인삼재배지 180지점으로부터 토양을 채취하여 토양산도, 유기물함량 및 유효인산함량을 측정한 결과 재배년수별 유의한 차이는 나타나지 않았다. 채취한 토양의 메탄올추출액으로 상추종자 발아실험을 실시한 결과 5~6년 재배지의 토양에서 종자발아나 유묘생장을 강하게 억제하는 토양추출액을 선발하였다. 선발된 토양 추출액중 발아와 유묘생장을 억제하였던 추출액은 인삼배양세포의 활력을 최대 90%까지 억제하였으나 전해물질의 누출은 증가하지 않았다. 토양추출액으로 세가지 종류의 항산화 효소 활성을 측정한 결과 superoxide dismutase는 거의 영향을 받지 않았으나, 상추유묘의 생체중억제형 토양추출액을 처리한 인삼배양세포의 peroxidase의 활성이 현저하게 억제되었고, catalase의 활성은 발아억제형 및 생체중억제형 토양추출액 모두에서 유의한 억제를 보였다.

Chinese milk vetch (CMV) is a winter legume that is commonly used as cover crop in Korea. Kill date of cover crop for addition into soil affects N content in cover crop and N availability in soil. This study was conducted to evaluate the effect of CMV as green manure cover crop according to kill dates before growing corn without artificial fertilizer. Top of CMV cut three times on 13 April, 27 April, and 11 May were added into soil at a rate of 600 kg per 10a. Sugar content in CMV litter was persistently decreased from mid-April to late-May. The decrease of sugar content might be due to the transformation into starch and/or other storage or structural constituents. The decreased amount of sugars was greater than 12% and the increased amount of starch was less than 0.2%. Concentration of NH4+ in soil treated by CMV litter cut on May 11 was slightly higher than that in the treatment with early-cut (April 13) CMV, the concentration at 28 and 49 DAT (days after treatment) was higher in the treatment with late-cut CMV litter. Regardless of cut (kill) date of CMV, the phosphatase activity in the treatment of CMV litter was higher compared to the untreated control. Soil dehydrogenase activity was increased steadily by addition of CMV litter implying total microbial activities in the soil were increased. Our results demonstrate that the status of cover crop species at kill date is an important factor influencing soil enzyme activities derived from microorganisms. Therefore, the optimal kill date of cover crop should be examined to improve the efficiency of cover crop as green manure crop regarding the practical sequence in cropping system