Influence of Microbiologically Enriched Mineral Fertilizers on Selected Groups of Microorganisms in the Rhizosphere of Strawberry Plants

In recent years, the use of bio-fertilizers enriched with specially selected microorganisms has been used more and more often. The beneficial effects of bio-fertilizers enriched with consortia of microorganisms on strawberry plants have been reported previously. The purpose of the research was to determine the effect of bio-fertilizers containing selected fungal and bacterial strains on the microorganisms living in the rhizosphere of strawberry plants. In the experiments described in this paper, synthetic mineral fertilizers were enriched with selected microorganisms. The fertilizer urea was enriched with the fungi Aspergillus niger and Purpureocillium lilacinum, while the fertilizers Polifoska 6 and Super Fos Dar 40 with strains of the bacteria Bacillus sp., Bacillus amyloliquefaciens, and Paenibacillus polymyxa. Bacteria and fungi belonging to these species can exert a positive effect on the growth of many plants. The results obtained in this study showed that the application of fertilizers enriched with microorganisms had different effects on the analyzed populations of soil microorganisms in the rhizosphere of strawberry plants. There were evidences of both, an adverse effect of the applied fertilizer and/or microorganisms, but more often, the beneficial effect was found on the abundance of the microorganisms in the rhizosphere of the strawberry. The most effective for the population of Pseudomonas bacteria was application of urea and fungi and Polifoska and bacteria. The highest number of phosphorus utilizing bacteria B was scored in the treatments containing NPK, NPK + fungi and urea 60% + fungi. The application of NPK + fungi and urea 100% + fungi as well as Super Fos Dar with bacteria was most beneficial for population of actinomycetes.