One of the main objectives of crop establishment is adjustment of physical properties of soil, on which indicators of soil fertility as well as economic appreciation of the resulting yield depend. During 2014–2016 yield of corn and sorghum was observed in semi‑operational experiments of ZD Budišov in relation to the quantity of the applied digestate and simultaneously, the following physical properties of soil were analysed: porosity, compaction and soil structure. After the application of digestate the porosity and minimal air capacity decreased, and reduced bulk density increased. Soil structure was affected negatively too. Overall, a trend of degradation of physical state of soil in variant with doubled dose of applied digestate was registered. Yields were always higher in variants with digestate due to a higher supply of higher amount of nutrients. Results of this observation indicate that crop yields may be higher but at the same time physical properties of soil may be impaired which may, while increasing doses of digestate, lead to irreversible degradation of soil.

DOBEK TOMASZ K., RYNKIEWICZ MAREK, ČERVINKA JAN, MAREČEK JAN: Energy and economic eff ectiveness of winter rape and winter wheat cultivation for liquid biofuel production. Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis, 2013, LXI, No. 5, pp. 1255-1259 Aim of this study was an analysis and assessment of the economy and energy eff ectiveness of winter wheat and winter rape cultivation for liquid biofuel production. The cost of production and economical eff ect index is more profi table in case of winter rape. Also the fi nal balance of energy eff ectiveness has shown better values if the biodiesel had been produced from winter rape as compared with bioethanol from winter wheat. Calculation of the obtained products and their comparison with an energy unit has shown that the netto energy from biodiesel was positive while that from bioethanol was negative, which means that in the latter case expenditure is greater than that gained in the produced biofuel.biodiesel, bioethanol, production cost, energy input, labour input, energy eff ectiveness, fuel use Study possibility of using agricultural row materials for energy needs has been taken for several years (Mokrzycki, 2005). Processing biomass to energy has got a lot of advantages such as reduction of chemical compound emission, greenhouse eff ect reduction, and biodegradation. An important advantage of this type of fuel is its possibility of continuity of its production (it is possible to renew this type of fuel). The cost of biofuel production is determinated by raw materials price. The price of raw materials depends on technologies and allocation system for agriculture. Costs of production of the most known liquid fuels such as bioethanol, rape's ester are about 2.4-2.6 times higher than costs of production of mineral fuels. However, decreasing of natural energy recourses (gas, oil, coal) causes that people are more interested in this type of energy. An important component of valuation of fuel's production, besides costs, is an energy eff ectiveness calculation. The energy eff ectiveness calculation shows how much energy must be used to get biofuel energy unit (Dobek, 2004). The advantage of energy eff ectiveness calculation is its independence of prices. Independence enables to compare the results.An aim of a study was to evaluate a technology of winter wheat and winter rape production, to evaluate processing agricultural products into biofuels and to count energy and economical eff ectiveness coeffi cients of biodiesel production from winter rape and of bioethanol production from winter wheat. MATERIALS AND METHODSStudies were made in 2010−2012 on agricultural farms placed on the terrain of north-western Poland. In winter rape production traditional technology of cultivation was used (moldboard plough and disc harrows), in secondary tillage compactor was used. Fertilizer application was done three times by using trailed fertilizer distributor. Seeding was done by using multipurpose drill. During a vegetation season spraying was done...

Within the period of 2008–2011, changes in soil structure were studied in two selected localities: one of them was situated in vineyards of the University Training Farm of Mendel University in Žabčice near Brno, the other was in vineyards situated in the cadastre of wine-growing municipality Velké Bílovice. Established were altogether three variants of experiments with application of crushed grapevine wood (chips): Variant 1 – control; Variant 2 – crushed grapevine wood ploughed down to the depth of 0.10 m; Variant 3 – crushed grapevine wood + grass spread on the soil surface as a mulch. Grapevine canes were crushed to chips using a special agricultural machinery while the soil in inter-rows was processed using conventional tilling machines. The obtained results showed that the best coefficient of structurality (expressing the degree of destruction of soil structure) was recorded in Variants 2 in both localities. Considering values of this coefficient it could be concluded that just this variant showed a positive effect on soil structure. This variant reduced the compaction of soil caused by the movement of agricultural machines in vineyard inter-rows Crushed grapevine waste wood can therefore compensate losses of organic matter in soil. Better values of structurality coefficient were recorded in the locality Žabčice.

Abstract. The significance of the influence of operating propellers on the aircraft aerodynamic characteristics is well-known. Wind tunnel testing of an airplane model with operating propellers is a complex task regarding the required similarity of the full-scale and the model case. Matching sufficient similarity in axial and rotational velocities in the propeller slipstream is the primordial condition for the global aerodynamic similarity of the windtunnel testing. An example of the model power units with related devices is presented. Examples of the wind tunnel testing results illustrate the extent of the propeller influence on aerodynamic characteristics of an aircraft of unconventional configuration with power units positioned at the fuselage afterbody.

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