The study of the nitrogen-fixing activity of nodule bacteria of soybean plants and features of the formation of the number and mass of nodules depending on variety, sowing method and seeding rate influenced by water regime of the soil and different lighting intensity.
 Methods: Field and laboratory experiments, evaluation and comparison. A series of laboratory experiments in sand culture have explored the influence of water logging and dehydration of the root system and light intensity on soybean nitrogenase activity and the release of CO2 by nodules of plants. According to the results of field research it was found that the intensity of nodule formation was increased from the phase of the third trifoliate leaf prior to flowering. At a sowing rate of 500 seeds it made from 20,0 PCs. for the variety Ustya to 27,4 in the variety of Romance. The increase in seeding rate contributed to the increase in the number of nodules to 28,1 per piece (Romance), 27,5 pieces (Ustya) and 25,5 units (Vorskla). The mass of active nodules was within 75% of the total number. Seed rate more than method of sowing influenced the amount of soybean yield. Increase the seeding rate to 800 thousand/ha of viable seeds, especially of sowing on later dates, have not contributed to a significant increase in productivity. Therefore it is most expedient to sow soybean normal line (15 cm) or in wide (45 cm) methods with a seeding rate of 700 thousand/ha of viable seeds. In the line way of sowing increasing the seeding rate contributed to the increase in the number of nodules to 28,1 per piece (Romance), 27,5 pieces (Ustya) and 25,5 units (Vorskla). In wide way of sowing these figures were less than 4,5% to 10,6%. The mass of active nodules was within 75% of the total number. It is advisable to sow soybean normal line (15 cm) or in wide (45 cm) methods with a seeding rate of 700 thousand/ha of viable seeds.