What roles do ammonification, nitrification, and denitrification play in the nitrogen cycle?

In the nitrogen cycle, microorganisms perform essential transformations that recycle nitrogen through the biosphere. These processes ensure that nitrogen remains available for living organisms rather than being permanently lost to the atmosphere or trapped in organic waste.12

• Ammonification: When plants and animals die, or through the excretion of waste, microorganisms decompose organic nitrogen into ammonia (NH₃) and ammonium (NH₄⁺). This process provides a vital, constant supply of ammonia to the soil.12
• Nitrification: Carried out by specific aerobic bacteria, this oxidative process transforms soil ammonia into nitrites and subsequently into nitrates (NO₃⁻). Nitrates are a key form of nitrogen that plants can readily incorporate into their tissues.12
• Denitrification: Performed by denitrifying bacteria, this process occurs primarily in anaerobic, water-logged soils. These bacteria break down nitrates to obtain oxygen, releasing free nitrogen gas back into the atmosphere. While this depletes soil nitrogen, it is a necessary ecological balance; without it, nitrogen would accumulate excessively in the oceans due to leaching.123

Would you like to know more about how nitrogen fixation initiates this cycle?