Soybean (Glycine max L.) is the prominent oilseed crop in world accounting for more than 50% of the world oilseeds production. Legumes plants have higher requirements to nutrition for acceptable grain yields and higher contents of oil. Soybean seed production may be limited by environmental abiotic factors such as low soil fertility of phosphorus (P). Carbonated chernoziom in the republic of Moldova is characterized by low availability of phosphates. The solution of the potential problems associated with chemical P fertilizers together with the higher cost involved in their manufacture and acquirement, has led to identify environmentally compatible and economically feasible alternative strategies for improving crop productions in low or P-deficient soils. The use of rhizobacteria as inoculants is of great agronomical interest especially in countries with scarce P resources, especially in the republic of Moldova. The main objective of this study was, therefore, to evaluate the effect of combined application of two rhizobacria strains namely Bradyrhizobium japonicum and Pseudomonas putida on the grain yield of soybean, cultivated on carbonated chernoziom in the central region of the republic of Moldova. A two factorial experiment consisting of two rhizobacteria strains (Bradyrhizobium japonicum and Pseudomonas putida) and two application rates of phosphorus fertilizer was laid out in a randomized complete block design with four replications. The P treatments were 0 kg P/ha and 60 kg P/ha fertilizer with or without inoculants. The soybean (Glycine max L. Merr) cultivar used in the present study was Horboveanca which is sensitive to P deficiency. Before sowing, the field soil was fertilized with 30 N kg /ha (ammonium nitrate) and 60 kg P per hectare as single superphosphate. The rhizobacteria treatments were uninoculated soybean seeds (control), inoculated soybean seeds with B. japonicum alone and co-inoculated soybean seeds with B. japonicum and P. putida in 1:1 (v/v) ratio. Bacterial inoculation was done immediately before the sowing. The plants were grown to seed maturity under rain-fed conditions while the necessary management practices also were performed. The data were analyzed statistically using Ftest according to Dospehov ‘procedure. The results of this study showed that under no P supplementation and no-inoculation (control treatmnet) with rhizobacteria there were low yields of soybean. The grain yield of soybean was significantly positive influenced by phosphorus fertilization as well as by bacteria strains inoculation. Seed inoculation with Bradyrhizobium promoted significant increases in grain yield when compared to the non-inoculated control. Likewise, the grain yield increased under dual inoculation of Bradyrhizobium japonicum and Pseudomonas putida. But their effect was more pronounced on unfertilized plots than in bacterial treatments in conjunction with P supplementation. Coinoculation of B. japonicum and P. putida increased seed yields by 4% over single inoculation and by 12% compared to control plants (uninoculated). Therefore, experimental results demonstrated that combined application of two rhizobacteria displayed better agronomic effect than inoculation of B. japonicum alone. However, no prominent enhancement in plant growth of soybean by inoculating the soybean with P. putida and N2-fixer bacteria was observed under P fertilization conditions in comparison to application of B. japonicum alone. This trend of rhizobacteria influence was registered in both experimental years (2016-2017). Biofertilizers had beneficial impact on nitrogen and phosphorus contents in soybean grains. The nitrogen concentration in soybean seeds registered the lowest value in treatment without inoculation and no fertilized plants. The grain nitrogen content of plants inoculated with B. japonicum was higher than those of the uninoculated plants. Experimental data shown that single inoculation with B. japonicum increased seed N contents by 10,5% but there not significant increasing due to combined use of these bacteria strains. Similarly, the beneficial effect of B. japonicum in nitrogen content (by 7,1%) was observed under P supplementation but at low level. As regard phosphorus concentrations, it was revealed an increase of P contents in seeds under combined use of two rhizobacteria in treatment without chemical fertilization of P. However, the application of biofertilizers in conjunction with P supplementation did not change significantly the P concentration in soybean seeds compared with phosphoric fertilizer alone. Hence, under field environmental conditions a combined application of plant growth-promoting rhizobacteria (B. japonicum and P. putida) has the potential to improve nutrient supply and subsequently yield of soybeans cultivated on carbonated chernoziom with low P availability. In conclusion, combined inoculation with B. japonicum and P. putida was found to be efficiently for improving the productivity of soybean under low P supply over single inoculation with B. japonicum. Further research is needed to elucidate on the mechanisms behind this synergetic effect of bacterial inoculants in relation to unfavorable environment conditions.