The objective of the research is to determine optimal method of irrigation, irrigation regime, and background of mineral nutrition for bulb onion in the South Steppe of Ukraine. The study was carried out in 2008–2010 at the fields of experimental farm in the Kherson region. Soil cover in the farm was relatively homogeneous. Soils in the experimental sites were south chernozems with sandy loam texture. The depth of humus layer was up to 56 cm and humus content was 1.2–1.5 %. Method of irrigation (rainfed, drip irrigation, micro-sprinkler), the level of pre-irrigation threshold of root-inhabited soil layer (80–70–70 % of field capacity (FC), 90–80–70 % of FC), and the level of mineral nutrition (without fertilization, calculated doses for the yield of 60, 80, and 100 t/ha) were included in the scheme of multifactor experiment. It was found that maximal bulb onion yield 90.53 t/ha was obtained at the background of micro-sprinkler irrigation. In average it was greater by 2.75 t/ha (4.8 %) comparing with drip irrigation and in 3.6 times with the variant without irrigation. Minimal coefficients of water consumption were in the variants maintaining pre-irrigation threshold 90–80–70 % FC (52.9–154.8 m³/t). Growing onion without irrigation provided coefficient of water consumption 188.8–260.0 m³/t. Applying of mineral fertilizers at the background of irrigation facilitated to decreasing of this indicator from 150.5–162.9 m³/t, when onion were grown at non-fertilized plots, to 52.6–56.4 m³/t in the variants with calculated dose for the yield of 100 t/ha. The average uptake of onion plants for the yield of 10 t of bulbs was 44.6 kg of nitrogen, 12.4 kg of phosphorus, and 21.5 kg of potassium.
Keywords: bulb onion, water consumption, yield, uptake of nutritive elements, fertilizing dose, irrigation method.
