What is the phosphorus cycle?
The phosphorus cycle is a biogeochemical cycle of nature, fundamental for life on the planet.
This cycle describes the movement of phosphorus through a series of phases within ecosystems.
Phosphorus is a chemical element on the periodic table, also identified with the symbol P. It is one of the scarcest and most important elements for the development of life.
Steps of the phosphorus cycle
Phosphorus is the scarcest element, hence its presence is fundamental for the growth of ecosystems, mainly aquatic ones.
It moves through terrestrial and aquatic ecosystems through a series of stages that we will describe below.
Phosphorus cycle on dry land
Phosphorus is taken in the form of phosphates by living beings, thanks to the process of weathering of rocks, since the rocks, when decomposing, release phosphates.
These phosphates pass through the soil to the vegetables, and from these to the animals that feed on the plants or other animals that have obtained them, and are returned to the soil through their outgrowths.
Already in the soil, decomposers act on animal excrement, producing phosphates again.
Likewise, phosphorous can also be released during the decomposition of corpses. From there, it passes to plant organisms in the form of organic phosphate.
Human beings are also responsible for the mobilization of phosphorous when they exploit rocks that contain phosphates.
Phosphorus cycle in the sea
A part of the phosphates reaches the sea transported by the terrestrial hydric currents. There they are taken by algae, fish, and seabirds; the latter, when excreted, produce guano, a type of fertilizer used by agriculture, rich in phosphate.
For its part, at the bottom of the sea, the remains of marine animals give rise to phosphate rocks. From the rocks, phosphorus is released into the soil, which in turn is used by plants and animals that feed on them.
Phosphorous does not take the form of volatile fluids (as it does with nitrogen, carbon and sulfur), which would allow it to pass from the sea to the atmosphere and from this to land.
Therefore, there are only two ways that phosphorus that has reached the sea returns to terrestrial ecosystems:
- By the action of seabirds, which return it to land through their excrement
- By lifting sediments from the ocean to dry land, a geological process that can take thousands of years.
Importance of the phosphorus cycle
Phosphorus is essential for life on the planet. It is considered the limiting nutrient, since, since it is the scarcest, it restricts growth in aquatic ecosystems.
Phosphorus is also found in nucleic acids (DNA), in cells, in bones, in teeth, in adenosine triphosphate (ATP) and its role is essential in photosynthesis.
Likewise, phosphorus is highly valued as a fertilizer in agriculture.