Productivity of sowed cereal grass depends on the doses and ratio of nitrogen, phosphorus and potassium fertilizers

Aim. To establish the peculiarities of crop formation by sown cereal grasses on sod-podzolic soil, depending on the doses and ratios of the main nutrient elements of mineral fertilizers. Methods. Field, laboratory, mathematical statistics. Results. It was shown that on average for 2017−2019 on linear growth and productivity on sown cereal grasses from timothy grass, awnless fescue and meadow fescue, nitrogen was the most effective mineral nutrient. When applying N25 under the 1st mowing, the height of cereal grasses increased on average from 56−59 to 77−80, or 1.4 times, and when applying N50 – to 91−93 cm or 1.6 times. When applying its total dose of N75 with distribution under each of the three mowing of N25 on different backgrounds of phosphorus-potassium fertilizers, the productivity of cereal grasses increased on average over three years from 2.53−3.47 t/ha to 5.35−6.53 t/ha of dry matter or by 2.82−3.06 t/ha or 1.8−2.1 times, and when applying N150 (50+50+50) – to 7.46−8.80 t/ha or by 4.93−3.33 t/ha or 2.5−2.9 times. The highest productivity of grass fodder was obtained with the application of N150. However, the payback of 1 kg of nitrogen fertilizers by dry mass yield was higher with the application of N75. With the application of this dose, the payback of 1 kg of nitrogen fertilizers by dry mass was 38−41 kg or 3−5 kg ​​more compared to the application of nitrogen at the dose of N150. Conclusions. Using modern methods of planning and modeling of the experiment, a mathematical model of the productivity of cereal grass stands depending on the doses and ratios of nitrogen, phosphorus and potassium of mineral fertilizers was developed, which is described by a quadratic mathematical function (polynomial of the second degree), which with sufficient accuracy makes it possible not only to determine doses, predict the yield of meadows depending on them, but also, based on the predicted yield, to assess the effectiveness of the application of mineral fertilizers.