Effect Of Combined Application Of Manure With Nitrogen Fertilizer On The Diversity Of Nitrifier In Installed Vegetable Fields

In soil ecosystem,nitrification is a key process of soil nitrogen transformation.It has an important influence on the sustainable development of soil quality,plant growth,nitrogen utilization,environmental pollution and food safety etc..Nitrification is a continuous process drived by nitrifying bacteria which can convert ammonia to nitrate.The microorganisms involved in this process are known as nitrifier community,including ammonia oxidizing bacteria(AOB),ammonia oxidizing archaea(AOA)and nitrite oxidizing bacteria(NOB).Fertilization mainly affected the nitrification by changing the soil microbial diversity and community structure.This study was carried out in the long-term fertilization experiment field of Shenyang Agricultural University.Using Biolog and high-throughput sequencing technology to discuss the effect of the organic fertilizer with nitrogen fertilizer on soil fertility and nitrifier.The purpose is to clarify the interaction between nitrifying bacteria and soil fertility,so as to provide the data for the study of nitrifying bacteria.Especially,nitrite oxidizing bacteria.At the same time,this paper also can provide microbial parameters in soil fertility evaluation and health management in greenhouse,and provide the scientific basis for improving nitrogen utilization and reducing agricultural N2O emission.The main results of this study are as follows:1.The application of organic manure and nitrogen fertilizer can improve soil fertility and soil enzyme activity.Especially the organic fertilizer with nitrogen fertilizer can increase the content of soil organic matter,total nitrogen,available phosphorus and available potassium;in no organic fertilizer treatments or organic fertilizer amount fixed,soil ammonium nitrogen,nitrate nitrogen,available nitrogen content and conductivity is increased with the increase of nitrogen amount,and pH has the opposite trend.The application of organic fertilizer can increase the activity of urease,invertase,cellulose decomposing enzyme and fluorescein diacetate hydrolase.The activity of neutral phosphatase is most sensitive to fertilization;long-term application of nitrogen fertilizer has certain inhibitory effect on catalase;Only inputting the high amount of nitrogen fertilizer(N2,MN2)has significant effect on polyphenol oxidase activity2.The functional diversity of soil microbial community was studied by Biolog technique.The single application of nitrogen inhibits the soil microbial diversity function,but combined with a certain amount of organic fertilizer can improve the microbial functional diversity.However,when combined excessive nitrogen fertilizer also leads to a decline in the function of microbial diversity.Long term N fertilization promotes the amino acid carbon source to be the most important carbon source,and the carbon source utilization rate is higher in organic fertilizer treatments than that in single nitrogen fertilizer treatments.Comprehensive comparison,the long-term organic fertilizer combined with nitrogen fertilizer(MN1)is the best suitable ratio,N2 is the worst.3.Based on high throughput sequencing technology,preliminarily analyzed the greenhouse soil bacteria and archaea.A total of 37 phylum,1507 species of bacteria,and 7 phylum,40 species of Archaea are identified(including unclassified group).Proteobacteria is the advantage colony;Thaumarchaeota is the predominant microorganism in archaea.On the phylum level,fertilization has great effect on the bacterial and archaeal community structure in each treatment,N2 has the largest difference with other treatments,and Archaea is MN1.4.Based on high throughput technique,the interaction between nitrifying bacteria and soil fertility was evaluated.This study detectes 4 AOB groups,a total of 15 species of AOB in greenhouse soil.They are belong to Nitrosococcus,Nitrosomonas,Nitrosospira and uncultured Nitrosomonadaceae,Nitrosomonadaceae uncultured is the dominant bacteria.There are 3 genera,5 species of AOA are detected.They are belong to Nitrosoarchaeum,Nitrososphaera and Nitrosotalea,respectively.Nitrososphaera is dominant AOA;4 genera,14 species of NOB are detected,belong to nitrification Spirillum,Nitrococcus,Nitrospina and Nitrolancea,Nitrospira is the dominant NOB.On the whole,the relative abundance of AOA was more than 80%in all treatments,which indicated that AOA might play a leading role in ammonia oxidation under the conditions of this fertilizer regime.5.In this study,with organic fertilizer inputting,soil nutrients show a increasing trend,but the total abundance of nitrifier has shown a downward trend,so there are different negatively correlated between nutrients and nitrifier abundance.Above the whole nitrifying community,only NOB has the significant correlation with many physicochemical properties,soil enzyme activity and soil functional diversity,indicated that NOB(especially Nitrospira)is more sensitive to soil environment changing,and may play a greater potential role in soil biochemical and microbial metabolic activity.In conclusion,single application of nitrogen fertilizer is beneficial to the increase of quantity and abundance of Archaea and nitrifying bacteria,while organic fertilizer input is beneficial to enrich the species diversity of two species.On the whole,N2 has the greatest influence on the community structure of nitrifying bacteria.