Salinity Regulation Of Saline Soils By Different Salt Barrier Materials

For a long time,a large amount of abandoned land has been generated in the process of industrialization and urbanization in China,which has not been reclaimed and utilized in time,and with the continuous development of economic construction,the number of abandoned land continues to rise and seriously pollutes the ecological environment.In the construction of Chengdu-Kunming railroad,the abandoned site in Heijing area of Yunnan is the most typical construction waste land.The stratum of the area is characterized by the richness of gypsum,mannite,chloride salt and other salt rock weathering materials,due to the construction of the railroad,Heijing area abandoned slag field exposed to the surface,the surface layer of slag soil has been weathered and cracked or even into powder,coupled with a large amount of water evaporation,the surface of the slag field has precipitated a layer of white salt crystals.Subsequently,cultivated soil backfill was carried out,and sub-salinization of the soil occurred,and soil salt precipitation slabbed,which seriously affected the regional ecological environment.The soil of the dump site consists of mostly raw soil,a small amount of topsoil and gravel,with extremely low soil fertility,poor soil physical and chemical properties,extreme p H value,high salt content,extremely weak water and moisture retention capacity,difficult for natural vegetation to grow,and difficult for ecological restoration.Therefore,the adoption of reasonable saline soil management measures to improve its physicochemical properties and biological characteristics is of great practical and strategic importance for the expansion of arable land resources,ecosystem construction,and regionalized high-quality development.Therefore,the study selected purple-stemmed Zelenia,sisal and wheat straw as soil salt barrier materials,and carried out indoor soil column experiments to study the distribution pattern of soil water and salt under different salt barrier materials and different mixed application amount treatments,in order to be able to improve soil texture,improve soil salinization and achieve the purpose of regional ecological restoration,mainly Research conclusions and results:(1)Under the treatment of one-dimensional water infiltration experiment,the infiltrati on epochs of different salinity barrier mixed application treatments were CK(279min)<F2(512min)<F1(674min),CK(279min)<X2(429min)<X1(587min),CK(279min)<D2(331min)<D1(413min).Different salt barrier materials reduced the infiltration performance of soil,and when the mixing amount was certain,the hindering effect of Ziziphiopsis on soil water infiltration was stronger than that of sisal and wheat straw,which was Ziziphiopsis>sisal>wheat straw.When the amount of salt barrier material was quantified,the ability of soil water infiltration decreased gradually with the increase of different salt barrier material mi xes.The buried salt barrier can significantly reduce the water infiltration capacity and has a significant infiltration reduction effect.(2)The power function can better fit the relationship between wetting front advance distance and time under different salt barrier treatment,and the correlation coefficient R~2is between 0.990-0.997.The Kostiakov infiltration model can accurately reflect the change of soil water infiltration amount under different salt barrier treatment,and the correlation coefficient R~2is between 0.994-0.991.The correlation coefficient R~2was between(0.962-0.993)and(0.962-0.993),and the linear relationship between the advance distance of wetting fronts and the accumulated infiltration amount under the treatment of different salt barrier materials.(3)The buried salt barrier was able to inhibit soil water evaporation.On the fifth day of evaporation,the cumulative evaporation amount of each treatment was,532.4g for CK treatment,489.2g for D1 treatment,485.1g for F1 treatment and 452.9g for X1 treatment,indicating that the buried salt barrier played an evaporation suppressing role compared with the unset.On the fortieth day of evaporation,the cumulative evaporation amounts of CK,D1,F1 and X1 were 1732.7g,1143.2g,1422.3g and 1642.4g,and the evaporation inhibition rates of D1,F1 and X1 were 5.22%,17.91%and 22.69%,and the soil water evaporation inhibition was shown as sisal>purple-stemmed Zeeland>wheat straw.(4)The relationship between the cumulative evaporation of soil water and time under the treatment of different salt barrier materials could be simulated by Black evaporation model and Rose evaporation model,and the correlation coefficient R^2 ranged from 0.982-0.996,which had a strong correlation.(5)Different salt barrier materials can improve the soil water holding capacity.During the evaporation stage,the soil column of each treatment had a greater reduction in soil water content in 0-18 cm than the homogeneous soil,and the reduction in soil water content in 18-30 cm was less than the homogeneous soil,and the water holding capacity showed that purple-stemmed Zeelandia>sisal>wheat straw.After 42 days of evaporation experiment,F1,X1 and D1 treatments reduced 34.83%,23.61%and 12.5%in 0-18 cm compared with CK,and the average salt content of 30-42 cm soil layer in CK,F1,X1 and D1 treatments were 24.61 g,26.26 g,26.08 g and 25.68 g,which indicated that the buried compartment could effectively inhibit the salt to soil The effect of salt inhibition of Ziziphus vulgaris was the most obvious among the treatments.(6)Using soil moisture sensors to study the soil moisture change pattern is an effective way,the experimental process can reflect the soil moisture change process more carefully,enhance the amount of experimental data and less damage to the soil structure,which helps to discover new patterns in the research and can reduce the workload and research cost.