Following are the three aspects of nutrient cycles:

(a) Nutrients input: Nutrients are supplied to the ecosystem via external resources for further use in biological processes.

(b) Nutrients output: Nutrients move out of the ecosystem, and some nutrients become inputs for another ecosystem.

(c) Internal nutrient cycling: Decomposers such as bacteria, fungi and actinomycetes continuously regenerate nutrients in the soil by the process of decomposition and store them in the forms that are available to plants.