Iskanje po katalogu digitalne knjižnice

Opis: The study aimed to investigate the effectiveness of biochar application on fertile soils in a temperate climate during the first year of application. The field trial was conducted on a nutrient-rich silt loam soil at two experimental sites in north-eastern Slovenia (Biš and Skorba). The effect of biochar applied alone or in combination with compost or mineral fertiliser on soil properties and yield of white cabbage was studied. In addition to the control (C), the soil received five treatments including biochar (B; 1.5 t/ha), compost (CO; 1.5 t/ha), biochar-mixed compost (BCO; 3.0 t/ha), standard mineral fertilisers (NPK; NPK 0.35 t/ha, potassium sulphate 0.25 t/ha and calcium ammonium nitrate 0.25 t/ha) and combined application of half the amount of NPK and BCO (NPK+BCO). The results showed that the applied treatments had no significant influence on the measured soil chemical parameters, except for the amount of total organic carbon, electrical conductivity and pH in Biš and total carbon in Skorba. All investigated parameters (cabbage head weight, head circumference, total and market yield) were higher at the experimental site Skorba. Statistically significant differences were found only at the experimental site Biš, where the treatment influenced all parameters (p < 0.01), except for the head circumference of the cabbage. The NPK and NPK+BCO treatments produced significantly higher total yields (66.7 t/ha and 65.8 t/ha, respectively) and marketable yields (53.2 t/ha and 51.8 t/ha, respectively) compared to the other treatments (41.3-52.6 t/ha and 30.5-42.4 t/ha, respectively). Although the differences between the other treatments were insignificant, a trend of decreasing cabbage yields towards CO > BCO > B was observed. Similar results were also obtained when analysing the average data of the two experimental sites.
Ključne besede: biochar, soil amendments, fertilisers, soil chemical properties, cabbage yield
Objavljeno v DKUM: 23.04.2025; Ogledov: 0; Prenosov: 0
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Opis: The objective of this work was to investigate the fracture behavior of a heterogeneous I-shaped welded joint in the context of yield load solutions. The weld was divided into two equal parts, using the metal with the higher yield strength and the metal with the lower yield strength compared to base metal. For both configurations of the I-shaped weld, one with a crack in strength in the over-matched part of the weld and one for a crack in the under-matched part of the weld, a systematic study of fracture toughness SE(B) specimen was carried out in which the crack length, the width of the weld and the strength mismatch factor for both weld metals were varied, and the yield loads were determined. As a result of the study, two mathematical models for determination of yield loads are proposed. Both models were experimentally tested with one strength mismatch configuration, and the results showed good agreement and sufficiently conservative results compared to the experimental results.
Ključne besede: yield load, heterogeneous weld, numerical analysis, SE(B) specimen
Objavljeno v DKUM: 21.03.2025; Ogledov: 0; Prenosov: 2
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Opis: Optimal planting speed of vacuum maize planters is usually suggested by planter’s manufacturers, while increased planting speed may influence plant spacing and finally yield. Our hypothesis was that by increasing planting speed over the suggested level plant spacing variability will also increase which will result in decrease of silage and grain yield and saving of seed and energy. The field trial consisted of three planting speeds of 7, 9 and 11 km/h in the form of random blocks. The following measurements were taken as follows: plant spacing, silage and grain yield, fuel and energy use at planting. Results in this study show that planting speed did not have significant influence on silage and grain yield of maize, while up to 10% less seed was needed per hectare and fuel and energy use was lower for 15%. By the increase of planting speed the distance between the plants in a row, and in most cases also the plant spacing variability increased. It was noticed that by increasing planting speed plant density decreased. This research established that at higher planting speeds significant increase of the silage yield per individual plant and of the grain yield per individual plant was achieved. The ear parameters also show that the kernel mass per individual ear, the ear mass, and the cob mass, as well as the individual kernel mass, are larger at the planting speed of 11 km/h than at the planting speed of 7 km/h. At the latter planting speed, significantly higher fuel consumption per hectare and higher energy use was achieved than at the other two planting speeds. Overall the main benefits of planting speed of 11 km/h is saving seed and energy at planting while maintaning the same level of silage and grain yield compared to lower planting speeds used in the trial.
Ključne besede: energy use, grain yield, maize, planting speed, plant spacing, seed savings, silage yield, vacuum planter
Objavljeno v DKUM: 11.03.2025; Ogledov: 0; Prenosov: 4
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Opis: In 2013 and 2014, a long-term trial (which was established in 2007) was conducted at the University Agricultural Centre in Pivola near Hoče. It included different production systems (conventional, integrated, organic, biodynamic), carried out in a field trial with oil pumpkins. The aim of the research was to analyse the effects of different production systems, varieties (hybrid and population variety) and years of production, on formation of oil pumpkin yields. The agricultural practice has been carried out in accordance with the applicable legislations and standards for the individual production system. When sowing, before fertilizing with nitrogen in early June and after the harvest, the amount of soil mineral nitrogen was monitored. We evaluated the number and weight of harvestable, unripe and decayed fruits, and yield of oil seed pumpkins and calculated the agronomic efficiency of the applied nutrients. The results showed that the year of production, the production system and the variety have a significant effect on some fruit characteristics and the yield of oil pumpkin seeds. The content of soil mineral nitrogen in May and September was significantly influenced by the production system and the year. In June, only the production system had a significant effect. The hybrid significantly increased the yields of oil pumpkin seeds in all production systems, even in the year that was less suitable for production. The agronomic efficiency of the applied nutrients in the biodynamic and organic production system is higher or equal than in the conventional production system, similarly, agronomic efficiency is higher in the hybrid compared to the oldest population variety efficiently. A comparable oil pumpkin yield can be expected in biodynamic and organic production, when proper nutrition and well carried out cultivation practices are combined with a new variety, when compared to less sustainable production systems, which often cause damage to the environment.
Ključne besede: production systems, variety, oil pumkins, mineral nitrogen, agronomic efficiency, yield
Objavljeno v DKUM: 10.10.2018; Ogledov: 2139; Prenosov: 385
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Opis: Subaqueous, fine-grained, cohesive sediments are continuously fluidized by waves and other disturbances that cause their movement, which can be described with numerical models incorporating rheological parameters. The rheological behaviour depends on the soil (solid) type, the volume concentration, the salinity and the testing methods. In this study, rheological investigations of marine sediments from the Port of Koper were carried out by using two coaxial cylinder rheometers (DV3T HB, Brookfield and ConTec Viscometer 5). The influence of the specimen volume, the size of the gap and the type of measuring spindles were analysed and compared. The measured data were evaluated using the Bingham model. For each data set, the boundary between the sheared (“fluid”) and the un-sheared (“solid”) material was calculated and then the calculated boundary was used instead of the outer radius of the cylinder for the evaluation of the rheological parameters, where necessary. A good comparison of the results was found when using this approach. The results are also in agreement with the literature data. The ConTec Viscometer 5, primarily designed for mortars and concrete, was shown to be also suitable for the investigation of sediments.
Ključne besede: marine sediments, Bingham model, yield stress, plastic viscosity, coaxial cylinder rheometer, plug flow, Bay of Koper
Objavljeno v DKUM: 18.06.2018; Ogledov: 1252; Prenosov: 83
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