| Soda saline-alkali soil is characterized by heavy soil texture,high p H,high salt content,and low soil fertility.In view of the characteristics of the above-mentioned saline-alkali soil,this thesis takes soda saline-alkali soil in the Baichenglai area of Jilin Province as the test soil,and uses modified iron tailings to improve it to construct a desalinated soil layer.During the improvement process,the focus is on the release of characteristic components(iron and silicon)in iron tailings and the desalination effect of modified iron tailings added to saline-alkali soil,and the improvement effect is further verified by planting rice.The specific research results are as follows:Sulfuric acid and citric acid were used as modifiers to soak iron tailings with different particle sizes,and different concentration gradients were set to measure the dissolution of iron ions and available silicon in iron tailings.The measurement results show that with the increase of modifier concentration,the content of iron ions first increases and then tends to the level,while the content of effective silicon increases first and then decreases.The smaller the particle size of iron tailings,the higher the leaching of iron ions and available silicon;the leaching of iron ions from 400-mesh iron tailings immersed in 40% sulfuric acid as a modifier was 637.21 mg/kg,effectively The dissolved silicon amount reached 511.55 mg/kg.The leached amount of iron ions in 400 mesh iron tailings soaked with 40% citric acid as modifier was523.87 mg/kg and the effective silicon leached amount was 458.06 mg/kg.The p H value of the sulfuric acid treatment group fluctuated between 1.3 and 7.5,and the p H value of the citric acid treatment group was always around 7.5.400 mesh iron tailings,water,sulfuric acid(or citric acid)were mixed at a ratio of 20:60:40 to make acidic iron tailings improvement materials for pot experiments.The results showed that adding acidic improvement materials to soda saline-alkali soil It can reduce the p H value and salinity of the soil,and increase the percentage of soil organic matter and aggregates.With the increase of application rate,p H and salinity showed a downward trend,and the percentage of soil aggregate content increased.Through the principal component analysis,it is found that when 80 g of sulfuric acid modified iron tailings are added to 1920 g of soda saline-alkaline soil,the desalination effect on the soil is the best.The organic matter content increased by 72%;the p H value decreased to 8.41;the salt content decreased to 3.44%,the percentage of soil aggregate content increased to 0.21%,and the rice yield was 28.01 g.Add CaO and MgO(the ratio of the two is 100:20)to the acid modified iron tailings until the p H reaches 2.0 and mix to make acidic iron tailings composite improved materials for field experiments.The results show that adding acidic iron tailings composite improvement materials to the soda saline-alkali soil to construct the desalinated soil layer,after two consecutive years of improvement,the soil p H value decreased from 9.07 to 8.14,the salt content decreased from 3.91% to 3.41%, and the organic matter The content increased from 4.12 g/kg to 4.45 g/kg,the percentage of soil aggregate content increased from 6.9% to 10.5%,and the content of carbonate root decreased from 0.24 g/kg to 0 g/kg.The content of hydrogen radicals decreased from 2236.31 g/kg to 541.76 g/kg,and the content of sodium ions decreased from 987.39 g/kg to 401.77 g/kg.Compared with the control group,the improvement effect is very obvious.At the same time,the yield of rice increased significantly.When the amount of improved material added was 80kg/mu,the yield of rice was 420.24 kg. |
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