Dynamics of NPK Complex in Soil Depending on Forms of Fertilizers and Their Combinations

Abstract

The research was carried out to study the influence of different forms of fertilizers and their combinations on the content of mobile forms of basic nutrients in the soil and the yield of oats. The work was carried out in the forest-steppe of Volga region in 2019-2021. The objects of study: chernozem heavy loamy soil, oat plants of Rysak variety. The experimental design involved studying the following options: basic nitrogen fertilizer (factor A) - without nitrogen fertilizers, ammonium nitrate (N34.4); pre-sowing complex fertilizer (factor B) - without fertilizers, BisolbiFit, azophosphate in full dose (N15P15K15), biomodified azophosphate in full (N15P15K15m) and half (N7.5P7.5K7.5m) doses. The field experiment was carried out in 3 repetitions in a crop rotation of pure fallow - winter wheat - spring wheat - barley - oats. The most rational was the combination of N15P15K15m with the addition of ammonium nitrate, which ensured the formation of an average oat yield over the years of research at the level of 2.71 t/ha. All fertilizers studied in the experiment led to an increase in the value of this indicator, which was 2.28...2.28 t/ha without nitrogen, and 2.50...2.64 t/ha with nitrogen. The best nitrification ability against the background without nitrogen was noted in the variant with biomodified azofoska (N15P15K15m), in which the content of nitrate nitrogen in the soil was 41.0% higher than in the variant without fertilizers. When using BisolbiFit, the value of this indicator increased by 21.4%, in variants with N15P15K15 and N7,5P7,5K7,5m - by 16.0...16.7%. Biomodified azofoska contributed to improving the supply of soil under oats with mobile phosphorus and potassium by 4.3...4.9 and 4.0...5.6%, respectively, compared to other options. When ammonium nitrate was applied at a dose of N34.4, the content of nitrate nitrogen, compared with the background where nitrogen fertilizers were not used, increased on average by 5.1% over the background, mobile phosphorus and potassium - by 1.7% and 12.6 , respectively %.