Peculiarities of formation the grain productivity of spring barley depending on terms and norms of foliar fertilization.

One of the ways to improve the nutritional conditions of plants and therefore increase the productivity of agrocenoses of spring cereals, is the use of mineral fertilizers, both in their main application and in the spring fertilization of vegetative plants. And that is why the purpose of study was to improve agro-technical measures for growing spring barley, which would be based on the use of biological potential of the crop and the use of resource-saving technologies in the Northern Steppe of Ukraine. The study was conducted at the Erastivka Experimental Station of SI Institute of Grain Crops of NAAS during 2017–2019, according to generally known methods. Soil of experimental field – ordinary chernozem, low-humic, loamy. The humus content in arable soil layer (0–30 cm) – 4,0–4,5 %, total nitro-gen – 0,23–0,26 %, phosphorus – 0,11–0,16 %, potassium – 2,0–2,5 %, pH of water extract – 6,5–7,0. Field experiments were laid in six-field crop rotation after predecessor winter wheat. In experi-ments seeded spring barley of variety Stalker with seeding rate 4,5 million of grains/ha. Soil prepara-tion, sowing, care of crops and harvesting were carried out strictly according to the zonal recommendations. Variants in a field experiment designed systematically, with three replications. Accounting plots area – 25 m2. Arid conditions of Ukraine’s Steppe zone is quite complex. Two-thirds of land in Ukraine referred to zone of risky agriculture, but even here you can use 30–50 % and more of varieties capacity, in consideration of importance the local gene pool in creating highly adapted varieties based on local varieties and using the developed agrotechnical growing measures, that promotes plants to be resistant to dry conditions of Steppe zone of Ukraine. Weather conditions during the investigation were different, which made it possible to fully assess its impact on grain productivity potential of spring small cereals. Phenological observations, analysis of yield structure elements and grain productivity of spring barley of variety Stalker when grown without fertilizers and fertilizing with N30P30K30 as well as the use of different terms and doses of foliar fertilization of plants with ammonium nitrate and humic preparation humisol plus in conditions of Steppe zone of Ukraine are presented. It was found that the growth, development and formation of productivity elements of spring barley plants were significantly influenced by the timing and dosing of fertilization. Earlier fertilization of plants with ammonium nitrate and humisol plus, carried out on seedlings and in the tillering phase, contributed to better plant growth and development, formation of productive tillering and yield structure elements, compared with fertilization in the phase of stem elongation as in the variant of fertilized background (N30P30K30), as in the variant without the using of mineral fertilizers. Key words: spring barley, mineral fertilizers, foliar fertilization of plants, elements of head structure, grain yield.