The Nitrogen Cycle

Nitrogen CycleNitrogen Cycle

Nitrogen is an Nitrogen is an elementelement. It is found in . It is found in living thingsliving things like like plantsplants and and animalsanimals. It is . It is also an important part of non-living things also an important part of non-living things like the air above and the dirt below.like the air above and the dirt below.

Atoms of NitrogenAtoms of Nitrogen

AtomsAtoms of nitrogen don't just stay in one place. of nitrogen don't just stay in one place. They move They move slowlyslowly between living things, dead between living things, dead things, the air, soil and water. These things, the air, soil and water. These movements are called the movements are called the nitrogen cyclenitrogen cycle. .

Nitrogen

Air

Water Soil

AtmosphereAtmosphere

Most of the nitrogen on Earth is in the Most of the nitrogen on Earth is in the atmosphereatmosphere. . Approximately 80% of the molecules in Earth's Approximately 80% of the molecules in Earth's atmosphere are made of two nitrogen atoms atmosphere are made of two nitrogen atoms bonded together (N2). bonded together (N2).

Which graph shows the percent Which graph shows the percent Nitrogen in the air?Nitrogen in the air?

a.

b.

c.

d.

Living Things Need NitrogenLiving Things Need Nitrogen

All plants and animals need All plants and animals need nitrogen to make amino nitrogen to make amino acids, proteins and DNA acids, proteins and DNA

The nitrogen in the atmosphere is not in a The nitrogen in the atmosphere is not in a form that plants and animals can use.form that plants and animals can use.

N2

N

N2N2

N2

N2

N2N2

N2

N2

N2

N2

N2

N2

N2

Nitrogen CycleNitrogen Cycle

The molecules of nitrogen in the atmosphere can The molecules of nitrogen in the atmosphere can become usable for living things when they are broken become usable for living things when they are broken apart during lightning strikes or fires, by certain types apart during lightning strikes or fires, by certain types of bacteria, or by bacteria associated with bean plants. of bacteria, or by bacteria associated with bean plants.

Plants and NitrogenPlants and Nitrogen

Most plants get Most plants get the nitrogen the nitrogen they need to they need to grow from the grow from the soils or water in soils or water in which they live.which they live.

Animals and NitrogenAnimals and Nitrogen

Animals get the nitrogen they need by eating plants Animals get the nitrogen they need by eating plants or other animals that contain nitrogen.or other animals that contain nitrogen.

Recycling NitrogenRecycling Nitrogen

When organisms die, their bodies decompose bringing When organisms die, their bodies decompose bringing the nitrogen into soil on land or into ocean water. the nitrogen into soil on land or into ocean water. Bacteria alter the nitrogen into a form that plants are Bacteria alter the nitrogen into a form that plants are able to use. able to use.

Nitrogen Returns to the AirNitrogen Returns to the Air

Other types of Other types of bacteria are able to bacteria are able to change nitrogen change nitrogen dissolved in dissolved in waterways into a waterways into a form that allows it form that allows it to return to the to return to the atmosphere. atmosphere.

People Affect the Nitrogen CyclePeople Affect the Nitrogen Cycle

Certain actions of humans are causing changes to the Certain actions of humans are causing changes to the nitrogen cycle and the amount of nitrogen that is nitrogen cycle and the amount of nitrogen that is stored in the land, water, air, and organisms. stored in the land, water, air, and organisms.

Farming and NitrogenFarming and Nitrogen

The use of nitrogen-rich fertilizers can add too much The use of nitrogen-rich fertilizers can add too much nitrogen in nearby waterways as the fertilizer washes nitrogen in nearby waterways as the fertilizer washes into streams and ponds. into streams and ponds.

Farming and NitrogenFarming and Nitrogen

The waste associated with livestock farming also adds large amounts The waste associated with livestock farming also adds large amounts of nitrogen into soil and water. The increased nitrate levels cause of nitrogen into soil and water. The increased nitrate levels cause plants to grow rapidly until they use up the supply and die. plants to grow rapidly until they use up the supply and die.

Farming and NitrogenFarming and Nitrogen

The number of plant-eating animals will increase when The number of plant-eating animals will increase when the plant supply increases and then the animals are the plant supply increases and then the animals are left without any food when the plants die.left without any food when the plants die.

Nitrogen Cycle VocabularyNitrogen Cycle Vocabulary

NitrogenNitrogen ElementElement AtmosphereAtmosphere Nitrogen CycleNitrogen Cycle DecomposeDecompose Organic matterOrganic matter FertilizerFertilizer Nitrogen cycleNitrogen cycle