Abstract

The rhizosphere microbiome plays a crucial role in mediating plant-soil interactions that determine crop productivity and soil ecosystem functioning, yet the specific linkages between microbial community composition and agricultural outcomes remain poorly understood. This study investigated relationships between rhizosphere microbiome composition, crop productivity, and soil functionality across 54 field sites encompassing major crop species over three growing seasons. High-throughput 16S rRNA and ITS sequencing revealed distinct rhizosphere microbiomes that consistently correlated with crop performance and soil health indicators. High-productivity sites (>8.5 t ha⁻¹ grain yield) showed 85% higher rhizosphere microbial diversity compared to low-productivity sites (<5.2 t ha⁻¹), with Shannon indices of 6.2±0.4 versus 3.3±0.5 respectively. Beneficial microbial taxa including plant growth-promoting bacteria (PGPB) were 3.2-fold more abundant in high-productivity rhizospheres, with Rhizobium (+420%), Pseudomonas (+285%), and Bacillus (+195%) showing the strongest associations. Arbuscular mycorrhizal fungi (AMF) colonization rates reached 78% in high-productivity systems compared to 35% in low-productivity systems, correlating strongly with phosphorus uptake efficiency (R = 0.82). Functional gene analysis revealed enhanced metabolic diversity in productive rhizospheres, with 2.8-fold higher abundance of genes for nutrient cycling, stress tolerance, and biocontrol. Soil functionality metrics including aggregate stability (92% vs 64%), enzyme activities (+150%), and nutrient availability (+85%) were consistently higher in systems with diverse rhizosphere microbiomes. Machine learning models using rhizosphere microbial composition predicted crop yields with 89% accuracy and soil health scores with 87% accuracy. Economic analysis demonstrated that microbiome-guided management could increase net returns by $245-380 ha⁻¹ through optimized productivity and reduced input costs. Network analysis identified 23 keystone microbial taxa that disproportionately influenced both crop performance and soil functionality. These findings establish rhizosphere microbiome composition as a critical determinant of agricultural sustainability, providing new targets for microbiome-based crop improvement strategies.