Effects Of Water On The Transformation,gene Function And Microbial Nitrogen In Black Soil

Due to the increasing greenhouse effect,global warming is a natural phenomenon.The energy absorption and emission between the ground and the atmospheric system are unbalanced.Ground and atmospheric energy is increasing,which leads to a gradual rise in temperature and global warming.N2O,a greenhouse gas,has a high warming potential and has a long residence time in the atmosphere,so many scientists around the world have begun to study this phenomenon.Soil is the largest source of N2O gas,accounting for more than 80%of the N2O emissions from the biosphere.The material cycle and energy transformation in soil are driven by microorganisms.The effect of soil moisture on soil is very obvious.Black soil is a kind of soil with good properties and high fertility,which is very suitable for plant growth.However,due to the variation of water content in the environment,the transformation of nitrogen,functional genes,microbial populations and quantity of soil have also changed.In this paper,black soil in Jilin and Heilongjiang was taken as the research object.Indoor cultivation methods,combined with extraction of DNA,real-time fluorescence quantitative analysis PCR(q-PCR)agarose gel electrophoresis,high throughput sequencing and other molecular biological techniques,were carried out to study the changes of nitrifying and denitrifying functional genes and microorganism in different pretreated water conditions,as well as the different stages,dry and wet alternation,constant and delivery.Change of soil nitrogen transformation,functional genes and microorganisms under the condition of increasing water content.It provides a basis for the optimum moisture content of black soil under actual conditions.(1)After a week of pre-culture of Jilin black soil,the number of genes of ammonia-oxidizing bacteria,archaea,nirS and nosZ were relatively small at 40%WHC and 60%WHC.At high water content,especially at 100%WHC,ammonia-oxidizing bacteria and archaea are abundant.In high water condition,especially in flooding condition,the gene numbers of nirS and nosZ increased dramatically,which indicated that denitrification took place strongly under this water condition.The quantity of low moisture Betaproteobacteria is small.Actinobacteria and Nitrosovibrio are less abundant in high water.(2)After a week of pre-incubation in Heilongjiang black soil,the higher the water content,the more Archaea ammonia-oxidizing bacteria,and the most ammonia-oxidizing bacteria at 40%WHC.The number of nirS and nosZ was higher under high water content.In March,Acidobacteria-6;Gemmatimonadetes and other microorganisms increased with the increase of water content,while Alicyclobacillus and Alphaproteobacteria were the opposite.In May,Acidobacteria-6,Nitrospira,Actinobacteria,Cytophagia and other microorganisms were suitable for growth under high water content.(3)Under the condition of gradient increasing water content,soil nitrogen conversion rate is proportional to the change of soil water content within a certain range of soil water content.Gradient incremental water change is not conducive to the accumulation of NO3--N and NH4+-N,while constant water is conducive to accumulation.80%WHC is suitable for nitrification and denitrification,and there are more four functional genes.Nitrification and denitrification microorganisms also change with the change of water content.Dry-wet alternation has significant effects on soil nitrification and denitrification,four functional genes and the number and species of microorganisms.Under 80%WHC,it is more suitable for soil nitrogen conversion.