The way nitrogen exists in the air it is useless for living beings. Life needs reactive nitrogen! Reactive nitrogen develops through the high energy released by lightning during thunderstorms. Tiny protista developed their own mechanism 2.5 billion years ago. Some of these bacteria live in the ground, some live in the ocean, some inhabit the roots of certain plants. Those are called nudule bacteria. They provide the plants with activated nitrogen and receive protection and sugar in return. They receive protection and some sugar in exchange.

But the soil also contains other bacteria that do exactly the opposite: they transform reactive nitrogen back into atmospheric nitrogen - the cycle closes.


There are 243 species of clover. And many people believe that a four-leaf clover brings good luck. Clover belongs to the group of the so-called legumes, in whose roots the nodule bacteria reside. These species of bacteria live in symbiosis with the plants and bind the nitrogen in the air to the ground. In exchange for providing active nitrogen the bacteria get sugar and nourishment from the plants. As a result of this cooperation, clover contains an especially high amount of nitrogen. Therefore, cows love it since this nitrogen is essential for their production of milk. Where clover or other legumes are planted, the nitrogen content of the soil increases. Clover has been planted as a green fertilizer since the 17th century and increases harvest yields significantly.


There are plants which cover their nitrogen needs in a predatory style. They catch animals and digest them. These plant groups are designated as carnivores (meat-eaters). Such plants live mostly in nutrient-poor locations, for example on trees or in moors.


Apart from sugar as an energy-provider, butterflies also require amino acids as building and repair material for their muscles and tissues. For this reason, some species of butterflies love sweat, since it contains, besides salt, amino acids.
Butter, cream and fat also contain these amnino acids and they attract many species, hence the name “butterfly” (in German: Schmetterling – “Schmandling”). Many butterflies even find feces and dead animals attractive because they contain utilizable nitrogen. In the picture you can see the “little kingfisher” (Kleiner Eisvogel) that is suckling at the leg of a run-over toad.


Where muscles are growing, the body needs reactive nitrogen. Besides carbohydrates, vitamins, minerals and fats we need proteins, and indeed, not too few! Proteins are nitrogen compounds. One needs about 1 gram per kilogram of body weight per day. Proteins help with building body tissues, for example muscles, but also skin, hair and the brain. During athletic effort the body uses proteins as fuel, because they are easier to burn than fat. Besides urea, ammonia is also generated by some people as a waste product. It is secreted in sweat and causes the eye-stinging smell in fitness studios.