The phosphorus cycle describes how phosphorus moves through the biosphere. Phosphorus is found in rocks and made biologically available through weathering of rocks and erosion of soil. Plants absorb phosphorus from the soil through their roots. Animals obtain phosphorus by eating plants or other animals. Phosphorus is returned to the soil through the decomposition of animal and plant waste or remains. Some phosphorus is buried deep underground through sedimentation and compaction, and through geologic uplift, this phosphorus can be returned to the surface to restart the cycle.

1. The Phosphorus Cycle

2. Phosphorus
• Phosphorus is an essential
nutrient for plant growth
• It does not exist as a gas, but is
mainly found in water, soil, and
sediment

3. Phosphorus Cycle
• Phosphorus is found naturally in
rocks
• Erosion by rainfall, weathering,
and runoff allows phosphorus to
be available to plants

4. Phosphorus Cycle
• Phosphorus is absorbed by roots in plants
• Animals eat the plants and it is passed up the food chain
• Phosphorus is returned to the soil by animal excretion and
decomposition

5. Phosphorus Cycle
• The phosphorus cycle is the process in which phosphorus
travels from its main source of rocks through ecosystems
to living organisms.

6. Phosphorus Cycle
• Phosphate Mining
Phosphate rock is found from 15-50ft below the ground in
a phosphate matrix. The matrix is comprised of phosphate
pebbles, sand, and clay. The sandy layer is removed by
electrically operated drag lines. Then high pressure water
guns turn the sandy layer into a mixture called slurry. The
slurry is then sent to a processing facility. After the
phosphate is collected it is use for common human
products, such as fertilizer.
• Ingestion
Animals eat plants and other organic materials containing
phosphates.

7. Phosphorus Cycle
• Excretion
Animals are a key element in the phosphorous cycle. They
consume plants containing phosphorous and then excrete.
The excrement is then turned into run-off in water and
decomposed in either the ground or nearby water bodies
by decomposers.
• Decomposition
Organic material breaks down, returning organic
phosphorus to the soil as inorganic phosphorus. The
inorganic phosphorus then enters the oceans through
runoff and erosion of rocks containing phosphorus.

8. Phosphorus Cycle
• Burial and Compaction
After decomposition organisms are compacted into
sediments to form rock. This then allows phosphorous to
become trapped inside rocks until geologic uplift occurs.
• Geologic Uplift
Uplift exposing underground rocks to the surface allows
phosphorus to be made available to under go the
phosphorus cycle.

9. Phosphorus Cycle
• Erosion
Rocks or soil are broken down, transporting phosphorus
across land or into water.
• Absorption
Plants absorb phosphates through their roots.

10. Effects of Human Activities
on the Phosphorous Cycle
• We remove large amounts of phosphate from the earth to make
fertilizers and detergents.
• We reduce phosphorous in tropical soils by clearing forests.
• We add excess phosphates to aquatic systems from runoff of animal
wastes and fertilizers.
• Humans mine phosphate rocks to make fertilizers and detergents
• Increasing erosion by removing vegetation
• Adding excess phosphorus to water from runoff from fertilizers and
livestock waste

11. IMPORTANCE OF PHOSPHOROUS CYCLE
• 1.Phosphorous is an essential nutrient of both plants
and animals.
• 2. It is part of DNA molecules which carry genetic
information.
• 3. It is part of ATP and ADP) that store chemical energy
for use by organisms in cellular respiration.
• 4. Forms phospholipids in cell membranes of plants and
animal cells.
• 5. Forms bones, teeth, and shells of animals as calcium
phosphate compounds.