From thirty four strains of Rhizobium japonicum, infield conditions and insymbiosis with soybean (Glycine max. variety Bucuria), three best strains have been selected and tested. The selected strains were compared with three control lots and showed good nodule formation rate and increased dry matter of the plant. Using GC methods, it was appreciated the potential capacity to fix atmospheric nitrogen for nodule and rhizospheric soils. It was revealed that a new selected strain have the same nitrogen fixing capacity like a standard strain but it stimulates better plant growth and development.