Biogas Residue Composting And The Bio-control Effect Of Its Bio-organic Fertilizer On Tomato Bacterial Wilt

Anaerobic digestion residue（biogas residue）is a byproduct of biogas engineering,which contains more organic matter.If it is not used,it may cause secondary pollution to the environment.The common way to treat biogas residue is to apply it directly to the farmland after simple composting,which has a good promoting effect on crop growth.At present,the research on the utilization of biogas residue resources mainly focuses on the fertilizer efficiency,and there are few studies on the evaluation of disease resistance of biogas residue bio-organic fertilizer made from biogas residue combined with biocontrol bacteria.In this paper,pig manure anaerobic digestion residue was used as the main raw material,fresh cow manure and rice straw were mixed for composting,and its composting products were taken as the object of study.The composting formula was optimized by detecting the changes of physical and chemical properties in the composting process.An actinomycete strain G33,which had strong antagonism to Tomato bacterial wilt,was screened in the early stage of the laboratory and used as the research strain.Bio-organic fertilizer was produced by secondary fermentation of compost products,and its potential application in promoting tomato growth and controlling tomato bacterial wilt was studied.The main results are as follows:（1）Using fresh dairy cow dung,rice straw and pig manure biogas residue to mix in different proportions,four treatments（R1-R4）were set up（cow manure:straw and biogas residue（mass ratio）were set as 3:1:1,2:1:2,1:3,0:1:4）.Regulate C/N at 35:1 with an average moisture content of 68.5%.Aerobic composting fermentation was carried out.The results showed that all the four treatments could reach maturity in about 35 days,but the effects of different ratios on the composting process of pig manure and biogas residue and the properties of compost products were significantly different.Through the determination of composting parameters and the analysis of physicochemical properties,it is concluded that R2 and R3 are the optimum ratios.（2）A strain of actinomycete G33 with strong antagonistic ability and broad antimicrobial spectrum was screened from tomato plantations.Combining morphological characteristics and physiological and biochemical properties,16S rRNA gene sequence analysis and homology comparison,the homology with Streptomyces microflavus（MH707030）was 99%,and was preliminarily identified as Streptomyces microflavus.S.microflavus G33 has a certain inhibitory effect on bacterial wilt.R2 and R3 were used as secondary fermentation substrates to ferment with strain G33,respectively.The results showed that strain G33 reached the highest level at the 8th day of growth in R3,and the number of live bacteria could reach 8.33×10¹00 CFU g^-1,which decreased slightly thereafter.Therefore,the optimum fermentation formula for strain G33 is R3 and fermentation time is 8 days.（3）Pot and field experiments were conducted to evaluate the resistance of bio-organic fertilizer from biogas residue to bacterial wilt of tomato.The results of pot experiment showed that compared with the control,the biocontrol effect of BOF-G33 treatment was as high as 51.72%,and the dry and fresh weight of above ground parts（stems and leaves）increased by 290.29%and 195.95%,respectively.In addition,compared with the control,the number of pathogenic bacteria in rhizosphere soil was significantly affected by BOF-G33 treatment,which decreased by 15.22%compared with the control,while the number of actinomycetes was about 240%of the control.The results of field experiment showed that the biocontrol effect of BOF-G33 treatment reached 48.72%and the yield of tomato reached 144.01 g/plant,which increased by 70.30%compared with the control.Abundance analysis of soil microorganisms at generic level also showed that applying BOF-G33 could effectively increase the abundance of Streptomyces and reduce the abundance of Lawrence.In summary,the bio-organic fertilizer（BOF-G33）made from 60%biogas residue,20%cow manure and 20%rice straw mixed in proper proportion can effectively promote the growth and development of tomato plants,prevent and control tomato bacterial wilt.It has good application prospects and provides a new way for the development and utilization of biogas residue.