The key difference between nitrogen fixation and nitrification is that the nitrogen fixation is the process of converting atmospheric nitrogen into ammonium ions while the nitrification is the process of converting ammonium ions into nitrite or nitrate ions.
The nitrogen cycle is one of the main biogeochemical cycles that describe the behaviour and conversion of nitrogen molecule through the atmosphere, terrestrial and marine ecosystems. Approximately 80% of the atmosphere is occupied by the nitrogen gas. However, microorganisms covert this atmospheric nitrogen into a usable form. Afterwards, this nitrogen circulates through the nitrogen cycle. Therefore, there are four main steps of the nitrogen cycle namely nitrogen fixation, nitrification, denitrification, ammonification and assimilation.
CONTENTS
1. Overview and Key Difference
2. What is Nitrogen Fixation
3. What is Nitrification
4. Similarities Between Nitrogen Fixation and Nitrification
5. Side by Side Comparison – Nitrogen Fixation vs Nitrification in Tabular Form
6. Summary
What is Nitrogen Fixation?
Human and other animals do not have a mechanism or enzymes to convert atmospheric nitrogen into a usable form. However, some microorganisms such as bacteria, blue-green algae, lichens, etc. are capable of doing that.
Figure 01: Nitrogen Cycle
Furthermore, several natural processes such as lightning, volcanic eruption, etc. can convert atmospheric nitrogen into usable forms. Therefore, nitrogen fixation is this conversion process of atmospheric nitrogen into ammonium ions in the soil. Furthermoore, symbiotic and free-living bacteria are mainly involved in nitrogen fixation. Azatobacter is one bacterial genus that fixes atmospheric nitrogen. And also Rhizobium is another bacterial genus that comprises of symbiotic bacteria that fix atmospheric nitrogen into ammonium ions.
What is Nitrification?
Nitrification is the conversion of ammonium ions or ammonia into nitrate ions. This is a two-step process. Firstly, ammonium ions convert into nitrite ions by Nitrosomonas bacteria. Secondly, nitrite ions convert into nitrate ions by Nitrobacter bacteria.
Figure 02: Nitrification
Thus, this is an important process because nitrate is the accessible plant form of nitrogen. Hence, this is a crucial and vital step in plant nutrition. Similarly, the microorganisms involved in this step are known as nitrifying bacteria.
What are the Similarities Between Nitrogen Fixation and Nitrification?
- Nitrogen Fixation and Nitrification are two major steps of the nitrogen
- Microorganisms are involved with both steps.
- They both are biological processes.
- Both steps produce accessible plant forms of nitrogen in the soil.
What is the Difference Between Nitrogen Fixation and Nitrification?
Nitrogen fixation is the process of converting atmospheric nitrogen into ammonium ions in the soil. Nitrification is the process of converting ammonium ions into nitrate via two steps. Nitrogen fixers carry out the nitrogen fixation while nitrifying bacteria carry out the nitrification. Both processes are extremely important. The below infographic presents the difference between nitrogen fixation and nitrification in a tabular form.
Summary – Nitrogen Fixation vs Nitrification
Nitrogen fixation and nitrification are two major steps of the nitrogen cycle that is driven mainly by microorganisms. The conversion of atmospheric nitrogen into ammonium or ammonia in the soil is the nitrogen fixation process while the conversion of these ammonium ions into nitrate in the soil is the nitrification process. Nitrogen fixation is followed by the nitrification. Therefore, both these steps are biological processes. Nitrogen fixers carry out the nitrogen fixation while nitrifying bacteria perform the nitrification. This is the difference between nitrogen fixation and nitrification.
Reference:
1.“The Nitrogen Cycle.” Khan Academy, Khan Academy. Available here
Image Courtesy:
1.”Nitrogen Cycle”By Johann Dréo (CC BY-SA 3.0) via Commons Wikimedia
2.”7138863595″ by KoiQuestion (CC BY-SA 2.0) via Flickr