The studies were conducted in 2017-2019. in order to study the fractional application of liquid and solid mineral nitrogen fertilizers in early spring fertilizing to determine the content of leached nitrate and ammonium nitrogen in the 0-20 cm layer of chernozem and the yield of winter wheat in the conditions of the Stavropol Upland. The scientific novelty of the research was that for the first time in the Stavropol Territory, a comprehensive study of the types, doses and frequency of application of nitrogen fertilizers in winter wheat crops was carried out. Depending on the factors studied, the optimal content of available forms of nitrogen in the soil and the effect on the level of crop yield have been established. The experimental design involved the study of the following options: The experiment was launched at the training and experimental station of the Stavropol State Agrarian University. factor A - type of fertilizer (ammonium nitrate; CAS-32); factor B - dose of fertilizer (35, 70, 105, 140 kg/ha a.i.); factor C - frequency of fertilizer application (single, fractional). The first nitrogen fertilization was carried out in the full tillering phase in the spring when the growing season of winter wheat plants resumed, and with fractional application - the second at the end of tillering. The plots were placed using the method of randomized repetitions in 3 replicates. The total area of the plot is 72 m2; accounting - 40 m2. The use of ammonium nitrate on average significantly increases the content of nitrate nitrogen (19.8 mg/kg), and compared with the urea-ammonium mixture (19.3 mg/kg), the difference was 0.5 mg/kg. Regardless of the frequency and dose of application, the tested nitrogen fertilizers significantly increased the content of nitrate nitrogen in the soil layer 0-20 cm by 2.9-10.5 mg/kg compared to the control variant. With fractional application, the content of nitrate nitrogen seemed to be higher compared to a single application, and the difference was 1.1 mg/kg in the 0-20 cm soil layer. The introduction of increasing doses of nitrogen fertilizers contributed to a significant increase in the yield of winter wheat by 0.82-2.80 t/ha compared to the control. Compared to a single application of a full dose, the use of fractional fertilizer increased the grain yield by 0.18 t/ha.
chernozem vyschelochennyy, ozimaya pshenica, ammiachnaya selitra, karbamidno-ammiachnaya smes', nitratnyy azot, ammoniynyy azot, urozhaynost'