The phosphorus cycle is a biogeochemical cycle that regulates the flow of phosphorus in various chemical forms across diverse earth systems, including the biosphere, hydrosphere, and lithosphere. The phosphorus cycle is made up of a number of chemical, biological, and microbiological activities that all occur throughout time. Phosphates quickly move through plants and animals, but they move slowly through the soil and ocean, making the phosphorus cycle one of the slowest biogeochemical cycles in the world. This article will explain to you the Phosphorus Cycle which will be helpful in preparing the Environment syllabus for the UPSC Civil service exam.

What is a Phosphorus Cycle?

• The sedimentary biogeochemical cycle that describes the transport of phosphorus through the lithosphere, hydrosphere, and biosphere is known as the phosphorus cycle.
• Phosphorus is a mineral that is abundant in phosphate rocks and enters the cycle through weathering and erosion.
• After millions of years, the crustal plates rise from the seafloor, exposing the phosphates.
• There are four primary processes that make up the global phosphorus cycle:
  • Tectonic uplift and surface weathering of phosphorus-bearing rocks such as apatite.
  • Phosphorus-bearing rocks are weathered by physical erosion, chemical weathering, and biological weathering to supply dissolved and particulate phosphorus to soils, lakes, and rivers.
  • Phosphorus is transported to numerous lakes and run-off to the ocean by riverine and subterranean transportation.
  • Particulate phosphorus sedimentation and burial in marine sediments (e.g., phosphorus related with organic matter and oxide/carbonate minerals) (this process can also occur in lakes and rivers).

Phosphorus Cycle

Steps Involved In Phosphorus Cycle

The phosphorus cycle is divided into four stages:

Weathering

• Phosphorus is found in abundance in the rocks, where it is combined with other nutrients to form one of the most important sources and reserves of the mineral.
• The phosphorus is then carried to the soil by rain or acid generated by certain microbes.
• Actinomycetes, pseudomonas, bacillus, aspergillus, penicillium, and other microbes are involved in the creation of phosphorus in the soil, which is present in plants and other animals.
• In addition, rainfall allows inorganic phosphorus to dissolve and be discharged into the oceans.
• Natural activities like volcanic eruptions and asteroid impacts aid in the extraction of phosphorus from the soil.

Absorption by Plants

• Phosphorus is a mineral present in soil that is absorbed by a variety of living species, including plants and microbes.
• As soil plants contain very little phosphorus, phosphorus-containing fertilizers should be used to boost plant development and soil fertility.
• Phosphorus is also absorbed by marine plants from the lower sections of aquatic species.
• However, certain phosphorus salts may not dissolve effectively in water, limiting the amount of phosphorus in the water.
• Plants can absorb phosphorus directly from the soil, or symbiotic bacteria can make phosphorus available to plants.

Absorption by Animals

• Producers use phosphorus absorbed by plants to make a variety of natural chemicals.
• Organic chemicals then move up the food chain as animals eat the plants, causing phosphorus to move from one species to the next.
• As it passes through animals, organic phosphorus undergoes modifications.
• Animals ingest phosphorus, which is used to make biomolecule-like nucleotides and connective tissue-like bones.

Decomposition

• The action of bacterial decomposition on dead plants and animals can recycle organic phosphorus into the lithosphere reservoir.
• The process of mineralization is used to change organic phosphorus species into their unique forms.
• This measure of phosphorus concentration in the ecosystem involves a variety of decomposing or saprophytic microorganisms, such as fungus and bacteria.
• During the rainy season or when soil evaporates into water bodies, phosphorus from the ground is transferred into the sea.
• The absorption of phosphorus in the sea continues, generating layers of organisms that lead to the production of rock, and the cycle continues.

Steps Involved In Phosphorus Cycle

Human Impact on the Phosphorus Cycle

• The phosphorus cycle is greatly influenced by a variety of human activities, such as fertilizer use, artificial eutrophication, and so on.
• Phosphorus fertilizers raise the phosphorus level in the soil.
• Overuse of these fertilizers decreases soil fertility and is detrimental to soil microbes.
• When these are washed into surrounding bodies of water, they pose a threat to aquatic life.
• The amount of phosphorus washed away in water during the transportation of food from farms to cities promotes eutrophication.
• Algae grows as a result of this. These either produce algal blooms or die, both of which are harmful to the aquatic ecosystem.

Importance of Phosphorus

• Phosphorus is an essential ingredient for all living organisms.
• It's found in nucleic acids like DNA and the phospholipids that make up the cell membrane.
• It, too, creates the supporting components of our bones, much like calcium phosphate.
• Phosphorus is typically a limited nutrient, meaning it is a small nutrient that inhibits growth in both freshwater and aquatic organisms.
• Many creatures require considerable amounts of phosphorus to develop their shells, bones, and teeth.
• A rock that contains phosphorus in the form of phosphates is referred to as a natural phosphorus reservoir. Small amounts of these phosphates dissolve in soil solution and are absorbed by plant roots when rocks are placed together.
• Plants provide phosphorus to herbivores and other animals. Trash and dead organisms decay as a result of bacterial-mediated phosphate release.
• There is no respiratory release of phosphorus into the atmosphere, unlike the carbon cycle.

Conclusion

As phosphorus is such a powerful element, it is usually found in conjunction with other elements. For the generation of soluble phosphate from unmixed substances, acid-producing bacteria are required. With phosphorus from the earth flowing into the sea and phosphorus in the sea, the purification of phosphorus in various reservoirs changes over time, resulting in phosphorus poisoning.