Chemical Characteristics and Its Irrigation Effect of Drainage Water in Ditches, Yinbei Irrigation Districts,Ningxia

摘要

Taking five drainage reuse sites in Yinbei irrigation districts, Ningxia for example, this paper analyzed the chemical characteristics of drainage water in ditches, saline-alkaline hazard and its impact of drainage reuse on soil. The result showed that the hydro-chemical type of drainage water is CNa at Nuanquan farm and CINa at other four pilots. Every alkaline index in the drainage water was obviously smaller during the middle-late irrigation than those during the early irrigation. Except Qianjin Farm, the saline-alkaline hazard of drainage reuse for irrigation was relatively slight. The dominant soluble salt in the soil was the Chloride-sulfate bearing sodium and calcium. The soil texture had an obvious impact on soil saline-alkaline after irrigation. Salt was not easy to accumulate the lightly textured soils, such as sandy loam. In the area where the rice was planted for a long term, the groundwater level was higher and the better choice was to adopt the paddy-upland rotation system in order tomaintain the effect of soil improvement. Adopting rotation systems with anti-saline crops, soil flushing with fresh water, paddy-upland rotation and so on would play an important role in controlling soil water-salt and improving the soil. The effects ofdrainage reuse for irrigation were good.