INFLUENCE OF SOIL TILLAGE SYSTEMS AND INOCULATION ON SOYBEAN NODULATION AND YIELD

A field study was conducted over two agricultural years, 2015 - 2016, and was aiming to establish the influence of some soil tillage systems and inoculation on soybean nodulations and grain yield. The experimental design of the research, was organized using a split plot method and the following factors were analyzed: Factor A - soil tillage system: Conventional tillage (CT): Ploughing at 20 cm (control, A(20)); Minimum Tillage (MT): Chisel plow at 20 cm (C-20), Chisel plow at 40 cm (C-40), Disking at 10 cm (D-10), Disking / Ploughing at 20 cm (D/A(20)) and Disking/ Chisel at 40 cm (D/C-40); Factor B - soybean varieties from different maturity groups: Carla, 000, PR92B63, 0; Factor C - soybean seeds inoculation with Nitragin Bac Soya: non - inoculated; inoculated. Influenced by nitrogen - fixing bacteria and soil tillage systems, the soybean nodulation recorded an increase of 37.9%. After two years of research, the average grain yield for soybean varieties sowed in variants treated with Bradyrhizobium japonicum, ranged from 2177 kg/ha (D) to 2044.6 kg/ha (D/C-40). For variants, where soybean seeds weren't inoculated with nitrogen - fixing bacteria, the grain yield ranged in average from 2044.6 kg/ha (D) to 2422.7 kg/ha (D/C-40). An increase of soybean grain yield with 5.4 % was brought by seed inoculation with nitrogen-fixing bacteria.