Learn about The Nitrogen Cycle in this educational video from dizzo95.
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The Nitrogen Cycle Gaseous nitrogen forms about 80% of the air. Nitrogen from the atmosphere is fixed in the soil by bacteria, algae, and as a result of lightning which causes the formation of nitrogen oxides. Animal waste and dead animals and plants also contribute to the nitrogen in the soil. Soil nitrates are taken up by the roots of plants. The action of de-nitrifying bacteria releases nitrogen from the soil. Nitrogen is returned to the atmosphere and the cycle is repeated.