1. Bracken-induced increase in soil P availability, along with its high P acquisition efficiency, enables it to invade P-deficient meadowsAntun Jelinčić, Nina Šajna, Željka Zgorelec, Aleksandra Perčin, 2022, izvirni znanstveni članek Opis: Changes in soil chemistry after invasion by bracken (Pteridium aquilinum) have been studied in heathlands, but comparable studies in meadows are lacking. We investigated if bracken invasion into P-deficient meadows alters the soil nutrient-resource pool, as well as the mechanisms behind it linked to soil processes and bracken nutrition. Furthermore, we investigated how community composition responds to differences in soil chemistry before and after the invasion. Soil and plant material sampling, along with vegetation survey, were performed during bracken peak biomass. Data analyses included analysis of variance and canonical correspondence analysis (CCA). Bracken invasion increased soil P availability, soil organic C concentration, as well as C:N, C:S and N:S ratios, while decreasing Fe and Co concentrations. Bracken pinnae were rich in P, and its rhizomes were rich in K, whereas N:P of pinnae and rhizomes was low. CCA showed contrasting abundance patterns of frequent meadow species related to P and K availability. Holcus lanatus exhibited competitive advantage under extremely low P availability. Increase in P availability under bracken may have occurred through promoting the leaching of Fe and Al. By increasing P availability for its growth and increasing N limitation for other species, bracken can gain a competitive advantage from the soil resource-niche perspective. Its ability to increase soil P availability, along with the physiological mechanisms behind its high P acquisition efficiency, seem to differentiate bracken from other species of competitive ecological strategy, which are mainly confined to nutrient-rich environments. This enabled bracken to invade P-deficient meadows.
Ključne besede: vegetation succession, invasive species, biogeochemical processes, soil ecology, plant invasion
Objavljeno v DKUM: 17.06.2024; Ogledov: 148; Prenosov: 8
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2. Cross-Hole GPR for Soil Moisture Estimation Using Deep LearningBlaž Pongrac, Dušan Gleich, Marko Malajner, Andrej Sarjaš, 2023, izvirni znanstveni članek Opis: This paper presents the design of a high-voltage pulse-based radar and a supervised data processing method for soil moisture estimation. The goal of this research was to design a pulse-based radar to detect changes in soil moisture using a cross-hole approach. The pulse-based radar with three transmitting antennas was placed into a 12 m deep hole, and a receiver with three receive antennas was placed into a different hole separated by 100 m from the transmitter. The pulse generator was based on a Marx generator with an LC filter, and for the receiver, the high-frequency data acquisition card was used, which can acquire signals using 3 Gigabytes per second. Used borehole antennas were designed to operate in the wide frequency band to ensure signal propagation through the soil. A deep regression convolutional network is proposed in this paper to estimate volumetric soil moisture using time-sampled signals. A regression convolutional network is extended to three dimensions to model changes in wave propagation between the transmitted and received signals. The training dataset was acquired during the period of 73 days of acquisition between two boreholes separated by 100 m. The soil moisture measurements were acquired at three points 25 m apart to provide ground truth data. Additionally, water was poured into several specially prepared boreholes between transmitter and receiver antennas to acquire additional dataset for training, validation, and testing of convolutional neural networks. Experimental results showed that the proposed system is able to detect changes in the volumetric soil moisture using Tx and Rx antennas.
Ključne besede: ground penetrating radar, cross-hole, L-band, deep learning, convolutional neural network, soil moisture estimation
Objavljeno v DKUM: 03.04.2024; Ogledov: 446; Prenosov: 20
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3. δ13C as a tool to determine the origin of soil organic carbon : Case study of a restored sloping orchardMateja Muršec, Jean Leveque, 2023, izvirni znanstveni članek Opis: The effect of drip irrigation on the origin and size fraction of soil organic carbon was studied in the soils of an apple orchard (Malus domestica Borkh.) on hilly (20%) terrain in northeastern Slovenia in three slope positions (upslope, midslope and downslope), comparing irrigated with non-irrigated soils. Physical fractionation of soil organic carbon was performed on three soil layers (0–0.05, 0.05–0.15 and 0.15–0.30 m) in three size fractions: fraction A (> 0.0002 m), fraction B (0.0002‒0.00005 m) and fraction C (< 0.00005 m). Fraction A was the richest in soil organic carbon (7.7%), but fraction C was the dominant fraction in the total soil volume (86‒92%), making it the largest source of soil organic carbon (73%). The δ13C signature was performed to determine the existence of two different types (origins) of soil organic carbon: fresh and sedimentary. Fresh organic carbon dominates in the A fraction, while sedimentary organic carbon dominates in the C fraction and may contribute to higher structural stability, besides higher carbonates in the finest fraction. Irrigation mainly contributes to the higher stock of soil organic carbon (predominantly fresh and less sedimentary) in the coarse A fraction (21.14 t/ha in irrigated and 14.17 t/ha in non-irrigated soils).
Ključne besede: CaCO3, carbon isotopes, drip irrigation, physical fractionation, soil organic matter
Objavljeno v DKUM: 02.02.2024; Ogledov: 360; Prenosov: 19
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4. A Student’s Guide to Practical Work in Soil ScienceMateja Muršec, 2022, učbenik za višje in visoke šole Opis: The student's guide is intended for foreign students choosing Soil science subject at UM. It contains the basics of the geological composition of the lithosphere, classification, mineral composition, and recognition of various rocks. Students are guided through the use of proper equipment and methods of sampling, transportation, preservation, and sample preparation prior to further analysis. Field work and laboratory procedures for determining various physical (soil structure, texture, bulk density, porosity, soil moisture, soil colour) and chemical (soil reaction, organic matter content, nitrogen, phosphorus, and potassium content) characteristics of soil quality are described. Finally, it helps students to describe the soil profile with an accurate description of the general soil horizons and the determination of the soil type.
Ključne besede: rocks, soil quality, field work, laboratory methods, soil profile
Objavljeno v DKUM: 24.10.2022; Ogledov: 664; Prenosov: 90
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5. Agronomski in okoljski vidiki prekrivnih posevkov v ekološki pridelavi zelenjadnicMartina Robačer, 2019, doktorsko delo/naloga Opis: Cover crops can reduce the use of external inputs such as pesticides and fertilisers and can at the same time suppress weeds as well as improve or maintain soil fertility. Cover crops can also modify the microclimate which affects pest populations and diseases. Determining cover crop species and management practices is based on the needs and goals of production. The effects of introducing living mulch (LM) and management strategies on cash crop yield, product quality and energy use were studied in certain European countries (Slovenia, Italy, Germany and Denmark) in different climatic and soil conditions. In Slovenia, in organic production of cauliflower and leek, the effects of two terms of sowing white clover with additive design were compared with a production with black foil and with the usual agricultural practice by hoeing. In the field experiments the effect of LM on arthropod dynamics and activity density was investigated. The results demonstrated that the LM systems with a substitutive design, can be effectively implemented in vegetable production if the value of the ecological services (positive externalities) delivered by LM can counterbalance the yield loss due to the cash crop density reduction. If an additive design is used, the LM should be sown several weeks after the cash crop planting. Different cash crop genotypes (i.e., open pollinated/local cultivars in comparison with the hybrids) performed similarly. Use of human labor (HL) and fossil fuel (FF) energy slightly increased in LM systems (7%). The farmers’ acceptance of the LM techniques was quite high (75% of the interviewed sample). The LM technique did not affect the infestation of cabbage caterpillar Pieris spp., showing no detrimental effect of this technique on this key pest of cabbage. In Denmark, aphid populations were higher in the sole crop system than in the LM system. In Italy, a level of larval parasitization was detected and in the first year the percentage of parasitization was higher in LM (88%) than in sole crop (63%). Overall, the LM positively affected the activity density of Carabid beetles, also increasing the diversity and evenness of species (Slovenia and Italy) or activity density of some taxa (Slovenia and Denmark). Due to numerous agroecological services of cover crops, growing simultaneously with vegetables as LM, this could be promising technique for organic and others production systems in the future.
Ključne besede: organic vegetable production, cover crops, agroecological service, living mulch, energy consumption, biodiversity, soil arthropod
Objavljeno v DKUM: 01.02.2019; Ogledov: 2202; Prenosov: 281
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6. A general analytical solution to the one-dimensional consolidation problem for unsaturated soil under various loading conditionsJiwei Li, Changfu Wei, Yanlin Zhao, 2018, izvirni znanstveni članek Opis: A general analytical solution is developed for the onedimensional consolidation problem of unsaturated soil under various time-dependent loading conditions based on a differential transformation method (DTM). In particular, analytical solutions are obtained for different relationships between the coefficients in the governing equations for unsaturated soil consolidation. The Fourier series expansion technique is adopted to account for both the continuous differentiable loading and the periodic piecewise loading. A comparison between the results of the current solution and the existing theoretical solution indicates that the proposed solution yields excellent results, while it is straightforward to obtain the analytical solution of the unsaturated consolidation problems. It was also found that the variations in the coefficients in the governing equations can significantly influence the dissipation of both the excess pore-air pressure and the excess pore-water pressure, though the magnitudes of their variations are different.
Ključne besede: one-dimensional consolidation problem, unsaturated soil, analytical solution, time-dependent loading
Objavljeno v DKUM: 11.10.2018; Ogledov: 1427; Prenosov: 533
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8. Engineering properties of tropical clay and bentonite modified with sawdustIsaac I. Akinwumi, Oluwapelumi O. Ojuri, Adebanji S. Ogbiye, Colin A. Booth, 2017, izvirni znanstveni članek Opis: Construction engineers typically avoid the use of expansive soils as construction materials because they are usually difficult to work on and can cause structural failure. This research work investigates how the application of sawdust to tropical clay and bentonite influences their geotechnical properties in order to determine their suitability for use as landfill-liner materials for the effective containment of toxic substances from landfills. X-ray diffractometry, X-ray fluorescence spectroscopy and scanning electron microscopy were used to determine the mineralogical composition, oxide composition and microstructure, respectively, of the clay and the bentonite. A series of laboratory tests were conducted to determine the specific gravity, Atterberg limits, compaction, unconfined compressive strength and permeability characteristics of the clay and the bentonite for varying proportions of sawdust application. Generally, increasing the percentage of sawdust caused a reduction in its specific gravity, maximum dry unit weight and unconfined compressive strength, while it caused an increase in the optimum moisture content and permeability of the modified clay and bentonite. The clay and bentonite both have a sufficiently low permeability that satisfies the hydraulic conductivity requirement for use as clay liners. Eight percent sawdust application to a clay having similar properties as that in this study is recommended as an economic way of modifying it – with the potential of improving its adsorbent property – for use in landfill-liner systems in order to prevent the toxic substances leaching from the landfills, thereby protecting the environment and public health.
Ključne besede: geotechnical properties, hydraulic barrier, landfill, construction, soil improvement, sustainability
Objavljeno v DKUM: 18.06.2018; Ogledov: 1109; Prenosov: 153
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9. Critical setback distance for a footing resting on slopesRajesh Prashad Shukla, Ravi Sankar Jakka, 2017, izvirni znanstveni članek Opis: Structures are often constructed on slopes in hilly regions, which results in a lack of soil support on the sloping side of the footings. This causes a reduction in the bearing capacity of the footings. Though there are number of studies about foundations on slopes, most of these studies are confined to surface footings only (i.e., without the depth of embedment). Furthermore, there is no consensus in the literature over the influence of the setback distance on bearing capacity. This paper presents the results of finite-element analyses on a strip footing resting on stable slopes. A very large number of possible soil slopes with different footing depths were analysed. From the results it is found that the critical setback distance increases with an increase in the internal friction angle of soil, the depth of the footing and the slope gradient. The critical setback distance is varying between 2 to 4 times the footing width for soils with a low internal friction angle, while it is more than 10 times the footing width for soils with a higher internal friction angle. A regression equation is also developed based on the outcomes of the study. The developed equation is able to predict the influence of various parameters affecting the bearing capacity of a footing resting over the slopes. The results are compared with earlier experimental and numerical studies.
Ključne besede: bearing capacity ratio, cohesionless soil, footing, setback distance, slopes
Objavljeno v DKUM: 18.06.2018; Ogledov: 1316; Prenosov: 255
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10. Numerical study of the dynamic active lateral earth pressure coefficient of cohesive soilsMehrab Jesmani, Hossein Alirezanejad, Hamed Faghihi Kashani, Mehrad Kamalzare, 2017, izvirni znanstveni članek Opis: Retaining walls are proposed in many projects, such as bridges, coastal structures, road constructions and wherever lateral support is required for the vertical surface of an excavation. The active lateral pressure coefficient of soil, Ka , is an important parameter for studying the static and dynamic behaviors of these retaining walls. Many studies have evaluated this coefficient in static situations, but in most previous dynamic studies, researchers have worked on the behavior of cohesionless backfill soil or made simplifying assumptions (e.g., pseudo-static status) for cohesive soils as backfill soil. In this study, the size of the active lateral earth pressure coefficient (Ka) was studied in a full dynamic situation (Kae). A retaining wall with cohesive backfill soil is evaluated using the finite-difference method (FDM) and the effects of important soil and loading properties are assessed. The model is based on Mohr-Coulomb failure criteria under seismic loading. The results show that the value of Kae at the top of the wall, where it is highly sensitive to any variation in the soil and loading properties, is greater than one due to the high pressure value induced by the horizontal dynamic acceleration and the presence of tension cracks.
Ključne besede: dynamic active lateral earth pressure coefficient (Kae), cohesive backfill soil, finite difference method (FDM), tension cracks, retaining wall, seismic loading
Objavljeno v DKUM: 18.06.2018; Ogledov: 1546; Prenosov: 108
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