Effects Of Different Types Of Fertilizer On Nitrification And Denitrification Of Tobacco Field Soil

Tobacco is one of the main economic crops in China.In order to meet the demand for tobacco leaf production,the use of inorganic fertilizers in tobacco cultivation is constantly increasing.However,the input of a large amount of inorganic fertilizers has seriously deteriorated the quality of the tobacco field,resulting in the waste of resources,and reduced the quality of the tobacco leaves.The effective use of organic fertilizers or combined application of organic and inorganic fertilizers to improve soil structure and cultivate soil fertility,which can improve the tobacco quality and the economic benefits.Inthis study,the tobacco field were took as the sample in Qingdao experimental base,Tobacco Research Institute of Chinese Academy of Agricultural Sciences,in Jimo District,Qingdao City,Shandong Province.Through the setting of different fertilization treatments,using q PCR,high-throughput sequencing technology and other means,to explore the effects of different fertilization treatments on soil nitrification and denitrification microbial population abundance,community structure and diversity,and the correlation analysis of soil physical and chemical properties.The response mechanism of soil nitrification and denitrification microbes to different fertilization was established,and combined with the determination of soil nitrification and denitrification potential;the function changes of soil microbial community structure were established.The main results are as follows:（1）The variance analysis of the soil p H,DOC,nitrogen,phosphorus,potassium,sulfur and other physical and chemical indicators after different fertilization treatments was carried out.It was found that the p H value of the soil after applying organic fertilizer was0.28～0.34 higher than that of the inorganic fertilizer treatment group.The content of soil organic matter in the organic fertilizer treatment group was about 8%higher than that in the inorganic fertilizer treatment group,but the available nitrogen,phosphorus,sulfur,and potassium in the organic fertilizer treatment group were significantly lower than those in the inorganic fertilizer treatment group,of which ammoniacal nitrogen,available potassium,and The content of available sulfur is only 1/3 of the high sulfur and high potassium inorganic fertilizer treatment group.Short-term application of a large amount of inorganic compound fertilizer can significantly increase the content of effective nutrient elements in the soil,thereby quickly and effectively increasing the fertility of the soil.But the application of organic fertilizer can alleviate soil acidification,increase the content of organic matter in the soil,and improve the physical and chemical properties of the soil and continuous utilization potential.（2）Correlation analysis of soil nitrification potential,physical and chemical properties,and nitrifying microbial community abundance,combined with analysis of soil ammonia oxidation microbial community structure,finally concluded that the soil nitrification potential with organic fertilizer was significantly higher than that with inorganic fertilizer,but increased in sulfur and potassium.The application amount can increase the soil nitrification potential of the inorganic fertilizer treatment group.The abundance of soil ammonia oxidizing bacteria（AOB）treated with organic fertilizer was lower than that of inorganic fertilizer treatment group,while the abundance of ammonia oxidation archaea（AOA）was higher than that of inorganic fertilizer treatment.In addition,the dominant populations of AOB（24 OTUs）and AOA（20 OTUs）were also identified.These results showed that the different fertilizer treatment groups had their own unique dominant populations.Through cluster analysis,PCA analysis and RDA analysis of soil ammonia oxidation microbial community structure,it was found that fertilization generally reduced the diversity of AOB and AOA in the soil,and organic fertilizers and low-sulfur and low-potassium inorganic fertilizers had relatively little effect.（3）The denitrification potential of the soil with organic fertilizer was significantly higher than that of the inorganic fertilizer treatment group.When the inorganic fertilizer was treated,increasing the content of sulfur and potassium could reduce the denitrification potential of the soil.Organic fertilizer enriches the phosphorus and soluble organic carbon（DOC）in the soil and optimizes the soil C/N ratio.Compared with inorganic fertilizers,organic fertilizer increases the community abundance of denitrifying microorganisms in the soil,and increases the application of sulfur and potassium which reduced the community abundance of denitrifying microorganisms in the soil.The three denitrifying bacteria communities,nir K type,nir S type,and nos Z type,all responded significantly to different fertilization treatments,but the nir S denitrifying bacteria hardly responded to the soil sulfur and potassium content;most importantly,due to the different fertilization systems on the soil’s nutritional structure,physical and chemical properties and The changes in the ecological structure are different and the degree of influence is also different,resulting in the dominant groups of three denitrifying bacteria in the soil,responding to organic and inorganic fertilization programs are completely different,but different to different sulfur potassium There is a great similarity in the response of the quantitative fertilization program.In short,the advantage of organic fertilizer is that it is rich in nutrients,especially phosphorus and organic.Organic fertilizer can improve the soil environment and optimize the ecological structure of soil microorganisms;however,organic fertilizer activates soil-nitrifying microorganisms and activates denitrifying microorganisms.The emission of N₂O from the soil increases the burden of nitrogen loss and the greenhouse effect.The advantage of inorganic fertilizer is that it has sufficient fertility,which can improve soil fertilityeffectively and quickly.Sulphur and potassium in compound fertilizer can inhibit the denitrification activity of soil and improve the activity of nitrification reaction.Therefore,the combined application of organic fertilizer and inorganic fertilizer,while increasing the amount of sulfur and potassium in the fertilizer in an appropriate amount,can save the cost of fertilization,ensure soil fertility and quality,improve the utilization rate of fertilizer efficiency,increase the economic benefits,and also ensure the sustainable development of modern agricultural ecology.