Study On Water And Salt Transport Characteristics And Control Technology Of Saline Soil In The Yellow River Delta

Under the background of serious shortage of water and soil resources in the Yellow River Delta,the development and utilization of the rich coastal saline soil resources in the Yellow River Delta was an effective way to ensure sustainable agriculture,The efficient use of water in the process of reclamation of coastal saline soil was an important part of the improvement of salt soil.The Taking Kenli County of the Yellow River Delta as the study area,water and salt transport in soil and groundwater at county scale was researched by field monitoring.At the same time,in order to analyze the relationship between groundwater evaporation and soil surface salt accumulation under different salinities and different leaching methods,a large number of indoor simulation tests were carried out.In this paper,the law of soil desalination and the migration of ions were studied under different salinities and different leaching methods.The dynamic mechanism of water and salt in the process of saturated soil salinization were studied,which can provide reliable scientific basis and technical guidance for the improvement of saline alkali soil in the future.The main results are as follows:The groundwater level in the Yellow River Delta is low and the depth of groundwater depth in many years is 0.07~2.37 m affected by rainfall and phreatic evaporation.The variation range of groundwater conductivity in farmland and wasteland is between 20.21~29.8 mS/cm and 44.79~48.62 mS/cm.The variation of groundwater depth is the same as the conductivity.Under the condition of continuous leaching and interval,the amount of leaching water is 550-900 mm and 350-700 mm,to reach the average crop(planned wetting layer is 0~60cm),the required leaching water was 472.70 mm and 411.60 mm,Intermittent leaching is more water saving than continuous leaching.14.8% ?Therefore,in order to make more efficient use of fresh water resources,we should choose the intermittent leaching method to plan the wet soil.Leaching has played a very positive role in improving the soil environment.The leaching rate of Yellow River water and brackish water was550-900 mm and 450-1125 mm.At the end point of the leaching,the total salt content of soil to plant acceptable and the composition of soluble salt ions was also more reasonable,and the concentration of Na+ and Cl-which more significant plant root damage were respectively reduced to 0.03mol/L and 0.05 mol/L.Therefore,brackish water irrigation can also make the soil meet the requirements of plant growth,in order to reached the average crop(planned wetting layer is 0~60cm),the elution desalting water of Yellow River water and brackish water respectively required 472.70 mm and 754.2 mm.The groundwater depth of 100 cm and 140 cm were 55 days and 116 days,respectively,to reach the limit of general plant growth.With the formation of the surface salt crust,the salt shell has an inhibitory effect on evaporation,and the average evaporation intensity is 11.27 mm/d and 7.52 mm/d.Under different groundwater conditions,Na+ and Cl-ions accumulate fastest to the surface of the soil column,and the concentration is highest.In Kenli County of the Yellow River Delta,the main crops were wheat,corn and cotton,and their net irrigation water requirement is 442 mm,133 mm and 353 mm respectively.Besides,the proportion of the planting area was 7.59%,9.35% and 60.84% respectively.The gross irrigation water requirement of the three main crops was 3.384 million m3,1.033 million m3 and 21.664 million m3,and the proportion of water consumption was 12.98%,3.96% and 83.06% respectively.