| The western part of jilin is one of the three major saline-alkali soil areas in the world and the largest saline-alkali soil area in China,with an area of 2.13×106hm2.The soil in this area has high degree of alkalinization,high salinity,weak soil permeability,hard and hard when dry,soft and muddy when wet.To improve the performance in west jilin soda saline soil water infiltration,improve irrigation and drainage system in the soda saline area of effect,in this paper,in the west of jilin province taonan stability capacity of soda saline soil as the research object,to the soda saline soil of adding different ratio of river sand,corn stalk,rice husk,based on the one-dimensional soil column test,studying the characteristics of different additives on the soda saline soil water infiltration,the influence of different additives to increase permeability effect of soda saline soil.By comparing the infiltration effects of different additives in different proportions on soda saline-alkali soil in western jilin,3% rice husk and 5% corn stalk were selected to mix with the soil to study the water and salt transport characteristics of the concealed pipe system.According to the theory of soil hydrodynamics,taking the dark pipe system as the research object and based on the indoor soil box test,the characteristics of soil water and salt transport during irrigation and drainage of dark pipe system with different water supply pressure mixed with additives were studied.HYDRUS 2D/3D software was used to establish a two-dimensional numerical model of soil water transport during dark pipe irrigation and verify the accuracy of the model.Research indicates:(1)Using rice husk and corn straw to mix uniformly can increase the permeability of soda alkali soil in the west of Jilin Province.There is no significant difference between the effect of 3% and 5% rice husk,but the effect of corn straw to increase the permeability of soda alkali soil in the west of Jilin Province is better under the same mixing proportion.Comprehensive consideration and analysis show that it is more economical and effective to select 3% rice husk and 5% corn straw to increase the infiltration of soda alkali soil in the west of Jilin Province;even mixing of river sand can improve the parameters of soil water infiltration characteristics,but the improvement rate is relatively low.(2)The greater the water supply pressure of 3% rice husk,5% corn straw mixed with soil,the farther the moving distance in each direction of the same irrigation duration wet front,and the vertical upward distance > horizontal right distance > vertical downward distance.The greater the water supply pressure of the concealed pipe is,the shorter the time for the wetting front to reach the soil surface is,and the shorter the irrigation time is;the greater the water supply pressure of the concealed pipe is,the greater thecumulative infiltration of the concealed pipe per unit length is;under the same direction,the soil moisture content of the same distance with different water supply pressure of the concealed pipe decreases with the increase of the water supply pressure of the concealed pipe;under the same distance,the same concealed pipe is used for water supply The soil moisture content in different directions of water pressure is: horizontal to right > vertical to up.(3)3% rice husk,5% corn stalk dark pipe water supply pressure soil profile under different mixed with salt overall trend is starting from the dark tube filter tip from near to far gradually increasing,soil surface and horizontal to the right up near the wetting front salinity is greater than 0.45%,says when use subsurface pipe system irrigation salt accumulation in the soil near the wetting front of the wetted body exceeds the threshold value of the middle salt soil.(4)The total amount of drainage salt is larger when 5% corn stalk is added than when3% rice husk is added,the drainage time is shorter,and the amount of irrigation water is smaller.Therefore,the drainage effect of 5% corn stalk is better when 5% corn stalk is added in the dark tube system than when 3% rice husk is added. |
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