Abstract

Long-term tillage practices fundamentally alter soil microbial communities and their networks, with cascading effects on nutrient cycling processes that determine agricultural sustainability. This study investigated the impacts of conventional tillage (CT), reduced tillage (RT), and no-tillage (NT) practices on soil microbial networks and nutrient dynamics across 45 long-term experimental sites over 20 years. High-throughput sequencing of 16S rRNA and ITS genes revealed that NT systems supported 78% higher microbial diversity compared to CT systems, with Shannon indices of 5.8±0.4 versus 3.3±0.5 respectively. Network analysis demonstrated that NT soils contained significantly more complex microbial networks with 2.3-fold higher connectivity and 65% more keystone species compared to CT systems. Fungal: bacterial ratios increased from 0.3 in CT to 1.2 in NT systems, indicating enhanced fungal networks critical for soil aggregation and nutrient transport. Enzyme activities for carbon, nitrogen, and phosphorus cycling were 45-85% higher in NT soils, with β-glucosidase, urease, and phosphatase showing the strongest responses. Soil organic carbon accumulated at rates of 0.85±0.12 t C ha⁻¹ yr⁻¹ under NT compared to -0.15±0.08 t C ha⁻¹ yr⁻¹ under CT. Nitrogen mineralization potential increased by 125% under NT, while phosphorus availability improved by 85% due to enhanced microbial phosphorus cycling. Economic analysis revealed that enhanced microbial nutrient cycling in NT systems reduced fertilizer requirements by 25-40%, saving $95-180 ha⁻¹ annually. Network resilience analysis showed that NT microbial communities were 3.2 times more stable to environmental perturbations compared to CT systems. These findings demonstrate that tillage practices create distinct trajectories of microbial network development that profoundly influence soil ecosystem functioning and agricultural sustainability through enhanced biological nutrient cycling processes.