Community Characteristics And Function Analysis Of Functional Microorganisms Of Nitrogen Cycle In Fluvo-aquic Soil Of Hebei Plain

Aiming at the problem of soil nitrogen pollution and over exploitation of groundwater,this paper studied the nitrogen cycle process and microbial function and selected representative fluvo-aquic soil samples of different depth to culture,using surface water/groundwater drip irrigation of enhanced bacteria(efficient nitrogen transformation mixed bacteria)liquid and growth-promoting bacteria liquid(bacillus amyloliquefaciens)on the basis of the investigation of the soil types in Hebei plain.Then the paper studied the change of soil physical and chemical properties,analyzed community structure changes of bacterial flora and the characteristic of the microbial community structure by using phospholipid fatty acid biomarkers and high-throughput sequencing.It could provide basis for the development of surface water irrigation and microbial remediation of soil.Determination results of soil physical and chemical properties showed that,ammonia nitrogen degradation time was short and the overall degradation effect was not ideal.The content of the nitrite nitrogen fluctuated greatly because of its instability.The degradation degree of organic matter,total nitrogen and nitrate nitrogen were different in different regions,and the degradation time was the first five weeks.The overall degradation effect of surface water irrigation was not different from the groundwater and it showed that surface water drip irrigation technology had development potential.The growth-promoting bacteria was not as good as the enhanced bacteria to accelerate the degradation of organic matter.The degradation degree of total nitrogen and nitrate nitrogen was large from enhanced bacteria and growth-promoting bacteria and the former improvement effect was greater than the latter if as the agent to repair the soil.The results of the phospholipid fatty acid spectra analysis showed that,bacterial biomass showed an increasing trend of different depths soil and the biomass on 0~20 cm soil depth was more than 20~40 cm depth and the enhanced bacteria could adapt to the soil environment better than the growth-promoting bacteria.The order of biomass of the characteristic phospholipid fatty acids indicating different microbial types was that gram-positive bacteria features tag quantity was greater than the unknown type microbial biomass which in turn was greater than the gram-negative bacteria and aerobic bacteria features tag quantity was greater than the unknown type microbial biomass which was greater than the anaerobes/facultative anaerobes.High-throughput sequencing results of bacteria showed that,proteobacteria,Actinobacteria and Acidobacteria were dominant phylums,Bacillus was dominant ammonifying bacteria genera,Nitrospira was dominant nitrifying bacteria genera and Bacillus was dominant denitrifying bacteria genera.The number of OTUs treated with enhanced bacteria liquid was more than the other treatments and surface water or groundwater drip irrigation had no effect on the number of OTUs.The microbial diversity of the fifth samples was higher,and the composition of bacteria in the fifth samples was close while the differences of the tenth samples were obvious.High-throughput sequencing results of archaea showed that,the predominant phylums were Thaumarchaeota,Crenarchaeota,Euryarchaeota.And Thaumarchaeota was dominant phylum among them.The species that could be used for the study of the archaea ammonia oxidizing characteristics were uncultured Nitrososphaera sp.,Cenarchaeum symbiosum and Candidatus Nitrosoarchaeum limnia,and the first two were dominant archaea.Sampling time and drip irrigation types had little effect on the number of OTUs.Archaea diversity varied greatly of enhanced bacteria and growth-promoting bacteria liquid treatments,the differences of the composition of the same batch samples were particularly obvious.