Iskanje po katalogu digitalne knjižnice

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: 368
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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: 79
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Opis: The field experiment aimed at determination of influence of autumn harvest on rhythm of the growth of lucerne (Medicago sativa L.) and yield quality of the first cut in the following year was carried out in Spodnji Gabernik (258 m above sea level, 46°15′54.94″ N and 15°34′6.05″ E), in the fourth growth year of the lucerne variety ‘Soča’. The experiment was designed as a randomized block in four replications. The individual treatments represented weekly autumn cuttings (1) 24/9/2014, (2) 01/10/2014, (3) 08/10/2014, (4) 15/10/2014 and (5) 22/10/2014. The paper presents data associated with the amount of lucerne dry matter yield (DMY) per treatment compared with the DMY of the first spring cut in the year 2015 (18/05/2015). The growth rhythm of lucerne in each treatment, which took place before the first cut in year 2015, was based on the measurements of the height of the plants. The yield quality was evaluated by NIRS method for determination of crude protein (CP), the net energy of lactation (NEL) and metabolic energy (ME) in dry samples regarding to DMY of each treatment. In autumn 2014, statistically significant higher dry matter yields were obtained in later harvested treatments (5 and 4). Similarly, in spring 2015 the trend of higher crop dry matter yield was observed in treatments harvested later in the autumn of 2014. However, the differences were not significant. Statistically significant differences between treatments were acquired within CPY, NELY and MEY. Before the first mowing, in spring 2015, statistically significant trend of higher plants was also detected in treatments with later cutting in 2014.
Ključne besede: Medicago sativa, cutting regime, growth rhythm, dry matter yield
Objavljeno v DKUM: 14.11.2017; Ogledov: 1940; Prenosov: 400
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Opis: Understanding the relationship between interest rates and term to maturity of securities is a prerequisite for developing financial theory and evaluating whether it holds up in the real world; therefore, such an understanding lies at the heart of monetary and financial economics. Accurately fitting the term structure of interest rates is the backbone of a smoothly functioning financial market, which is why the testing of various models for estimating and predicting the term structure of interest rates is an important topic in finance that has received considerable attention for many decades. In this paper, we empirically contrast the performance of cubic splines and the Nelson-Siegel model by estimating the zero-coupon yields of Austrian government bonds. The main conclusion that can be drawn from the results of the calculations is that the Nelson-Siegel model outperforms cubic splines at the short end of the yield curve (up to 2 years), whereas for medium-term maturities (2 to 10 years) the fitting performance of both models is comparable.
Ključne besede: Cubic splines, Nelson-Siegel, yield curve, zero-coupon bonds, term structure of interest rates
Objavljeno v DKUM: 14.11.2017; Ogledov: 1561; Prenosov: 371
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Opis: Prediction of the expected milk yield is important for the management of the primiparous cows (PPC) with a few or no data on their own milk productivity. We developed a system of regression equations for predicting milk yields in standard lactation. The models include the systematic effects of the calving season, the five-year rolling herd average of milk yield of PPC, the breeding values of the parents for milk production, and daily milk recordings. A total of 21,901 lactations of Holstein PPC were collected during the regular monthly milk recordings of cows in the Republic of Slovenia. By including daily milk recordings in the model, the coefficients of determination of regression models for the prediction of milk yield increase: without known recordings (M0) R 2 =0.80; with one recording (M1) R 2 =0.82; with two first consecutive recordings (M2) R 2 =0.86; and with three recordings (M3) R 2 =0.89. Deviations of milk yield up to 500 kg in a standard lactation (<1.6 kg/day) were as follows: with the model M0, they occurred in 53.4% of PPC; with M1, they occurred in 56.3% of PPC; with M2, they occurred in 64.5% of PPC; and with M3, they occurred in 70.9% of PPC. We concluded that the developed system of regression models is an appropriate method for milk yield prediction of PPC.
Ključne besede: primiparous cows, milk yield, prediction, lactation curves, regression equations
Objavljeno v DKUM: 24.07.2017; Ogledov: 1364; Prenosov: 494
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