Alleviating soil acidification to suppress Panax notoginseng soil-borne disease by modifying soil properties and the microbiome

Planting medicinal herbs under forests is popular as a new cultivation mode for producing high quality herbal medicine. However, soil acidification under forests could aggravate soil-borne diseases, posing a major threat to production. The objective of the study was to investigate strategies for mitigating soil acidification and elucidate its underlying mechanism. We used Panax notoginseng planted under forests with different acidified soil backgrounds to test the effects of exogenous soil amendments on soil chemical properties and rhizosphere microbial communities and then decipher their relationship with root rot disease in P. notoginseng. The results indicated that the appropriate dosage of soil amendments with lime, calcium magnesium phosphate, and organic manure individually and their mixture could alleviate root rot disease and promote the growth of P. notoginseng by increasing pH and modifying other soil chemical properties. The abundance and diversity of rhizobacteria increased with increasing soil pH, especially beneficial rhizobacteria including Bradyrhizobium, Rhodoplanes, Mesorhizobium and Gemmatimonas, which modified the soil microbial community by enriching beneficial bacteria and suppressing pathogens to alleviate root rot disease. However, high EC and AN caused by over-dose amendments had the negative impacts on soil microbial communities, resulting in root rot disease exacerbation. Alleviating soil acidification to a suitable level could suppress root rot disease by modifying soil chemical properties and enriching beneficial soil rhizobacteria. The findings would be an effective practice toward ameliorating acidic soil under forests to reduce soil-borne disease.