• Energy Research

The paper assessed the topicality and returns of solar system utilization to heating of water. Practical measurements were conducted after reconstruction of the family house. (in Nesvady, Slovak republic), on which the solar system were assembled. The system consists of the gas heater, solar panels, distributions and circulation pump. The solar system was assembled due to decreasing of operation costs and connected with conventional already used gas heating system by boiler Quantum (V = 115 L). The conventional system was used for 21 days to gather basic values for evaluation. At this point it was observed that 11.93 m3 of gas is needed to heat up 1 m3 of water. Used water in this case was heated from initial 16.14 °C to 52.04 °C of output temperature. Stand by regime of boiler was characterized by 0.012 m3.h-1 consumption of gas. The rest of the measurements represent the annual (from 03/2013 to 02/2014) operation process of boiler Tatramat VTS 200L (trivalent) with 200 litres of volume (as a part of Thermosolar solar system). The solar collectors TS 300 are also part of the solar system. An input and output temperatures of heating water we observed along with water and gas consumption, intensity of solar radiation and actual weather conditions. The amount of heat produced by solar system was then calculated. Total investment on solar system were 2,187.7 € (1,475.7 € with subsidy). Therefore, return on investment for the construction of the solar system was set at 23 years even with subsidy.

The study deals with the use of energy crops for the production of thermal energy in the form of briquettes and devising appropriate parameters for their production. Briquettes were produced from seven kinds of energy crops, Salix viminalis, Miscanthus sinensis, Rosa multiflora, Polygonum sachalinensis, Helianthus tuberosus, Sida hermaphrodita and Spartina pectinata, specifically. In the production of briquettes, moisture is the most important properties of material to be pressed, which ranges from 8 to 15 % as it was observed. At a higher humidity it has not been possible to produce briquettes farther in the study conditions. Another important condition for the successful production of briquettes was the particle size of chopped mass. The optimum particle size range from 8 to 20 %. The briquettes were pressed at a pressure of 21 MPa and with diameter of 50 %. Subsequently, physical and mechanical properties (density, moisture, mechanical resistance) and chemical properties (chlorine, iron, nitrogen, calcium, ash, lignin content) were measured. The briquettes density reached from 800 to 900 kg.m−3 with calorific value from 14 to 19 MJ.kg−1 which refers to fact that energy crops are competitive to fossil fuels by their calorific value.

In recent years, research has focused on verifying various ways of dosing organic matter into the soil in Central European conditions. The main reason for this is to search for the optimal management methods for soils with permanent vegetation. In this article, we state and evaluate the results of experiments carried out at the Lednice experimental site (Sauvignon Blanc variety) and the Velké Bílovice experimental site (Pinot Gris variety) between 2018 and 2020. The experiments evaluated the deep placement of compost and compost enriched with lignohumax at a rate of 30 t·ha−1 in the areas around vineyard tree trunks on the basic physical properties of the soil and the yield and quality of grapes. Results proved the positive effect of compost heaps and compost combined with the applied lignohumax on improving soil density (2–10% difference compared with the unfertilized reference variant) and porosity, which ultimately resulted in improved soil moisture conditions at both experimental sites (8–25% difference compared with the unfertilized reference variant). At the same time, the results demonstrated the positive effect of the applied compost and the chosen method of application on the yield and quality of grapes. In the case of Sauvignon Blanc, the increase in yield in the fertilized variants was 12–34%, while, in the case of Pinot Gris, it ranged from 24 to 33%. Among qualitative indicators, the grapes of both varieties were evaluated for sugar content, total acidity, pH, and amount of yeast assimilable nitrogen. In this case, results were not unambiguous in favor of fertilized variants; however, in most cases, fertilization had a positive effect.

Infiltration is defined by the expression of the hydraulic conductivity of the soil, which we decided to monitor on an experimental field applying a modern system of land management (control traffic farming). The present study compared two different methods of monitoring the hydraulic conductivity of soil on a selected 16 ha plot of land in the suburbs of the village Kolíňany (Slovak Republic). During the growing seasons, crops such as oilseed rape, winter wheat, spring barley, winter barley, spring peas, and maize alternated in individual years. In addition to the study of hydraulic conductivity, a long-term experiment is underway to investigate the influence of technogenic factors on soil degradation using a system of controlled movement of machines in the field. A mini disk infiltrometer (method one) was used to evaluate the unsaturated hydraulic conductivity of the soil, and a double ring infiltrometer (method two) was used to measure the saturated hydraulic conductivity. Monitoring changes in soil infiltration capacity within the compacted and uncompacted lines required 26 monitoring points (20 for method one and 6 for method two). The first longitudinal line was compacted by an agricultural machinery chassis, and the second line remained uncompressed. The research also created transverse compacted lines at eight monitoring points (six for method one and two for method two). The results did not show a statistically significant difference when examining the effect of soil infiltration monitoring (compacted p = 0.123; uncompacted p = 0.99). When evaluating the statistical dependence on the compression caused by machinery in the track line, the hypothesis of significance was not confirmed (p = 0.12, at the level of 0.05). However, the results showed variability in the value of the difference factor between the two methods, ranging from 0 to 0.24. On average, it can be concluded that the results achieved using the double ring infiltrometer were 4.16 times higher than those measured with the mini disk infiltrometer. The variability of hydraulic conductivity was demonstrated not only in the compacted but also in the non-compacted part of the plot. In some places, the phenomenon of water repellency appeared, which could be caused by the drier location of the targeted plot.