Abstract
A.O. Rozhkov, S.S. Spilnyk, O.V. Gepenko, N.O. Didukh, I.O. Derevyanko and S.V. Stankevych*
Because of the high costs of fertilizers and the exacerbation of environmental problems, it is crucial not only to determine doses and timing of fertilization correctly but also to improve the absorption and assimilation of nutrients by plants. This will increase plant growth and development management efficiency and contribute to the fuller realization of the genetic potential of their performance that can be achieved only through a balanced selection of fertilizers. Simultaneously, it should be noted that for spring, barley long-acting fertilizers should be applied as essential fertilization in autumn and fast-acting ones – as supplementary foliar fertilization with soluble complexes. Combinations of these two types of fertilization ensure a highly efficient nutrition and cultivation technology in general. Our purpose was to study the complex influence of essential mineral fertilizers and foliar supplementary fertilizers (various mixtures of urea, water-soluble complex fertilizers, and humic compounds) on the grain yields and economic indicators of spring barley production in the southern steppe of Ukraine. The study was conducted in the Educational and Experimental Farm of the separate structural subdivision “Novokakhovskyi Professional College of the Tavriia State Agrotechnological University named after Dmytro Motorny” (the central part of the Kakhovkyi Raion, Khersonska Oblast) in 2018–2020. According to the conventional method, the two-factor experiment was performed in segregated plots arranged in two bands in four replications. We studied five variants of essential mineral fertilization and five variants for supplementary foliar fertilization. The plot area was 120 m2; the recording area was 80 m2. Various temperatures and significant fluctuations in the precipitation amount and its distribution during the spring-summer vegetation of spring barley greatly influenced the growth processes in plants, which significantly affected the grain yield. Simultaneously, this made it possible to more fully determine the impact of the studied nutrition variants on the grain yield of this crop. The highest gain in the spring barley grain yield was achieved due to the primary application of complex fertilizer polyphosphate at a dose of N20P60K60S22.5. However, through the lens of economic efficiency, a mixture of ammophos (N15P60) with potassium chloride (K30) was the best basic fertilization. The difference in the spring barley grain yield between these two variants was only 0.05 t/ha, while the additional costs of applying polyphosphate at a dose of 250 kg/ha were 1820 UAH/ha higher than the costs of ammophos + potassium chloride mixture. The use of ammophos (N15P60) + potassium chloride (K30) significantly reduces the chemical load on the soil compared to traditional fertilizer doses, as it decreases the nitrogen inflow, which, when applied in autumn, can pollute groundwater or evaporate. The number of applied potassium decreases because 30 and 60 kg/ha of potassium on the grain yields are very similar. Of the studied foliar supplementary fertilization, the most significant rise in the yield and the highest economic efficiency were recorded after a single application of urea at a dose of N10 in a mixture with growth stimulant EFISOIL Renovation at a dose of 0.4 L/ha and concentrated fertilizer Foliq Micro at a dose of 1.5 L/ha during microphase 31 and the second fertilization with a mixture of EFISOIL Renovation at a dose of 0.4 L/ha and highly concentrated fertilizer Foliq Micro at a dose of 3.0 L/ha during microphase 39.