Phosphorus Cycle

Phosphorus Cycle Definition

“Phosphorus cycle is a biogeochemical process that involves the movement of phosphorus through the lithosphere, hydrosphere and biosphere.”

What is Phosphorus Cycle?

Phosphorus is an important element for all living organisms. It forms a significant part of the structural framework of DNA and RNA. They are also an important component of ATP. Humans contain 80% of phosphorus in teeth and bones.

Phosphorus cycle is a very slow process. Various weather processes help to wash the phosphorus present in the rocks into the soil. Phosphorus is absorbed by the organic matter in the soil which is used for various biological processes.

Since phosphorus and phosphorus-containing compounds are present only on land, atmosphere plays no significant role in the phosphorus cycle.

Let us have a brief look at the phosphorus cycle, its steps and the human impact on phosphorus cycle.

Also Read: Carbon Cycle

Steps of Phosphorus Cycle

Following are the important steps of phosphorus cycle:

  1. Weathering
  2. Absorption by Plants
  3. Absorption by Animals
  4. Return to the Environment through Decomposition


Phosphorus is found in the rocks in abundance. That is why the phosphorus cycle starts in the earth’s crust. The phosphate salts are broken down from the rocks. These salts are washed away into the ground where they mix in the soil.

Absorption by Plants

The phosphate salts dissolved in water are absorbed by the plants. However, the amount of phosphorus present in the soil is very less. That is why the farmers apply phosphate fertilizers on agricultural land.

The aquatic plants absorb inorganic phosphorus from lower layers of water bodies. Since phosphate salts do not dissolve in water properly, they affect plant growth in aquatic ecosystems.

Absorption by Animals

The animals absorb phosphorus from the plants or by consuming plant-eating animals. The rate of the phosphorus cycle is faster in plants and animals when compared to rocks.

Return of Phosphorus Back to the Ecosystem

When the plants and animals die they are decomposed by microorganisms During this process, the organic form of phosphorus is converted into the inorganic form, which is recycled to soil and water.

Soil and water will end up in sediments and rocks, which will again release phosphorus by weathering. Thus, the phosphorus cycle starts over.

Also Read: Oxygen Cycle

Human Impact on Phosphorus Cycle

A number of human activities, use of fertilizers, artificial eutrophication, etc. has a great impact on the phosphorus cycle.

The phosphorus fertilizers increase the level of phosphorus in the soil. Overuse of these fertilizers reduces the fertility of the soil and is also harmful to the microorganisms present in the soil. When these are washed away into the nearby water bodies, they are hazardous to aquatic life.

During the shipping of food from farms to cities, the amount of phosphorus that is washed away in water causes eutrophication. This leads to the growth of algae. These form algal blooms or die, which is toxic to the aquatic ecosystem.

Also Read: Nitrogen Cycle

For more information on phosphorus cycle, its steps, and the impact of human activities on the phosphorus cycle, keep visiting BYJU’S website or download BYJU’S app for further reference.

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