Effects of Cultivation Mode on Growth of American Ginseng (Panax quinquefolius L.) and Soil Microecology

(1) Background: American ginseng (Panax quinquefolius L.) cultivation faces severe continuous cropping obstacles, presenting a trade-off between short-term quality and long-term soil microecological health under different planting systems. (2) Methods: This study compared the agronomic traits, rhizosphere soil physicochemical properties, enzyme activities, and microbial communities (via high-throughput sequencing) of American ginseng under the “1 + 1” and “0 + 2” systems across three growth stages. (3) Results: The “0 + 2” system exhibited higher root quality indicators, including total ginsenosides (+27.5%) and protein (+110%). In contrast, the “1 + 1” system maintained a higher total phosphorus content (+51%) and enhanced urease/sucrase activities. Furthermore, the “1 + 1” system reshaped the rhizosphere microbial community, improving soil microecological stability. Mantel tests indicated that soil nutrients, enzymes, and dominant microbial taxa were the key drivers mediating ginsenoside and polysaccharide synthesis. (4) Conclusions: While the “0 + 2” system performed excellently in short-term quality, the “1 + 1” system demonstrated greater potential for long-term soil health and cultivation adaptability. These findings provide a basis for the sustainable cultivation of American ginseng.