Impact of microbial consortia and fertilization regimes on the soil microbiome in maize field trials

Beneficial microbial consortia provide an eco-friendly alternative to conventional inorganic fertilizers and can serve as a complementary management tool for enhancing soil fertility and crop productivity. This study aimed to assess the impact of microbial consortia application on the indigenous maize rhizosphere microbiome under different fertilization regimes in organically managed fields in Germany. Three experimental microbial consortia (MC_B, MC_C, MC_C_AMF) and one commercial product (Micosat F) were tested in combination with three fertilization levels (unfertilized, 110 kg nitrogen ha^- 1, and 200 kg nitrogen ha^- 1) in a split plot design. The diversity, composition and functional potential of the maize rhizosphere microbiome were analyzed at different maize growth stages. Fertilization levels exerted a stronger influence than microbial consortia, significantly shaping community composition and functional traits of the indigenous soil microbiome. Increasing fertilization intensity altered the abundance of specific plant growth-promoting (PGP)-determinants, either stimulating or suppressing potential PGP bacteria. In contrast, microbial consortia application did not impact PGP-associated abundance profiles. Overall, the results indicate that multifunctional microbial consortia can act as effective biofertilizers in sustainable maize cultivation without compromising resident microbiome diversity, thereby reducing long-term ecological risks on natural biodiversity.