Nutrient cycles, also called biogeochemical cycles, are the recycling and reutilization of nutrient elements and compounds among cells, organisms, and ecosystems, including both their living and non-living components. These nutrient elements and compounds include carbon, nitrogen, oxygen, phosphorus, calcium, sulfur and water.
In the cycle, nutrients get absorbed, transferred, released back into the environment, and then eventually reabsorbed. Nutrients consumed by plants and animals are returned to the environment by excretions (e.g., manure and fallen leaves) and after death and decomposition.