Soil is a biogeochemically dynamic natural resource that supports all critical components that comprise terrestrial ecosystems. It has been called Earth’s living skin. On its June 11, 2004, cover, Science declared soils to be “the final frontier.” The growing awareness that soil provides a variety of ecosystem services beyond food production has attracted interest in soil from nonsoil scientists. Collectively, soil is known as the pedosphere, and the processes occurring within soil are inextricably linked to ecosystem services such as water quantity and quality, are important in the exchange of atmospheric gases, and are central to the biogeochemical cycles of the nutrients and carbon that sustain life (see Figure.
