Experimental Study On Saline-alkali Soil Improved By Biochar Modified By Fulvic Acid

The soil pH of a mine dump in Inner Mongolia is 7.81 ～ 9.78,the total salt content is 0.60 ～ 3.4g/kg,the soil main nutrient content is low,the plant growth in the mine is affected by salt stress.if no effective measures are taken,the ecological environment of the mine will be further deteriorated.Therefore,in this thesis,the total salt content of the soil in the mine dump was 0.60-3.4 g/kg,and the plant growth was subject to salt stress as the research object.By adding four gradients of fulvic acid modified biochar(MBC)to the soil and setting three gradients of salt,the experiment of potted wheat was carried out.The effects of adding fulvic acid modified biochar on soil physical and chemical properties,saline-alkali indexes,main nutrients and main growth characters of wheat with different salt content were analysis and studied.It provides a thought for the application of MBC to the improvement of saline-alkali soil and plant growth in mining area.The main research results are as follows:1.The pH of biochar decreased from 10.08 to 5.85 after modification.After modification,the specific surface area,total pore volume and oxygen-containing functional groups of biochar are increased,and the biochar has stronger hydrophilicity and more polar functional groups.Scanning electron microscopy showed that the surface of MBC became rough and porous,the number of micropores increased,and the pore structure became more dense.2.Due to the porous surface structure and large adsorption capacity of MBC,salt can be adsorbed on the surface and pores of carbon.MBC can improve the physical structure of soil and increase the soil water content,so the salt can be transferred to the lower layer of soil,and the total salt content will be reduced eventually.The dosage of 3%MBC is the best,which can reduce 1.75g/kg at the highest.3.The application of MBC can increase the main nutrient content,organic matter content,total nitrogen,total phosphorus,and available phosphorus by 71.00% ～136.00%,16.00%～22.00%,17.60%～78.14%,6.23-16.77 times.The available potassium and ammonium nitrogen increased by 9.00%-191.00% and 8.30%-45.00%respectively.4.Adding MBC could increase germination percentage,plant height,leaf number,fresh weight,dry weight and leaf area index of wheat in soil with different salt content.Increased by 177.00%～194.12%,4.50～11.70cm/ plant,0.20～1.90 pieces/plant,11.50～18.17g/ basin,2.39～2.61g/ basin,2.50 ～15.55 times,respectively.The contents of chlorophyll,soluble protein and soluble sugar in wheat leaves increased,and the results showed that 3%MBC treatment had the best effect.In conclusion,the results of this study showed that the modified biochar with fulvic acid had the potential to improve saline-alkali soil and promote plant growth in barren mining areas.It can improve the germination rate of wheat seeds,the main growth index,improve the physical and chemical properties of soil,increase the main nutrient content,reduce the soil salinity,so as to achieve the effect of fertilizer and desalting.There are 30 figures,20 tables and 99 references in this thesis.