Preparation And Experimental Study Of New Carbon-based Microbial Agent

Biochar and microbial fertilizers can improve soil fertility and good soil microbial colony structure,and both can be used as soil remediation agents.However,the preparation process of biochar-based microbial fertilizer and its effect have been little studied.In this paper,we firstly prepare biochar and activate and cultivate microbial strains;secondly,we use microbial immobilization technology to try out charcoal-based microbial fertilizer;then we study the effects of biochar particle size,charcoal bacteria immobilization ratio and immobilization time on the number of effective live bacteria during the preparation of new charcoal-based microbial fertilizer and propose optimized process parameters;finally,we use pot test to verify the effect of new charcoal-based microbial fertilizer on crop-soil system.Finally,a pot test was conducted to verify the effect of the new charcoal-based microbial bacterial agent on the crop-soil system and provide basic support for the development and utilization of the new charcoal-based microbial agent.The main research contents and results of this thesis are as follows:1.In order to obtain materials for the preparation of new char-based microbial agents,firstly,rice husk biochar（RH）,corn straw biochar（CS）and rice straw biochar（RS）were prepared by high temperature and slow pyrolysis based on biomass pyrolysis system.Next,microbial strain activation technology was used to activate and culture Bacillus subtilis,Bacillus megaterium and Bacillus amyloliquefaciens lyophilized powder to obtain strain slants and then prepare Bacillus subtilis culture（BS）,Bacillus megaterium culture（BM）,Bacillus amyloliquefaciens solution（BA）and mixed bacteria culture（MB）.According to the analysis of the physicochemical properties of the three biochars and the four bacterial solutions,the CS showed superior performance among the biochars because it was in the middle of all the physicochemical properties,and the MB showed superior performance among the bacterial solutions because it had the highest growth rate and the highest number of effective live bacteria.2.In order to obtain the most suitable combination between the three biochar and the four bacterial liquids.By contrast test,three kinds of biochar and four kinds of bacterial culture medium were adsorbed and fixed one to one to prepare carbon-based microbial fertilizer,and the number of effective viable bacteria was taken as the evaluation index.The results showed that the effective viable bacteria number of T10（rice husk biochar+mixed bacteria）,T11（corn straw biochar+mixed bacteria）and T12（rice straw biochar+mixed bacteria）treatments was higher than other treatments.The effective viable bacteria number of different biochar fixation was ranked as T11>T12>T10,and the effect of corn straw biochar fixation mixed bacteria was better.Based on comprehensive consideration,corn straw biochar（CS）and mixed bacterial medium（MB）were selected as biochar and bacterial solution for the preparation of the new carbon-based microbial agent.3.In order to optimize the process parameters for the preparation of the new carbon-based microbial agent,response surface method BBD（Box-Behnken Design）experimental design method was adopted,and 15 groups of experiments were designed with biochar particle size,carbon fixation ratio and fixation time as three factors.The effective viable bacteria number was taken as the response value,and the regression model was established and fitted.The results showed that the effect of three factors on the response value（effective viable bacteria number）was ranked in the order of carbon fixation ratio>biochar particle size>fixation time.When corn straw biochar particle size was 0.5mm,the fixation ratio of carbon bacteria（CS+MB,i.e.corn straw biochar+mixed bacteria）was 10%,and the fixation time was 24 h,the optimal preparation process was to predict the maximum effective viable number of the new biochar microbial microbial agent(1.62×10¹²CFU/g).4.Pot test was conducted to verify the effectiveness of the new charcoal-based microbial agent.The fungicides were applied to neutral black soil and acidic red soil,and 10 groups of experiments were designed to compare the growth of chard and the changes of soil physicochemical properties and microbial species.The results showed that in the black soil treatment group,each index T3>T1>T2>T4>CK1 treatment,and in the red soil treatment group,each index T7>T6>T5>T8>CK2,and the richness of microbial species in the soil were improved,which indicated that the charcoal-based microbial fungicide had a good effect on the soil crop,and the charcoal-based microbial fungicide could play a better practical application effect when it was applied with NPK fertilizer.