Continuous cropping of lavender (Lavandula angustifolia Mill.) enhances essential oil yield without compromising...

Yield decline due to continuous cropping poses a significant challenge to agricultural sustainability. However, systematic investigations into the effects of continuous cropping in lavender (Lavandula angustifolia Mill.) remain scarce. This study was conducted in the Yili River Valley, Xinjiang, the largest lavender-producing region in China. Three representative cultivation zones were selected. Continuous cropping duration gradients of 1, 3, and 6 years were established (with three replicates per treatment). We assessed essential oil quality and yield, soil physicochemical properties, enzyme activities, and bacterial community structure. Multivariate statistical analyses were employed to elucidate the "soil-microbe-plant" interaction mechanisms under lavender continuous cropping. Continuous cropping (6 years) significantly increased essential oil yield (+37.9%, P < 0.05) without compromising oil quality, as the relative contents of signature constituents (linalool, camphor, linalyl acetate, lavandulyl acetate) remained stable Soil nutrients exhibited a triphasic pattern ("low-high-low"). Organic carbon and total nitrogen peaked during the 3-year continuous cropping phase, primarily attributable to reduced soil disturbance under perennial lavender cultivation. Continuous cropping exerted a vertical stratification effect on soil bacterial α-diversity: no significant change in 0-20 cm topsoil (P > 0.05), but a significant decrease in 20-40 cm subsoil (P < 0.05). Bacterial co-occurrence network complexity decreased with cropping duration across all layers. Random Forest and Partial Least Squares Path Modeling (PLS-PM) analyses revealed that the synergistic effect of intensified microbial carbon limitation and alleviated nitrogen limitation was the core driver of increased oil yield. The reduced microbial network complexity under long-term continuous cropping implies potential soil health and long-term productivity risks, supporting a 3-5 year continuous cropping plus rotation strategy to balance short-term gains and long-term ecosystem health. This study clarifies the unique "stable quality-enhanced yield" effect in lavender continuous cropping and its regulatory mechanisms, elucidating the short-term-long-term trade-off to provide a theoretical framework and practical guidelines for sustainable aromatic crop production under continuous cropping systems.