Denitrification

• When soils become waterlogged, and have a low oxygen concentration, the type of microorganism present changes. Fewer aerobic nitrifying and nitrogen-fixing bacteria are found, and there is an increase in anaerobic denitrifying bacteria.
• Anaerobic denitrifying bacteria convert soil nitrates into gaseous nitrogen. This reduces the availability of nitrogen-containing compounds for plants.
• For land to be kept productive, the soils on which crops grow must be kept well aerated to prevent the build-up of denitrifying bacteria.