Crops infestation with weeds and soybean yield depending on a method of soil treatment, sowing, and plant protection of weeds

The primary soil treatment along with herbicide application plays an important role in decreasing weed number in soybean sowings as this crop is differed with slow growth and is not competitive with weeds in the initial phase of development. The purpose of the research is improvement of soybean cultivation technology through increasing of the efficiency of main technological methods (primary soil treatment, sowing method, and chemical ways of weeds control) on leached black soil of the Western Ciscaucasia that will promote high yield of seeds. The research was conducted in 2020-2022. The experiment scheme includes two sowing methods: wide-row (70 cm interrow spacing) and common row (15 cm interrow spacing); three methods of the primary soil treatment: moldboard (25-27 cm), subsurface (25-27 cm), and surface (12-14 cm) ploughing; three herbicide applications in a phase of 1-3 true leaves: Concept, OD (1.0 l/ha), tank mixtures Geyzer, CCS (2.0 l/ha), Tanto, CCS (0.75 l/ha), Harmony, DFS (7.0 g/ha), Bazagran, WS (3.0 l/ha), and Shogun, EC (1.0 l/ha) (standard). The highest weed infestation of soybean sowings was stated in variants with subsurface and surface soil treatments. The application of Concept and the tank mixture of Harmony, Bazagran, and Shogun was very effective - to 87.7% and 88.3%, respectively. The highest yield (2.57-2.68 t/ha) was obtained in variants with subsurface and surface soil treatments in common row sowing at the application of a herbicide Concept and a tank mixture of Harmony, Bazagran, Shogun.