What Organisms Run the Nitrogen Cycle

The nitrogen cycle is a crucial process for most forms of life on Earth. The nitrogen cycle describes the way nitrogen moves between the atmosphere, plants, soil, animals and bacteria -- and how those various elements contribute to the ecosystem. The primary organisms that drive this process are plants, animals and bacteria, although fungi also play a role.

  1. Plants

    • Nitrogen is one of the elements plants need to grow and produce seeds. Plants primarily take nitrogen from the soil. When a plant dies, it decomposes and the releases its nitrogen back into the soil via the bacteria and fungi which act as decomposers.

    Animals

    • Animals are not necessarily a required component of the nitrogen cycle -- in the sense that the nitrogen cycle could function in the absence of animals. When they are present, animals contribute to the nitrogen cycle by creating an extra link in the process between plants and the bacteria and fungi in the soil. When animals eat plants or other animals that eat plants, they absorb nitrogen. When those animals die or produce waste, the nitrogen in those animals is released back into the soil, via the same bacterial and fungal decomposers that work on plant matter.

    Fungi

    • Fungi are one of the two primary decomposers that work to break down plant and animal matter and waste to release its component parts, including nitrogen, back into the soil.

    Bacteria

    • The most significant organisms participating in the nitrogen cycle are the various types of bacteria that act as conduits for the multiple chemical reactions that take place during the cycle. In addition to working with fungi as decomposers, bacteria are active in breaking ammonium and nitrate apart to release nitrogen as well as helping free nitrogen molecules affix themselves to plant roots.