Effect of Green Manure Crop Cultivation on Soil Chemical Properties and Root Rot Disease in Continuous Cropping Field of Ginseng
Background: Some plants have harmful effects on fungi and bacteria as well as plants. Incorporating into soil as green manures are effective in reducing population densities of soil pathogens. Methods and Results: Twenty-three species of green manure crops were cultivated after the harvest of 6-year-old ginseng and then incorporated green manure into the soil at the flowering stage. The following year, the root rot ratio of 2-year-old ginseng and soil chemical properties were investigated. Sorghum sudanense, Helianthus annuus, and Helianthus tuberosus were relatively high in dry matter production. Without incorporating green manure into soil, NO3, EC (electric conductivity) and K were decreased by 95%, 79% and 65%, respectively. When green manure was incorporated to soil, P2O5 and NO3, were reduced by 41% and 25%, respectively. The survived root ratio of 2-year-old ginseng were significantly increased by 56.2%, 47.5%, and 47.3% in Sorghum sudanense, Ricinus communis and Helianthus tuberosus, respectively, In addition, there was a significant increase in Secale cereale, Chrysanthemum morifolium, Atractylodes macrocephala, and Smallanthus sonchifolius. The survived root ratio of ginseng showed a significant positive correlation with soil pH and a negative correlation with NO3, and EC. Conclusion: Cultivation of Chrysanthemum family mainly using rhizome and root as green manure was effective for root rot disease of ginseng.