Nitrogen Cycle Diagram
Similar to other biogeochemical cycles, nitrogen cycle is essential for regulating the concentration of nitrogen in the atmosphere. Read on to know more about the nitrogen cycle diagram given below which will help you in understanding the steps of nitrogen cycle.
If you take a look at the composition of air, you will find that approximately 78.084 percent of the atmospheric air is composed of nitrogen (represented as N2). This percentage concentration of nitrogen is maintained at a constant rate with the help of nitrogen cycle. In this cycle, nitrogen from the air is assimilated by living organisms (plants and animals) and returned to the atmosphere through various processes.
As we all are aware, nitrogen is a crucial element for the survival of all living beings. It is an integral component of the amino acids, proteins and genetic material (nucleic acids). In case of plants, nitrogen is also a major essential nutrient, present in the chlorophyll molecules, which are responsible for carrying out photosynthesis. This article discusses in brief regarding the successive nitrogen cycle steps with respect to the nitrogen cycle diagram.
The Processes involved in a Nitrogen Cycle
The atmosphere is the largest reservoir of nitrogen. Other nitrogen pools include soil and oceans. Nitrogen in the atmosphere (N2) cannot be used directly by plants. After conversion of nitrogen into usable compounds, plant assimilate them and transfer them to the animals. Nitrogen from the plants and animals are recycled back to the reservoirs through dead and decayed wastes. Refer to the simple diagram of the nitrogen cycle for better understanding of the processes and steps of nitrogen cycle.
Nitrogen Fixation
The chemical nature of nitrogen gas (with triple bonds), makes it unusable in its elemental form. Thus, atmospheric nitrogen is fixed as ammonium by means of lightening (natural fixation), microbes (biological fixation) and industrial fixation (under high pressure and temperature). Nitrogen is also converted into nitrogen oxides (NOx) by burning fossil fuels.
Nitrogen Assimilation
Soil nitrogen is contributed by application of plant manures and fertilizers. Nitrogen from the soil reservoir is absorbed by some species of plants in the chemical form of ammonium ions or nitrate ions. Animals, on the other hand, derived their nitrogen requirements by consumption of plants and other organic matter.
Nitrogen Mineralization
Also known a ammonification, organic form of nitrogen from the animal wastes, death and decayed living organisms is converted into inorganic form. In this nitrogen cycle step, decomposers (bacteria and fungi) act on the decayed organic matter containing nitrogen and convert it into ammonium (NH4+).
Nitrification
By the process of nitrification, the ammonium NH4+ is converted into nitrates NO3- that are assimilated by plants. First, ammonium is oxidized into nitrites (NO2-), which are further oxidized to form nitrates (NO3-). In this nitrogen cycle step, oxygen is essential for conversion of the nitrates by nitrifying bacteria (mostly soil bacteria).
Denitrification
Denitrification is the process, wherein nitrates are converted to the molecular nitrogen form (N2) in an anaerobic condition by the process of reduction. Heterotrophic bacteria and autotrophic denitrifiers are responsible for carrying out this nitrogen cycle step. This is the end of nitrogen cycle, in which the molecular nitrogen is returned to the atmosphere and soil.
This natural operation of nitrogen cycle is greatly influenced by human intervention. For example, supplementation of soil with fertilizers changes the nitrogen level in the soil, which overall disturbs the nitrogen cycle to some extent. You can always correlate nitrogen cycle diagram with the detailed explanation of each step given above for easy interpretation.
As we all are aware, nitrogen is a crucial element for the survival of all living beings. It is an integral component of the amino acids, proteins and genetic material (nucleic acids). In case of plants, nitrogen is also a major essential nutrient, present in the chlorophyll molecules, which are responsible for carrying out photosynthesis. This article discusses in brief regarding the successive nitrogen cycle steps with respect to the nitrogen cycle diagram.
The Processes involved in a Nitrogen Cycle
The atmosphere is the largest reservoir of nitrogen. Other nitrogen pools include soil and oceans. Nitrogen in the atmosphere (N2) cannot be used directly by plants. After conversion of nitrogen into usable compounds, plant assimilate them and transfer them to the animals. Nitrogen from the plants and animals are recycled back to the reservoirs through dead and decayed wastes. Refer to the simple diagram of the nitrogen cycle for better understanding of the processes and steps of nitrogen cycle.
Nitrogen Fixation
The chemical nature of nitrogen gas (with triple bonds), makes it unusable in its elemental form. Thus, atmospheric nitrogen is fixed as ammonium by means of lightening (natural fixation), microbes (biological fixation) and industrial fixation (under high pressure and temperature). Nitrogen is also converted into nitrogen oxides (NOx) by burning fossil fuels.
Nitrogen Assimilation
Soil nitrogen is contributed by application of plant manures and fertilizers. Nitrogen from the soil reservoir is absorbed by some species of plants in the chemical form of ammonium ions or nitrate ions. Animals, on the other hand, derived their nitrogen requirements by consumption of plants and other organic matter.
Nitrogen Mineralization
Also known a ammonification, organic form of nitrogen from the animal wastes, death and decayed living organisms is converted into inorganic form. In this nitrogen cycle step, decomposers (bacteria and fungi) act on the decayed organic matter containing nitrogen and convert it into ammonium (NH4+).
Nitrification
By the process of nitrification, the ammonium NH4+ is converted into nitrates NO3- that are assimilated by plants. First, ammonium is oxidized into nitrites (NO2-), which are further oxidized to form nitrates (NO3-). In this nitrogen cycle step, oxygen is essential for conversion of the nitrates by nitrifying bacteria (mostly soil bacteria).
Denitrification
Denitrification is the process, wherein nitrates are converted to the molecular nitrogen form (N2) in an anaerobic condition by the process of reduction. Heterotrophic bacteria and autotrophic denitrifiers are responsible for carrying out this nitrogen cycle step. This is the end of nitrogen cycle, in which the molecular nitrogen is returned to the atmosphere and soil.
This natural operation of nitrogen cycle is greatly influenced by human intervention. For example, supplementation of soil with fertilizers changes the nitrogen level in the soil, which overall disturbs the nitrogen cycle to some extent. You can always correlate nitrogen cycle diagram with the detailed explanation of each step given above for easy interpretation.
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