Nitrification

Nitrification is a crucial process in the nitrogen cycle, where certain bacteria convert ammonium (NH4+) into nitrites (NO2-) and then into nitrates (NO3-). This process occurs in two main stages, involving different types of bacteria: ammonium-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB).

Stage 1: Ammonium Oxidation

Ammonium-oxidizing bacteria (AOB), such as Nitrosomonas, are responsible for oxidizing ammonium (NH4+) to nitrites (NO2-). This process releases energy that the bacteria use for growth and metabolism.

Stage 2: Nitrite Oxidation

Nitrite-oxidizing bacteria (NOB), such as Nitrobacter, further oxidize the nitrites (NO2-) produced in the first stage into nitrates (NO3-). This step also releases energy for the bacteria's use.

Importance of Nitrification

Nitrification is essential for converting ammonium, which is readily taken up by plants but can also be toxic in high concentrations, into a form (nitrate) that is still accessible to plants but less harmful. Nitrates are a vital source of nitrogen for plants, and they also play a critical role in the nitrogen cycle and ecosystem functioning.

Study Guide

1. What is nitrification?
2. Describe the two stages of nitrification and the bacteria involved in each stage.
3. Explain the importance of nitrification in the nitrogen cycle and ecosystem.
4. Discuss the role of nitrates in plant nutrition.
5. Compare nitrification with other nitrogen cycle processes, such as ammonification and denitrification.