Agronomic Efficiency of Signum Inoculant in Pre-inoculation of Soybean at 35 and 20 Days Before Sowing in Treated Seeds

Pre-inoculating soybean seeds can make sowing faster and provide additional benefits to farmers. However, it needs to guarantee the nitrogen supply to maintain the viability and sustainability of the technique. In this study, we evaluated the agronomic efficiency of SIGNUM® inoculant in the pre-inoculation at 20 and 35 days before sowing chemically treated soybean seeds. Experiments were conducted in four field experiments located at Paraná, Brazil, with a history of soybean cultivation managed under no-tillage systems, with crop rotation according to regional edaphoclimatic conditions. Agronomic efficiency in fields were compared with standard inoculation with a registered product used by farmers. Chemical treatment of soybean seeds with Standak Top® or Maxin XL® + Cruiser® associated with pre-inoculation of the inoculant SIGNUM® for 25 and 30 days reduced the concentration of viable Bradyrhizobium cells recovered from seeds. However, no significant difference was observed regarding nodulation, biological nitrogen fixation, and yield between the soybean inoculated with standard inoculation on farm or pre-inoculation with SIGNUM® in most studied areas.