Study On Submerged Cultivation And Draining Time On Soil Properties Of Facilities

With the development of facilities agriculture in our country, facility cultivation area is growing. The repeated use of facilities, long-term continuous cropping of dry raw vegetables, the blind application of chemical fertilizers, and the semi closed facility environment may result in poor soil texture, soil salinity and nutrient accumulation, soil enzyme activity decreased and soil salinization problems, resulting in the decline in the production of facility vegetables and poor quality, and thus harm human health. Zhou Zenghui et al. (2015) and Zhang Na et al. (2014) research suggest facility paddy upland rotation can be effective prevention and control of soil salinization. To explore optimal submerged cultivation time on soil salinization prevention, taking the plastic back cover cultivation bucket for cultivating device, set processing and repeated in greenhouse, compared the effect of different time of the submerged cultivation of aquatic vegetable on normal facility soil properties, and then utilized the facility salinization soil determined the changes of soil properties in the process of the submerged cultivation of aquatic vegetable in 40 days and 32 days draining, and then to compare the changes of soil properties in the process of different submerged cultivation and draining. The followings are the major findings:1、From the winter of 2013 to the spring of 2014, the experiment of effects of different time on soil properties of normal facilities in submerged cultivation with watercress, the results showed that:with the extension of submerged cultivation time, the soil EC value and the content of NO3--N, available N, available P and available K in 0-20 cm soil layer decreased gradually, and the fall range was more obvious, while which in 20-40 cm soil layer showed a downward trend after the first rise, but the amplitude was small. In the experiment, the fall range of soil salt and available nutrients content in 0-20 cm soil layer was larger, and soil available nutrients in 20-40 cm soil layer started to decrease. This shows that when submerged cultivation to 110 days, crops begin to use soil nutrients in the lower soil layers. With the extension of submerged cultivation time, soil urease and invertase activity in 0-20 cm soil layer gradually decreased, which in 20～40 cm soil layer first increased and then decreased. The submerged cultivation of 36 to 110 days can promote soil urease activity increased in 20～40 cm soil layer, The submerged cultivation of 36 to 86 days can promote invertase activity increased in 20～40 cm soil layer, and the inhibition of invertase activity in 0-20 cm soil layer was relatively small; The submerged cultivation of 36 to 110 days can improve soil acid phosphatase activity in 0-40 cm soil layer. This showed that submerged cultivation with aquatic vegetables in normal facilities soil in winter to 110 days harvested then drained to plant of drought, which not only can prevent soil salinization, but also can maintain soil ecological environment relatively stable.2、During the summer and autumn of 2014, the experiment of determining soil properties in the process of submerging cultivation water spinach 40 days and draining 32days by soil salinization. The results showed that submerging cultivation can significantly reduce the 0～10 cm surface soil EC value and NO3--N content, while soil EC value and NO3--N content increased significantly in 10～40 cm soil layer.32 days after draining after submerged cultivation, the soil EC value, NO3--N content in 0-10 cm soil layer has gone up, but compared with submerged soil before still significantly decreased, and the soil EC value close to normal growth of vegetable of the critical value of 500 μs·cm-1, the soil EC value (between 377～440 μs·cm-1) in 10-40 cm soil layer decreased compared with 40 days after submerged cultivation, had risen than that in control. Available P and available K contents in 0-30 cm soil layer decreased after 40 days submerged cultivation, and 32 days after draining they continued to decline. The content of organic matter in 0-40 cm soil layer increased after 40 days of submerged cultivation. There was a significant decrease in soil urease activity in 0-20 cm soil layer and soil urease in 0～10 cm surface soil in submerged cultivation 40 days after and draining 32 days after; and acid phosphatase activity of surface soil were significantly increased. The results showed that summer submerged cultivation with aquatic vegetable one month more on soil salinization has a very good treatment effect.3、During the spring and summer of 2015,the experiment of submerged cultivation time affecting different levels of soil salinization and staining time on soil properties. The results showed that the basic content of salt in soil was different, and eventually the degree of the soil salt was also different after submerging cultivation. Light salinization of the soil EC value of around 800 μs·cm-1 can be eased after relatively short time submerged cultivation, while moderate salinization of the EC value of around 1000 us·cm-1 need a long time submerged cultivation to effectively solve the probem.Previous submerged cultivation processing time is longer, then with draining time extension, magnitude of salt recovery is smaller. When submerged cultivation time is similar and the soil EC value is lower at the end of submerged cultivation, the longer the salt back up to the same value. Therefore, the application of submerged cultivation planting aquatic vegetables preventing and controling of soil salinization, should choose suitable submerged cultivation time according to the degree of salinization.