Nitrogen Cycle
Nitrogen Fixation
Nitrogen is the most abundant gas in the Earth's atmosphere (80%). Plants need nitrogen to grow and animals rely on plants to sustain life. Before nitrogen can be used by plants it must be fixed.
* Animals eat the plants, getting the nitrogen compounds passed on to them.
* When an organism dies, decomposers break down the tissues. As decomposition occurs, Nitrogen is given off as a gas and returned to the atmosphere. It is also returned through animal waste as fertilizer for new plants.
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How is nitrogen fixed?
* Lightning changes nitrogen gas in the atmosphere to nitrogen compounds that fall to the ground when it rains. * Nitrogen-fixing bacteria in the soil converts it to usable nitrogen compounds that plants can take in. |
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