Response of symbiotic interrelationship between soybean and the indigenous or inoculated microsymbiont,Bradyrhizobium japonicum, to soil application of manganese and molybdenum.

Soybean nodulation was induced indigenously by three strains ofBradyrhizobium japonicum inoculated in each of the two previous seasons. The same strains were applied, as a peat-based inoculum in similar cell density as the indigenous ones, to a rhizobia-free soll from the same field. Inoculation was tested under soll application of 10 or 20 ppm Mn and/or 2 or 4 ppm Mo. Inoculation with the peat-based inoculum significantly increased nodule numbers and weight, dry weight, N content and mg N/g of the 50-day-old plants, number of pods and seeds per plant, seed yield, seed N content and percentage, and mg N/g of the empty pods. Increasing the application of Mn and Mo fed to further increases. There was a complex response of nodulation, vegetative growth and yield to the applications of Mn and Mo.