In a one-year vegetation pot experiment we compared the effect of the digestate from a biogas station and mineral fertilisers on yield and quality parameters of kohlrabi, variety Seguza. Four treatments were used in the trial: 1) untreated control, 2) urea, 3) digestate, 4) urea, triple super phosphate, KCl, MgSO4. The rate of N was the same in treatments 2–4, 1.5 g N/pot. In treatment 4 the rate of P, K and Mg corresponded with the rate of these nutrients in the digestate treatment (3). The weight of single bulbs of the control unfertilised treatment were significantly the lowest (22.9%), as well as the nitrate (6.0%) and ascorbic acid content (66.2%) compared to the urea treatment (100%) and the other fertilised treatments. After the application of the digestate (treatment 3) and mineral fertilisers (treatment 4) the weight of single bulbs significantly increased by 27.9 and 29.2%, respectively, compared to the urea treatment (2). The content of ascorbic acid in the fertilised treatments did not differ (772–789 mg/kg) but it increased significantly compared to the unfertilised treatment (511 mg/kg). There were no significant differences between the two treatments fertilised with mineral fertilisers in the bulb nitrate content (678 and 641 mg NO3−/kg fresh matter, respectively). After digestate application their contents decreased significantly to 228 mg NO3−/kg fresh matter. Digestate treatment resulted in comparable or better yield and qualitative parameters compared to treatment with mineral fertilisers.

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In a one-year vegetation pot experiment, we compared the effect of digestate from a biogas station and mineral fertilisers on yield and quality parameters of kohlrabi, variety Segura F1. Four treatments were used in the trial: 1) untreated control, 2) urea, 3) digestate, 4) urea, triple super phosphate, KCl, MgSO4. The N dose was the same in treatments 2–4, 1.5 g N/pot. In treatment 4 the P, K and Mg doses corresponded to those supplied in the digestate treatment (3). The weight of single kohlrabi bulbs in the unfertilised control was significantly lower (36.2%) than in the urea treatment (100%) and the other fertilised treatments. After application of digestate (treatment 3) and mineral fertilisers (treatment 4), the weight of single bulbs significantly increased by 36.2 and 33.6%, respectively, compared with the urea treatment (2). The content of ascorbic acid did not differ between the fertilised treatments (282–301 mg/kg), but was significantly lower than in the unfertilised control (334 mg/kg). There were significant differences between all fertilised treatments (2, 3, 4) in bulb nitrate content (745, 187, 462 mg NO3−/kg fresh matter, respectively). After digestate application the content decreased significantly, to 187 mg NO3−/kg fresh matter. The soil Nmin content after harvest varied between 4.19–5.79 mg/kg in all fertilised treatments and the N-NH4+ form prevailed over N-NO3− only in the digestate treatment (3.45/2.34 mg/kg). We recommend the use of digestate to kohlrabi as it results in comparable or better yield and qualitative parameters of kohlrabi compared with mineral fertilizers.

Brunensis, 2013, LXI, No. 6, pp. 1769-1777 Water sorption tests of Roselle (Hibiscus sabdariff a L.) carried out under laboratory conditions are presented together with mathematical analyses of the moisture sorption isotherms (MSI's). Moisture equilibrium data for adsorption and desorption of water from Roselle powder were investigated at near ambient air temperatures in the range of 5 and 35 °C and water activity (Aw) ranging from 0.11 to 0.97. The manometric method has been used for water sorption tests. Models for MSI's are exponential equations. Coeffi cients of determination are 0.998 and 0.996 (for adsorption and desorption at 5 °C, respectively), 0.998 and 0.999 (for adsorption and desorption at 20 °C, respectively), and 0.998 and 0.999 (for adsorption and desorption at 35 °C, respectively). The equilibrium moisture content (EMC) of Roselle samples increased with an increase of Aw at a constant temperature both for adsorption and desorption. Adsorption curve equates to desorption curve at higher temperatures of tests carried out. Critical values of EMC of samples tested corresponding to the Aw equal to 0.6 were between 13.401% moisture content wet basis (MC w.b.) and 15.934% MC (w.b.) for moisture adsorption and desorption, respectively. These values are useful for storing conditions optimisation from point of view microorganisms grow and structural changes analyses. Crystal structure changes were observed during adsorption and desorption in the microscope, too. It was found out glass transition in dependence on the water content of samples tested.water activity, equilibrium moisture content, hysteresis, prediction, grow of microorganisms, glass transition Roselle (Hibiscus sabdariff a L.) belongs to the family Malvaceae. It originated in India and it is widely distributed in tropical and subtropical regions as a potential new food crop of considerable economic potential. Roselle is a short-day annual erect shrub and can grow to a height of 1-3 m, depending on the species. Its calyces have been suggested for the production of so drinks, Roselle tea, jam, juices, and natural food colourants (Chen et al., 2005;Chang et al., 2012). The extracts of calyces and leaves of Roselle show a signifi cant antihyperlipidemic activity (Ochani and D'Mello, 2009).Roselle calyx (Fig. 1) is usually harvested at high MC (w.b.), 85%. Therefore, drying is an important postharvest treatment prior to reduce the MC and to increase the shelf life. Moreover, the main purpose of drying the products is to minimize packaging requirements, to prolong the shelf life and to reduce shipping weights (Vengaiah and Pandey, 2007). Tab. I shows the chemical composition of Roselle calyces (Babalola et al., 2001).

Konrád Z., Los J., Fryč J., Kudělka J., 2014. Analysis of using brewery mash for energy. Res. Agr. Eng., 60: 10-16.In contrast to waste in a full sense of the word, brewery mash is not considered as waste nowadays but rather as a material for various kinds of use. It can be fed to animals or processed to produce biogas. Various scientific and state institutions conduct experiments to find other possibilities of its use. Our experiment was focused on analysing the energy potential of this material.