Simulation Of Soil Water And Salt Transport And Analyzed Of Salt Removal In Drip Irrigation Cotton Field Based On HYDRUS-2D Model

The development of water-saving irrigation agriculture is the most important aspect of irrigated irrigated areas.In order to adapt to the climate factors of strong evaporation and less rainfall in Xinjiang,the Xinjiang Production and Construction Corps increased the mulching on the basis of drip irrigation in 1996 and created a suitabledrip irrigation technology for arid and semi-arid regional in Xinjiang.However,with the increase of the application period of drip irrigation technology,secondary salinization caused by this phenomenon has become one of the new challenges in the test of sustainable agricultural cultivation in Xinjiang Oasis.Due to the characteristics of “less water and ground irrigation”,drip irrigation technology only changes the distribution of water and salt in the root zone of the crop,and it is difficult to effectively leaching the soil salinity to the depth.In addition,the irrigation water itself has high salt content,and salt will remain in the soil.Generate a certain amount of accumulation.Therefore,this study focused on the issue of soil salt accumulation in drip-irrigated cotton soil under the membrane,and conducted a two-year test on cotton drip irrigation in a row of salt shallow trenches.Using the method of combining the pit test with the HYDRUS model simulation,the HYDRUS-2D model was established to simulate the soil moisture and salinity movement processes in shallow depth and varying depth,and the soil water and salt distribution and changes in the pit were analyzed to determine the salt removal mode suitable for drip irrigation in cotton fields under film.(1)The root mean square error of measured values and simulated values of the water content and electricity conductivity of salt drainage ditch at different depths was 0.019,0.157.And The t-test probability is 0.787 and 0.120 respectively.The root mean square error of measured values and simulated values of the water content and electricity conductivity of salt drains treated at different width was 0.027,0.161.And The t-test probability is 0.178 and 0.105 respectively.It shows that there is no significant difference between the simulated and measured values of the HYDRUS-2D model,so the model simulation results can be accepted.(2)The soil water content at the drippers of three salt drainage ditch decreases with the increasing depth and the soil moisture content at the salt drainage ditch increases with the increasing depth.The water content at the same depth under the dripper is greater than that at the salt drainage.Different depths of salt drainage ditch have a significant effect on soil salinity.At the end of the growth period,the 30 cm salt drainage ditch not only has a more pronounced concentration of salt,but also forms a salt desalination area below the dripper.(3)The soil moisture content of the three widths salt drainage ditch is basically the rule that the dripper is larger than the row of salt trench bottom than the row of salt trench slope.The 5?25cm soil surface at the drippers first showed an increased trend and then decreased trend;the water content of the soil layer at the bottom of the salt drain trenches and the row of salt ditches decreased continuously.The change law of soil electrical conductivity is contrary to the law of water content change.It shows that the slope of row salt trench is larger than the drain head at the bottom of row salt trench.The three widths salt drainage ditches are set to form a salt desalination area below the emitters;the accumulation area of 30 cm and 50 cm depths of salt drainage ditch is formed at 40 cm below the row of salt ditches.(4)According to the experiment result,due to the 30 cm depth and 30 cm wide salt drainage ditches is closer to the soil exposed area,which is conducive to the further development of large-washing salt,mechanical scraping salt,etc.Therefore,the selection of this size of salt drains is more conducive to effective salt control and salt drainage.Because the experiment was conducted in the pit,the soil conditions and boundary conditions were different from those in the field.Therefore,the salt discharge test was needed to verify the conclusion of the article in Datian.In the design test,only the width and depth of the salt drain were considered,and the bottom width was not taken into account.Therefore,the bottom width test of different salt drains should be added in future studies.At the same time,the test did not consider the desalination method after salt concentration,so it is necessary to add large-washing salt in the later test.