¹ ³C labeling unveils soil and microbial changes in continuously cropped Pogostemon cablin

Continuous cropping (CC) disrupts agriculture by causing soil degradation, yield decline, and microbial imbalances due to nutrient loss and pathogen buildup. However, the mechanisms underlying these impacts on Pogostemon cablin remain unclear. A greenhouse pot experiment was conducted during the rapid growth stage when CC-induced stress is most pronounced to address this gap. The ¹ ³C stable isotope labeling was employed to trace microbial shifts and decomposition of organic matter within the plant-soil-microbe interface. The results indicated that CC significantly alleviated plant growth and soil multifunctional index. Specifically, it enhanced the levels of available phosphorus (AP), available potassium (AK), total nitrogen (TN), and soil organic carbon (SOC) while leading to a decline in pH, water holding capacity (WHC), and total potassium (TK) over the years. While ¹ ³C-labeled bacteriome under CC obstacles positively influenced microbial diversity and community composition, highlighting the pivotal role of a diverse microbial community in promoting ecosystem resilience, nutrient cycling, disease suppression, and overall soil health. Specific taxa, including Escherichia_coli, Comamonadaceae, Planococcaceae, and Gaiella, were identified as key contributors to these improvements. Additionally, Mantel test analyses indicated that Aneurinibacillus, Actinomadura, E._coli, Acinetobacter, and Moraxellaceae enhanced soil multifunctionality. Functional predictions using FAPROTAX revealed increased microbial processes such as nitrogen (N) fixation, aromatic compound degradation, animal parasites or symbionts, N respiration, and nitrate respiration under ¹ ³C-labeled conditions. These findings emphasize the inter-annual variations in rhizosphere bacteriomes under CC and demonstrate the effectiveness of ¹ ³C labeling in elucidating C turnover and microbial interactions. This study provides actionable insights for mitigating CC-induced soil challenges and advancing sustainable agricultural management.