SummaryIn the years 2005-2007, a study was carried out to investigate the effect of surface and subsurface drip irrigation on the yield of witloof chicory in flatground and ridge cultivation. Irrigation began at a soil water potential of 30-40 kPa. Irrigation was found to have a beneficial effect on the yield and quality of the roots of witloof chicory. The largest increase in yield was obtained in the first year, in which there was a drought during sprouting and scarcity of rainfall during vegetative growth. In flat-ground cultivation, and in the year with insufficient soil humidity in ridge cultivation, surface irrigation was more beneficial in comparison with subsurface irrigation because it created better conditions in terms of moisture levels, particularly for the germinating seeds. In the years with sufficient rainfall during germination and sprouting no significant differences were found in the yield of chicory roots between surface and subsurface irrigation.Chicory plants were forced hydroponically in water using a standard nutrient solution. The roots obtained from irrigated plots, as well as those from flatground cultivation, produced significantly longer and tighter chicons. Over the three years of the study, internal browning of the stem, which is a physiological disorder lowering the quality of chicons, occurred only in 2005. It might have been caused by high temperatures during sprouting and high moisture deficiency in the soil during vegetative growth. The use of irrigation significantly reduced the incidence of this phenomenon, especially in flat-ground cultivation.

Pelletized plant-based fertilizers Ekofert K (red clover) and Ekofert L (lucerne) was compared to non-fertilized control and mineral N-fertilization (100 kg N ha-1) in sustainable onion cultivation (2012-2013). The organic fertilizers at pre-plant rates equivalent to 120, 180 and 240 kg N ha-1 were applied on a field fertilized with compost (25 t ha-1). The fertilizers Ekofert K and L significantly increased onion production as compared to the basic fertilization with compost alone. The increase in yield was favorably correlated with the applied fertilizer rates. The lowest rate of organic fertilizers ensured a yield at the level of mineral fertilization at the rate of 100 kg N ha-1 as single application. The higher rates of Ekofert K and L (180, 240 kg N ha-1) resulted in a marketable yield increase relative to single mineral fertilization. The use of organic as well as mineral fertilization increased nitrogen and chlorophyll contents in onion leaves, compared to the non-fertilized control treatment. The increase was positively correlated with fertilizer rates. The N-NO 3 content in onion bulbs was in general not influenced by the application of organic fertilizers, compared to non-fertilized control treatment. Nitrogen content in the top soil (0-30 cm) was the highest after 5 weeks from incorporation of the fertilizers and diminished in following 4 weeks on average by 46% due to plant development and intensive nutrient uptake. After onion harvest, continued mineralization of soil organic matter and lack of uptake by plants increased average nitrogen content nearly to the level at stage of early plant growth. The N-NO 3 content in soil increased with rates of the Ekofert fertilizers. In subsoil horizon (30-60 cm), the N-NO 3 content was 2.5 times lower than in topsoil and significant only for the highest rate of the fertilizers.

Determination of the Optimal Nitrogen Content in a Fertigation Medium for the Greenhouse Cucumber Grown on Slabs of Compressed StrawIn the years 2004-2008, research work was carried out whose aim was to determine the optimal nitrogen fertilization dose for greenhouse cucumbers grown on mats made of compressed, finely shredded straw. In the experiments, the short-fruited variety of the greenhouse cucumber, Milenium F1, was used. The level of nitrogen in the nutrient solution was varied in the range of 200-350 mg·dm-3. The nitrogen content in the solution in the amount of 200 mg·dm-3was not sufficient and caused the cucumber yield to fall. The increasing N concentrations in the medium were found to have a significant effect on the nitrogen content in the indicator parts of cucumber plants. The highest nitrogen content was found in the plants fertilized with a nutrient solution containing the highest concentration of N-NO3, which was 350 mg·dm-3. Cucumber plants grown on straw need to be more intensely fertilized with nitrogen for about 1/3 of the growing season, and then to have its level in the fertigation medium reduced for the remaining part of the cultivation period.

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