Present study was aimed to evaluate the liquid inoculation of ten Bradyrhizobium japonicum with fungi Aspergillus niger (plant growth promoting) in pot experiments for determination of nitrogen fixation potential. Commonly grown JS-335 cultivar of Soybean around Ujjain region was used as host plant. Nodule number, shoot length, root length and their dry weight were taken as criteria for nitrogen fixation. Inoculation in pot along with fertilizer significantly increase the nodulation, shoot and root length at 5% of probability over inoculation of only B. japonicum and uninoculated. Total 12 treatments (10 tests + 2 controls) with three replicates were set and total 36 pots were arranged. Results revealed that B. japonicum increases the nitrogen fixation in combination with A. niger and induces the plant growth directly like phosphate solubilization, through IAA production, ammonia production and indirectly by inhibiting the pathogenic fungi. Co-inoculation was found suitable and effective over single inoculums. The present study supports that liquid inoculum of more than one organism results in increase in nodulation, and can effectively increase the crop productivity.