Transfer and Recycling of Nutrients

Nutrient Cycles Overview

Nutrient cycles are essential for life on Earth, continually transforming and redistributively elements such as carbon, nitrogen, and phosphorus.
Nutrient cycles are also known as biogeochemical cycles, highlighting their combination of biological, geological, and chemical aspects.

The Carbon Cycle

The carbon cycle describes the movement of carbon between living organisms and the environment.
Carbon is taken up by plants through photosynthesis, converted into carbohydrates and other forms of stored energy.
Animals consume plants and other animals, taking in this carbon and releasing it via respiration.
Decomposition of organic matter also releases carbon back into the atmosphere, some can store it long term as fossil fuels.
Human activities, particularly burning of fossil fuels and deforestation, can disrupt the natural balance of the carbon cycle, leading to increases in atmospheric carbon dioxide.

The Nitrogen Cycle

The nitrogen cycle outlines how nitrogen transforms and circulates within ecosystems.
Nitrogen is needed for the creation of proteins and nucleic acids, but atmospheric nitrogen cannot be directly used by most organisms.
Bacteria in the soil or associated with plant roots can fix nitrogen, converting it into ammonium or nitrate ions that plants can use.
Nitrogen is passed up the food chain when animals eat plants or other animals.
Bacteria and fungi in the soil can also break down dead organic matter, returning nitrogen to the soil as ammonia in a process called ammonification.
Other types of bacteria in the soil convert ammonia back to nitrates (nitrification) or return it to the atmosphere as nitrogen gas (denitrification).

The Phosphorus Cycle

The phosphorus cycle describes the movement of phosphorus through the environment.
Unlike carbon and nitrogen, phosphorus rarely exists in a gaseous form and is mainly cycling between rocks, water, and living organisms.
Phosphorus in rocks can be released slowly over time through weathering, becoming accessible to plants.
Animals obtain phosphorus by consuming plants or other animals, while decomposition returns phosphorus to the soil.
Phosphorus can be washed into rivers and eventually into oceans, where it may eventually create new sedimentary rocks, starting the cycle again.
Overuse of phosphorus in agriculture can disrupt natural cycles, leading to eutrophication of water bodies.

Recycling of Nutrients

Dead plants, animals, and waste products return nutrients back into the ecosystem, a process known as nutrient recycling.
Decomposers, including bacteria, fungi, and certain types of animals, play a crucial role in nutrient recycling by breaking down organic material.
Humans can assist in nutrient recycling through practices like composting, where organic waste is collected and decomposed to produce a rich soil amendment.