Study On The Improvement Effect Of Bamboo Charcoal And Its Immobilized Microorganisms On Saline-alkali Soil In The Coastal Area Of Eastern Zhejiang Province

The physical and chemical properties of saline-alkali soil are poor,which seriously hindered the growth of crops.Saline-alkali soils area in China are widely distributed,which is characterized by large area and significant proportion of cultivated land.At present,the research on saline-alkali soil improvement mostly focuses on agricultural measures,engineering improvement,etc.There is very little research on the improvement of saline-alkali soil by new types of modifiers such as bamboo charcoal and immobilized microorganisms.Saline-alkali soil as a reserve resource,has the potential to develop into agricultural soil resources.Saline-alkali soil improvement has attracted extensive attention of scientists and the government.Aiming at the problem of soil salinization in the coastal area of eastern Zhejiang,this paper analyzes the characteristics of soil carbon pool and its influencing factors of reclamation on the coastal beaches and clarifies the physical and chemical properties of soil and soil microorganisms by bamboo charcoal and immobilized microorganism diversity,impact on plant biomass,photosynthetic indicators,and antioxidant enzymes,etc.This study provides a theoretical basis for the remediation.This study draws the following main conclusions:(1)The evolution of soil carbon pool composition and chemical properties after tidal flat reclamation is influenced by the years of reclamation and human activities.With the increase of reclamation years,the organic carbon content of the surface soil gradually decreased,and the organic carbon content of the soil layer of 10—90 cm increased significantly after 31 years of reclamation.The soil inorganic carbon content(0—30 cm)increased significantly after 10years of reclamation.The inorganic carbon content of each soil layer reached its maximum value after 31 years of reclamation.Redundancy analysis indicates that the accumulation of salt content in the surface soil is an important reason for the reduction of soil organic carbon content.The decrease of soil p H and electrical conductivity is one of the important environmental factors that promote the accumulation of soil organic carbon and inorganic carbon.(2)Bamboo charcoal and immobilized microorganisms increased the content of soil organic carbon,alkali-decomposed nitrogen,available phosphorus,K⁺,Ca²⁺,and reduced the content of Na⁺.The content of organic carbon and K+was the highest at 5%concentration bamboo charcoal treatment,with increments of 25.55%and 6.82 times respectively;the alkali-hydrolyzed nitrogen and Ca²⁺contents were the highest at 5%concentration immobilized microorganism treatment,with increments of 90.2%and 22.4%,respectively;effective Phosphorus content is the highest with 1%concentration bamboo charcoal treatment,with increment of 14.6 times.In addition to 5%concentration of bamboo charcoal and 1%concentration of immobilized microorganisms,the remaining concentration of additives increased the soil Mg²⁺content.The application of bamboo charcoal increased the microbial alpha diversity,while the application of bamboo charcoal immobilized microorganisms decreased the microbial alpha diversity.Bamboo charcoal and its immobilized microorganisms have significantly increased the relative abundance of the fungi Basidiomycotina,Agaricomycetes,and the bacteria Acidobacteria and Actinomycetes,and reduced the relative abundance of the Mycobacteria.(3)Application of different concentrations of bamboo charcoal and its immobilized microorganisms increased plant biomass.Among them,3%bamboo charcoal had the best effect on the improvement of total biomass and root biomass,which increased by 105.67%and109.38%compared with the control.The 1%bamboo charcoal immobilized microorganism had the best effect on improving aboveground biomass,which was an increase of 173.45%compared with the control.The effect of applying bamboo charcoal immobilized microorganisms on plant chlorophyll content was better than that of bamboo charcoal.The 1%concentration of bamboo charcoal immobilized microorganisms had the best effect on increasing total chlorophyll content,which was 13.8%higher than the control.Bamboo charcoal and its immobilized microorganisms significantly improved the plant's photosynthetic index,with 1%bamboo charcoal being the most effective.The net photosynthetic rate(A),stomatal conductance(g),and transpiration rate(E)were significantly increased by 107.9%,113.5%,105.35%compared to ck.The application of bamboo charcoal and its immobilized microorganisms increased plant antioxidant enzyme activity.The 3%concentration of bamboo charcoal immobilized microorganisms had the best effect,with SOD and POD enzyme activities increased by 49.56%and 7.36%,respectively.When the concentration of bamboo charcoal used to immobilize microorganisms exceeds 5%,the activity of plant antioxidant enzymes will decrease.Comprehensive index evaluation shows that adding appropriate concentration of bamboo charcoal and immobilized microorganisms is conducive to plant growth and development.As the concentration of additives increases,the comprehensive index shows a downward trend.When the concentration of immobilized microorganisms exceeds 5%,it is not conducive to plant growth and development.