Analysis of Nitrification Characteristics and Ammonia Oxidizing Microorganisms in Four Typical Tobacco Planting Soils

This study aims to explore the nitrification characteristics of different tobacco soils and the differences of nitrogen transforming microorganisms. Laboratory experiments of microcosm cultivation were conducted in four typical tobacco planting soils (Zhucheng brown soil, Shaowu rice soil, Meitan yellow soil and Xuan’en yellow brown soil) , and the nitrification process of nitrogen and the characteristics of their ammonia oxidizing microorganisms (ammonia-oxidizing archaea AOA and ammonia-oxidizing bacteria AOB) in different tobacco soils were investigated. Results showed that the nitrate nitrogen content and nitrification rate of the four types of tobacco soils differed significantly, and their nitrification rates exhibited fluctuating decline with incubation time. Relatively higher nitrate nitrogen content and nitrification rate occurred in yellow and yellow-brown soils. The N₂O emission rate in the four types of soils behaved fluctuating decline firstly, followed by tending to be stable, among which the paddy soils displayed the highest emission rate and cumulative emission. AOA dominated the ammonia oxidation process in the four types of soils, while the abundance of AOA and the ratio of AOA/AOB exhibited significantly higher in yellow and rice soil than in other soils. Correlation analysis was taken between soil nitrification parameters and physicochemical traits, and the result showed that soil pH, organic carbon, total nitrogen content, inorganic nitrogen content, and carbon to nitrogen ratio were the key factors leading to the differences in N₂O emission and ammonia oxidizing microbial diversity in different tobacco planting soils. In conclusion, the nitrification rate and N₂O emission of different tobacco-planting soils are affected by soil physicochemical properties, among which yellow and yellow-brown soils exhibit higher nitrification rates, while rice soils displays the largest N₂O emission, and the ammonia-oxidizing archaea AOA are generally predominant.