The Study On Organic Materials Alleviating Cucumber Continuous Cropping Obstacle And Mechanism

To elucidate the mechanism of organic materials alleviating cucumber continuous cropping obstacle and the influencing the cucumber physiological and biochemical proprieties, aerial moist cultivation and potting experiments were carried out to study the change of soil available nutrients, pH, EC, root activities of Dehydrogenase, Nitratase, ATPase and Peroxidase. We found these factors have some relations with the continuous cropping obstacle mechanism. The result showed that rice straw, pig feces and wood chip contain some kinds of phenolic acids such as p-hydroxybenzoic acid, p-coumaric acid and frulic acid. The p-coumaric acid content in rice straw and pig feces was higher than frulic acid and the p-hydroxybenzoic acid content in wood chip was higher than p-coumaric acid. The total phenolic acid content in rice straw was highest and the pig feces, wood chip followed. The content in three organic materials reached maximum after 20 30 days , and remained stable and minimum after 4O-5O days. The three organic materials can lower soil pH and the pig feces influence was the largest, followed by rice straw and wood chip. The soil EC value of pig feces treatment increased remarkably with its rising amount, but rice straw and wood chip treatment reduced a little. The total amount of bacteria, actinomyces and epidhyte in pig feces treatment was highest, followed by rice straw and wood chip treatment. The amount of bacteria and actinomyces in pig feces treatment was more than control treatment, but the epidhyte was Less. The microbe amount in the rice straw treatment was more than in the control treatment, but wood chip treatment was less. The change of soil available nutrients during the decomposition was obvious. Rice straw and pig feces can enhance the soil available P and K content, but wood chip had little effect. The pig feces can raised the soil NH4- N content, but wood chip reduced its level, and the rising level of rice straw treatment was not remarkable. The root dehydrogenase, ATPase and NR activity increased, but POD activity decreased in pig feces and 0.5% rice straw treatment, which resulted in accelerating the uptakes of nutrient. But the condition was reverse in the wood chip and the higher rice straw addition treatment. The total N, P, K amount uptakes by cucumber of different organic materials treatment varied greatly. So did the cucumber growth. The cucumber growth of pig feces treatment is the best under the continuous cropping obstacle, then followed by 0.5% rice straw treatment. But wood chip and the higher rice straw addition treatments had the negative effect.