Cultivation Duration Reshapes Arbuscular Mycorrhizal Fungi and Soil Aggregation in Relation to Ginseng Growth and Quality

Understanding how prolonged cultivation reorganizes belowground biological and structural processes is critical for maintaining the productivity and quality of perennial medicinal crops. However, the linkages among arbuscular mycorrhizal fungi (AMF), glomalin-related soil protein (GRSP), soil aggregation, and plant performance across cultivation durations remain poorly resolved. We hypothesized that increasing ginseng cultivation duration would alter soil physicochemical properties and AMF functional attributes, thereby affecting soil aggregate stability and ginseng growth and quality. Here, we investigated garden-cultivated Panax ginseng across four cultivation durations (1–4 years) to determine how changes in soil conditions were associated with AMF functional attributes, GRSP fractions, aggregate stability, and ginseng performance. AMF spore density and root colonization exhibited cultivation-duration-dependent variation, whereas GRSP fractions showed contrasting temporal patterns, indicating a decoupling between current AMF functional status and the accumulated soil GRSP pool. Soil aggregate-size distribution and stability also shifted markedly across cultivation durations. Correlation and Mantel analyses further revealed close associations among soil environmental variables, AMF functional attributes, GRSP, aggregate properties, and ginseng traits. Structural equation modeling further revealed distinct pathways linking cultivation duration to ginseng biomass and medicinal quality. Cultivation duration was positively associated with soil environmental conditions and aggregate properties, while soil environmental variation was strongly associated with AMF functional traits. Ginseng weight was positively associated with cultivation duration but negatively associated with aggregate properties, whereas total ginsenoside content was positively associated with aggregate properties and showed no significant direct association with cultivation duration. The direct pathway from AMF functional traits to aggregate properties was not significant, suggesting that AMF responses to cultivation-induced environmental variation did not translate into an independent effect on soil aggregation within the fitted model. Collectively, these findings reveal that prolonged ginseng cultivation reorganizes belowground environmental, mycorrhizal, and structural components in distinct ways and that soil aggregate properties represent an important interface linking cultivation-associated belowground changes with ginseng biomass and medicinal quality.