Nutrient regime of the soil depending on the share of sunflower in short-rotational crop

Sunflower requires a sufficient amount of nutrients for growth and development. Therefore, it is important to determine the impact of sunflower cultivation on the soil nutrient regime, taking into account the frequency of its return to the previous place. The aim of the study was to determine the influence of the share of sunflower in short rotation crop rotations on the soil nutrient regime. The research was conducted at the experimental field of the Kharkiv V.V. Dokuchaev National Agrarian University, which is located in the Left-Bank Forest-Steppe of Ukraine. The research and accounting were carried out on typical heavy loamy chernozem in accordance with generally accepted methods. The experimental scheme included five-field crop rotations with sunflower saturation of 0, 20, 40 and 60%. The research results show that an increase in the share of sunflower in short rotation crop rotations does not lead to a deterioration in the nutrient regime of the topsoil. There was no significant difference between the variants in the content of nutrients. The most supplied with nutrients was the topsoil in the control variant (crop rotation without sunflower). With an increase in the share of sunflower in crop rotations, the amount of nutrients in the tilth layer of soil decreased slightly. Regardless of the studied crop rotation options, the availability of easily hydrolysable nitrogen was low, mobile phosphorus was average, and exchangeable potassium was high. Increasing the share of sunflower in short rotation crop rotations led to a decrease in the yield of the crop itself. The yield of sunflower seeds was at the same level in the variants with 20 and 40%. There is a close relationship between sunflower yield and its saturation, which significantly depends on the soil nutrient regime. The yield level is most affected by the content of phosphorus and potassium in the topsoil. The correlation is 0.91 and 0.98, respectively. The practical value of this study is due to the possibility of using the obtained results to justify the feasibility of increasing the share of sunflower in the structure of crop rotations