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The splash phenomenon is one of the stages of water erosion, i.e. a process that causes soil degradation. The crux of splash is the detachment and displacement of soil particles due to the impact of raindrops. Another important aspect of the phenomenon is that a deformation called a crater is formed at the point of the impact. Research on craters helps to expand the knowledge of the splash phenomenon and may contribute to understanding its relationship with successive stages of water erosion. The quantities used to describe the deformation include static dimensions (e.g. depth or diameter of the crater) and dynamic quantities to describe the course of the deformation (e.g. the time for the crater to reach a stable shape). The small size of the craters and the high dynamics of their formation induce the use of accurate and advanced measurement methods.The aim of the work is to present selected non-contact methods for measuring craters formed on soil after a drop impact.The study was focused on photography, high-speed imaging, 3D surface modelling, and computed tomography (CT). The discussion of the methods includes a brief description of the measurements, the range of quantities that can be determined with the methods, and indication of their strengths and weaknesses. Knowledge of these issues allows making an informed choice of measurement methods when planning new experiments or projects, which may significantly affect the results that can be obtained. ReferencesMazur, R.; Ryżak, M.; Sochan, A.; Beczek, M.; Polakowski, C.; Bieganowski, A. Soil Deformation after Water Drop Impact—A Review of the Measurement Methods. Sensors 2023, 23, 121. https://doi.org/10.3390/s23010121This work was partially supported by the National Science Centre, Poland within the framework of project no. 2020/37/N/ST10/03363.

Summary. In this study, we presented the experience of two high-speed laser diffractometry methods for measuring particle size distribution (PSD) and microaggregate stability (MiAS%) of soils, which parameters have a significant influence on the soil water management properties. PSD results obtained with sieve-pipette and laser diffractometry method were compared on a continental (LUCAS), a national (HunSSD) and a regional (TOKAJ) database. We found significant differences between the results of the two methods at all three scales. When the clay/silt boundary was modified to 7 µm for the LDM, significantly better results were obtained. The LDM was also suitable for the determination of the MiAS% of soils, which was influenced mainly by organic matter, pH and exchangeable Na+ content of soils. Összefoglalás. Tanulmányunkban a lézerdiffraktométerrel végzett talajfizikai mérések tapasztalatait és alkalmazási lehetőségeit vizsgáltuk a vízgazdálkodási kutatásokban. A talajok mechanikai összetétele, azaz az elemi talajrészecskék méret szerinti százalékos eloszlása, az egyik legfontosabb talajfizikai paraméter, mely számos egyéb tulajdonságot, így a talajok szerkezetét, vízgazdálkodását befolyásolja. Meghatározása több módon történhet: pl. a hagyományos szitás-pipettás ülepítéses módszerrel (SZPM), vagy az egyik legmodernebbnek számító lézerdiffraktométeres (LDM) eljárással. Kutatásunk során e kétféle módszerrel kapott mechanikai összetétel eredményeket három nagyobb adatbázison hasonlítottuk össze: egy kontinentális (LUCAS), egy hazai (HunSSD) és egy regionális (TOKAJ) adatállományon. Azt tapasztaltuk mindhárom adatbázis esetében, hogy a lézerdiffrakciós vizsgálatok az agyagtartalmat alulbecslik a pipettás módszerrel kapott eredményekhez képest, míg a portartalmat felülbecslik (az adatsorok eltérését jellemző RMSE értékek az agyagfrakciókra: 16,30; 19,29 és 24,97; a porfrakciókra: 15,68; 19,82 és 26,95. A homoktartalmak közt lényegesen kisebb eltéréseket tapasztaltunk (RMSE: 7,26; 9,25 és 5,25 a három adatbázis esetében). Ha azonban az LDM vizsgálati eredményeknél módosítottuk az agyag és a por frakció mérethatárát 2 µm-ről 7 µm-re, szignifikánsan jobb eredményeket kaptunk az összehasonlítás során mind az agyagtartalom (RMSE: 8,99; 6,77 és 6,54), mind a portartalom esetében (RMSE: 8,87; 7,46 és 5,74). A különböző módszerekkel mért és számított PSD eredményeket textúra háromszög diagramokon is ábrázoltunk. A lézerdiffrakciós eljárás alkalmas a talajok mikroaggregátum stabilitásának (MiAS%) meghatározására is, melyet a HunSSD hazai adatbázis talajain mutattunk be. Megállapítottuk, hogy erős, szignifikánsan pozitív kapcsolat van a MiAS% és a talaj szervesanyag-tartalma között; és erős, szignifikánsan negatív kapcsolat a mikroaggregátumok stabilitása és a pH, a mésztartalom, a sótartalom és a kicserélhető nátriumtartalom között. A tanulmányban vizsgált talajfizikai tulajdonságok szorosan összefüggnek a talajok vízgazdálkodási tulajdonságaival. A talajok vízgazdálkodási tulajdonságait jellemző hidrofizikai paraméterek (víztartó képesség, vízvezető képesség) becslése általában a mechanikai összetétel adatok felhasználásával történik. A becslési módszerek (pedotranszfer függvények) pontosítására egyre gyakrabban figyelembe veszik a talaj szerkezeti tulajdonságait is. Amennyiben gyorsan és megbízhatóan tudjuk mérni a talajok mechanikai összetételét és aggregátum-stabilitását lézerdiffrakciós módszerekkel, akkor a hidrofizikai tulajdonságok becsléséhez szükséges input adatokat is gyorsan, nagyobb számban tudjuk előállítani, így a talajok vízgazdálkodását is több minta alapján, nagyobb részletességgel, megbízhatóbban tudjuk jellemezni.

Soil, i.e. the natural outer layer of the lithosphere and an important component of many ecosystems, may be subjected to various degradation processes dependent on different factors. One of the forms of physical degradation is water erosion, where the first stage is the splash phenomenon caused by water drops hitting the soil surface during rainfall. This process results in detachment and ejection of splashed material and transport thereof over different distances. One of the factors that influences the magnitude of soil splash is the incline of the surface (slope). The aim of this study was to check the effect of the slope on the course of the splash phenomenon caused by single-drop impact, with respect to the mass and proportions of the ejected material, taking into account its division into solid and liquid phases i.e. soil and water.The measurements were conducted on three types of soil differentiated in terms of texture, in moistened conditions (pressure head corresponding to -1.0 kPa). Three slope inclines were investigated: 5°, 15°, and 30°. After a single-drop impact (with a diameter of 4.2 mm), the ejected material was collected using a splash cup. Based on this the following quantities of splashed material were measured: the total ejected mass, the mass of the ejected solid phase and the mass of the ejected liquid phase. Also, the distribution and proportions (soil/water) of the splashed material were analysed in both the upslope and downslope directions. The results showed that: a) the change of slope had a variable influence on the measured quantities for different soils; b) the measured values were mainly influenced by the texture; c) with the increase of slope, the splashed material was mostly ejected in the downslope direction; d) the ejected material consisted mostly of water, this occurred for material ejected both upslope and downslope. This work was partly financed from the National Science Centre, Poland; project no. 2018/31/N/ST10/01757. References:Beczek M., Ryżak M., Mazur R., Sochan A., Polakowski C., Bieganowski A.: Influence of slope incline on the ejection of two-phase soil splashed material. PLOS ONE 17(1): e0262203, 2022

The formation of craters is an important issue in the investigations of the surface of the earth and other planets. The aim of the study was to check whether the different textures of sand beds affect the size and dynamics of the formation of craters and ejection curtain after high-velocity impacts. The experiments were conducted using an aluminium impactor at two impact speeds (~700 and ~1300 m∙s-1) and a sand bed composed of either a broad range of sizes (V, π2 and α). The texture of the sand most clearly influenced the diameters of the craters, its effect could also be seen in the case of the distance covered by the ejected material. This information appears to be relevant for future research, providing some rationale to help assess in which aspects of the phenomenon the texture may be important.

Soil splash is the first step of water erosion, therefore a good understanding of it is important in order to describe this multifaceted phenomenon. One of the methods describing this process is the use of splash cups, which allow us to determine the mass of soil material ejected by the impact of water drops. The aim of this study was to determine the mass ratio of splashed particles during raindrop splash on the soil surface, including their division into a splashed liquid phase and a solid phase. The investigation was carried out using three types of soil with different particle size distributions. In the first stage of the experiment, three initial moisture contents were applied (pressure head equal to 0.1 kPa, 1.0 kPa and 3.16 kPa) and the second stage measurements were based on the soil with the highest splash efficiency in the case of the different kinetic energy of the impacting drop. It was found that: (i) the texture of soil sample had a significant effect on the mass of splashed material; (ii) the lower the initial moisture content of the sample, the lower the mass of splashed material; (iii) the highest values of the mass of splashed material (both the liquid phase and solid phase) were obtained for soil with the highest sand fraction; (iv) for all types of soils, the mass of the splashed water was significantly larger than the collected mass of splashed soil; (v) the ratio of splashed masses (the proportions) was dependent on initial moisture content for soil with a higher amount of finer fractions. The obtained results are important for the physical description of the splash erosion. For instance, the knowledge of the masses of solid (soil) and water parts of the ejected material and their ejection kinetic energy will allow the estimation of the total energy needed for the displacement of splashed material. Moreover, the investigation of the water phase in the splash phenomenon is significant because of the transport processes of pollutants and pathogenic microorganisms.

The impact of a spherical intruder on a bedding of spherical particles and the behaviour of particles during the splashing phenomenon were studied experimentally and via discrete element method (DEM) simulations. The objective of this study was to gain deeper insight into the physical mechanisms governing the behaviour of the particle bedding during low-velocity impact. The experiments were performed using a high-speed camera to capture the splash of the particles. A piezoelectric ceramic pressure sensor located at the bottom of the container was employed to measure the pressure impulse generated by the intruder impact. We obtained good agreement between the DEM simulations and experimental results for all the considered parameters of the impact process. The study allowed a better understanding of the interactions in a granular bedding during impact at micro-scale. The results indicated that the dynamics of the intruder-particles, particle-particle, and particles-bottom interactions were similar, having a nonlinear increase that accompanied an increase in the impact velocity. This was caused by a local increase in the effective stiffness of the bedding resulting from simultaneous multi-collisions. The coefficient of particle-particle friction significantly affected all the measures considered: speed of the compression wave, amplitude of the impact force, amount of kinetic energy transferred from the intruder to the particles, depth of penetration and crater diameter, and number of ejected particles and their kinetic energy.

The soil splash phenomenon is the initial stage of the water erosion process. It occurs when a rain drop hits the soil surface and causes a few processes e.g. i) detachment of soil particles and their transport over different distances, ii) breakdown of soil aggregates, iii) surface runoff or iv) formation of a crusted surface.The aim of the study was to carry out an analysis of the splash erosion in mineral soil in 4 variants of sample preparation: a) dry natural soil, b) wet natural soil, c) dry burnt soil, d) wet burnt soil.In both cases (natural soil and soil modified with high temperature), full moistening was achieved by capillary rise. Fire simulation was carried out in several variants at varying temperature and duration. Variant that affected soil wettability to the greatest extent was selected for the splash analyses. "Natural" and "modified" wettability were measured using the water drop penetration time (WDPT) method. "Natural" wettability classified soil into the "wettable" group (WDPT < 5s), while the modification of the surface properties by high temperature changed the wettability group of the analyzed soil into "slightly to moderately repellent" (5 s > WDPT < 60s).Each time, the soil material was placed in aluminum rings with an internal diameter of 36mm and a height of 10mm, and the surface was leveled without excessive compaction of the sample.A single drop of distilled water with a diameter of 4.2 mm fell on the sample prepared in this way from a height of 1.5m. The drops were dosed with a peristaltic pump and reached the final velocity of 4.98 m/s.Three synchronized Phantom Miro M310 cameras (Vision Research, USA) were used to register the splash phenomenon. The recorded films were used to analyze the splash phenomenon through measurements of the velocity, angle and distance of ejected particles.A Scan3D UNIVERSE 10 MPiX structural light scanner (Smarttech 3d, Poland) was used to determine the magnitude of the surface deformation caused by the drops. The analyses made it possible to determine e.g. the depth, diameter, and volume of craters and the height of surrounding rims.The analysis of the results showed significant differences in the size and dynamics of the emerging splash depending on the degree of soil wettability.The study was partially funded by the National Science Centre, Poland, as part of project no. 2017/26/D/ST10/01026.

Background Predatory attacks on horses can become a problem in some parts of the world, particularly when considering the recovering gray wolf populations. The issue studied was whether horses transformed by humans and placed in stable-pasture environments had retained their natural abilities to respond to predation risk. The objective of the study was to determine the changes in cardiac activity, cortisol concentrations, and behavior of horses in response to the vocalizations of two predators: the gray wolf (Canis lupus), which the horses of the breed studied had coevolved with but not been exposed to recently, and Arabian leopard (Panthera pardus nimr), from which the horses had been mostly isolated. In addition, we hypothesized that a higher proportion of Thoroughbred (TB) horse ancestry in the pedigree would result in higher emotional excitability in response to predator vocalizations. Nineteen horses were divided into groups of 75%, 50% and 25% TB ancestry. The auditory test conducted in a paddock comprised a 10-min prestimulus period, a 5-min stimulus period when one of the predators was heard, and a 10-min poststimulus period without any experimental stimuli. Results The increase in heart rate and saliva cortisol concentration in response to predator vocalizations indicated some level of stress in the horses. The lowered beat-to-beat intervals revealed a decrease in parasympathetic nervous system activity. The behavioral responses were less distinct than the physiological changes. The responses were more pronounced with leopard vocalizations than wolf vocalizations. Conclusions The horses responded with weak signs of anxiety when exposed to predator vocalizations. A tendency towards a stronger internal reaction to predators in horses with a higher proportion of TB genes suggested that the response intensity was partly innate. The more pronounced response to leopard than wolf may indicate that horses are more frightened of a threatening sound from an unknown predator than one known by their ancestors. The differing response can be also due to differences in the characteristic of the predators’ vocalizations. Our findings suggested that the present-day horses’ abilities to coexist with predators are weak. Hence, humans should protect horses against predation, especially when introducing them into seminatural locations.

The phenomenon of splash caused by water drop has been widely studied in recent years. There are many measurement methods, including the method based on the use of so-called high-speed cameras. Due to the possibility of recording of the phenomenon with a high time frequency (thousands of recorded frames per second), this method provides detailed information about the process of splashed particles, which were previously unavailable. These include, among others, precise tracking of single ejected particles, determination of their ejection angle, displacement distance, and division of splashed elements into groups depending on the place or moment of ejection from the particle bedding. Despite the numerous advantages of the method, there is no information about the percentage of splashed particles that the cameras are able to detect and identify. In order to determine such effectiveness, it is necessary to have a reference method that guarantees 100% identification of splashed particles.The aim of this work was to determine the effectiveness of high-speed cameras in identification of particles ejected from the granular bedding during the water drop impact. Sticky paper was used as a reference method.Dry spherical glass beads (425–600 μm size range), which were placed into an aluminium ring (30mm diameter, 10mm height) were used in the experiments. The aluminum ring was placed in a drilled hole (only slightly larger than the ring) in a horizontal wooden plate, and therefore, the surface of the beads was at the same level as the surrounding plane. Drops (d=4.2mm) of distilled water were created in a peristaltic pump and fell free from 1.5m. The final velocity of each drop was 4.98 m/s.Three synchronized Phantom Miro M310 cameras were used to register the splash phenomenon (307 μs time interval, 1280x800 px resolution). The camera calibration process facilitated analysis of the trajectories of the splashed particles and determination of their velocities, ejection angles, and displacement distances. The analysis of the recorded images was carried out using the Dantec Dynamics Studio software. The particles were tracked by the Volumetric 3DPTV module, and the trajectories were further analyzed by our script written in LabVIEW.A hole (30mm diameter) was cut out of a piece of sticky paper, and the paper was placed concentrically over the ring. This allowed recording of all splashed particles while avoiding their rebounding or rolling from the plane. Following the impact, the beads were photographed using a Nikon D7100 camera, and images were analyzed using ImageJ software. The number of particles and the distance from the geometrical center of the drop impact were recorded.Measurements using the high-speed cameras and the sticky paper method were carried out in 16 repetitions.The results obtained with both methods were compared with each other. Regarding the sticky paper method as a reference, the efficiency of identification with the high-speed cameras for the splash of glass beads was determined, which was estimated at 53%.The study was partially funded by the National Science Centre, Poland, in the frame of the project no. 2017/26/D/ST10/01026.

Keywords: soil texture, aggregate stability, organic additives, earthworms, microbial activity,Lubbers et al. (2017) emphasised that earthworm by creating macroaggregates increase the amount of organic carbon in the soil. Such macroaggregates contain particulate organic matter, fungal hyphae, or roots, and afterwards, during the decomposition of macroaggregates, the organic matter becomes more resistant to microbial attack (Pulleman et al. 2005). Earthworms, through feeding and burrowing, are important elements in C cycling (Curry and Schmidt 2007). However, the type of introduced organic matter (Huang et al. 2018) and abiotic factors (Six et al. 2004) are equally important in creating stable organic-mineral components as well as the presence of earthworms.A six-month experiment was carried out to test how the soil structure (the stability of soil aggregates) behave under the influence of various organic additives. For each soil, except the reference samples, one of the listed additives was introduced, i.e. straw, straw with fulvic acid, peat (garden soil), compost, compost with active bacteria cultures and straw with fulvic acids, humus and active bacteria cultures. The research was carried out on soils with four types of texture, i.e. sandy, loamy, silty and clayey soil. In the project, three different species of earthworms commonly occurred in Polish soils were a structure-forming factor (Apporectodea rosea, Apporectodea calliginosa and Dendrobena rubillus). After the experiment, the amount of organic carbon in the soil, dissolved organic carbon, humus forms and microbiological activity of the soil were evaluated. The stability of the soil aggregates was determined using two methods: the sieve method (Kemper and Rosenau 1986) and laser diffraction method (Bieganowski et al. 2018),Based on this research it was noted that the aggregate stability is correlated mainly with soil texture. The applied additives had the most significant influence on the transformation of organic carbon in the soil. Soil organic carbon, which may be incorporated into the soil in the form of the organic-mineral colloids, is an essential element in the balance of the carbon in nature. Among the tested additives, organic carbon from compost, peat and compost with active bacteria cultures was in the highest amount associated with fine earth particles (about 36-48%). For comparison, only less than 8.5% of the organic carbon from the straw was incorporated into the mineral part of the soil.Two methods to measures aggregate stability are not comparable for sandy soils. In the wet-sieving method the sand fraction higher than 0.25 mm pretend to be stable aggregates. The study was financed by The National Science Centre, Poland, grant No. 2017/01/X/ST10/00777, statistical analysis was made based the knowledge and skills achieved during the training: organized as part of the project: Integrated Program of the University of Agriculture in Kraków, which is co-financed by the European Union (POWR.03.05.00-00-z222/17)

Splash, which is the first stage of the water erosion, is a dynamic and complex phenomenon. The ejection of soil particles occurs within fractions of a second after the impact of a drop. The diameter of the deformation formed on the surface can be measured in millimeters. The complicated nature of the phenomenon necessitates the use of advanced equipment (high-speed cameras or surface scanners) and models for simplification of the subject of the study to analyze selected aspects of the splash.The work presents the results of research in which glass beads were used as a soil model. The aim of the experiments was to determine the influence of the initial position of the deposit elements on their displacement as a result of a droplet impact.A water drop with a diameter of 4.2 mm falling freely from a height of 1.5 m was used in the study. The beds were placed in aluminum rings with a diameter of 40 mm. The measurements were based on the initial and final position of the beads used as markers; these beads differed in color from the rest of the deposit. The source of data included pictures taken with a digital camera before and after the impact and control recordings made with high-speed cameras to correct possible errors. Additionally, some of the samples were scanned with a microtomograph, which allowed characterizing the surface deformation. Taking into account their structure, the beds used in the measurements were divided into two groups. The first one was used to analyze the influence of drops on individual elements - symmetrical patterns from colored beads were prepared on the sample surface; the second group was used to analyze the influence of drops on groups of elements - layers of beads with the same color were prepared on the surface of these samples.Based on the experiment results, the movement of the deposit elements was divided into three types: displacement inside the area wetted by a drop, ejection, and placement on the crater rim. The initial location of the beads displaced over the greatest distances was a narrow ring covering the area from 4 to 8 mm from the point of the drop impact. It is worth noting that this area was associated with strong surface deformation. The use of "monolayers" helped to indicate that 97% of the beads ejected outside the ring with the deposit originated from the bed surface layer.ReferencesMazur R., Ryżak M., Sochan A., Marciszuk K., Beczek M., Lamorski K., Bieganowski A., 2020. Surface deformation and displacement of bed elements during splash – Model tests. Catena 185, 104277The study was partially funded from the National Science Centre, Poland in the frame of project no. 2014/14/E/ST10/00851.

Soil, i.e. the natural outer layer of the lithosphere and an important component of many ecosystems, may be subjected to various degradation processes dependent on different factors. One of the forms of degradation is water erosion, where the first stage is the splash phenomenon. This process is caused by water drops hitting the soil surface during rainfall, which results in detachment and ejection of splashed material and transport thereof over different distances. The aim of this study was to present the application of the high-speed camera technique for investigations of surface phenomena (effects) influenced by the impact of a single water-drop onto the soil surface.The measurements were conducted on types of soil differentiated in terms of texture and variants of initial moisture content, which helped to observe different aspects of the soil splash phenomenon. Water drops with a diameter of 4.2 mm fell on soil samples with various kinetic energy values depending on the height of the drop fall (up to 7m). Phantom Miro M310 high-speed cameras were used to observe the effects of the drop impact. The devices registered images with a speed of 3260 fps (frames per second) at the highest available resolution (1280x800 pixels). The following phenomena were observed: I) ejection of splashed particles (including solid soil particles, water droplets, solid particles within the water sheath); II) crown formation – when the drop impacting onto wet soil surface forces the liquid layer to rise up and form a crown (important for the mode and amount of transferred material); III) micro-crater formation – the deformation of the surface and formation of a shallow pool after the drop impact. This work was partly financed from the National Science Centre, Poland; project no. 2018/31/N/ST10/01757. References:Beczek M., Ryżak M., Sochan A., Mazur R., Bieganowski A.: The mass ratio of splashed particles during raindrop splash phenomenon on soil surface. GEODERMA 347, 40-48, 2019 Beczek M., Ryżak M., Lamorski K., Sochan A., Mazur R., Bieganowski A.: Application of X-ray computed microtomography to soil craters formed by raindrop splash. Geomorphology 303, 357-361, 2018 Beczek M., Ryżak M., Sochan A., Mazur R., Polakowski C., Bieganowski A.: The differences in crown formation during the splash on the thin water layers formed on the saturated soil surface and model surface. PLoS ONE 12, 2017

The current predation threat of domestic horses is generally low, and horses do not know predators' frightening cues. We studied whether horses still recognise predation threats. The aim of the study was to analyse the emotional response of purebred Arabian horses (Arabian) and Polish Konik horses (Konik) to an Arabian panther (Panthera pardus nimr) (panther) growl and a grey wolf (Canis lupus) (wolf) howl. Panther vocalisation was known to Arabian ancestors, whereas ancestors of Konik knew wolf vocalisation. The response to the howls of golden jackals (Canis aureus) (jackal), which did not prey on equids, was also studied comparatively. Two groups of 10 adult horses of each breed were subject to predator sounds of one predator daily for 5 min during a turn out on pasture. The test was performed for 18 days in total. The sound of each predator was interchangeably featured from one loudspeaker for 3 days followed by four loudspeakers simultaneously to imitate a group of predators for 3 days. The horses' emotional agitation in response to the sounds was measured based on the parameters of heart rate variability (HRV) using telemetric devices. The results showed that the predators' sounds were identified by horses as stressful or neutral. Horses generally retained their anti-predator responses even in the current habitat, which typically lacks predation cues. The results are not always coherent and may demonstrate that the response is somewhat attenuated. The wolf howl elicited a stronger response in Koniks. The panther growl more strongly influenced Arabians, whereas the jackal howl minimally elicited an agitation in the horses. The differentiated response of the two horse breeds to the three predator species suggests that the response is an innate adaptation to the predation risk in the habitat of the breed ancestors. This response occurs regardless of the emotional arousal specific to a breed, and the frightening cue is not the sound per se but the possible attack of predators. Horses display a type of understanding of the sound meaning. Their HRV response seems to be adequate for the threat signalised by the sound.

The aim of the study was to assess the behavioural reaction and emotional arousal of warmblood horses in response to sounds of different origin, and to classify those sounds into neutral ones, those causing a behavioural change and those causing a behavioural and physiological stress response. We tested the hypothesis that the perception of a sound as neutral or potentially threatening does not simply depend on the sound origin per se, but rather on the context in which the sound occurrs (predictability), additionally enhanced by the novelty effect. Recordings of 40 sounds, known (KS) and unknown (US), from four groups: anthropogenic (AS), neutral animal (NAS), predator (PS), and inanimate environment sounds (IES), were played to 20 warmblood horses remaining in their familiar paddock. The duration, frequency or occurrence of certain behaviours (e.g. walking, feeding, standing alert, stopping current activity), the heart rate (HR) and heart rate variability (HRV) were measured. The horses’ reactions were rather weak and short-term. Most of the sounds resulted in distraction (increase in alertness). The horses ate less, walked and stood alert longer, and had a higher HR after certain sounds were played. The strongest stress response (physiological and behavioural) to NAS, mostly US, was observed. PS caused behavioural disturbance, but no cardiac activity changes. The weakest responses were observed for AS and IES. Modern, stable-kept horses remain vigilant to auditory stimuli in their environment and differentiate their responses to different sounds. The perception of a threat posed by sounds depends on their unpredictability and novelty.

Splash is the first step of the water erosion process initiated when raindrops hit the earth’s surface and eject particles of soil. The ability to physically describe this phenomenon is important in order to counteract it. One of the research aspects of splash is energy dissipation of the impacting drop where the ejection of particles is significant part. Therefore, the main aim of this work is the presentation of an improved method for calculation of the kinetic energy of two-phase splashed material (water/solid soil particles). Measurements were carried out on Haplic Luvisol soil surface and single drop impact. Different methodologies allowed for obtaining key parameters that influence particles’ energy, including measuring the number of ejected particles, their mass, and their ejection velocity. High-speed cameras registered the phenomenon, identified particles, and reconstructed their flight trajectories. Based on the analysis of particle trajectories, it was possible to determine the distribution of particles’ ejection velocity with the average value equal 2.60 m·s−1. Splash cup measurements provided data on the total mass of splashed material, including its division into the solid phase (soil) and the liquid phase (water), and calculation of the average density of ejected particles (1.31 g·cm−3). An alternative method for particles’ mass calculation, the 2D image analysis method, was calibrated with the results obtained with the splash cup. Based on the input data, three variants of kinetic energy calculation of the splashed material were tested. The variants differed in assumptions and approximations, and it was difficult to determine which was preferable. Taking into account the results from all variants, however, it can be stated that the total kinetic energy of splashed particles in relation to the kinetic energy of a water drop hitting the soil surface ranged between 4.6% and 7.4%. To the best of the authors’ knowledge, this study is the first report of kinetic energy calculation which takes into account the two-phase nature of splashed material.

Aggregate size distribution of soil is an important parameter to describe soil properties. For many years, the size of soil aggregates has been measured using the dry sieving method. During sieving, particularly less-stable aggregates may have broken down. However, apart from the sieve method, there was no method enabling direct measurement of aggregates on a dry basis. The modification of the measurement system presented in this paper allows such measurements to be conducted using the laser diffraction method. The average coefficient of variation of the proposed method was about 2.6 %.

In this study, we determine the coefficients of restitution (CoRs) of seeds coming from three plants, namely the pea (Pisum sativum L. cv. Piast), soybean (Glycine max (L.) Merr. cv. Annushka) and rapeseed (Brassica napus L. cv. Licosmos), at three levels of moisture content for an impact velocity V0 ranging from 0.17 to 8.8 m s−1. We obtain high-speed camera measurements as well as single-drop and repeated-bounce tests. We record the impact force–time relationships Fn(t) using a piezo-ceramic pressure sensor. The results show that the rate of decrease of the CoR with an increase in V0 was the highest for rapeseed having the highest moisture content (MC), and it was the lowest for pea seeds having the lowest MC. We perform experiments to model the relationships CoR(V0) using visco-elastic contact models based on Hertz contact theory. The impacts of dry seeds for three crops were best illustrated using three different contact models, for pea – Kuwabara and Kono (1987), soybean – Alizadeh et al. (2013) and rapeseed – Hu et al. (2011). For higher MC, models which provide a more nonlinear CoR(V0) relationship appeared to be more appropriate, i.e. Kuwabara and Kono (1987) for the pea and soybean, while the model of Alizadeh et al. (2013) better described the behaviour of rapeseed. Visco-elastic contact models which were selected using the least-square method provided a very good approximation of CoR(V0) and impact time tc(V0) relationships, and a sufficiently good approximation of the shape of Fn(t) relationships.

Soil splash is the first step of water erosion. There are many methods for splash investigations however the use of high-speed cameras is becoming increasingly popular. This study describes the methodological aspects of using high-speed cameras and a PTV (Particle Tracking Velocimetry) system to investigate the soil splash phenomenon. The purpose of the research was to examine the impact of image processing and the choice of settings for particle tracking software on the effectiveness of detecting and identifying splashed/ejected particles (with their flight trajectories). Experiments were carried out on moisturized Haplic Luvisol soil samples and the impact of single water-drop onto the surface was recorded by three calibrated Phantom Miro M310 high-speed cameras. Registered frames were subjected to image processing in Dantec DynamicStudio software, where the selection of the optimal set of parameters/settings was validated, in the context of maximum detection of the splashed particles. The resulted images provided the input data for the Volumetric 3D PTV module (DynamicStudio) to identify/track the ejected particles and then determine their trajectories. The study presents the use of different settings (variants) of tracking modules, enabling the most efficient identification and description of the particles’ trajectories (76%). The incomplete trajectories detected (excluding starting and landing fragments), were subjected to a reconstruction process based on mathematical extrapolation. The analyze of the registered images and reconstructed trajectories of splashed particles gave the possibility to determine the following parameters describing soil splash phenomenon: a) number of splashed particles, b) ejection angle (for each particle), c) ejection velocity, d) displacement range, e) altitude (the maximal height reached by the particle).

The phenomenon of splash is connected with soil erosion, occurs commonly, and has a complex nature. The study presents the results of research in which glass beads (dry and saturated beds) with a diameter size range of 0.425–0.6 mm were used as a soil model. Patterns and layers of glass particles (beads), distinguished by their colour were placed on the surface of the samples. Displacements of the marked beads were used for the analysis of movement caused by splash. The measurements were supplemented with recordings made with high-speed cameras and photographs from an X-ray microtomograph. Three types of displacement for dry bed elements were distinguished: (i) displacement inside the surface area wetted with a falling drop of water, (ii) ejection and (iii) placement on the crater rim, as well as two types of displacement for elements from saturated beds: (i) displacement inside the deformation and (ii) ejection. The distance travelled by the beads was related to the specificity their displacement, which was associated with the initial location of the beads on the sample surface. In the case of dry beds, glass beads with an initial location equal to 14 mm or more from the centre of the drop impact were not moved. In the case of saturated beds, this distance was about 10 mm. More than 95% of the beads ejected from dry beds came from the surface layer of the sample. All the measurement methods applied show that the deformations of the dry bed surfaces were greater and more diversified than those of the saturated beds. The results presented in the study are important for understanding the mechanisms of transport of bacteria, fungi, and pollutants transferred with ejected soil particles during splash. The results can also be used for a physical description of the phenomenon for the computer modelling of both splash and water erosion.

Knowledge about splash of water drops on leaf surfaces is required inter alia in studies of rainfall modification by plant canopies, the spread of plant diseases, and washing out and transportation of pollutants and plant protection products that have settled on leaves. Splash drop generation is a complex process that cannot yet be precisely predicted theoretically, and it is dependent on surface properties. Hypothesizing that water drop splash on leaves will be dependent on surface wettability, we aimed to describe this effect quantitatively using leaves from N. nucifera and B. oleracea (highly non-wettable); E. aureum (non-wettable); A. macrorrhizos (wettable); N. lutea, A. glutinosa, N. alba and H. tuberosus (highly wettable); and R. makoyana (super-hydrophilic). Leaf wettability was defined by the contact angle value, measured using the sessile drop method. Surface leaf structures were described based on photographs from a scanning electron microscope. Splashes were caused by single water drops (4.2 mm) falling freely from 1.5 m. The phenomena were recorded by a set of high-speed cameras. It can be concluded that falling water drop behaviour is closely related to both wettability and surface structure, particularly the presence of trichomes. Greater hydrophobicity causes this at the moment of impact; the water drop propagates faster and expands to a larger surface area. The effect of the presence of trichomes is more pronounced when there is a relation between the average number and velocity of ejected droplets and the equivalent diameter of the largest residual droplet remaining on the leaf versus contact angle. The presence of trichomes on the leaf surface causes resistance, which leads to energy losses from the hitting drop and disturbs the process of water spreading over the leaf surface.

The laser diffraction method (LDM) is a relatively new technique that is increasingly used in measurements of the particle size distribution (PSD) of soil and sediments. It has significant advantages (high precision, simple and rapid measurement) but the PSDs obtained by LDM often differ from those obtained with previously used sieve-sedimentation methods (SSMs). The main factors influencing the measurements that use LDM (among others: soil pretreatment, construction of the device settings of the operator, specificity of soil material, and the problem of fulfilling the assumptions of the method) are presented and the problem of comparability with SSM. New areas of investigations using LDM are also discussed. The work concludes with a set of postulates that should be taken into account to standardize LDM and increase the comparability of results, not only with SSMs but also with the PSDs obtained in other laboratories, including the diffractometers deriving from other producers.

The splash phenomenon is the first stage of water erosion on the soil. It occurs when the water drops of the rain strike the surface. The impact of the water drop is fast. But if one has a fast enough measuring system, it can be considered as a temporally extended phenomenon. The aim of this paper is to describe a system for the measurement of the dynamic of the changing forces when a water drop interacts with the surface during impact. The constructive assumptions and validation of the measurement system, which has been based on piezoelectric sensors, are also presented. The system allows one to measure the changes of the force with the frequency of 150 kHz. The maximum force is 200 N, which is quite sufficient for all sizes of water drops which occur in nature and their maximum speeds. The results of test measurements, that is, the changes of the force obtained from water drops falling on the sensors, are also shown.

Particle-size distribution (PSD) is one of the most important and frequently measured soil parameters. The assumptions inherent in the use of Stokes’ law in the standardized sieve–sedimentation method (SSM) are known to introduce bias into the estimates of PSD. We used the laser diffraction method (LDM) to quantitatively estimate the bias in the SSM. Pipette samples collected at standardized times during the SSM of three different soils were analyzed with LDM to detect the largest particles in suspension. Light microscopy was used to verify the LDM estimates. Particle sizes in suspension were compared as a function of time to the predicted sizes by Stokes’ law. Our findings suggest that (i) real sedimentation in a soil suspension deviated from Stokes’ law in all the soils investigated; (ii) larger particles then predicted by Stokes’ law occurred in all fractions of all investigated soils where counts of anomalously larger particles ranged from several to around 40%; (iii) the longer the time of the sedimentation, the larger the deviation from Stokes’ law with the effect of irregularly shaped particles becoming more evident; and (iv) sieving soil samples appears to not be an effective method for the separation of the sand fraction from finer fractions. Our observations on the deviation from Stokes’ law has previously been widely discussed in the literature. However, quantification of this phenomenon, as described in this paper, should help to better estimate the uncertainty of the pipette method.

Particle size distribution (PSD) is a major soil characteristic, which is essential and commonly used for the development of pedotransfer functions (PTFs) to estimate the water retention of soils. The laser diffraction method (LDM) became a popular alternative to the standard sieve-hydrometer method (SHM) of PSD measurement. Unfortunately, PSDs determined with LDM and SHM methods differ sometimes substantially. Moreover, it is claimed that the laser diffraction method underestimates finer fractions in favor of coarser fractions. Several authors have tried to elaborate on methods to recalculate LDM PSD into its SHM counterparts, but no universal methodology has been developed to this date. In this paper, we use PSD determined by LDM directly for PTF development and compare it with the classical PTF approach based on PSD measured by SHM. Four different PTF models based on LDM particle size distribution data were developed, with different PSD characteristics taken as the models' input variables. The possibility of using alternative PSD characteristics, such as deciles, area moment mean and volume moment mean, for PTF development was examined. The accuracy of PTF models constructed on the basis of LDM-measured PSD was comparable with that of the developed models using texture data obtained from SHM, giving approximately the same RMSE and R2 values. Our study shows that LDM-measured particle size distribution may be directly used for PTF developments without any recalculations to their sieve-hydrometer counterparts.

The aim of this paper was to show how the shape of sand particles affects the results of particle size distribution obtained by the laser diffraction method. On the basis of the results obtained one can conclude: the shape of the investigated particles influences particle size distribution obtained by the laser diffraction method. This phenomenon occurs in the sand fraction, as shown in our investigation. The importance of this effect depends on the type of the measured material and on the aim of the investigations. For most researchers in soil science and sedimentology who investigate sand fractions, this impact can be negligible. Further investigations with other soil and sediment fractions are needed.

The paper presents a study on the possibility of using the laser diffraction method for measuring the size of the activated sludge particles. Susceptibility of the particles to mechanical disintegration, dependent on the programmed value of stirring intensity, was observed (stirring was caused by required dynamic flow of analysed suspension through the measurement unit). According to the conclusions presented in this paper, it may be assumed that the laser diffraction method can be applied for measurement of activated sludge particle diameters under the following conditions: 1) the size of activated sludge particles measured by the laser diffraction method is not a real value, but after standardisation of measurement conditions can be treated as a parameter describing the sludge; 2) the particle diameters of activated sludge should be stabilised before the measurement, eg by mixing in the measurement unit or by ultrasound waves application.

Pocket forms several decimetres in diameter, 0.5–1.5 m deep and infilled mainly with glaciogenic sands, silts and clays of Saalian age are commonly developed on the top of the karstified chalk massif of the Lublin Upland, eastern Poland. Analysis of lithofacies, particle-size distribution and micromorphology of three pocket infills in the Chelm chalk quarry reveals a prominent clay cortex between the host chalk and the glaciogenic infill and suggests that periglacial processes have played a considerable role in the formation of the pockets and in the redistribution of their primary glaciogenic infill. A conceptual model for epikarst morphogenesis for the chalk karst of Lublin Upland is proposed, involving three stages. Stage I: In the absence of permafrost, precipitation water infiltrates unconsolidated glaciogenic deposits. Stage II: Periglacial transformation with underlying permafrost. Primary cryoturbation structures became protokarst forms, and then epikarst forms. Stage III: Degradation of the permafrost, with increased carbonate dissolution and development of a clay karst cortex. Copyright © 2012 John Wiley & Sons, Ltd.

Comparison of soil texture determined by two dispersion units of Mastersizer 2000The comparison of particle size distributions measured by sedimentation methods and laser diffraction shows the underestimation of the fine (clay) fraction. This is attributed mainly to the shape of clay particles being different than spherical. The objective of this study was to demonstrate differences in the results of particle size distributions of soils determined with the method of laser diffraction using two different dispersion units of the Malvern Mastersizer 2000.

A new practical and precise method for determining soil aggregate stability is described. Four air-dry aggregate fractions (d50) particle-size distribution decrease (interpolated with a logarithmic function) was assumed to be the measure of soil aggregate stability. In order to show the applicability of the new method, the results obtained (for selected and diverse soils) were compared with those from the wet sieving standard method. The main conclusion is that the proposed method is convenient and can be successfully used for the estimation of soil aggregate stability. Moreover, it has wider application because standard sieving methods are restricted to aggregates >0.25 mm whereas, with the use of the laser diffraction method, smaller aggregates can be measured. The energy delivered to the aggregates in the process of aggregate disintegration is more reproducible in the method described here. The method also provides an opportunity to verify that the soil aggregates are completely destroyed (lack of the changes of the median value shows the end of soil aggregate disintegration).

The splash phenomenon is being increasingly explored with the use of modern measurement tools, including the high-speed cameras. Recording images at a rate of several thousand frames per second facilitates parameterization and description of the dynamics of splash phases. This paper describes the impact of a single drop of a liquid falling on the surface of the same liquid. Three single-phase liquid systems, i.e., water, petrol, and diesel fuel, were examined. The falling drops were characterized by different kinetic energy values depending on the height of the fall, which ranged from 0.1 to 7.0 m. Four forms, i.e., waves, crowns, semi-closed domes, and domes, were distinguished depending on the drop energy. The analysis of the recorded images facilitated determination of the static and dynamic parameters of each form, e.g., the maximum height of each splash form, the width of the splash form at its maximum height, and the rate of growth of the splash form. We, Re, Fr, and K numbers were determined for al...