Why do waterlogged soils lose nitrates through denitrification?

Waterlogged soils lose nitrates through the process of denitrification because they create anaerobic, or oxygen-depleted, environmental conditions.12

In these saturated environments, specific microorganisms known as denitrifying bacteria thrive. Unlike aerobic organisms that require oxygen, these bacteria utilize nitrates ($N{O}_3^{-}$) in their metabolic processes, converting them into free atmospheric nitrogen gas.123

This biological transformation effectively removes nitrogen from the soil, which can significantly reduce soil fertility and agricultural productivity by depleting the supply of nitrates available for plant uptake. While this process is a natural and essential component of the global nitrogen cycle, it is particularly pronounced in swampy or waterlogged soils where oxygen levels are insufficient to support the aerobic bacteria that would otherwise facilitate nitrification.124