Study On The Technology Of Water-saving Improvement And Soil Water-salt Transport In Saline Soil Of Hetao Irrigation Area

Hetao irrigation area, with its features of high salty soil parent material, high underground water level, severe soil salinization and secondary salinization, is located in the arid and semi arid area of Inner Mongolia. Thus, it becomes a typical soil salinization area of our country. Improving saline soil has been an important part of researches and productions of agriculture in irrigation district. In order to seek for the best optimal coupling of the amount of soil amendment and irrigation water by applying the most suitable sorts and amount of amendment for different soil texture, this study,with the research results of domestic and foreign scholars on soil salinization improvement and the transportation of soil water and salt, and based on the growth situation of growing sunflower in severe saline soil test field, focuses on experimental research on saline soil improvement technique and the law of water and salt transportation to find out the changes of physicochemical properties, the movement of water and salt, and the growth situation of growing oil-sunflower. Meanwhile, to provide basic technical supports for the improvement and prevention of soil salinization by finding out the influence of amendments on the transpotation of water and salt of soil profile, this essay, based on indoor soil column test, is to seek the transportation laws of water and salt with the influence of irrigation level and amendments and to build a dynamic model of the transportation of water and salt in soil and its numerical solution in the improvement process. Conclusions are as follows:1. The application of fly ash, FGD gypsum, dual modifier, can significantly reduce the pH value of salinization soil, electrical conductivity (EC) and total salt content (TDS), as a result, the migration direction of salt is adjusted, the physical and chemical properties are improved, and the growth of the crops is promoted.the growth index of oil-sunflower is obviously better than those whitout admendment; what’s more, the emergence rate and yield increased significantly. By combining field experiments with indoor soil column experiment and choosing desulfurized gypsum as representative, its effect on water and salt transportation of soil and the accumulation of salt ions in the soil profile are analyzed. The results show that, modifiers have a significant impact on the distribution of moisture, salinity and salt ions transportation, controlling soil moisture, improving soil structure and reducing soil salinity.2. In the process of improving saline soil by modifier, not only suitable sorts and reasonable amount of modifier should be chosen, but also appropriate irrigation amount should be macthed with, that is to say, to achieve the optimal improving effect is based on achieving the best coupling of the amount of modifier and irrigation.The improving effect of amendments on saline soil and application amount is not linear positive correlation, too much modifier dosage increases the amount of salinity in the soil, as a result, it is harmful to crop growth. While, dosage is too little to achieve the improving objective. Therefore, the amount of all kinds of amendments should be set a theoretical computation as safe dosage, R as the lower limit, and R/η as the Upper limit, in which η is the modified utilization coefficient. It is a coefficient to take leakage, insufficient substitution, incomplete leaching of the modifier into consideration, normally 0.6-0.8.3. According to the theory of soil water dynamics, a one-dimensional vertical transportation model of water and salt in the soil profile is established. Under the condition of saving water, choosing desulfurization gypsum of the modifier as the main interference factors, the dynamic change process of soil water and salt were simulated by using the model after adding r modifying agent to salinized soil. Trough the verification and analysis of the model, the model has better accuracy and can predict the content and distribution of water and salt in the soil.4. Based on the results of three-years field test, saline soil improving techniques and integrated methods, in the condition of water-saving irrigation, are concluded in Hetao irrigation area. Through benefit analysis, soil improving techniques and integrated methods can obtain better economic benefits, social benefits and ecological benefits, it has good application and popularization value.