Arbuscular mycorrhizal fungi (AMF) and rhizobium play a significant role in plant symbiosis. However, their influence on the soil microbiome associated with plant growth and soil health is not well defined in the Northern Great Plains. This study investigated the effect of microbial inoculants as seed treatment on plant yield, nutrient uptake, potential microbial functions, and rhizosphere soil microbial communities using high-throughput sequencing of 16S and ITS rRNA genes. The experiment was conducted under two contrasting dryland conditions with four treatments: control, single inoculation with AMF or Rhizobium, and dual inoculations of AMF and Rhizobium (AMF+Rhizobium). Our findings revealed that microbial inoculation efficacy was site-specific. In a non-P nutrient limiting condition, AMF+Rhizobium exhibited a synergistic effect on grain yield in Sidney, Montana (MT), dryland field site (DFS) 2. While AMF conferred plant resilience but marginal yield in low soil organic matter and acidic soil conditions in Froid, MT (DFS 1). Noteworthy, variation in microbial community structure and composition indicates site-specific response to AMF and AMF+Rhizobium microbial inoculants. Overall, site-specific factors had a greater influence on plant nutrient uptake, microbial community dynamics and functional potential. It underscores the need for tailored management strategies that consider site-specific characteristics to optimize benefits from microbial inoculation.