The Nitrogen Cycle

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The Nitrogen Cycle

Most nitrogen is found in the atmosphere. The nitrogen cycle is the

process by which atmospheric nitrogen is converted to ammonia or


Nitrogen is essential to all living systems. To become a part of an

organism, nitrogen must first be fixed or combined with oxygen or


Nitrogen is removed from the atmosphere by lightening and nitrogen

fixing bacteria. During electrical storms, large amounts of nitrogen

are oxidized and united with water to produce an acid which is carried

to the earth in rain producing nitrates. Nitrates are taken up by

plants and are converted to proteins.

Then the nitrogen passes through the food chain from plants to

herbivores to carnivores. When plants and animals eventually die, the

nitrogen compounds are broken down giving ammonia (ammonification).

Some of the ammonia is taken up by the plants; some is dissolved in

water or held in the soil where bacteria convert it to nitrates

(nitrification). Nitrates may be stored in humus or leached from the

soil and carried to lakes and streams. It may also be converted to

free nitrogen (denitrification) and returned to the atmosphere.

The nitrogen cycle is one of the most difficult of the cycles to

learn, simply because there are so many important forms of nitrogen,

and because organisms are responsible for each of the introversions.

Remember that nitrogen is critically important in forming the amino

portions of the amino acids which in turn form the proteins of your

body. Proteins make up skin and muscle, among other important

structural portions of your body, and all enzymes are proteins. Since

enzymes carry out almost all of the chemical reactions in your body,

it's easy to see how important nitrogen is. The chief reservoir of

nitrogen is the atmosphere, which is about 78% nitrogen... Nitrogen

gas in the atmosphere is composed of two nitrogen atoms bound to each

other. It is a pretty non-reactive gas; it takes a lot of energy to

get nitrogen gas to break up and combine with other things, such as

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