Study On Afforestation Technology In Qaidam Saline Alkali Land Based On New Salt-isolated Material

The problem of salinization in the Qaidam Basin severely restricted the construction of the basin's ecosystem and the sustainable development of agriculture,forestry,and animal husbandry.Under the existing farming and irrigation systems,about half of the farmland in the basin will face the risk of salinization,and this high-salinity farmland accounts for 44.92%of the existing farmland.Therefore,it is necessary to carry out research on the governance of salinized land in the Qaidam Basin.Saline-alkali afforestation is a long-term,effective,and sustainable comprehensive improvement measure for saline-alkali land,which can improve the microclimate in the field,reduce the groundwater level,inhibit soil salinity,increase soil organic matter and fertility,thereby improving salinized soil,and achieve certain ecological and economic value.Because the saline-alkali soil is very thin,the climate is harsh,and the ecological environment is fragile,the difficulty of afforestation is generally high.Therefore,it is of great significance to study a suitable afforestation technology for saline-alkali land.The study focused on the new afforestation techniques of saline-alkali land in Gahai town,Qaidam.And using the indoor soil column simulation test to screen the salt blocking materials for afforestation.After the afforestation test in saline-alkaline land,a suitable afforestation technology model for the saline-alkali land in Qaidam was proposed.The soil preparation method in the model is liquid film and agricultural film.In the mode of land rectification,two salt-separated materials,liquid mulch and agricultural film,were placed at the Acupoint of Populus cathayana Rehd.at different locations(Lower layer of salt,upper layer of salt,upper and lower combination),and the afforestation effect of the saline-alkali land was determined through a field afforestation test.The results of the study show that:(1)According to the simulation of the 100 cm soil salinity migration test in the groundwater table,the surface sedimentation of 3cm did not effectively block the upward flow of capillary water.Covering the agricultural film,covering the liquid film,sand coating 6cm can effectively suppress the uplink of salt.Only trace amounts of salt reach the 60cm soil layer on the 50th day of the test.The salt transport is basically the result of the water gradient and salt gradient diffusion.After combining the actual conditions in the field,liquid mulch and agricultural film were selected for field afforestation tests.(2)Aiming at the saline-alkali land in Qaidam Basin,a technology model for afforestation of Qaidam saline-alkali land based on engineering salt washing,salt-blocking materials,salt-tolerant planting and local tree species suitable for planting was proposed.(3)All salt resistance treatment can significantly reduce the total soil salt in the depth of 0-60cm tree acupoint.It is most effective to place salt separation materials on both top and bottom of the layout.Total salt content is less than 1.5g/Kg.The effect of the lower layout is better than the upper layout.In material selection,the upper layer of salt resistance measures preferred agricultural film,the lower layer of salt measures preferred liquid film,Up and down combination measures preferred liquid film.(4)All salt resistance treatment can significantly increase the soil moisture content of 20-60cm tree acupoint.It is most effective to place salt separation materials on both top and bottom of the layout.The effect of the upper layer is better than the lower layout.Two kinds of material's capacity of increasing the soil moisture content is equivalent.(5)All salt resistance treatment can significantly reduce the soil PH value in the depth of 0-60cm tree acupoint.It is most effective to place salt separation materials on both top and bottom of the layout.In material selection,the upper layer of salt resistance measures preferred agricultural film,the lower layer of salt measures preferred liquid film,Up and down combination measures preferred liquid film.(6)The survival rate of afforestation after engineering salt washing and salt-separated material treatment was higher than that of salt-tolerant tree species in the conventional afforestation model.Placing liquid mulch and agricultural film at tree planting sites is beneficial to the survival of afforestation trees.The survival rate of the liquid film(bottom),liquid film(top),liquid film(top+bottom)was 3.5 times,2.75 times,and 3.85 times that of the control,respectively.The survival rates of the agricultural film(upper),agricultural film(lower)and agricultural film(upper+lower)were 3.25,2.25,and 3.5 times of the control,respectively.Through the field trials,it was determined that both the liquid film and the agricultural film can play a good salt resistance effect;Liquid film is suitable for Large-scale engineering afforestation,which is simple and quick to apply;Ordinary agricultural film is suitable for small-scale afforestation,which is relatively economic and convenience.Salt-tolerant plants can be planted in areas where there is no salt washing project.At the same time,under sufficient irrigation,the surface layer of tree acupoint is covered and the cover is covered with soil.A good salt suppression effect can also be achieved by covering more than 3cm of sand.