Screening Of Straw Degrading Bacteria And Application Of Compound Microbial Agent

Our country has produced about 9 tons of straw in the process of agricultural production,while the straw as a kind of recyclable resource has not been applied in time,which has caused waste and environmental pollution.If we can convert straw resources through biological treatment technology,it will have important ecological and environmental benefits.Straw compost can provide rich nutrients for soil,enhance soil fertility and improve soil properties.Saline-alkali soil is difficult to treat because of its characteristics of high salinity,high alkalinity and low soil fertility.For example,it is of great significance to apply straw compost to the ecological restoration of saline-alkali soil.In this thesis,cellulose straw degrading bacteria were screened from corn straw,and efficient composite bacteria were prepared,which were applied to straw compost,and the fertilizer was used to improve saline-alkali soil.Specific research results are as follows:In the medium with corn straw as the only carbon source,7 strains of cellulose degrading bacteria that can effectively degrade straw were finally screened out,and their numbers were S381-8,S81-7,S81-3,S81-4,S81-2,S876-2 and S876-6,respectively.After identification,The seven strains were Priestia megaterium,Brevibacillus brevis,Bacillus amyloliquefaciens,Bacillus velezensis,Streptomyces bacillaris,Trichoderma reesei and Penicillium purpurogenum.The seven strains were prepared into microbial agent.The composting experiment of corn straw showed that the temperature of the composite agent treatment（H1）was higher than that of the control treatment（CK）,and the temperature of the composite agent treatment（H1）was higher than that of the control treatment（CK）,and more days were maintained above 50℃in the whole composting cycle.Compared with CK,adding bacteria agent can improve the seed germination index（GI）and reduce the water content,organic matter and C/N of the reactor,and the treatment effect of adding compound bacteria agent is better than that of the control group.Bacterial agent promoted straw rot and straw composting process.The results of single factor experiment on improved saline-alkali soil showed that 8%～16%of straw biological fertilizer was the best addition amount according to the growth of rice seedling.8%～16%of iron tailings was the best additions.Microbial agent 50～150 was the better dilution times;pH 6～7 was a good addition.Through orthogonal experiment and principal component analysis,it is concluded that the optimal ratio of saline-alkali soil improvement is A₃B₁C₃D₂of treatment,that is,4kg saline-alkali soil,16%straw organic fertilizer,8%iron tailings,200 times dilution of microbial agent,pH of saline-alkali soil adjusted by citric acid is6.5.Compared with the blank group,the height of rice seedlings increased by 46.6%,pH decreased by 11.98%,electrical conductivity decreased by 41.68%,total salt content decreased by 7.51%,and organic matter increased by 57.29%.Alkali-hydrolyzed nitrogen increased by 108.89%and available phosphorus increased by 136.6%compared with the control group.