Why is Nitrogen Important?

• Nitrogen is important to both _______________ and ________________. Nitrogen is used in making _____________, ______, and ______________.

How does nitrogen become part of living organisms?

• The atmosphere is made up of approximately __________________. This _______________________________ (_____) is not in a form that can be used by plants and animals.

Nitrogen Fixation and Nitrification: are the processes where _____________________________________ is converted into a ____________________ of nitrogen.

• Nitrogen fixation by lightning accounts for only _______ of fixation. The energy from ____________ causes nitrogen in the air to combine with oxygen forming ____________ (________)

• Nitrogen fixation by bacteria . Some bacteria (_____________________________) convert ____________________________ (______) into ____________________ (_______). Some ________________________ will break down plant and animal wastes to release ___________________ as well.

• Nitrifying bacteria convert _____________________ into a usable form for plants. These bacteria convert __________________ into _______________ (_________).

Denitrification

• Denitrifying bacteria convert_______________(______) back into ____________________________ (_______).

• This completes the nitrogen cycle

Human Impacts on the Nitrogen Cycle

• The use of nitrogen-rich fertilizers can cause nitrogen to leach into nearby waterways. The increased nitrate levels cause plants to grow rapidly until they use up the nitrate supply and then die. The number of herbivores will increase when the plant supply increases and then the herbivores are left without a food source when the plants die. This can affect the entire food chain. Farming also affects the nitrogen cycle. The waste from livestock farming releases a large amount of nitrogen into soil and water. In the same way, sewage waste adds nitrogen to soils and water.