Evaluation of the effect of rhizobacteria strains application on common bean cultivation under the conditions of Haplic Vertisol and Alluvial-meadow soil

The development of good agricultural practices related to nutrient management and fertilization is important given the increase of greenhouse gas emissions and the pollution of underground waters and rivers by unabsorbed nitrates and phosphates. Microorganisms from the Rhizobium, Bacillus, Azotobacter, and Azospirillum improve the supply of nutrients in the soil through natural processes of nitrogen fixation, phosphorus and potassium uptake, and production of plant hormones. In this study, an experiment with common bean seeds of the cultivar “Obraztsov Chiflik 12” treated before sowing with selected strains of rhizobacteria from the genus Rhizobium and Bacillus was conducted under the conditions of Haplic Vertisol (HV) and Alluvial-meadow (AM) soil types. The strains and their combinations were evaluated in terms of their effectiveness on the diversity and activity of microorganisms in the soil. The levels of macroelements in the soil and plant biomass were measured. The influence of bacterial inoculation on biometric indicators for improving plant growth was monitored. The results demonstrated the positive effect of pre-sowing seed treatment of common bean with a fresh bacterial suspension of the selected rhizobacterial strains, applied individually or in combination. The effect of the given bacterial inoculant is strongly related to the type of soil. Taken together, the combined agrochemical, microbiological, and biometric data indicate that the selected rhizobacterial strains have potential as biofertilizers/biostimulants to improve common bean cultivation and substitute the mineral fertilization under suitable soil conditions.