Effects of UV-B Radiation on the Chemical Composition of Azolla and Its Decomposition after Returning to the Field and Nitrogen Transformation in Soil

In the present research, effects of UV-B radiation (5.00 kJ·m−2) on chemical composition Azolla were investigated, and decomposition residues after radiation, nitrogen form, enzyme activity, bacterial community in paddy soil analyzed. Compared to natural light treatment, total content was significantly increased by 17.0% under treatment. returned grown light, rate cellulose, lignin, increased, which led an increase activities transformation enzymes, including neutral protease, ammonia monooxygenase, nitrogenase, nitrate reductase, nitrite contents different forms (NH4+-N, NO3−-N, soluble organic nitrogen, microbial biomass nitrogen) soil, while N2O emission flux reduced 20–30%. The dominant bacteria supplied with Firmicutes, Clostridia, Clostridiales, Lachnospiraceae. However, returning changed structure resulting a decrease number ammonifying bacteria, nitrifying nitrogen-fixing denitrifying inducing changes Methanomicrobiales, Methanoregulaceae, Methanoregula. According structural equation model, field would reduce emissions increasing lignin monooxygenase reducing reductase activity soil. Thus, can directly change phytochemical components their thus indirectly affecting structure, transformation, play important ecological roles regulating nutrient terrestrial ecosystems.