| Near this experiment in tailings pile under the environment of high Mn farmland as the research object,on the basic physical and chemical properties of soil in the study area were analyzed,and through the agent and nucleating agent in strengthening where induced carbonate precipitation(microbial)in the process of curing effect and repair after improvement on soil properties,soil of high Mn environment restoration,And the remediation effect of the restored soil was verified by planting plants.The main conclusions are as follows:(1)Soil p H ranged from 7.12-7.44 throughout the study area,with slightly alkaline soil properties,and conductivity ranged from 23-273 us/cm,with a large conductivity span,indicating uneven distribution of soil salinity throughout the study area.Soil organic carbon ranged from 14-32 mg/kg,with uneven distribution of organic carbon in the surrounding surface soil,total soil nitrogen content of 4-39 mg/kg,total phosphorus content of 5-36 mg/kg,and total potassium content of 5-97 mg/kg,according to the national soil nutrient grading standard nitrogen is grade 3(moderate),potassium is grade 5(deficient),phosphorus is grade 5(deficient),and organic matter is grade 4(more deficient).The composition of the microbial community at different Mn concentration gradients was mainly concluded as follows: under high Mn concentration,the soil potential species in the study area were Actinobacteriota,Proteobacteria and Chloroflexi.The change in Mn content did not have much effect on the composition of dominant species,but only a certain increase or decrease in relative abundance.(2)The MICP technique will only change the p H of the soil transiently and will not affect the background values of the soil.The mixture of auxin and different bacterial agents elevated the soil p H to some extent.The effects on the total N,effective P and fast-acting K contents of the soil under different remediation treatment conditions were significantly different.The total N content of the medium,mycorrhizal agents and complexes increased by 15.29 %,16.98 %,14.85 % and 31.46 %,respectively,after reinforcement by the addition of auxins and nucleating agents.The content of organic matter in the soil was increased by 1.94 % to 8.15 % in the medium,mycorrhizal agent and composite mycorrhizal agent after reinforcement with auxins and nucleating agents compared to the soil restored without auxins and nucleating agents.After the application of mycorrhizal agents,the looseness,porosity and hydraulic conductivity of the soil were improved by the action of soil microorganisms,and the soil bulk weight decreased in all treatments compared with that under the blank control(CK).The addition of microbial agents improved the soil structure and water content of the soil,especially the best effect was achieved by the compound agents.(3)For heavily as well as lightly contaminated soils,the addition of the complex bacterial agent significantly increased the germination rate of chard seeds compared to the control group.Statistically the germination rate of seeds of Brassica juncea treated with the complex bacterial agent reached 90.25 % and 80.34 % in the light and heavily contaminated areas,respectively.At 30 d of sowing of chard,the increase of above-and below-ground part length in the heavily contaminated area reached significant levels in both the compound fungicide and compound fungicide plus auxin treatment groups,and there was no significant difference between the two groups. |
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