The influences of iron plaque on nitrogen emissions from paddy soils under different water management practices

Iron plaque (IP), commonly found on rice roots, influences nitrogen emissions, particularly nitrous oxide (N₂O) and dinitrogen (N₂) gases, under different water management practices. However, the mechanisms underlying this influence remain unclear. In this study, the cylinder-in-cylinder method was employed to determine nitrogen emissions from rice soils under alternate wetting and drying or continuous flooding conditions in a laboratory pot experiment. The effects of iron plaque on N₂O and N₂ emissions were investigated. It was found that iron plaque increased N₂O and N₂ emissions, particularly under continuous flooding conditions. The abundance of nosZ gene was positively related to N₂ emission, and the relationship was significant under continuous flooding condition (p ≤ 0.05). The presence of iron plaque increased the richness of nirS- and nosZ-type denitrifiers (p ≤ 0.001) and led to alteration in denitrifier community composition. Specifically, the relative abundance of Pseudomonas was increased (p ≤ 0.001), which probably influenced N₂O and N₂ emissions. These findings help to better understand the effects of iron plaque on N emissions from agricultural ecosystems.