All living organisms need nutrients to live, grow, and reproduce. The continual process used in nature to obtain these nutrients is known as nutrient cycling. Generally speaking, nutrients continuously move from nonliving environments, through living organisms, and return to the nonliving environment.
The basic components of nutrients, elements such as carbon, nitrogen, iron, and oxygen, occur across the Earth in fixed quantities. Nature relies on a closely regulated balance of available nutrients for all life. Human activities have altered how these recycling systems function. Soil erosion, mining of resources, increased use of fertilizers, and the release of greenhouse gases can alter how nutrients flow through ecosystems.
Nutrient cycling occurs everywhere but at varying rates. Relationships between available biomass (living organisms), organic matter, and soils determine the rate at which nutrient cycling occurs within a specific ecosystem. As one example, nutrient cycling takes place at a faster rate in an agricultural field than it does in the bare, rocky alpine areas.