Nitrogen cycle and its importance

Nitrogen cycle and its importance

into the nitrogen cycle

The nitrogen cycle is one of the fundamental biogeochemical cycles that are essential to maintaining the ecosystem on Earth. Through this cycle, nitrogen is used and recycled. This is critical because nitrogen is one of the most important elements for the life and growth of all organisms.

The role of nitrogen

Nitrogen is an essential building block of life. It is needed to form amino acids, which are the basis for proteins. Nitrogen is also essential for the formation of nucleotides, which in turn are the building blocks of DNA and RNA, i.e. our genetic material. Nitrogen also plays a crucial role in the formation of chlorophyll, which is necessary for photosynthesis in plants.

Despite the enormous amount of nitrogen in the atmosphere - about 78% of it is nitrogen gas (N2) - most life cannot use this nitrogen directly. This is because the nitrogen atoms in N2 are strongly bonded together with a triple bond. Converting or “fixing” this atmospheric nitrogen into a usable form therefore requires a considerable amount of energy.

Nitrogen fixation

Nitrogen fixation is the process by which atmospheric nitrogen is converted into usable nitrogen compounds by specialized microorganisms - called nitrogen fixers. These microorganisms are usually bacteria that live either freely in the environment or in a symbiosis (a type of partnership) with plants.

Nitrogen fixation occurs by converting N2 into ammonia (NH3), which is extremely energy-intensive. This process is made possible by the enzyme nitrogenase, which has the ability to break the strong triple bond in N2. As soon as nitrogen is available in this form, plants can convert it into amino acids and use them to form proteins.

The nitrogen cycle in detail

The nitrogen cycle consists of several interwoven processes that occur continuously in nature. In addition to the nitrogen fixation already mentioned, these include nitrification, denitrification and ammonification.

Nitrification

Nitrification is a two-step process through which ammonia (NH3) is converted into nitrate (NO3-). This conversion is also carried out by bacteria. In the first step, ammonia is converted into nitrite (NO2-) and in the second step into nitrate. Nitrate is the preferred source of nitrogen for many plants.

Ammonification

Ammonification is the process by which dead biomass is converted into ammonia or ammonium by fungi and bacteria. This usually happens in the soil and is an important source of nitrogen available to plants.

Denitrification

Denitrification is the opposite of nitrification and nitrogen fixation. This is the process by which nitrate is converted back into atmospheric nitrogen by microorganisms under oxygen-poor conditions. This process can occur in oxygen-poor soils and waters and results in nitrogen being lost from ecosystems and released back into the atmosphere.

Human influence on the nitrogen cycle

Humans have significantly influenced the natural nitrogen cycle through numerous activities. In particular, the industrial extraction of nitrogen for the production of fertilizer and the burning of fossil fuels have led to previously bound nitrogen now entering the environment as reactive nitrogen.

Overfertilization

The production and excessive use of fertilizer releases a large portion of this reactive nitrogen into the environment. This can lead to over-fertilization and thus eutrophication of water bodies. This means that too many nutrients are released into the water, which greatly accelerates the growth of certain plants and algae. When these plants and algae die, their decay leads to a lack of oxygen in the water - with devastating consequences for marine life.

Ending

The nitrogen cycle is a biologically and chemically complex process that is crucial to life on Earth. Without the nitrogen cycle, the essential nitrogen compounds that all life forms require would not be available. Nevertheless, it is important that we coordinate our activities so as not to endanger the natural balance of this cycle. Our understanding of the nitrogen cycle and its importance is therefore crucial to maintaining the diversity of life on our planet.