The key difference between nitrogen cycle and carbon cycle is that the nitrogen cycle describes the conversion of nitrogen into multiple chemical forms and the circulation between the atmosphere, terrestrial and marine ecosystems while the carbon cycle describes the movement of carbon and its multiple chemical forms between the atmosphere, oceans, biosphere and geosphere.
In an ecosystem, biochemical cycles are important in order to maintain the natural balance. Therefore, for many elements in an ecosystem, we can draw a cycle that summarizes the movement of the element through the different components of the ecosystem. In the cycle, elements are converted to complex molecules and later broken down in decomposition to simpler molecules. All cycles have a larger reservoir pool, which is abiotic usually. Nitrogen cycle, carbon cycle, phosphorus cycle and hydrological cycles are some of the important biochemical cycles in nature. Therefore, understanding the cycling of matter and maintaining effective cycling is important to save the environment from pollution.
CONTENTS
1. Overview and Key Difference
2. What is Nitrogen Cycle
3. What is Carbon Cycle
4. Similarities Between Nitrogen Cycle and Carbon Cycle
5. Side by Side Comparison – Nitrogen Cycle vs Carbon Cycle in Tabular Form
6. Summary
What is Nitrogen Cycle?
The nitrogen cycle is one of the most important geochemical cycles occurs in nature. It explains the circulation of different chemical forms of nitrogen through the atmosphere, terrestrial and marine ecosystems. The main nitrogen reservoir is the atmosphere. It has about 78% nitrogen gas, but it cannot be used by many organisms. So nitrogen should be converted to forms which can be used by plants. This process is known as nitrogen fixation.
Moreover, nitrogen fixation occurs in several ways. One method is biological fixation. Symbiotic bacteria like Rhizobium who live in the root nodules of the leguminous plants can fix atmospheric nitrogen. Also, there are some free-living bacteria like Azotobacter who can fix nitrogen. Another method of nitrogen fixation is the industrial nitrogen fixation. Through Heber process, nitrogen gas can be converted to ammonia which is used to make fertilizer and explosives. Other than this, naturally nitrogen transforms into nitrate when lightning strikes.
Figure 01: Nitrogen Cycle
Most plants depend on a supply of nitrate from the soil for their nitrogen requirement. Animals depend on plants directly or indirectly to get their nitrogen supply. When the plant and animals die, their nitrogen-containing compounds like proteins return into nitrates by saprotrophic bacteria and fungi. It happens through a series of oxidation reactions where protein converts into amino acids and afterwards amino acids convert to ammonia. Accordingly, the process is ‘nitrification’, and Nitrosomonas and Nitrobacter are two bacteria participating in this. Nitrification can be reversed by denitrification bacteria. They reduce nitrate in the soil to nitrogen gas and release into the atmosphere.
What is Carbon Cycle?
Carbon cycle is another geochemical cycle that depicts the conversion of different carbon chemical forms and the circulation them through the atmosphere, hydrosphere, biosphere and geosphere. The main carbon source for living organisms is carbon dioxide present in the atmosphere or dissolved in the surface waters. Photosynthetic plants, algae, and blue-green bacteria can convert carbon dioxide into carbonic compounds like carbohydrates. Carbohydrates become the building blocks for most other organic compounds they need, for their structures and functions.
Animals get carbon from the plants directly or indirectly. The carbon dioxide absorbed by the plants for photosynthesis is counterbalanced by the respiration of both plants and animals. Therefore, photosynthesis and respiration are the main mechanisms that cause to maintain the natural balance of the carbon cycle.
Figure 02: Carbon Cycle
Likewise, some of the fixed carbon dioxide through photosynthesis is stored in the bodies of living organisms. Afterwards, when they die, those carbon returns to the soil and water bodies. When these dead matters accumulate for a longer time in the soil, they convert into fossil fuel deposits. Carbon dioxide again returns into the atmosphere when people burn fossil fuel. In this way, the carbon compounds circulate through different spheres.
What are the Similarities Between Nitrogen Cycle and Carbon Cycle?
- Both the nitrogen cycle and the carbon cycle are important biogeochemical cycles.
- They illustrate how multiple chemical forms of each element circulate in the environment.
- Both cycles make these elements available for plants and animals.
- Atmospheric gases involve in both cycles.
- Not only that, both cycles start and end with atmospheric gas.
- And also compounds circulate through the soil in both cycles.
- Microorganisms fulfil a greater part of each cycle.
What is the Difference Between Nitrogen Cycle and Carbon Cycle?
Nitrogen cycle shows the cycling of different chemical forms of nitrogen in the environment whereas carbon cycle shows the cycling of carbon. Therefore, this is the key difference between nitrogen cycle and carbon cycle. The reservoir for nitrogen cycle is atmospheric nitrogen gas whereas for carbon it is carbon dioxide gas. Hence, it is also a difference between nitrogen cycle and carbon cycle. Also, nitrogen reservoir is much larger with comparison to a carbon reservoir.
Furthermore, one more difference between nitrogen cycle and carbon cycle is that a disturbance in the carbon cycle can be much more affected to humans and animals rapidly compared to a disturbance in the nitrogen cycle.
The below infographic on the difference between nitrogen cycle and carbon cycle shows more differences between both.
Summary – Nitrogen Cycle vs Carbon Cycle
Nitrogen cycle and the carbon cycle are two important nutrient cycles that occur in nature. Nitrogen cycle shows the circulation of various forms of nitrogen through nature. On the other hand, carbon cycle shows the circulation of various forms of carbon through nature. Thus, it is the key difference between nitrogen cycle and carbon cycle. Furthermore, nitrogen cycle occurs via nitrogen fixation, nitrification, nitrate assimilation, ammonification, denitrification while the carbon cycle occurs via photosynthesis, respiration, combustion, decomposition, etc. Also, the microorganisms involve in both cycles. In addition, nitrogen cycle starts with nitrogen fixation while the carbon cycle starts with photosynthesis. This is the summary of the difference between nitrogen cycle and carbon cycle.
Reference:
1. “The Nitrogen Cycle.” Khan Academy, Khan Academy. Available here
Image Courtesy:
1.”Nitrogen Cycle”By Johann Dréo, Burkhard (CC BY-SA 3.0) via Commons Wikimedia
2.”8263952221″ by AIRS, the Atmospheric Infrared Sounder (CC BY 2.0) via Flickr