Effects Of Different Soil Treatments On Continuous Cropping Obstacle Of Panax Quinquefolium L.

The experiment was conducetd in the farm of Hougou village, Tanghekou town, Huairou District,Beijng. It was completely randomized block design of five factors and three levels. The farm had already planted American ginseng for four yeas, sandy alkaline soil. Ginseng seedlings were plump buds with no diseases, whole roots and same size. The buds were transplanted by 20×8 cm spacing in the row and plants in mid-March. The experiment studied on the American ginseng's yield and disease condition, soil fertility, enzyme activities and the number of mail soil rhizosphere microorganism. The results were as follows:1. Effects of different soil treatments on emergence rate, survival rate and yield.The proper amount of hydrated lime was 50g·m-2. Comparing with CK, it's emergence rate increased 28.21%, survival rate increased 80.93% and yield increased 100.93%. The proper amount of biogas slurry was 1kg·m-2. Comparing with CK, it's emergence rate increased 36.09%, survival rate increased 67.20%, and yield increased 125.23%. The proper concentration of EM was 12mg·m-2and the emergence rate increased 32.26%, survival rate increased 96.82%, and yield increased 139.25%. The proper amount of Selenium was 2mg·m-2. Comparing with CK, it's emergence rate increased 32.59%, survival rate increased 20.32%, and yield increased 95.33%. The proper amount of organic germanium was 5mg·m-2. Comparing with CK, it's emergence rate increased 29.38%, survival rate increased 91.71%, and yield increased106.54%.2. Effects of different soil treatments on organic matter, total nitrogen, rapidly availablephosphorus, and rapidly available potassium. To a certain degree, all treatments had increased the the content of organic matter, total nitrogen, rapidly available phosphorus and available potassium, except that hydrated lime treatment reduced the content of the organic matter. Comparing with different amount(concentration)under the same treatment, the proper amounts of hydrated lime was 200g·m-2 . The proper amount biogas slurry was 1.5kg·m-2. The proper concentration of EM was 12kg·m-2.3. Effects of different soil treatments on soil enzyme activities. Comparing with CK, the hydrated lime treatment had no significant differences for invertase activities and polyphenoloxidase activities Also there was no significant differences between different amounts under the same treatment. Hydrated lime treatment had inhibitory effect on urease activities. Comparing with CK, the low and middle amounts had no significant differences while there were significant differences between high amounts and CK. Comparing with CK, EM treatment had significantly increased invertase activities, but there were no significant differences between different concentration. The urease activities were increased to some extent compared with CK. also there were no significant differences between different concentration. The proper concentration of EM was 30ml·m-2 for polyphenoloxidase activities, but there were no significant differences between middle and high concentration. The biogas slurry treatment had increased soil enzyme activities to some extent. The proper amount of biogas slurry was 1.5kg·m-2 for invertase activities and polyphenoloxidase activities, but there were no significant differences between middle and high concentration. The best amount of biogas slurry was 1kg·m-2 biogas slurry.4. Effects of different soil treatments on the number of main soil rhizosphere microorganisms.In gerenal, with American ginseng's growth period gonging on, rhizosphere bacteria and actinomyce showed downtrend, while rhizosphere fungi showed an increasing trend. The hydrated lime treatment had no significant effect on the trend of rhizosphere bacteria, actinomyce and fungi. And it decreased the numbers of rhizosphere bacteria, actinomyce and fungi in every period EM treatment had no effect on the trend of rhizosphere bacteria and actinomyce, while it oversized the rising range of fungi. And the EM increased all the numbers of rhizosphere bacteria, actinomyce and fungi in every period .The proper concentration is 30ml·m-2. The biogas slurry treatment had no effect on the trend of rhizosphere bacteria while it oversized rising range of fungi and slowed down the descent range of fungi. The biogas slurry increased the numbers of rhizosphere bacteria, actinomyce and fungi in every period. The proper amount was 1.5kg·m-2...