Experiment Research On Reclaimed Water Irrigation Under The Conditons Of Different Groundwater Depths

The aim of the article is to provide theoretical foundation for safe and efficient utilization of reclaimed water in the areas of different depths of groundwater. The experiment is made in the lysimeter, and the groundwater tables are 2m, 3m and 4m controlled by Mariotte. In the experiment, the reclaimed water acquired from sewage treatment plant is used to irrigate winter wheat and summer corn, and the variation of all indexes and nitrogen transportation of the wheat and corn are studied. The results are as following:1. The reclaimed water irrigation greatly affects the leaf area index, the dry matter accumulation and the output of the winter wheat. Under the same condition of irrigation amount and fertilization, the output of winter wheat with low water treatment has the exponential correlation with groundwater table, and the output of winter wheat with high water treatment has the polynomial correlation with groundwater table. Low water handling is better for reclaimed water irrigation in the areas of groundwater depth of 2m through analyzing the physiological indexes, the dry matter accumulation, the output and the water use efficiency. In the meantime, high water handling is better for reclaimed water irrigation in the areas of groundwater depth of 3m and 4m.2. The leaf area index of summer corn is affected by the groundwater depth, and it decreases with the groundwater depth raising. The groundwater depth of 4m has the most significant influence. Under the same condition of irrigation amount and fertilization, the output of summer corn with low or high water treatment has the polynomial correlation with groundwater table. And under the same condition of groundwater, the output with high water treatment is more than the output with low water treatment.3. The nitrate nitrogen content of soil firstly increases along depth direction, and after getting to a summit decreases along depth direction, no matter before irrigation or after irrigation. Compared with the time before irrigation, the summit of nitrate nitrogen content after irrigation shifts down, from the summit on the soil layer of 20-40cm before irrigation to the summit on the soil layer of 40-80cm after irrigation, which illustrates that irrigation has the dramatically leaching influence to nitrate nitrogen of surface soil. 4. The average content of nitrate nitrogen on the soil layer of 0-200cm has increased after irrigation. And with the same groundwater depth, the increasing of nitrate nitrogen content of high water handling is more than low water handling, because the more irrigation amount contains more nitrogen. With the same irrigation amount, the increasing of nitrate nitrogen content both in the soil and groundwater has the polynomial correlation with groundwater table.