Nitrogen: The Kokini Experiment Ground – Science Spectrum

The dilemma was only resolved when the first plants invaded the Earth more than 500 million years ago. They perform photosynthesis in their leaves, spatially separated from nitrogen fixation. Microorganisms predominated in the soil or on the roots of plants. There they were better protected from the high levels of oxygen in the air. In the communities, both plants and microbes benefited from the exchange of sugar and nitrogen compounds, the oxygen content in the atmosphere continued to rise to its current level of about 21 percent, and the evolution of new species accelerated.

Like a fern, the cold of the earth

This kind of symbiosis between CO₂Fixing plants and nitrogen-fixing microbes also control Earth’s climate. Researchers doubt that The azolla aquatic fern reproduced en masse about 50 million years agowhich live in symbiosis with nitrogen-fixing cyanobacteria of the genus Nostoc.

In a separate, low-salt marine area in the Arctic, they found ideal growing conditions where other plants lack nitrogen – and thanks to the nitrogen suppliers on board, they formed a huge carpet. For more than 800,000 years, its massive biomass has derived large amounts of carbon dioxide₂ From the air. The result: the climate became colder, and the previous warm period turned into an ice age, which officially continues to this day.

Human intervention in the current nitrogen cycle also has an impact on the climate – on the one hand cooling, and on the other, warming. Among other things, harmful aerosols of nitrogen oxides and ammonia contribute to temporary cooling. In addition, forests grow to a limited extent in Certain regions of the world are better because of human nitrogen input Thus binding more carbon dioxide₂

On the other hand, nitrous oxide (N₂s). Greenhouse gases are 271 times more powerful than carbon dioxide. It is created primarily through natural microbial processes in soil and water, including what is known as denitrification. In the process, microbes convert the nitrate back into molecular nitrogen in the atmosphere. This process helps complete the cycle between unreacted N₂ in the atmosphere and reactive nitrogen in the biosphere. Without denitrification and similar processes, more reactive nitrogen would likely accumulate on Earth. From a human perspective, denitrification reduces planetary eutrophication, but at the same time contributes to climate change.

Nitrogen trend is on the rise

Globally, the formation of nitrous oxide associated with microbes is primarily promoted by excess nitrogen fertilizers from agriculture. According to experts, this is also the determining factor for the climatic impact of excess nitrogen from human sources. “Because nitrous oxide emissions are related to food production and because nitrous oxide remains in the atmosphere for an average of 109 years, The bottom line is that the warming effect will prevail in the long run‘, explains Sönke Zaehle, Director of the Max Planck Institute for Biochemistry in Jena.