Efficiency of the spring wheat nutrition by nitrozen fertilizers on the medow-chernozemic soil

Abstract

Nitrogen - one of the major elements of soil, which determines the intensity of the metabolic processes in plants. For cereals the primary role of nitrogen is its entry into the main components of the grain: protein, gluten and other nitrogenous substances [2]. Therefore, the regulation of nitrogen content in the soil and its receipts into the plant spring wheat is of paramount importance both at the beginning of the vegetation and during its growth and development [3, p. 78]. For the formation of 1t / ha of wheat graine, on average, need 35-45 kg of nitrogen, 8-12 kg of phosphorus, 17-27 kg of potassium and 3-5 kg of sulphur [6]. The main nitrogen fertilizers for the cereals cultivation are ammonium nitrate, urea and urea-ammonia nitrate (UAN). However, today the assortment of nitrogen fertilizers is expanding due to the creation of their new species. Thus, in order to increase the nitrogen activity in the UAN, a sulphur-containing component was introduced into its composition. Was received brand of fertilizer named UAN + S (23% nitrogen, 3.6% sulphur) [5, p. 63]. Therefore, the effect different nitrogen fertilizers on the soil and productivity of plants, in particular spring wheat, needs to further observation. Similar studies are also carried out on winter wheat crops, which indicates the relevance and practical value of the results obtained [4, p. 111]. The aim of the researching was study the efficiency of spring wheat fertilization by traditional fertilizers (ammonium nitrate, urea, UAN) and urea-ammonium nitrate with sulphur (UAN + S). The influence of top-dressing of these fertilizers on the nitrogen compounds content in the soil and grain yield of wheat were analyzed.
Materials and methods of research. The investigation was carried out in an additional experiment of the of Agrichemistry and quality of crop production department in the «Agronomic Experimental Station» NULES of Ukraine. The object of the research is the dynamic of available nitrogen compounds of meadow-chernozemic soil and the productivity of spring wheat of sort Kharkivska-26 under the influence of several types of nitrogen fertilizers that application in spring topdressing nutrition.  Variants of the research: Control (without fertilizers); N80P80K80; N50P80K80 (background) + N30 (Naa) ammonium nitrate; Background + N30 (Nm) urea; Background + N30 (UAN) urea-ammonium nitrate; Background + N30 (UAN+ S) urea-ammonium nitrate with sulphur. The wheat was sown in the second decade of April. The spring adding of the nitrogen fertilizers at a dose of 30 kg N / ha was carried out in the first decade of May. Soil samples were taken during the wheat growing in the critical period of its vegetation. In samples the content of mineral nitrogen (nitrate and ammonium) and alkali hydrolyzed nitrogen compounds was determined by ionselective electrode and by Nessler's and Kornfield's method. Research results. The influence of diverse types of nitrogen fertilizers by topdressing application on the dynamics of nitrogen compounds in the meadowchernozem calcareous soil has been established. Mineral nitrogen is the main source of plant nutrition, but the immediate reserve for the nitrogenous compounds formation in the soil is alkali hydrolyzed nitrogen, which contains ammonium and amide form. In the experiment the content of mineral and alkali hydrolyzed nitrogen in soil was depended on the variants of the fertilization. The control variant and N80P80K80 had the lowest nitrogen content. The cultivation of spring wheat without any fertilization was cause the depletion of the possible available compounds of soil nitrogen. It negatively influenced on the formation of productivity of culture in the future. It was determined that during the period of wheat booting the greatest influence on the soil mineral nitrogen content in the arable layer had dose of N30 which was added with ammonium nitrate and UAN-32. The significant effect on the content of
alkaline hydrolyzed nitrogen in the soil was indicated by the top-dressing of UAN and urea, because these types of fertilizers contain NH2-form of nitrogen. In the second period of the spring wheat vegetation the changes were made in the distribution of mineral nitrogen and alkali hydrolyzed nitrogen in the soil. In the variant with ammonium nitrate was established a significant decrease in the nitrogen content in the soil, while the more stable indicators of N were showed in the variants with introducing amide fertilizer forms. A similar distribution of mineral nitrogen was obtained for a 25-50 cm layer of meadow-chernozemic soil. As a result, the effect of the different nitrogen fertilizers top-dressing was manifested in the wheat grain yield. The variants with urea and UAN and UAN + S provided the best results of the wheat harvest. Compared with ammonium nitrate the traditional UAN-32 gave 0.23 t / ha of grain and traditional urea - 0.35 t / ha. That is because the presence of amid nitrogen in their composition made possible to prolong the supply of nitrogen during the wheat growth and development.  The application of a new type nitrogen fertilizer - UAN + S - in the top-dressing nutrition increased the yields of spring wheat compared with traditional fertilizers. Thus, adding sulphur to the UAN contributed to the growth of grain harvest by 0,2 t / ha compared with the UAN-32 and 0.8 t /ha compared with urea. Consequently, the researching had shown that the top-dressing nitrogen fertilization of spring wheat is a way to stabilize the content of soil nitrogen compounds that available to plants and increase the yield of the crop.