolate decomposition. CO2emissions in the cover cropped plots were generally higher compared to the fallow, indicating an enhanced soil microbiological activity. Dissolved organic carbon was found as a sensitive indicator related to the greenhouse gas emissions. We concluded that the environmental benefits from cover cropping are not achieved at the cost of an enhanced greenhouse gas emission and that pure stands of late sown brassica cover crops should be avoided to prevent any risk of increased N2O losses.

Soil erosion by water is one of the most severe soil degradation processes. Splash erosion is the initial stage of soil erosion by water, resulting from the destructive force of rain drops acting on soil surface aggregates. Apart from rainfall properties, constant soil physical properties (texture and soil organic matter) are crucial in understanding the splash erosion. However, there is lack of information about the effect of variable soil properties such as soil initial water content and surface condition (seal formation) on splash erosion. The objective of the present study was to determine how initial water content and surface condition affected soil splash erosion under simulated rainfall. The changes in soil surface condition were characterized by hydraulic variability (saturated hydraulic conductivity) due to surface seal formation. Slit loam and loamy sand soil textures were used in the experiment. The soil samples were collected from the top layer; air dried, and filled into modified Morgan splash cups for splash erosion measurements. Rainfall was created in the laboratory using two types of rainfall simulators covering intensity range from 28 to 54 mm h−1 and from 35 to 81 mm h−1. The soil samples were exposed to three consecutive rainfall simulations with different time intervals between simulations and different initial water content and surface conditions (air-dried, wet-sealed, and dry-crusted). Wet-sealed soil samples had up to 70% lower splash erosion rate compared to air-dried samples, due to surface ponding followed by seal formation. A significant decrease in soil saturated hydraulic conductivity indicated the formation of surface seal for silt loam soils. A non-significant decrease in saturated hydraulic conductivity for loamy sand soil was attributed to earlier formation of stable seals. Two different rainfall simulators produced different amount of splash erosion rates; however, the splash erosion development for increasing rainfall intensity was almost equal considering same initial surface condition. These results provide insight into dynamic changes of individual soil parameters affected by rainfall, and could find wider application for more complex soil erosion prediction models.

A soil map of a watershed provides a wealth of knowledge and can be vital for implementing site-specific soil managements. Hence, watershed-based soil assessment was conducted to select an optimum spatial interpolation method, while aiming for sustainable soil managements. Intensive soil sampling was undertaken to investigate the performance of ordinary kriging (OK), inverse distance weighting (IDW), and radial basis functions (RBF) for predicting the spatial distribution of soil texture, pH, soil organic carbon (SOC), and available phosphorus (AP). The 72 ha study area was divided into a 100 x 100 m grid and approximately at the center of each grid, topsoil samples (roughly from 10-25cm depth) were collected from over 75 locations across the entire watershed. The exponential and Gaussian models were best fitted in the semivariogram of measured soil. The performance of each interpolation method was assessed quantitatively in terms of Nash-Sutcliffe efficiency (E), coefficient of determination (R2), and index of agreement (d). The interpolated maps generated based on the highest value of E displayed OK was best performed for SOC and sand. RBF was most suitable for mapping of AP and clay, while IDW gave better results when applied to pH. The highest value of R2, E, and d (0.51, 0.51, and 0.83, respectively) resulted from the spatial interpolation of AP. Overall, the cross-validation statistics for each interpolation method showed there was no single method that significantly outperformed the others. Therefore, one of the interpolation methods could be applied for surface map generation in future studies of similar regions.

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

An experimental laboratory setup was developed and evaluated in order to investigate detachment of soil particles by raindrop splash impact. The soil under investigation was a silty loam Cambisol, which is typical for agricultural fields in Central Europe. The setup consisted of a rainfall simulator and soil samples packed into splash cups (a plastic cylinder with a surface area of 78.5 cm2) positioned in the center of sediment collectors with an outer diameter of 45 cm. A laboratory rainfall simulator was used to simulate rainfall with a prescribed intensity and kinetic energy. Photographs of the soil&rsquo, s surface before and after the experiments were taken to create digital models of relief and to calculate changes in surface roughness and the rate of soil compaction. The corresponding amount of splashed soil ranged between 10 and 1500 g m&minus, 2 h&minus, 1. We observed a linear relationship between the rainfall kinetic energy and the amount of the detached soil particles. The threshold kinetic energy necessary to initiate the detachment process was 354 J m&minus, 1. No significant relationship between rainfall kinetic energy and splashed sediment particle-size distribution was observed. The splash erosion process exhibited high variability within each repetition, suggesting a sensitivity of the process to the actual soil surface microtopography.

Sorghum is cultivated on Vertisols in the Ethiopian Highlands. An experiment was conducted in the Gumara-Maksegnit watershed in 2013 and 2014 to assess the effect of rate and timing of nitrogen fertilizer application on the possibility to shorten the maturity period and to improve the productivity of sorghum. The experiment was laid out as Randomized Complete Block Design with three replications. Treatments were nitrogen doses between 0 and 87 kg N ha−1 as urea applied at planting, at knee-height stage or in split doses at both stages. Results showed that application of 23, 41, 64 and 87 kg ha−1 N gave a yield increase of 40, 53, 62 and 69% over the control (0 kg N ha−1), respectively. In addition, split application of 41 kg ha−1, 64 kg ha−1 and 87 kg ha−1 of nitrogen fertilizer, half at planting and half at knee height stage, gave 19%, 15% and 18% increase in sorghum grain yield over a single dose application, respectively. Applying 87 kg ha−1 nitrogen fertilizer with split application half at pl...

Long-term contribution of soil loss events depends on both – the magnitude and the occurrence probability – but oftentimes, a limited observation period impedes the assessment of the temporal soil loss distribution. In this research, the event-based soil loss from two plot locations in Lower Austria (Mistelbach and Pixendorf) was linked with the event-based rainfall erosivity (EI30) to assess the temporal soil loss distribution using long-term rainfall data from two meteorological stations in Lower Austria. For both plot locations, a risk analysis was performed to (i) assess the long-term average annual soil loss and to (ii) evaluate the contribution of incremental erosion events according to different event return periods. The risk analysis showed that in Pixendorf the events 20 years return period is progressively reduced through the low occurrence probability. On the contrary, in Mistelbach the soil loss magnitudes of the extreme events overcome the effect of the low occurrence probability, and consequently, the contribution of the extreme events (>20 years return period) is dominant. The spatially variable contribution of the erosion events reveals the need for spatially customized soil conservation strategies. A risk analytical approach may help to allocate the driving events and thus to define proper event design magnitudes for local soil conservation planning. Copyright © 2014 John Wiley & Sons, Ltd.

Rainfall erosivity is the main driver for soil detachment and sediment transport, and represents the climatic factor most influencing the risk of soil erosion at a given site. Our objectives were to explore 15 min rainfall breakpoint data from 51 rain gauges in the northeastern part of Austria to (1) calculate rainfall erosivity values for this region, and (2) analyze statistically whether there exists a temporal evolution in rainfall erosivity. Rainfall data (May to October) covered between nine and 53 years. Rain gauges were located at elevations between 150 and 970 m a.s.l., and mean rainfall depths were 514 (±169) mm and 652 (±156) mm for Lower Austria (LA) and Upper Austria (UA), respectively. The calculated rainfall erosivity factor (R factor) ranged from 273 to 1599 with an average of 884 MJ mm ha -1 h -1 in LA and from 637 and 1697 with an average of 982 MJ mm ha -1 h -1 in UA. Rainfall depths and erosivities showed greater variability in LA than in UA, which can be attributed to the different ranges of topographic regions in LA. For both states, relationships could be established between average rainfall from May to October and the R factor, with correlation coefficients between 0.77 (LA) and 0.85 (UA). Overall, for the same rainfall amounts, rainfall erosivity was lower in UA than in LA. In LA, time series analyses showed a significant temporal increasing trend in rainfall intensity, rainfall erosivity, and storm number and intensity. These positive trends at 90% of the stations with data sets of >25 years indicate possible future R factor increases and increasing erosion risk. In UA, only 25% of the rain gauges showed a significant positive trend in rainfall erosivity, and 40% showed a significant increase in rainfall intensity. Changes in rainfall patterns were more distinct in eastern Austria than in northern Austria, thus impacting runoff, infiltration, and erosion processes in this area in the future.

I n Ethiopia, one of the poorest countries in the world, soil erosion by water contributes significantly to food insecurity of rural households and represents a real threat to sustainability of the existing subsistence agriculture (Hurni 1993; Sutcliffe 1993; Sonneveld 2002). Ethiopia has a total surface area of 111.8 million ha (276.3 million ac); 24% of the land area, and 45% of the area used for agriculture, is significantly affected by erosion. Studies by Fikru (1990) and Sertsu (2000) estimate an annual total soil loss of 2 billion m3 (71 billion ft3), which corresponds to an overall mean annual soil loss of 18 t ha−1 (8.0 tn ac−1). Other studies suggest erosion rates ranging from 16 to 300 t ha−1 y−1 (7.1 to 133.8 tn ac−1 yr−1) (Hurni 1993; Hawando 1989, 1995). In the Ethiopian highlands, annual soil loss reaches rates up to 200 to 300 t ha−1 (89.2 to 133.8 tn ac−1), while global soil loss can reach up to 23,400 million t y−1 (25,787 million tn yr−1) (FAO 1986). Compared to rill and interrill erosion rates measured in Europe (Cerdan et al. 2010), these soil losses are much higher. Occurrence of wide and deep gullies is a common observation…

Understanding the spatial pattern of erosion in inter-rill and rill areas can be useful in locating sources of sediment and in determining down-slope sediment delivery. However, spatial information about erosion processes in the inter-rill and rill areas under field conditions is often limited owing to the non-availability of a detailed microtopography. This paper aims to present a method for the survey of microtopographic soil surface changes caused by erosion and to investigate the development of sediment transport and rill erosion in the inter-rill and rill areas for a given rainfall event. The approach is based on the application of close range digital photogrammetry to produce differences of digital elevation models (DEMs), automatically measured and generated but with manual 3D point editing. Quality analysis of the DEM measurements has shown that erosion and deposition can be detected with a relative error of ±2·8 to ±5·3 mm. The minimum average sediment yield from plots with an area of 53 m2after the occurrence of 46 to 70 mm of erosive rainfall was estimated to be 1·24 to 3·5 kg m−2. The spatial pattern of erosion and deposition on inter-rill and rill areas has proved the relative efficiency of rills to transport sediments from inter-rill areas with a sediment delivery ratio greater than one. Thus at erosive rainfall events, the transport capacity of the rill flow was not a limiting condition. The rill network was controlled by abrupt change in surface microtopography where rough surfaces produced many smaller rills but fewer contributing rills than relatively smooth surfaces. Tillage-induced surface roughness, the presence of stones and sparse vegetation, and the borders of individual plots were found to present challenges to the photogrammetric techniques, and to introduce errors which inhibit fully automatic DEM generation. The precision of the DEMs was constrained by the precision of ground control points (GCPs), camera lens distortion towards format edges and DEM extraction parameters. Despite this limitation, however, the application of digital photogrammetry enabled the measurement of high-frequency microtopographic surfaces and characterisation of the spatial distribution of erosion and deposition and of rill erosion development during highly erosive rainfall events.

SUMMARYThe goal of the present study was to assess the impact of selected soil protection measures on soil erosion and retention of rainwater in a 1·14 km2 watershed used for agriculture in the north-east of Austria. Watershed conditions under conventional tillage (CT), no-till (NT) and under grassland use were simulated using the Water Erosion Prediction Project (WEPP) soil erosion model. The period 1961–90 was used as a reference and results were compared to future Intergovernmental Panel on Climate Change (IPCC) scenarios A1B and A2 (2040–60).The simulations for the NT and grassland options suggested runoff would decrease by 38 and 75%, respectively, under the current climatic conditions. The simulation results suggest that, under future climate scenarios, the effectiveness of the selected soil conservation measures with respect to runoff will be similar, or decreased by 16–53%.The actual average net soil losses in the watershed varied from 2·57 t/ha/yr for conventional soil management systems to 0.01 t/ha/yr for grassland. This corresponds to a maximum average annual loss of about 0·2 mm, which is considered to be the average annual soil formation rate and therefore an acceptable soil loss. The current soil/land use does not exceed this limit, with most of the erosion occurring during spring time. Under future climate scenarios, the simulations suggested that CT would either decrease soil erosion by up to 55% or increase it by up to 56%. Under these conditions, the acceptable limits will partly be exceeded. The simulations of NT suggested this would reduce annual soil loss rates (compared to CT) to 0·2 and 1·4 t/ha, i.e. about the same or slightly higher than for NT under actual conditions. The simulation of conversion to grassland suggested soil erosion was almost completely prevented.The selected soil conservation methods maintain their protective effect on soil resources, independent of the climate scenario. Therefore, with small adaptations, they can also be recommended as sustainable soil/land management systems under future climatic conditions.However, based on the available climate scenarios, climate-induced changes in the frequency and intensity of heavy rainstorms were only considered in a limited way in the present work. As the general future trend indicates a strong increase of rainstorms with high intensity during summer months, the results of the present study may be too optimistic.

To control soil erosion and associated land degradation worldwide there is a need to assess the impact of major land use and the effectiveness of specific soil conservation technologies using various approaches. This study was conducted in an agricultural field at Mistelbach, Austria to assess the magnitude of deposition rates using Fallout RadioNuclides ‘FRNs’ ( 137 Cs and 210 Pb ex ) and the mid-term (13 years) erosion rates using conventional runoff plot measurements in a small agricultural watershed under conventional and conservation tillage/cropping practices. Long-term erosion measurements (1994–2006) from runoff plots located in the upper part of an agricultural field just up-slope from a deposition area reached 29.4 t ha − 1 yr − 1 from the conventional tilled plot, 4.2 t ha − 1 yr − 1 from the conservation tillage plot and 2.7 t ha − 1 yr − 1 from the direct seeding treatment. Soil losses were reduced significantly by a factor of 10 using no tillage, direct seeding treatment. Using 137 Cs data that integrate the 1954–2007 period, the sedimentation rates down slope of the field containing the runoff plots were estimated to be 26.1 t − 1 ha − 1 yr − 1 using the 137 Cs depth distribution profile and at 20.3 t − 1 ha − 1 yr − 1 using the Mass Balance Model 2 (MBM 2). The erosion rates under conventional tillage are in agreement with the sedimentation rates estimated down slope of the field by the 137 Cs depth distribution profile and MBM 2. In the lowest part of the watershed sedimentation rates of up to 50.5 t − 1 ha − 1 yr − 1 were estimated through the 137 Cs depth distribution profile. These rates were greater than the average erosion rates measured by the erosion plots because this area is more representative of sedimentation processes occurring in the study area due to its topographical position and the basin geomorphology. The 210 Pb data obtained did not fulfil the requirements for the successful application of the methodology under the experimental conditions. This study demonstrates the complementarities of both methodologies ( 137 Cs and runoff plots) to assessing erosion and sedimentation processes in an agricultural landscape.

Development of improved soil erosion and sediment yield prediction technology is required to provide catchment stakeholders with the tools they need to evaluate the impact of various management strategies on soil loss and sediment yield in order to plan for the optimal use of the land. In this paper, a newly developed approach is presented to predict the sources of sediment reaching the stream network within Masinga, a large-scale rural catchment in Kenya. The study applies the revised universal soil loss equation (RUSLE) and a developed hillslope sediment delivery distributed (HSDD) model embedded in a geographical information system (GIS). The HSDD model estimates the sediment delivery ratio (SDR) on a cell-by-cell basis using the concept of runoff travel time as a function of catchment characteristics. The model performance was verified by comparing predicted and measured plot runoff and sediment yield. The results show a fairly good relationship between predicted and measured sediment yield (R2=0·82). The predicted results show that the developed modelling approach can be used as a major tool to estimate spatial soil erosion and sediment yield at a catchment scale. Copyright © 2006 John Wiley & Sons, Ltd.

Rainfall and its kinetic energy, expressed by rainfall erosivity, drives soil erosion processes by water. One of the most commonly used erosivity parameters is the rainfall-runoff erosivity factor R of the Revised Universal Soil Loss Equation. The goal of this study was to investigate for the first time the spatial distribution of annual rainfall erosivity in New Zealand. High-resolution data from 35 weather stations were used to calculate the R-factors. Based on these results, region-specific equations were developed and were applied by using long-term precipitation records from 597 stations. The values were interpolated with a geographic information system to generate a map showing spatial variations of rainfall erosivity. Annual R-values vary across both islands by a factor of 30, from 16 000 MJ mm ha–1 h–1 in the Southern Alps. These large differences are related to climatic and topographic features. Nevertheless, the data show a high correlation to the precipitation. In most parts of New Zealand, highest erosivity values occurred in December and January, whereas the lowest values were observed in August.

Project Co-ordinators: Dr. Jose Alfonso Gómez Calero (Instituto de Agricultura Sostenible (IAS-CISC), Dr. Weifeng Xu (Fujian Agriculture and Forest University, FAFU)., Knowledge of crop water requirements and the effects of management practices on the amounts of water used for crop transpiration and that lost through soil evaporation is essential for efficient agricultural water management. Therefore, this study investigated the temporal evolution of weekly evaporation and transpiration rates under varying soil water conditions in a conventionally managed soybean field by partitioning evapotranspiration based on a water and δ18O-stable isotope mass balance. The estimated rates were considered in combination with vertical soil water distribution, atmospheric demand (based on crop evapotranspiration), actual evapotranspiration, and the plant development stage. This allowed for the weekly rates to be compared to the current conditions resulting from dry periods, rain or irrigation events, and the extent of the canopy. The range of weekly transpiration/evapotranspiration, from blossom to maturation, was between 0.60 (±0.11) and 0.82 (±0.10). Within this range, transpiration/evapotranspiration shifted depending on the vertical soil water distribution and meteorological conditions. During dry soil surface periods, evaporation dropped to almost zero, whereas a wet surface layer substantially increased evaporation/evapotranspiration, even under a closed canopy. Under given conditions, the application of a few intense irrigations before the drying of the soil surface is recommended., This work was supported by the European Union’s Horizon 2020 Research and Innovation Programme (Grant number 773903)(2018-2022).

Soil erosion in the northwestern Amhara region, Ethiopia has been a subject of anxiety, resulting in a major environmental threat to the sustainability and productive capacity of agricultural areas. This study tried to estimate soil erodibility factor (K-factor) using Universal Soil Loss Equation (USLE) nomograph, and evaluate the spatial distribution of the predicted K-factor in a mountainous agricultural watershed. To investigate the K-factor, the 54 km2 study watershed was divided into a 500 m by 500 m square grid and approximately at the center of each grid, topsoil samples (roughly 10 to 20 cm depth) were collected over 234 locations. Sand, silt, clay and organic matter (OM) percentage were analyzed, while soil permeability and structure class codes were obtained using the United States Department of Agriculture (USDA) document. The resulting coefficient of variation (CV) of the estimated K-factor was 0.31, suggesting a moderate variability. Meanwhile, the value of nugget to sill ratio of K-factor was 0.32, which categorized as moderate spatial autocorrelation. Prediction accuracy and model fitting effect of the Gaussian semivariogram approach was best, suggesting that the Gaussian ordinary Kriging model was more appropriate for predicting K-factor. The resulting value of the mean error (ME) was 0 and the mean squared deviation ratio (MSDR) was nearly 1, which indicates the Gaussian model was unbiased and reproduced the experimental variance sufficiently. The values of K-factor were smaller (0.0217 to 0.0188) in the northern part and gradually increased (0.0273 to 0.033 Mg h MJ−1 mm−1) towards the central and south of the study watershed.