Phosphorus Cycle

Geochemical Cycles continued

Objectives:

Describe the process of cycling phosphorus throughout environment.

Describe the role that fertilizer plays in both the nitrogen and phosphorus cycle.

What is phosphorus?

• An element [P] that forms molecules that make up the cells of living organisms

• Helps form bones and teeth in animals

How do organisms get P?

• Plants: get P from soil and water

• Animals: get P from eating the plants

Phosphorus cycle: movement of phosphorus from the environment to organisms and then back to the environment.

Phosphorus cycle

• Occurs very slowly

• Doesn’t occur in atmosphere because P is rarely a gas.

How does P get in soil and water? • 1st way: rocks erode and small amounts of P

dissolve in soil and water

• Plants absorb P in the soil through roots

• 2nd way: Excretion, death and decomposition

• 3rd way: washes off the land and into oceans– Phosphate salts-don’t dissolve in water-accumulate at

bottom

How can too much N or P effect an ecosystem?

• Fertilizers contain both Nitrogen and Phosphorus to stimulate faster plant growth

• What happens when there is an excessive amount of fertilizer used?

Overuse of fertilizer…• Excess fertilizer can enter

terrestrial and aquatic ecosystems through runoff

• Causes rapid growth of algae-Algal bloom

• Algal blooms can deplete ecosystems of nutrients like oxygen & kill organisms