Effects Of Irrigation With Reclaimed Water On The Vegetables Qualities And Soil Properties

The reclaimed water is a kind of water resource, which is reusable by recycling the sanitary sewage and industrial waste. Under the situation of serious water shortage, it will open a new channel for using agricultural water to realize the safe utilization of reclaimed water. Hydroponics experiments were conducted to study the germination, growth and the physiological characteristics of pakchoi, Chinese cabbage and radish seeds; the filed experiments were also performed to study the growth, nutritional quality and soil environment of pakchoi and cabbage.Irrigation with reclaimed water has different influences on germinations of vegetables. It promoted germination of radish seeds obviously and inhibited germination of Chinese cabbage seeds at a certain extent, but had no significantly impacted on germinations of pakchoi seeds. Reclaimed water promoted the overground part growth of vegetables, but inhibited the root growth of vegetables. The effect of irrigation with reclaimed water on antioxidant system of vegetables seedings changes with vegetables varieties in a short-term. Reclaimed water can activate antioxidant factor, ehance the ability of removing free radicals of pakchoi and radish and promote their growth; but increasesd superoxide dismutase obviously, and reduced peroxidase of Chinese cabbage. It shows that Chinese cabbage is suffered physiological stress by the reclaimed water.Irrigation with reclaimed water in a short-term can ehance growth and yield of pakchoi and cabbage obviously. Compared with the fresh water treatment, the yield of pakchoi and cabbage with different reclaimed water treatments increased 9.09%~16.67% and 6.21%~18.08% respectively. The yield of pakchoi and cabbage under different treatments were in the order all as follows: the full reclaimed water treatment>the mixed treatment>the rotation treatment>the full fresh water treatment. Irrigation with reclaimed water had different effects on Vitamin C, crude protein and soluble sugar of vegetables. In the growth phase, Vitamin C of pakchoi and cabbage decrease, while crude protein and soluble sugar increase gradually. Irrigation with full reclaimed water increases soluble sugar of pakchoi, has little affected on Vitamin C, reduces the crude protein content at a certain extent, but full reclaimed water has no significiantly effects on Vitamin C, crude protein and soluble sugar of cabbage. The effects of irrigation with reclaimed water on nutrients of pakchoi and cabbage are greater than the fresh water treatment in a short-term. The majority of elements under different treatments are no significant difference, except Ca and Zn in pakchoi, Cu and Zn in cabbage. It shows that reclaimed water promote the absorption of nutrients in vegetables. The effects of irrigation with reclaimed water on heavy metal in pakchoi and cabbage are no significant difference, compared with the fresh water treatment, except Cd in pakchoi roots and leaves, Cr in pakchoi leaves. It shows that irrigation with reclaimed water will not cause a significant impact on heavy metal in vegetables in a short-term. Nemerow comprehensive index was used to evaluate heavy metals in vegetables, and it is found that the index of the full reclaimed water treatment is the highest both in pakchoi and cabbage. It shows that irrigation with reclaimed water will increase the concentration of heavy metals in vegetables at a certain extent.The effects of irrigation with reclaimed water in a short-term effect on soluble salt at differernt depth on pakchoi and cabbage soil have no significant difference with the fresh water treatment. At the harvest time , soluble salt is higher than the blank soil. Reclaimed water has more amount of heavy metals than fresh water, but under different reclaimed water treatments, majority of heavy metals in soil has no significant difference with the fresh water treatment. It shows that for a short-term irrigation with reclaimed water will not cause heavy metal pollution in soil.To sum up, reclaimed water as a new type of water can replace the ground water and tap water for vegetables irrigation and plays an important role in alleviating the shortage of agricultural water. But we should adopt a cautious attitude.Although irrigation with reclaimed water with a short-term is not yet showing the adverse effects, more attention should be paid to the long-term effect and fixe points should be set up to monitor and evaluate irrigation with reclaimed water effect on vegetables quality and harmful elements accumulated in soil-vegetables system.