STUDY OF THE FACTORS OF THE DETERIORATION OF SOWING ACCURACY WITH PNEUMATIC SEEDERS

The purpose of the research is to establish the factors of deterioration of sowing accuracy by pneumatic seeders (using the John Deere 90 Series precision seeding seeder as an example) as a result of observations of their operation during numerical modeling and field experimental studies. Observation of the operation of the sowing section of the pneumatic precision seed drill was carried out in two stages: numerical modeling and field experimental studies. Numerical simulation involved the use of the Simcenter STAR-CCM+ software package and created 3D models of the main elements of the seeding section of the John Deere 90 Series precision sowing machine. Field experimental studies were carried out on grain-steam crop rotation on the territory of AFG "Olvia". Peas were sown with a John Deere 90 Series planter. The row spacing was 0.19 m, the sowing depth was 0.05 m. The sowing rate was 1.2 million units/ha. As a result of the numerical simulation of the operation of the seeding section of the precision seeding pneumatic seeder, a visualization of the distribution of soil aggregates and their velocities was obtained. Comparing the obtained values of the indicators with the normalized ones, it was established that the distribution of seeds along the x-axis meets the specified requirements. Along the seeding depth (z-axis), the distribution of seeds is quite high, which exceeds the normalized values. Thus, the obtained average value of sowing depth is 0.041 ± 0.03 m, and the normalized value is 0.05 ± 0.01. Visual analysis shows that some seeds do not even fall into the seed layer (0.04–0.08 m) of the arable horizon. A smaller value of the distance between seeds (< 0.029 m) explains the occurrence of "twins", and a larger value (> 0.059 m) - the occurrence of "skips". As a result of field experimental studies of the seeding section of the precision seeding pneumatic seeder, photographs were taken of the moment the seeds fly out of the seedbed for various designs of the seed pacifier using an action camera. After receiving seedlings of sown pea seeds, the distances between plants were determined and the corresponding statistical indicators were calculated: minimum value - 0.005 m, maximum value - 0.124 m, limit - 0.0595 m, root mean square deviation - 0.031 m, average value 0.045 m, coefficient of variation - 0.688 . Comparing the obtained experimental data with the results of numerical simulation, there is a sufficiently high agreement of the data (94%), which confirms the numerical model developed in the Simcenter STAR-CCM+ software package. As a result of observations of the operation of the seeding section of the John Deere 90 Series pneumatic seeder in the course of numerical modeling and field experimental studies, the factors of deterioration of seeding accuracy were established (high speed of the air flow and, accordingly, seeds, imperfect shape of the seed channel of the sowing shoe, imperfect shape of the seed stabilizer). Increasing the efficiency of the process of sowing seeds of cultivated plants can be achieved by improving the designs of the elements of the seed supply system of the pneumatic seeder (seed retarder, seed channel of the sowing shoe, seed pacifier) with justified structural and technological parameters that ensure accurate sowing, and structural materials that provide an increased resource their exploitation.