Describe the nitrogen cycle in nature.

Nitrogen is found in nature mainly in the form of atmospheric nitrogen. Plants synthesize proteins using nitrates from the soil, nitrates are formed from atmospheric nitrogen and ammonium salts present in the soil. The process of converting atmospheric nitrogen into a form digestible by plants and animals is called nitrogen binding.

Nitrogen binding can occur in two ways:

1. During a lightning strike, a certain amount of nitrogen and oxygen in the atmosphere combines with the formation of nitrogen oxides. They dissolve in water and form dilute nitric acid, which produces nitrates in the soil.
2. Atmospheric nitrogen is converted to ammonia, which then under the influence of bacteria turns into nitrates, this process is called nitrification. Such bacteria exist in the soil and in the nodules of the root system of nodule plants.

Atmospheric nitrogen is included in the cycle due to the activity of nitrogen-fixing bacteria and algae synthesizing nitrates suitable for use by plants. Part of the nitrogen is fixed as a result of the formation of oxides during electrical discharges in the atmosphere. Nitrogen compounds from the soil enter plants and are used to build proteins. After the death of living organisms, putrefactive bacteria decompose organic residues to ammonia. Chemosynthetic bacteria convert ammonia into nitrous, then into nitric acid. A certain amount of nitrogen, due to the activity of denitrifying bacteria, enters the air. Part of the nitrogen settles in deep-sea sediments and is switched off from the cycle for a long time. This loss is offset by the release of nitrogen into the air with volcanic gases.

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