One of the promising sowing methods is combined sowing and growing several crops on the same field. The authors have revealed the shortcomings of the existing designs of serial row sowing machines, which do not fully comply with the requirements of mixed crop patterns, including the design features of the seed disk and economic cost-estimation indicators of its manufacturing. Federal Agroengineering Centre VIM is designing seeders with an original seed dispenser based on new metering pneumatic systems. This paper presents a sowing machine with a universal seed disk of a new collapsible design used for dotted and mixed sowing of calibrated and uncalibrated seeds of different crops. Laboratory tests have experimentally determined the parameters of a cone-shaped cell of the seed disk, which ensures uniform dispension of seeds without gaps in a row: the diameter of through holes on side walls of the cone-shaped cells - 3 mm; the lower diameter - 6 mm; depth - 18 mm; the upper diameter - 24 mm. The authors have also studied the effect of excess pressure in a seed chamber (from 2.5 kPa to 4.5 kPa) on the quality of the metering unit as exemplified by maize seeds of the "Dobrynya" variety in Krasnodar Krai. They have determined the optimum value of excess pressure (3.0 kPa) for the considered design of a pneumatic device, which ensures single-seed sowing without gaps with a total number of 98,5%, which corresponds to agrotechnical requirements. The authors have experimentally determined the capabilities of the universal seed disk of a new design, providing reliable sowing of seeds with both dotted and mixed methods with a reduction in metal intensity of a unit by 20% as compared to analog units.