Study On The Combined Remediation Of An Ionic Rare Earth Tailings In Southern Jiangxi By Soil Improvement And Plants

There are some problems such as soil acidification,poor fertility,destruction of soil structure,loss of vegetation and serious soil erosion.Soil improvement and bio-remediation have always been common methods of ecological restoration in mining areas,But,the research on ecological restoration of ionic rare earth tailings still needs to be further expanded.In this experiment,soil chemical improvement combined with ecological restoration was adopted,A heap-soaked ionic rare earth tailings in Longnan County,Field trials,Three plant types(ornamental,legume and soil and water conservation)were selected for a total of 10 species,The soil was improved with amendments such as biochar,fly ash,organic fertilizer and inorganic fertilizer,4 soil treatments(tailings bare soil CK1,provided Tailing plants,Improved CK2,of bare soil Improved soil plants),To study the effects of soil improvement and plant types on the physical and chemical properties and plant growth characteristics of ion rare earth tailings in southern Jiangxi,And evaluate the repair effect,Finally,it provides help for ecological restoration of ion rare earth tailings in southern Jiangxi.The results show that:(1)Comparison with the CK1 treatment of ion rare earth tailings in southern Jiangxi,Improved soil CK2 treatment significantly reduced gravel and silt content,Significantly increased soil clay,Its content increased from 20.1%to 29.4%;After planting plants,Compared to bare land,There was no significant difference in soil mechanical composition.The tailings were improved,Soil bulk density decreased from 1.36 g/cm~3to 1.30 g/cm~3,Plant planting has no significant effect on soil bulk density.Contrary to the bulk density,the addition of soil a mendments had no significant effect on soil porosity,while plant planting significantly increased soil porosity.Adding improver,Soil field water holding capacity and saturated water content increased by 14.8%and 10.9%respectively;Compared to bare land,Planting plants significantly increased field water holding and saturated water content,increased by 48.5%and 18.7%respectively.Three plant types were compared,Landscape plants increase soil silt content,Soil soil clay content increased by soil conservation plants and legumes,There was no significant difference between soil bulk density,porosity and soil water content.(2)The pH value of all treatments of improved soil is generally higher than that of tailings,pH increased by 0.55.The improved soil CK2 treatment pH is the highest,5.68 per cent,higher than all other treatments.At the bottom of the treatment pH,To4.32.Compared to bare soil,Plant planting significantly reduced soil pH to 0.3 units.The average organic matter content of all treatments of improved soil is generally higher than that of tailings.The content of organic matter in the soil of planting plants was significantly higher than that of bare soil,The content of organic matter in the treatment of improved grass and improved leaf cassia was higher than that of other plants10.65 g/kg and 11.03 g/kg respectively.As a whole,the CEC content of the improved soil is higher than that of the tailings,Among them,CK2 treatment,Has the highest CEC content,11.48 cmol/kg,Higher than improved soil plant planting treatment;The CEC content of tailings CK1 treatment is the lowest of all treatments,6.88 cmol/kg.The average N,P,K nutrient content of the improved soil is generally higher than that of the tailings soil.Among them,the total nitrogen content of legumes was significantly higher.Compared with CK1 treatment of tailings,the total nitrogen content increased 4-6 times,Tenfold increase in available phosphorus,The content of alkali-hydrolyzed nitrogen and available potassium increased by about 2 times.(3)In CK1 treatment,the biomass of different microbial communities was the lowest.The total microbial biomass was 671.49ng/kg,the bacteria was 310.06ng/kg,the fungi was 80.56ng/kg,the actinomycetes were 33.32ng/kg,and the gram The positive bacteria(G+)was 147.28ng/kg,and the gram-negative bacteria(G-)was17.32ng/kg,which were statistically significantly lower than other treatments.The total microbial biomass was the highest in the treatment of planting landscape plants in the tailings soil area,and its content was 5529.11ng/kg,and the treatment content of legumes was 2262.35ng/kg,but it was still higher than the 671.49ng/kg of CK1treatment;In the improved soil area,the microbial biomass of the three treatments for planting plants was above 4500ng/kg,which was higher than that of the CK2treatment(2555.99ng/kg).For other microbial communities such as bacteria,they all show similar characteristics.(4)The survival rate of radish,mango and mango can not be used for mining area restoration.During the experimental period,the growth index of the improved soil was significantly better than that of the tailings.There was no significant difference between all the growth indexes of the improved Rhododendron and the treatment of the tailing soil Rhododendron,and all the growth indexes of the improved ryegrass were worse than that of the tailing soil.Among them,the highest coverage was that the improved soil was treated with 100 Xi grass and wide leaf paspalum,both of which reached 90%,and the coverage of the other four species except Rhododendron was lower than 35%.The coverage of ryegrass in tailing soil was higher than that of improved soil,reaching 55%,and that of rhododendron in both soils was 65%.(5)The comprehensive fertility index of all treatments in tailings area is below0.9,its fertility grade is grade III,and it is in a poor state of fertility.The outstanding characteristic is the serious lack of individual indexes.Soil available phosphorus and CEC,are the main obstacle factors of fertility index in mining area.